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Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic
chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds. A molecule consisting of atoms of only one element is therefor ...
. It is a simple
alcohol upright=0.8, The bond angle between a hydroxyl group (-OH) and a chain of carbon atoms (R) In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to a saturated carbon atom. The term alcoh ...

alcohol
with the
chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parent ...
C2H6O. Its formula can be also written as −− or (an
ethyl group 500px, Ethyl group (highlighted blue) as part of a molecule, as the ethyl radical, and in the compounds ethanol, bromoethane, ethyl acetate">bromoethane.html" style="text-decoration: none;"class="mw-redirect" title="ethanol, bromoethane">ethano ...
linked to a
hydroxyl A hydroxy or hydroxyl group is a functional group with the chemical formula -OH and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy groups. Both ...
group), and is often
abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters, or words taken from the full version of the word or phrase; for example, the word ''abbrevia ...
as EtOH. Ethanol is a volatile,
flammable , Germany Image:Tu braunschweig 750 grad ofen.jpg, 250px, Germany, German test apparatus for determining combustibility at Technische Universität Braunschweig A combustible material is something that can combust (burn) in air. Flammable mater ...
, colorless liquid with a slight characteristic odor. It is a
psychoactive substance A psychoactive drug, psychopharmaceutical, or psychotropic drug is a chemical substance that changes nervous system function and results in alterations in perception, mood, consciousness, cognition, or behavior. These substances may be used medica ...
,
recreational drug Recreational drug use is the use of a psychoactive drug to induce an altered state of consciousness either for pleasure or for some other casual purpose or pastime by modifying the perceptions, feelings, and emotions of the user. When a psychoac ...
, and the active ingredient in
alcoholic drink An alcoholic drink is a drink that contains ethanol, a type of alcohol produced by fermentation of grains, fruits, or other sources of sugar. The consumption of alcohol plays an important social role in many cultures. Most countries have laws re ...
s. Ethanol is naturally produced by the
fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food prod ...
of
sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Table sugar, granulated sugar, or regular sugar, refers to sucrose, a disaccharide composed of glucose and fructose. Simple sugars, also called ...
s by
yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitute ...
s or via
petrochemical Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sour ...
processes such as
ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or H2C=CH2. It is a colorless flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene ...

ethylene
hydration. It has medical applications as an
antiseptic Antiseptics (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction. Antisept ...
and
disinfectant Disinfectants are chemical agents designed to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than sterilization, wh ...
. It is used as a
chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., witho ...
solvent A solvent (from the Latin ''solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for polar mo ...
and in the
synthesis Synthesis or synthesize may also refer to: Science Chemistry and biochemistry *Chemical synthesis, the execution of chemical reactions to form a more complex molecule from chemical precursors **Organic synthesis, the chemical synthesis of orga ...
of
organic compound , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organi ...
s. Ethanol is an alternative fuel source.


Etymology

''Ethanol'' is the
systematic nameA systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivial ...
defined by the International Union of Pure and Applied Chemistry (IUPAC) for a compound consisting of an
alkyl group In organic chemistry, an alkyl substituent is an alkane missing one hydrogen. The term alkyl is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of C''n''H2''n''+1. A cycloalkyl is derived ...
with two carbon
atom An atom is the smallest unit of ordinary matter that forms a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small, typically around 100 picometers across. They are so sma ...

atom
s (prefix “eth-”), having a single bond between them (infix “-an-”) and an attached
functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest o ...
−OH group (suffix “-ol”). The “eth-” prefix and the qualifier “ethyl” in “ethyl alcohol” originally come from the name “ethyl” assigned in 1834 to the group − by
Justus Liebig Justus Freiherr von Liebig (12 May 1803 – 18 April 1873) was a German scientist who made major contributions to agricultural and biological chemistry, and is considered one of the principal founders of organic chemistry. As a professor at the ...

Justus Liebig
. He coined the word from the
German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citizens of Germany, see also German nationality law * German language * Germanic peoples * Ger ...
name ''Aether'' of the compound −O− (commonly called “ether” in
English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national identity, an identity and ...

English
, more specifically called “
diethyl ether Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colorless, highly volatile, sweet-smelling ("Ethereal odour"), extremely flammable liquid. ...

diethyl ether
”). According to the ''
Oxford English Dictionary The ''Oxford English Dictionary'' (''OED'') is the principal historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a comprehensive res ...
'', ''Ethyl'' is a contraction of the Ancient Greek αἰθήρ (', “upper air”) and the Greek word ὕλη (', “substance”). The name ''ethanol'' was coined as a result of a resolution that was adopted at the International Conference on Chemical Nomenclature that was held in April 1892 in Geneva, Switzerland. The term “
alcohol upright=0.8, The bond angle between a hydroxyl group (-OH) and a chain of carbon atoms (R) In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to a saturated carbon atom. The term alcoh ...

alcohol
” now refers to a wider class of substances in chemistry nomenclature, but in common parlance it remains the name of ethanol. It is a medieval loan from
Arabic Arabic (, ' or , ' or ) is a Semitic language that first emerged in the 1st to 4th centuries CE.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Wats ...

Arabic
'' al-kuḥl'', a powdered ore of antimony used since antiquity as a cosmetic, and retained that meaning in
Middle Latin Medieval Latin was the form of Latin used in Roman Catholic Western Europe during the Middle Ages. In this region it served as the primary written language, though local languages were also written to varying degrees. Latin functioned as the mai ...
. The use of “alcohol” for ethanol (in full, “alcohol of wine”) is modern, first recorded 1753, while before the late 18th century the term "alcohol" generally referred to any sublimated substance.


Uses


Medical


Antiseptic

Ethanol is used in medical wipes and most commonly in antibacterial
hand sanitizer Hand sanitizer (also known as hand antiseptic, hand disinfectant, hand rub, or handrub) is a liquid, gel or foam generally used to kill the vast majority of viruses/bacteria/microorganisms on the hands. In most settings, hand washing with soap a ...
gels as an
antiseptic Antiseptics (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction. Antisept ...
for its bactericidal and anti-fungal effects. Ethanol kills
microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in older t ...
s by dissolving their membrane
lipid bilayer The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around all cells. The cell membranes of almost all organisms and many virus ...
and denaturing their
protein Proteins are large biomolecules or macromolecules that are comprised of one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
s, and is effective against most
bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres ...
and
fungi A fungus (plural: fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, which is separa ...
and
virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovs ...
es. However, it is ineffective against bacterial
spores )'', growing on a thinned hybrid black poplar ''(Populus x canadensis)''. The last stage of the moss lifecycle is shown, where the sporophytes are visible before dispersion of their spores: the calyptra (1) is still attached to the capsule (2). ...
, but that can be alleviated by using
hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid, slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic. Concentrated hydrogen peroxide, or "high-te ...
. A solution of 70% ethanol is more effective than pure ethanol because ethanol relies on water molecules for optimal antimicrobial activity. Absolute ethanol may inactivate microbes without destroying them because the alcohol is unable to fully permeate the microbe's membrane. Ethanol can also be used as a disinfectant and antiseptic because it causes cell dehydration by disrupting the osmotic balance across cell membrane, so water leaves the cell leading to cell death.


Antidote

Ethanol may be administered as an
antidote An antidote is a substance that can counteract a form of poisoning. The term ultimately derives from the Greek term φάρμακον ἀντίδοτον ''(pharmakon) antidoton'', "(medicine) given as a remedy". Antidotes for anticoagulants are so ...
to
ethylene glycol poisoning Ethylene glycol poisoning is poisoning caused by drinking ethylene glycol. Early symptoms include intoxication, vomiting and abdominal pain. Later symptoms may include a decreased level of consciousness, headache, and seizures. Long term outcomes ...
and
methanol poisoning Methanol toxicity is poisoning from methanol, characteristically via ingestion. Symptoms may include a decreased level of consciousness, poor or no coordination, vomiting, abdominal pain, and a specific smell on the breath. Decreased vision may sta ...
.


Medicinal solvent

Ethanol, often in high concentrations, is used to dissolve many water-insoluble medications and related compounds. Liquid preparations of
pain medications An analgesic or painkiller is any member of the group of drugs used to achieve analgesia, relief from pain. They are distinct from anesthetics, which temporarily affect, and in some instances completely eliminate, sensation. Analgesic choice is ...
, cough and cold medicines, and mouth washes, for example, may contain up to 25% ethanol and may need to be avoided in individuals with adverse reactions to ethanol such as
alcohol-induced respiratory reactionsAlcohol-induced respiratory reactions, also termed alcohol-induced asthma and alcohol-induced respiratory symptoms, are increasingly recognized as a pathological bronchoconstriction response to the consumption of alcohol that afflicts many people wit ...
. Ethanol is present mainly as an antimicrobial preservative in over 700 liquid preparations of medicine including
acetaminophen Paracetamol, also known as acetaminophen, is a medication used to treat fever and mild to moderate pain. At a standard dose, paracetamol only slightly decreases body temperature; it is inferior to ibuprofen in that respect, and the benefits of i ...
,
iron supplement Iron supplements, also known as iron salts and iron pills, are a number of iron formulations used to treat and prevent iron deficiency including iron deficiency anemia. For prevention they are only recommended in those with poor absorption, heavy ...
s,
ranitidine Ranitidine, sold under the brand name Zantac among others, is a medication that decreases stomach acid production. It is commonly used in treatment of peptic ulcer disease, gastroesophageal reflux disease, and Zollinger–Ellison syndrome. It c ...
,
furosemide Furosemide, sold under the brand name Lasix among others, is a loop diuretic medication used to treat fluid build-up due to heart failure, liver scarring, or kidney disease. It may also be used for the treatment of high blood pressure. It can be ...

furosemide
,
mannitol Mannitol is a type of sugar alcohol used as a sweetener and medication. It is used as a low calorie sweetener as it is poorly absorbed by the intestines. As a medication, it is used to decrease pressure in the eyes, as in glaucoma, and to lower ...
,
phenobarbital Phenobarbital, also known as phenobarbitone or phenobarb, or by the trade name Luminal, is a medication of the barbiturate type. It is recommended by the World Health Organization (WHO) for the treatment of certain types of epilepsy in developing ...
,
trimethoprim/sulfamethoxazole Trimethoprim/sulfamethoxazole (TMP/SMX), also known as co-trimoxazole among other names, is an antibiotic used to treat a variety of bacterial infections. It consists of one part trimethoprim to five parts sulfamethoxazole. It is used for urinary ...
and
over-the-counter Over-the-counter (OTC) drugs are medicines sold directly to a consumer without a requirement for a prescription from a healthcare professional, as opposed to prescription drugs, which may be supplied only to consumers possessing a valid prescrip ...
cough medicine Cold medicines are medications used by people with the common cold, cough, or related conditions. There is, however, no good evidence that cough medications reduce coughing. While they have been used by 10% of American children in any given w ...
.


Pharmacology

In mammals, ethanol is primarily metabolized in the liver and stomach by
alcohol dehydrogenase Alcohol dehydrogenases (ADH) () are a group of dehydrogenase enzymes that occur in many organisms and facilitate the interconversion between alcohols and aldehydes or ketones with the reduction of nicotinamide adenine dinucleotide (NAD+) to NADH. ...

alcohol dehydrogenase
(ADH) enzymes. These enzymes catalyze the
oxidation (mild reducing agent) are added to powdered potassium permanganate (strong oxidizing agent), a violent redox reaction accompanied by self-ignition starts. Redox (reduction–oxidation, pronunciation: or ) is a type of chemical reaction in whi ...

oxidation
of ethanol into
acetaldehyde Ethanal (common name acetaldehyde) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is one of the most important aldehydes, occurring widely in nature and being produced on a la ...
(ethanal): :CH3CH2OH + NAD+ → CH3CHO +
NADH Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism. Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an adeni ...
+ H+ When present in significant concentrations, this metabolism of ethanol is additionally aided by the
cytochrome P450 Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that function as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compounds ...
enzyme
CYP2E1 Cytochrome P450 2E1 (abbreviated CYP2E1, ) is a member of the cytochrome P450 mixed-function oxidase system, which is involved in the metabolism of xenobiotics in the body. This class of enzymes is divided up into a number of subcategories, includin ...
in humans, while trace amounts are also metabolized by
catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting the ...
. The resulting intermediate, acetaldehyde, is a known carcinogen, and poses significantly greater toxicity in humans than ethanol itself. Many of the symptoms typically associated with alcohol intoxication — as well as many of the health hazards typically associated with the long-term consumption of ethanol — can be attributed to acetaldehyde toxicity in humans. The subsequent oxidation of acetaldehyde into acetate is performed by
aldehyde dehydrogenase Aldehyde dehydrogenases () are a group of enzymes that catalyse the oxidation of aldehydes. They convert aldehydes (R–C(=O)) to carboxylic acids (R–C(=O)). The oxygen comes from a water molecule. To date, nineteen ALDH genes have been ...
(ALDH) enzymes. A mutation in the ALDH2 gene that encodes for an inactive or dysfunctional form of this enzyme affects roughly 50% of east Asian populations, contributing to the characteristic
alcohol flush reaction Alcohol flush reaction is a condition in which a person develops flushes or blotches associated with erythema on the face, neck, shoulders, and in some cases, the entire body after consuming alcoholic beverages. The reaction is the result of an acc ...
that can cause temporary reddening of the skin as well as a number of related, and often unpleasant, symptoms of acetaldehyde toxicity. This mutation is typically accompanied by another mutation in the
alcohol dehydrogenase Alcohol dehydrogenases (ADH) () are a group of dehydrogenase enzymes that occur in many organisms and facilitate the interconversion between alcohols and aldehydes or ketones with the reduction of nicotinamide adenine dinucleotide (NAD+) to NADH. ...

alcohol dehydrogenase
enzyme
ADH1B Alcohol dehydrogenase 1B is an enzyme that in humans is encoded by the ''ADH1B'' gene. The protein encoded by this gene is a member of the alcohol dehydrogenase family. Members of this enzyme family metabolize a wide variety of substrates, includin ...
in roughly 80% of east Asians, which improves the catalytic efficiency of converting ethanol into acetaldehyde.


Recreational

As a
central nervous system#REDIRECT Central nervous system#REDIRECT Central nervous system {{Redirect category shell, 1= {{R from other capitalisation ...
{{Redirect category shell, 1= {{R from other capitalisation ...

central nervous system
depressant A depressant, or central depressant, is a drug that lowers neurotransmission levels, which is to depress or reduce arousal or stimulation, in various areas of the brain. Depressants are also occasionally referred to as "downers" as they lower the l ...
, ethanol is one of the most commonly consumed
psychoactive drug A psychoactive drug, psychopharmaceutical, or psychotropic drug is a chemical substance that changes nervous system function and results in alterations in perception, mood, consciousness, cognition, or behavior. These substances may be used medica ...
s. Despite alcohol having psychoactive properties, it is readily available and legal for sale in most countries. However, there are laws regulating the sale, exportation/importation, taxation, manufacturing, consumption, and possession of alcoholic beverages. The most common regulation is prohibition for minors.


Fuel


Engine fuel

The largest single use of ethanol is as an engine
fuel A fuel is any material that can be made to react with other substances so that it releases energy as heat energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but has ...
and
fuel additive Petrol additives increase petrol's octane rating or act as corrosion inhibitors or lubricants, thus allowing the use of higher compression ratios for greater efficiency and power. Types of additives include metal deactivators, corrosion inhibitors, ...
.
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At 8.5 million square kilometers (3.2 million square miles) and with over 211 millio ...
in particular relies heavily upon the use of ethanol as an engine fuel, due in part to its role as one of the globe's leading producers of ethanol.
Gasoline Gasoline () or petrol () (see the etymology for naming differences) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines. It consists mostly of organic compoun ...
sold in Brazil contains at least 25%
anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achiev ...
ethanol. Hydrous ethanol (about 95% ethanol and 5% water) can be used as fuel in more than 90% of new gasoline fueled cars sold in the country. Brazilian ethanol is produced from
sugar cane Sugarcane or sugar cane refers to several species and hybrids of tall perennial grass in the genus ''Saccharum'', tribe Andropogoneae, that are used for sugar production. The plants are 2-6 m (6-20 ft) tall with stout, jointed, fibrous stalks ...

sugar cane
and noted for high
carbon sequestration Carbon sequestration or carbon dioxide removal (CDR) is the long-term removal, capture or sequestration of carbon dioxide from the atmosphere to slow or reverse atmospheric CO2 pollution and to mitigate or reverse global warming. Carbon dioxid ...
. The US and many other countries primarily use E10 (10% ethanol, sometimes known as gasohol) and E85 (85% ethanol) ethanol/gasoline mixtures. Ethanol has been used as
rocket fuel Rocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical r ...
and is currently in
lightweight Lightweight is a weight class in combat sports and rowing. Boxing Professional boxing The lightweight division is over 130 pounds (59 kilograms) and up to 135 pounds (61.2 kilograms) weight class in the sport of boxing. Notable lightweight boxer ...
rocket-powered racing aircraft. Australian law limits the use of pure ethanol from sugarcane waste to 10% in automobiles. Older cars (and vintage cars designed to use a slower burning fuel) should have the engine valves upgraded or replaced. According to an industry
advocacy group Advocacy groups, also known as special interest groups, use various forms of advocacy in order to influence public opinion and ultimately policy. They play an important role in the development of political and social systems. Motives for action ...
, ethanol as a fuel reduces harmful
tailpipe emissions Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline (petrol), diesel fuel, fuel oil, biodiesel blends, or coal. According to the type of engine, it is discharged into the atmosphere through an e ...
of carbon monoxide, particulate matter,
oxides of nitrogenNitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds: Charge-neutral *Nitric oxide (NO), nitrogen(II) oxide, or nitrogen monoxide * Nitrogen dioxide (NO2), nitrogen(IV) oxide *Nitrogen trioxide (NO3), ...
, and other ozone-forming pollutants.
Argonne National Laboratory Argonne National Laboratory is a science and engineering research national laboratory operated by UChicago Argonne LLC for the United States Department of Energy. The facility is located in Lemont, Illinois, outside of Chicago, and is the larges ...
analyzed greenhouse gas emissions of many different engine and fuel combinations, and found that
biodiesel Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat (tallow), soybean oil, or some other vegetable oil with an ...

biodiesel
/petrodiesel blend ( B20) showed a reduction of 8%, conventional
E85 Logo used in the United States for E85 fuel E85 is an abbreviation typically referring to an ethanol fuel blend of 85% ethanol fuel and 15% gasoline or other hydrocarbon by volume. In the United States, the exact ratio of fuel ethanol to hydrocar ...
ethanol blend a reduction of 17% and
cellulosic ethanolCellulosic ethanol is ethanol (ethyl alcohol) produced from cellulose (the stringy fiber of a plant) rather than from the plant's seeds or fruit. It is a biofuel produced from grasses, wood, algae, or other plants. The fibrous parts of the plants are ...
64%, compared with pure gasoline. Ethanol has a much greater research octane number (RON) than gasoline, meaning it is less prone to pre-ignition, allowing for better ignition advance which means more torque, and efficiency in addition to the lower carbon emissions. Ethanol combustion in an internal combustion engine yields many of the products of incomplete combustion produced by gasoline and significantly larger amounts of
formaldehyde Formaldehyde ( , also ) (systematic name methanal) is a naturally occurring organic compound with the formula CH2O (H−CHO). The pure compound is a pungent-smelling colourless gas that polymerises spontaneously into paraformaldehyde (refer to s ...
and related species such as acetaldehyde. This leads to a significantly larger photochemical reactivity and more
ground level ozones over the period 1979 to 2000. In June to August, photochemical ozone production causes very high concentrations over the East Coast of the US and China. Ozone (O3) is a trace gas of the troposphere, with an average concentration of 20–30 parts p ...
. These data have been assembled into The Clean Fuels Report comparison of fuel emissions and show that ethanol exhaust generates 2.14 times as much ozone as gasoline exhaust. When this is added into the custom ''Localized Pollution Index (LPI)'' of The Clean Fuels Report, the local pollution of ethanol (pollution that contributes to smog) is rated 1.7, where gasoline is 1.0 and higher numbers signify greater pollution. The
California Air Resources Board The California Air Resources Board (CARB or ARB) is the "clean air agency" in the government of California. Established in 1967 when then-governor Ronald Reagan signed the Mulford-Carrell Act, combining the Bureau of Air Sanitation and the Motor ...
formalized this issue in 2008 by recognizing control standards for formaldehydes as an emissions control group, much like the conventional NOx and Reactive Organic Gases (ROGs). World production of ethanol in 2006 was , with 69% of the world supply coming from Brazil and the United States. More than 20% of Brazilian cars are able to use 100% ethanol as fuel, which includes ethanol-only engines and
flex-fuel#REDIRECT Flexible-fuel vehicle {{R from other capitalisation ...
engines. Flex-fuel engines in Brazil are able to work with all ethanol, all gasoline or any mixture of both. In the US flex-fuel vehicles can run on 0% to 85% ethanol (15% gasoline) since higher ethanol blends are not yet allowed or efficient. Brazil supports this fleet of ethanol-burning automobiles with large national infrastructure that produces ethanol from domestically grown
sugar cane Sugarcane or sugar cane refers to several species and hybrids of tall perennial grass in the genus ''Saccharum'', tribe Andropogoneae, that are used for sugar production. The plants are 2-6 m (6-20 ft) tall with stout, jointed, fibrous stalks ...

sugar cane
.
Sugar cane Sugarcane or sugar cane refers to several species and hybrids of tall perennial grass in the genus ''Saccharum'', tribe Andropogoneae, that are used for sugar production. The plants are 2-6 m (6-20 ft) tall with stout, jointed, fibrous stalks ...

Sugar cane
not only has a greater concentration of sucrose than corn (by about 30%), but is also much easier to extract. The
bagasse Bagasse ( ) is the dry pulpy fibrous material that remains after crushing sugarcane or sorghum stalks to extract their juice. It is used as a biofuel for the production of heat, energy, and electricity, and in the manufacture of pulp and building m ...
generated by the process is not wasted, but is used in power plants to produce electricity. In the United States, the ethanol fuel industry is based largely on
corn Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The leaf ...
. According to the Renewable Fuels Association, as of 30 October 2007, 131 grain ethanol bio-refineries in the United States have the capacity to produce of ethanol per year. An additional 72 construction projects underway (in the U.S.) can add of new capacity in the next 18 months. Over time, it is believed that a material portion of the ≈ per year market for gasoline will begin to be replaced with fuel ethanol.
Sweet sorghum Sweet sorghum is any of the many varieties of the sorghum grass whose stalks have a high sugar content. Sweet sorghum thrives better under drier and warmer conditions than many other crops and is grown primarily for forage, silage, and syrup produc ...
is another potential source of ethanol, and is suitable for growing in dryland conditions. The
International Crops Research Institute for the Semi-Arid Tropics The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) is an international organization which conducts agricultural research for rural development, headquartered in Patancheru (Hyderabad, Telangana, India) with several reg ...
(
ICRISAT The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) is an international organization which conducts agricultural research for rural development, headquartered in Patancheru (Hyderabad, Telangana, India) with several reg ...
) is investigating the possibility of growing sorghum as a source of fuel, food, and animal feed in arid parts of
Asia Asia () is Earth's largest and most populous continent, located primarily in the Eastern and Northern Hemispheres. It shares the continental landmass of Eurasia with the continent of Europe and the continental landmass of Afro-Eurasia with b ...
and
Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area and 20% of it ...

Africa
.
Sweet sorghum Sweet sorghum is any of the many varieties of the sorghum grass whose stalks have a high sugar content. Sweet sorghum thrives better under drier and warmer conditions than many other crops and is grown primarily for forage, silage, and syrup produc ...
has one-third the water requirement of sugarcane over the same time period. It also requires about 22% less water than corn (also known as maize). The world's first sweet sorghum ethanol distillery began commercial production in 2007 in Andhra Pradesh, India. Ethanol's high
miscibility Miscibility () is the property of two substances to mix in all proportions (that is, to fully dissolve in each other at any concentration), forming a homogeneous mixture (a solution). The term is most often applied to liquids but also applies to s ...
with water makes it unsuitable for shipping through modern pipelines like liquid hydrocarbons. Mechanics have seen increased cases of damage to small engines (in particular, the
carburetor A carburetor (American English) or carburettor (British English) is a device that mixes air and fuel for internal combustion engines in an appropriate air–fuel ratio for combustion. The term is sometimes colloquially shortened to ''carb'' in ...

carburetor
) and attribute the damage to the increased water retention by ethanol in fuel.


Rocket fuel

Ethanol was commonly used as fuel in early
bipropellant The highest specific impulse chemical rockets use liquid propellants (liquid-propellant rockets). They can consist of a single chemical (a monopropellant) or a mix of two chemicals, called bipropellants. Bipropellants can further be divided into t ...
rocket A rocket (from it, rocchetto, , bobbin/spool) is a projectile that spacecraft, aircraft or other vehicle use to obtain thrust from a rocket engine. Rocket engine exhaust is formed entirely from propellant carried within the rocket. Rocket engines ...
(liquid-propelled) vehicles, in conjunction with an
oxidizer 125px, Dangerous goods label for oxidizing agents In chemistry, an oxidizing agent (oxidant, oxidizer), or oxidising agent (oxidiser) is a substance that has the ability to oxidize other substances — in other words to accept their electrons. ...
such as liquid oxygen. The German A-4 ballistic rocket, better known by its propaganda name
V-2 rocket The V-2 (german: Vergeltungswaffe 2, "Retribution Weapon 2"), with the technical name ''Aggregat 4'' (A4), was the world's first long-range guided ballistic missile. The missile, powered by a liquid-propellant rocket engine, was developed during ...
of
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a global war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all the great powers—forming two opposing milit ...
, credited with beginning the space age, used ethanol as the main constituent of ''B-Stoff''. Under such nomenclature, the ethanol was mixed with 25% water to reduce the combustion chamber temperature.Braeunig, Robert A
"Rocket Propellants."
(Website). Rocket & Space Technology, 2006. Retrieved 23 August 2007.
The V-2's design team helped develop U.S. rockets following World War II, including the ethanol-fueled Redstone rocket which launched the first U.S. satellite. Alcohols fell into general disuse as more energy-dense rocket fuels were developed.


Fuel cells

Commercial fuel cells operate on reformed natural gas,
hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. With a standard atomic weight of , hydrogen is the lightest element in the periodic table. Hydrogen is the most abundant chemical substance in the universe, constitut ...

hydrogen
or
methanol Methanol, also known as methyl alcohol amongst other names, is a chemical and the simplest alcohol, with the formula CH3OH (a methyl group linked to a hydroxyl group, often abbreviated MeOH). It is a light, volatile, colourless, flammable liquid ...
. Ethanol is an attractive alternative due to its wide availability, low cost, high purity and low toxicity. There is a wide range of fuel cell concepts that have entered trials including direct-ethanol fuel cells, auto-thermal reforming systems and thermally integrated systems. The majority of work is being conducted at a research level although there are a number of organizations at the beginning of the commercialization of ethanol fuel cells.


Household heating

Ethanol fireplaces can be used for home heating or for decoration.


Feedstock

Ethanol is an important industrial ingredient. It has widespread use as a precursor for other organic compounds such as ethyl
halide A halide is a binary phase, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a, e.g., fluoride, chloride, or theoretically tennesside c ...
s, ethyl
ester An ester is a chemical compound derived from an acid (organic or inorganic) in which at least one –OH hydroxyl group is replaced by an –O– alkyl (alkoxy) group, as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...

ester
s, diethyl ether, acetic acid, and ethyl
amine In organic chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such ...
s.


Solvent

Ethanol is considered a universal
solvent A solvent (from the Latin ''solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for polar mo ...
, as its
molecular A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. Molecules are distinguished ...
structure allows for the dissolving of both
polar Polar may refer to: Geography Polar may refer to: * Geographical pole, either of two fixed points on the surface of a rotating body or planet, at 90 degrees from the equator, based on the axis around which a body rotates *Polar climate, the clima ...
,
hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are not at ...
and
nonpolar#REDIRECT Chemical polarity {{R from other capitalisation ...
,
hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). (Strictly speaking, there is no repulsive force involved; it is an absence of attraction.) In contras ...
compounds. As ethanol also has a low
boiling point The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding enviro ...
, it is easy to remove from a solution that has been used to dissolve other compounds, making it a popular extracting agent for botanical oils.
Cannabis ''Cannabis'' () is a genus of flowering plants in the family Cannabaceae. The number of species within the genus is disputed. Three species may be recognized: ''Cannabis sativa'', ''Cannabis indica'', and ''Cannabis ruderalis''; ''C. ruderalis ...
oil extraction methods often use ethanol as an extraction
solvent A solvent (from the Latin ''solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for polar mo ...
, and also as a post-processing solvent to remove oils, waxes, and
chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in the mesosomes of cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll is ...
from solution in a process known as
winterization Winterization is the process of preparing something for winter. Humanitarian aid In emergency or disaster response situations, such as managed by the UNHCR, winterization activities include the distribution of items including blankets, quilts, ...
. Ethanol is found in
paint Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture to objects. Paint can be mad ...
s,
tincture A tincture is typically an extract of plant or animal material dissolved in ethanol (ethyl alcohol). Solvent concentrations of 25–60% are common, but may run as high as 90%.Groot Handboek Geneeskrachtige Planten by Geert Verhelst In chemistry, ...
s, markers, and personal care products such as mouthwashes, perfumes and deodorants. However,
polysaccharides , a beta-glucan polysaccharide Image:amylose 3Dprojection.svg">350px, Amylose is a linear polymer of glucose mainly linked with α(1→4) bonds. It can be made of several thousands of glucose units. It is one of the two components of starch, th ...
precipitate Precipitation is the process of conversion of a chemical substance into a solid from a solution by converting the substance into an insoluble form or a super-saturated solution. When the reaction occurs in a liquid solution, the solid formed is ...
from aqueous solution in the presence of alcohol, and ethanol precipitation is used for this reason in the purification of
DNA The structure of part of a DNA double helix Deoxyribonucleic acid (; DNA) is a molecule composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, g ...
and
RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid (DNA) are nucleic acids. Along with lipids, proteins, and carbohydrates ...

RNA
.


Low-temperature liquid

Because of its low freezing point -173.20 °F (−114.14 °C) and low toxicity, ethanol is sometimes used in laboratories (with
dry ice Dry ice is the solid form of carbon dioxide. It is used primarily as a cooling agent, but is also used in fog machines at theatres for dramatic effects. Its advantages include lower temperature than that of water ice and not leaving any residue (o ...
or other coolants) as a
cooling bath A cooling bath, in laboratory chemistry practice, is a liquid mixture which is used to maintain low temperatures, typically between 13 °C and −196 °C. These low temperatures are used to collect liquids after distillation, to remove s ...
to keep vessels at temperatures below the freezing point of water. For the same reason, it is also used as the active fluid in
alcohol thermometer The alcohol thermometer or spirit thermometer is an alternative to the mercury-in-glass thermometer and has similar functions. Unlike the mercury-in-glass thermometer, the contents of an alcohol thermometer are less toxic and will evaporate quickl ...

alcohol thermometer
s.


Chemistry


Chemical formula

Ethanol is a 2-carbon alcohol. Its
molecular formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parent ...
is CH3CH2OH. An alternative notation is CH3−CH2−OH, which indicates that the carbon of a
methyl group A methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms — CH3. In formulas, the group is often abbreviated Me. Such hydrocarbon groups occur in many organic compounds. It is a ver ...
(CH3−) is attached to the carbon of a
methylene group In organic chemistry, a methylene group is any part of a molecule that consists of two hydrogen atoms bound to a carbon atom, which is connected to the remainder of the molecule by two single bonds. The group may be represented as CH2<, where th ...
(−CH2–), which is attached to the oxygen of a hydroxyl group (−OH). It is a constitutional
isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulas — that is, same number of atoms of each element — but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Isomers ...
of
dimethyl ether Dimethyl ether (DME, also known as methoxymethane) is the organic compound with the formula CH3OCH3, simplified to C2H6O. The simplest ether, it is a colorless gas that is a useful precursor to other organic compounds and an aerosol propellant tha ...
. Ethanol is sometimes abbreviated as EtOH, using the common organic chemistry notation of representing the ethyl group (C2H5−) with Et.


Physical properties

Ethanol is a volatile, colorless liquid that has a slight odor. It burns with a smokeless blue flame that is not always visible in normal light. The physical properties of ethanol stem primarily from the presence of its
hydroxyl A hydroxy or hydroxyl group is a functional group with the chemical formula -OH and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy groups. Both ...
group and the shortness of its carbon chain. Ethanol's hydroxyl group is able to participate in hydrogen bonding, rendering it more viscous and less volatile than less polar organic compounds of similar molecular weight, such as
propane Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used as a ...
. Ethanol is slightly more refractive than water, having a
refractive index In optics, the refractive index (also known as refraction index or index of refraction) of a material is a dimensionless number that describes how fast light travels through the material. It is defined as :n = \frac, where ''c'' is the speed of l ...
of 1.36242 (at λ=589.3 nm and ). The
triple point In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium.. It is that temperature and pressure at which the sublimat ...
for ethanol is at a pressure of .


Solvent properties

Ethanol is a versatile solvent,
miscible Miscibility () is the property of two substances to mix in all proportions (that is, to fully dissolve in each other at any concentration), forming a homogeneous mixture (a solution). The term is most often applied to liquids but also applies to s ...
with water and with many organic solvents, including
acetic acid Acetic acid , systematically named ethanoic acid , is a colourless liquid organic compound with the chemical formula CH3COOH (also written as CH3CO2H, C2H4O2, or HC2H3O2). Vinegar is no less than 4% acetic acid by volume, making acetic acid ...

acetic acid
,
acetone Acetone, or propanone, is an organic compound with the formula (CH3)2CO. It is the simplest and smallest ketone. It is a colourless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscible with water and se ...
,
benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, b ...
,
carbon tetrachloride Carbon tetrachloride, also known by many other names (such as tetrachloromethane, also recognised by the IUPAC, carbon tet in the cleaning industry, Halon-104 in firefighting, and Refrigerant-10 in HVACR) is an organic compound with the chemical ...

carbon tetrachloride
,
chloroform Chloroform, or trichloromethane, is an organic compound with formula CHCl3. It is a colorless, strong-smelling, dense liquid that is produced on a large scale as a precursor to PTFE. It is also a precursor to various refrigerants. It is one of t ...
,
diethyl ether Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colorless, highly volatile, sweet-smelling ("Ethereal odour"), extremely flammable liquid. ...

diethyl ether
,
ethylene glycol Ethylene glycol (IUPAC name: ethane-1,2-diol) is an organic compound with the formula (CH2OH)2. It is mainly used for two purposes, as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odorless, color ...
,
glycerol Glycerol (; also called glycerine or glycerin) is a simple polyol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic, but deliberate consumption is not recommended unless used as an intentional suppository. ...
,
nitromethane Nitromethane, sometimes shortened to just Nitro, is an organic compound with the chemical formula . It is the simplest organic nitro compound. It is a polar liquid commonly used as a solvent in a variety of industrial applications such as in extr ...

nitromethane
,
pyridine Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one methine group (=CH−) replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liq ...

pyridine
, and
toluene Toluene (), also known as toluol (), is an aromatic hydrocarbon. It is a colorless, water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH₃) attached to ...
. Its main use as a solvent is in making tincture of iodine,cough syrups etc. It is also miscible with light aliphatic hydrocarbons, such as
pentane Pentane is an organic compound with the formula C5H12—that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the ''n ...
and
hexane Hexane () is an organic compound, a straight-chain alkane with six carbon atoms and has the molecular formula C6H14. Hexane is a significant constituent of gasoline. It is a colorless liquid, odorless when pure, and with boiling points approxim ...
, and with aliphatic chlorides such as
trichloroethaneTrichloroethane (CHCl) may refer to either of two isomeric chemical compounds: * 1,1,1-Trichloroethane (methyl chloroform, CClCH) * 1,1,2-Trichloroethane (vinyl trichloride, CHClCHCl) {{Chemistry index ...
and
tetrachloroethylene Tetrachloroethylene, also known under the systematic name tetrachloroethene, or perchloroethylene, and many other names (and abbreviations such as "perc" or "PERC", and "PCE"), is a chlorocarbon with the formula Cl2C=CCl2. It is a colorless liquid ...
. Ethanol's miscibility with water contrasts with the immiscibility of longer-chain alcohols (five or more carbon atoms), whose water miscibility decreases sharply as the number of carbons increases. The miscibility of ethanol with
alkane , the simplest alkane In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree st ...
s is limited to alkanes up to
undecane Undecane (also known as hendecane) is a liquid alkane hydrocarbon with the chemical formula CH3(CH2)9CH3. It is used as a mild sex attractant for various types of moths and cockroaches, and an alert signal for a variety of ants.Hölldobler B, Wilso ...
: mixtures with
dodecane Dodecane (also known as dihexyl, bihexyl, adakane 12, or duodecane) is a liquid alkane hydrocarbon with the chemical formula CH3(CH2)10CH3 (or C12H26), an oily liquid of the paraffin series. It has 355 isomers. It is used as a solvent, distillatio ...
and higher alkanes show a
miscibility gapA miscibility gap is a region in a phase diagram for a mixture of components where the mixture exists as two or more phases – any region of composition of mixtures where the constituents are not completely miscible. The IUPAC Gold Book defines '' ...
below a certain temperature (about 13 °C for dodecane). The miscibility gap tends to get wider with higher alkanes, and the temperature for complete miscibility increases. Ethanol-water mixtures have less volume than the sum of their individual components at the given fractions. Mixing equal volumes of ethanol and water results in only 1.92 volumes of mixture. Mixing ethanol and water is
exothermic In thermodynamics, the term exothermic process (exo- : "outside") describes a process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), ...
, with up to 777 J/mol being released at 298 K. Mixtures of ethanol and water form an
azeotrope An azeotrope () or a constant boiling point mixture is a mixture of two or more liquids whose proportions cannot be altered or changed by simple distillation.Moore, Walter J. ''Physical Chemistry'', 3rd e Prentice-Hall 1962, pp. 140–142 This ha ...
at about 89 mole-% ethanol and 11 mole-% water or a mixture of 95.6 percent ethanol by mass (or about 97%
alcohol by volume Alcohol by volume (abbreviated as ABV, abv, or alc/vol) is a standard measure of how much alcohol (ethanol) is contained in a given volume of an alcoholic beverage (expressed as a volume percent). It is defined as the number of millilitres (mL) of ...
) at normal pressure, which boils at 351K (78 °C). This azeotropic composition is strongly temperature- and pressure-dependent and vanishes at temperatures below 303 K. Hydrogen bonding causes pure ethanol to be
hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance' ...
to the extent that it readily absorbs water from the air. The polar nature of the hydroxyl group causes ethanol to dissolve many ionic compounds, notably
sodium Sodium is a chemical element with the symbol Na (from Latin "natrium") and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable isotop ...
and
potassium hydroxide Potassium hydroxide is an inorganic compound with the formula KOH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), this colorless solid is a prototypical strong base. It has many industrial and niche applications, most o ...

potassium hydroxide
s,
magnesium chloride#REDIRECT Magnesium chloride {{R from other capitalisation ...
,
calcium chloride Calcium chloride is an inorganic compound, a salt with the chemical formula CaCl2. It is a white coloured crystalline solid at room temperature, and it is highly soluble in water. It can be created by neutralising hydrochloric acid with calcium h ...
,
ammonium chloride Ammonium chloride is an inorganic compound with the formula NH4Cl and a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of the natural, mineralogical form of ammoniu ...

ammonium chloride
,
ammonium bromide Ammonium bromide, NH4Br, is the ammonium salt of hydrobromic acid. The chemical crystallizes in colorless prisms, possessing a saline taste; it sublimes on heating and is easily soluble in water. On exposure to air it gradually assumes a yellow col ...
, and
sodium bromide Sodium bromide is an inorganic compound with the formula NaBr. It is a high-melting white, crystalline solid that resembles sodium chloride. It is a widely used source of the bromide ion and has many applications.Michael J. Dagani, Henry J. Barda ...

sodium bromide
.
Sodium Sodium is a chemical element with the symbol Na (from Latin "natrium") and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable isotop ...
and
potassium chloride Potassium chloride (also known as Sylvite, KCl, or potassium salt) is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and it ...
s are slightly soluble in ethanol. Because the ethanol molecule also has a nonpolar end, it will also dissolve nonpolar substances, including most
essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the oil ...
s''Merck Index of Chemicals and Drugs'', 9th ed.; monographs 6575 through 6669 and numerous flavoring, coloring, and medicinal agents. The addition of even a few percent of ethanol to water sharply reduces the
surface tension Surface tension is the tendency of liquid surfaces to shrink into the minimum surface area possible. Surface tension is what allows heavier than water i.e., denser than water objects such as razor blades, insects (e.g. water striders), to floa ...

surface tension
of water. This property partially explains the " tears of wine" phenomenon. When wine is swirled in a glass, ethanol evaporates quickly from the thin film of wine on the wall of the glass. As the wine's ethanol content decreases, its surface tension increases and the thin film "beads up" and runs down the glass in channels rather than as a smooth sheet.


Flammability

An ethanol–water solution will catch fire if heated above a temperature called its
flash point The flash point of a volatile material is the lowest temperature at which its vapors ignite if given an ignition source. The flash point is sometimes confused with the autoignition temperature, the temperature that causes spontaneous ignition. Th ...
and an ignition source is then applied to it. For 20% alcohol by mass (about 25% by volume), this will occur at about . The flash point of pure ethanol is , but may be influenced very slightly by atmospheric composition such as pressure and humidity. Ethanol mixtures can ignite below average room temperature. Ethanol is considered a flammable liquid (Class 3 Hazardous Material) in concentrations above 2.35% by mass (3.0% by volume; 6
proof Proof may refer to: * Proof (truth), argument or sufficient evidence for the truth of a proposition * Alcohol proof, a measure of an alcoholic drink's strength Formal sciences * Formal proof, a construct in proof theory * Mathematical proof, a co ...
). : Dishes using burning alcohol for culinary effects are called
flambé :''Flambé is also a type of ceramic glaze.'' Flambé (, ; also spelled flambe) is a cooking procedure in which alcohol is added to a hot pan to create a burst of flames. The word means "flamed" in French. Flambéing is often associated with tabl ...
.


Natural occurrence

Ethanol is a byproduct of the
metabolic process Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main purposes of metabolism are: the conversion of food to energy to run cellular processes; the conve ...

metabolic process
of yeast. As such, ethanol will be present in any yeast habitat. Ethanol can commonly be found in overripe fruit. Ethanol produced by symbiotic yeast can be found in bertam palm blossoms. Although some animal species, such as the pentailed treeshrew, exhibit ethanol-seeking behaviors, most show no interest or avoidance of food sources containing ethanol. Ethanol is also produced during the germination of many plants as a result of natural
anaerobiosis An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenated environme ...
. Ethanol has been detected in
outer space Outer space is the expanse that exists beyond Earth and between celestial bodies. Outer space is not completely empty—it is a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium, as well as elec ...
, forming an icy coating around dust grains in
interstellar cloud An interstellar cloud is generally an accumulation of gas, plasma, and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the interstellar medium (ISM), the matter and radiation that exists in ...
s. Minute quantity amounts (average 196 ppb) of endogenous ethanol and acetaldehyde were found in the exhaled breath of healthy volunteers. Auto-brewery syndrome, also known as gut fermentation syndrome, is a rare medical condition in which intoxicating quantities of ethanol are produced through
endogenous Endogenous substances and processes are those that originate from within a system such as an organism, tissue, or cell. Endogenous substances and processes contrast with exogenous ones, such as drugs, which originate from outside of the organism. ...
fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food prod ...
within the
digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller component ...
.


Production

Ethanol is produced both as a
petrochemical Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sour ...
, through the hydration of ethylene and, via biological processes, by
fermenting Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food prod ...
sugars with
yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitute ...
. Which process is more economical depends on prevailing prices of petroleum and grain feed stocks. In the 1970s most industrial ethanol in the United States was made as a petrochemical, but in the 1980s the United States introduced subsidies for corn-based ethanol and today it is almost all made from that source.


Ethylene hydration

Ethanol for use as an industrial feedstock or solvent (sometimes referred to as synthetic ethanol) is made from
petrochemical Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sour ...
feed stocks, primarily by the
acid An acid is a molecule or ion capable of donating a proton (hydrogen ion H+) (a Brønsted–Lowry acid), or, alternatively, capable of forming a covalent bond with an electron pair (a Lewis acid). The first category of acids are the proton do ...
-
catalyzed that utilizes a low-temperature oxidation catalyst to convert carbon monoxide to less toxic carbon dioxide at room temperature. It can also remove formaldehyde from the air. Catalysis () is the process of increasing the reaction rate, rate of a ...
hydration of
ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or H2C=CH2. It is a colorless flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene ...

ethylene
: :

+ → The catalyst is most commonly
phosphoric acid Phosphoric acid, also known as orthophosphoric acid or phosphoric(V) acid, is a weak acid with the chemical formula . It is normally encountered as a colorless syrup of 85% concentration in water. The pure compound is a colorless solid. All ...
,
adsorbed of multilayer adsorption is a random distribution of molecules on the material surface. Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' o ...

adsorbed
onto a porous support such as
silica gel Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other liq ...

silica gel
or
diatomaceous earth Diatomaceous earth (, DE), diatomite or kieselgur/kieselguhr is a naturally occurring, soft, siliceous sedimentary rock that has been crumbled into a fine white to off-white powder. It has a particle size ranging from less than 3 μm to more than ...

diatomaceous earth
. This catalyst was first used for large-scale ethanol production by the
Shell Oil Company Shell Oil Company is the United States-based wholly owned subsidiary of Royal Dutch Shell, a transnational corporation "oil major" of Anglo-Dutch origins, which is amongst the largest oil companies in the world. Approximately 80,000 Shell emplo ...
in 1947. The reaction is carried out in the presence of high pressure steam at where a 5:3 ethylene to steam ratio is maintained. This process was used on an industrial scale by
Union Carbide Corporation Union Carbide Corporation is an American chemical corporation wholly owned (since February 6, 2001) by Dow Chemical Company. It currently employs more than 2,400 people. Union Carbide produces chemicals and polymers that undergo one or more furth ...
and others in the U.S., but now only
LyondellBasell LyondellBasell Industries N.V. () is a Dutch-domiciled multinational chemical company with American and British roots, incorporated in the Netherlands, with U.S. operations headquarters in Houston, Texas, and offices in London, UK. The company ...
uses it commercially. In an older process, first practiced on the industrial scale in 1930 by Union Carbide, but now almost entirely obsolete, ethylene was hydrated indirectly by reacting it with concentrated
sulfuric acid Sulfuric acid (American spelling) or sulphuric acid (Commonwealth spelling), also known as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with molecular formula H2SO4. It is a colorless, odorless and vis ...

sulfuric acid
to produce
ethyl sulfate Ethyl sulfate (IUPAC name: ethyl hydrogen sulfate), also known as sulfovinic acid, is an organic chemical compound used as an intermediate in the production of ethanol from ethylene. It is the ethyl ester of sulfuric acid. History This substance w ...
, which was
hydrolyzed Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis is ...

hydrolyzed
to yield ethanol and regenerate the sulfuric acid: : +

H : H +

→ H +


From CO2

Ethanol has been produced in the laboratory by converting carbon dioxide via biological and
electrochemical Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential, as a measurable and quantitative phenomenon, and identifiable chemical change, with either electrical potential as an outcome of a pa ...
reactions.


Fermentation

Ethanol in
alcoholic beverage An alcoholic drink is a drink that contains ethanol, a type of alcohol produced by fermentation of grains, fruits, or other sources of sugar. The consumption of alcohol plays an important social role in many cultures. Most countries have laws re ...
s and fuel is produced by fermentation. Certain species of
yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitute ...
(e.g., ''
Saccharomyces cerevisiae ''Saccharomyces cerevisiae'' () is a species of yeast (single-celled fungus microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been originally isolated from the skin of ...
'')
metabolize Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main purposes of metabolism are: the conversion of food to energy to run cellular processes; the conve ...

metabolize
sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Table sugar, granulated sugar, or regular sugar, refers to sucrose, a disaccharide composed of glucose and fructose. Simple sugars, also called ...
, producing ethanol and carbon dioxide. The chemical equations below summarize the conversion: : → 2 H + 2 CO2 :

+ → 4 H + 4 CO2 Fermentation is the process of culturing yeast under favorable thermal conditions to produce alcohol. This process is carried out at around . Toxicity of ethanol to yeast limits the ethanol concentration obtainable by brewing; higher concentrations, therefore, are obtained by
fortification A fortification is a military construction or building designed for the defense of territories in warfare, and is also used to establish rule in a region during peacetime. The term is derived from Latin ''fortis'' ("strong") and ''facere'' ( ...
or
distillation Distillation, or classical distillation, is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation. Dry distillation is the heating of solid materials to produce gaseous products ...
. The most ethanol-tolerant yeast strains can survive up to approximately 18% ethanol by volume. To produce ethanol from starchy materials such as
cereal A cereal is any grass cultivated (grown) for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. The term may also refer to the resulting grain itself (specifically "c ...
s, the
starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. It is the most common carbohydrate in human diets and is conta ...
must first be converted into sugars. In brewing
beer Beer is one of the oldest and most widely consumed alcoholic drinks in the world, and the third most popular drink overall after water and tea. Beer is brewed from cereal grains—most commonly from malted barley, though wheat, maize (corn), ...
, this has traditionally been accomplished by allowing the grain to germinate, or
malt Malt is germinated cereal grain that has been dried in a process known as "malting". The grain is made to germinate by soaking in water and is then halted from germinating further by drying with hot air. Malting grain develops the enzymes (α ...
, which produces the
enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules k ...
amylase An amylase () is an enzyme that catalyses the hydrolysis of starch (Latin ) into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large amounts of st ...
. When the malted grain is
mashed ''Mashed'' is a vehicular combat racing video game developed by Supersonic Software. The game was originally released in Europe for PlayStation 2, Xbox and Microsoft Windows in June 2004. An updated version with additional features, titled ''Mashe ...
, the amylase converts the remaining starches into sugars.


Cellulose

Sugars for
ethanol fermentation Ethanol fermentation, also called alcoholic fermentation, is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by-products. Because yeasts perform this co ...

ethanol fermentation
can be obtained from
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall of ...
. Deployment of this technology could turn a number of cellulose-containing agricultural by-products, such as
corncob A corncob, also called cob of corn or corn on the cob, is the central core of an ear of corn (also known as maize). It is the part of the ear on which the kernels grow. The ear is also considered a "cob" or "pole" but it is not fully a "pole" un ...
s,
straw Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number of di ...
, and
sawdust Sawdust (or wood shavings) is a by-product or waste product of woodworking operations such as sawing, sanding, milling, planing, and routing. It is composed of small chippings of wood. These operations can be performed by woodworking machinery, ...
, into renewable energy resources. Other agricultural residues such as sugar cane bagasse and
energy crop Energy crops are low-cost and low-maintenance crops grown solely for energy production by combustion (not for food). The crops are processed into solid, liquid or gaseous fuels, such as pellets, bioethanol or biogas. The fuels are burned to genera ...
s such as
switchgrass ''Panicum virgatum'', commonly known as switchgrass, is a perennial warm season bunchgrass native to North America, where it occurs naturally from 55°N latitude in Canada southwards into the United States and Mexico. Switchgrass is one of the d ...
may also be fermentable sugar sources.


Testing

upright=1.35, Near-infrared spectrum of liquid ethanol Breweries and
biofuel Biofuel is fuel that is produced through contemporary processes from biomass, rather than by the very slow geological processes involved in the formation of fossil fuels, such as oil. Since biomass technically can be used as a fuel directly (e.g ...
plants employ two methods for measuring ethanol concentration. Infrared ethanol sensors measure the vibrational frequency of dissolved ethanol using the C−H band at 2900 cm−1. This method uses a relatively inexpensive solid-state sensor that compares the C−H band with a reference band to calculate the ethanol content. The calculation makes use of the
Beer–Lambert law The Beer–Lambert law, also known as Beer's law, the Lambert–Beer law, or the Beer–Lambert–Bouguer law relates the attenuation of light to the properties of the material through which the light is travelling. The law is commonly applied to ...
. Alternatively, by measuring the density of the starting material and the density of the product, using a
hydrometer A hydrometer is an instrument used for measuring the relative density of liquids based on the concept of buoyancy. They are typically calibrated and graduated with one or more scales such as specific gravity. A hydrometer usually consists of a se ...
, the change in specific gravity during fermentation indicates the alcohol content. This inexpensive and indirect method has a long history in the beer brewing industry.


Purification


Distillation

Ethylene hydration or brewing produces an ethanol–water mixture. For most industrial and fuel uses, the ethanol must be purified.
Fractional distillation Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. It uses distillation to fr ...
at atmospheric pressure can concentrate ethanol to 95.6% by weight (89.5 mole%). This mixture is an
azeotrope An azeotrope () or a constant boiling point mixture is a mixture of two or more liquids whose proportions cannot be altered or changed by simple distillation.Moore, Walter J. ''Physical Chemistry'', 3rd e Prentice-Hall 1962, pp. 140–142 This ha ...
with a boiling point of , and ''cannot'' be further purified by distillation. Addition of an entraining agent, such as
benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, b ...
,
cyclohexane Cyclohexane is a cycloalkane with the molecular formula C6H12. Cyclohexane is non-polar. Cyclohexane is a colourless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used). Cyclo ...
, or
heptane Heptane or ''n''-heptane is the straight-chain alkane with the chemical formula H3C(CH2)5CH3 or C7H16, and is one of the main components of gasoline (petrol). When used as a test fuel component in anti-knock test engines, a 100% heptane fuel is the ...
, allows a new ternary azeotrope comprising the ethanol, water, and the entraining agent to be formed. This lower-boiling ternary azeotrope is removed preferentially, leading to water-free ethanol.


Molecular sieves and desiccants

Apart from distillation, ethanol may be dried by addition of a
desiccant A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant. Commonly encountered pre-packaged desiccants are solids that absorb water. Desiccants fo ...
, such as
molecular sieves A molecular sieve is a material with pores (very small holes) of uniform size. These pore diameters are similar in size to small molecules, and thus large molecules cannot enter or be adsorbed, while smaller molecules can. As a mixture of molecules ...
,
cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall of ...
, and
cornmeal Cornmeal is a meal (coarse flour) ground from dried corn. It is a common staple food, and is ground to coarse, medium, and fine consistencies, but not as fine as wheat flour.Herbst, Sharon, ''Food Lover's Companion'', Third Edition, Pg. 165, Barr ...
. The desiccants can be dried and reused.
Molecular sieve A molecular sieve is a material with pores (very small holes) of uniform size. These pore diameters are similar in size to small molecules, and thus large molecules cannot enter or be adsorbed, while smaller molecules can. As a mixture of molecules ...
s can be used to selectively absorb the water from the 95.6% ethanol solution. Synthetic
zeolite Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents and catalysts. The term ''zeolite'' was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that rapidly heating the mater ...
in pellet form can be used, as well as a variety of plant-derived absorbents, including
cornmeal Cornmeal is a meal (coarse flour) ground from dried corn. It is a common staple food, and is ground to coarse, medium, and fine consistencies, but not as fine as wheat flour.Herbst, Sharon, ''Food Lover's Companion'', Third Edition, Pg. 165, Barr ...
,
straw Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number of di ...
, and
sawdust Sawdust (or wood shavings) is a by-product or waste product of woodworking operations such as sawing, sanding, milling, planing, and routing. It is composed of small chippings of wood. These operations can be performed by woodworking machinery, ...
. The zeolite bed can be regenerated essentially an unlimited number of times by drying it with a blast of hot
carbon dioxide Carbon dioxide (chemical formula ) is a colorless gas with a density about 53% higher than that of dry air. Carbon dioxide molecules consist of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth's atmospher ...

carbon dioxide
. Cornmeal and other plant-derived absorbents cannot readily be regenerated, but where ethanol is made from grain, they are often available at low cost. Absolute ethanol produced this way has no residual benzene, and can be used to fortify port and sherry in traditional winery operations.


Membranes and reverse osmosis

Membranes can also be used to separate ethanol and water. Membrane-based separations are not subject to the limitations of the water-ethanol azeotrope because the separations are not based on vapor-liquid equilibria. Membranes are often used in the so-called hybrid membrane distillation process. This process uses a pre-concentration distillation column as the first separating step. The further separation is then accomplished with a membrane operated either in vapor permeation or pervaporation mode. Vapor permeation uses a vapor membrane feed and pervaporation uses a liquid membrane feed.


Other techniques

A variety of other techniques have been discussed, including the following: * Salting using
potassium carbonate Potassium carbonate is the inorganic compound with the formula K2CO3. It is a white salt, which is soluble in water. It is deliquescent, often appearing as a damp or wet solid. Potassium carbonate is mainly used in the production of soap and glass. ...
to exploit its insolubility will cause a phase separation with ethanol and water. This offers a very small potassium carbonate impurity to the alcohol that can be removed by distillation. This method is very useful in purification of ethanol by distillation, as ethanol forms an
azeotrope An azeotrope () or a constant boiling point mixture is a mixture of two or more liquids whose proportions cannot be altered or changed by simple distillation.Moore, Walter J. ''Physical Chemistry'', 3rd e Prentice-Hall 1962, pp. 140–142 This ha ...
with water. * Direct
electrochemical reduction of carbon dioxide The electrochemical reduction of carbon dioxide is the conversion of carbon dioxide to more reduced chemical species using electrical energy. It is one possible step in the broad scheme of carbon capture and utilization. The first examples of elect ...
to ethanol under ambient conditions using copper nanoparticles on a carbon nanospike film as the catalyst; * Extraction of ethanol from grain mash by supercritical carbon dioxide; * Pervaporation; * Fractional freezing is also used to concentrate fermented alcoholic solutions, such as traditionally made Applejack (beverage); * Pressure swing adsorption.


Grades of ethanol


Denatured alcohol

Pure ethanol and alcoholic beverages are heavily Sin tax, taxed as psychoactive drugs, but ethanol has many uses that do not involve its consumption. To relieve the tax burden on these uses, most jurisdictions waive the tax when an agent has been added to the ethanol to render it unfit to drink. These include bitterant, bittering agents such as denatonium benzoate and toxins such as
methanol Methanol, also known as methyl alcohol amongst other names, is a chemical and the simplest alcohol, with the formula CH3OH (a methyl group linked to a hydroxyl group, often abbreviated MeOH). It is a light, volatile, colourless, flammable liquid ...
, naphtha, and
pyridine Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one methine group (=CH−) replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liq ...

pyridine
. Products of this kind are called ''denatured alcohol.''


Absolute alcohol

Absolute or anhydrous alcohol refers to ethanol with a low water content. There are various grades with maximum water contents ranging from 1% to a few parts per million (ppm) levels. If azeotropic distillation is used to remove water, it will contain trace amounts of the material separation agent (e.g. benzene). Absolute alcohol is not intended for human consumption. Absolute ethanol is used as a solvent for laboratory and industrial applications, where water will react with other chemicals, and as fuel alcohol. Spectroscopic ethanol is an absolute ethanol with a low absorbance in ultraviolet and visible light, fit for use as a solvent in ultraviolet-visible spectroscopy. Pure ethanol is classed as 200 proof (alcohol), proof in the U.S., equivalent to 175 degrees proof in the UK system.


Rectified spirits

Rectified spirit, an azeotropic composition of 96% ethanol containing 4% water, is used instead of anhydrous ethanol for various purposes. Spirits of wine are about 94% ethanol (188 proof (alcohol), proof). The impurities are different from those in 95% (190 proof) laboratory ethanol.


Reactions

Ethanol is classified as a primary alcohol, meaning that the carbon that its hydroxyl group attaches to has at least two hydrogen atoms attached to it as well. Many ethanol reactions occur at its
hydroxyl A hydroxy or hydroxyl group is a functional group with the chemical formula -OH and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy groups. Both ...
group.


Ester formation

In the presence of acid catalysts, ethanol reacts with carboxylic acids to produce ethyl
ester An ester is a chemical compound derived from an acid (organic or inorganic) in which at least one –OH hydroxyl group is replaced by an –O– alkyl (alkoxy) group, as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...

ester
s and water: :carboxylic acid, RCOOH + HOCH2CH3 → ester, RCOOCH2CH3 + H2O This reaction, which is conducted on large scale industrially, requires the removal of the water from the reaction mixture as it is formed. Esters react in the presence of an acid or base to give back the alcohol and a salt. This reaction is known as saponification because it is used in the preparation of soap. Ethanol can also form esters with inorganic acids. Diethyl sulfate and triethyl phosphate are prepared by treating ethanol with sulfur trioxide and phosphorus pentoxide respectively. Diethyl sulfate is a useful ethylating agent in organic synthesis. Ethyl nitrite, prepared from the reaction of ethanol with sodium nitrite and sulfuric acid, was formerly used as a diuretic.


Dehydration

In the presence of acid catalysts, ethanol converts to
ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or H2C=CH2. It is a colorless flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene ...

ethylene
. Typically solid acids such as silica are used: :   CH3CH2OH → H2C=CH2 + H2O Ethylene produced in this way competes with ethylene from oil refineries and fracking. Under alternative conditions,
diethyl ether Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colorless, highly volatile, sweet-smelling ("Ethereal odour"), extremely flammable liquid. ...

diethyl ether
results: :2 CH3CH2OH → CH3CH2OCH2CH3 + H2O


Combustion

Complete combustion of ethanol forms
carbon dioxide Carbon dioxide (chemical formula ) is a colorless gas with a density about 53% higher than that of dry air. Carbon dioxide molecules consist of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth's atmospher ...

carbon dioxide
and water: :C2H5OH (l) + 3 O2 (g) → 2 CO2 (g) + 3 H2O (l); −ΔHc = 1371 kJ/mol = 29.8 kJ/g = 327 kcal/mol = 7.1 kcal/g :C2H5OH (l) + 3 O2 (g) → 2 CO2 (g) + 3 H2O (g); −ΔHc = 1236 kJ/mol = 26.8 kJ/g = 295.4 kcal/mol = 6.41 kcal/g Specific heat = 2.44 kJ/(kg·K)


Acid-base chemistry

Ethanol is a neutral molecule and the pH of a solution of ethanol in water is nearly 7.00. Ethanol can be quantitatively converted to its conjugate base, the Alkoxide, ethoxide ion (CH3CH2O), by reaction with an alkali metal such as sodium: :2 CH3CH2OH + 2 Na → 2 CH3CH2ONa + H2 or a very strong base such as sodium hydride: :CH3CH2OH + NaH → CH3CH2ONa + H2 The acidities of water and ethanol are nearly the same, as indicated by their Acid dissociation constant, pKa of 15.7 and 16 respectively. Thus, sodium ethoxide and sodium hydroxide exist in an equilibrium that is closely balanced: :CH3CH2OH + NaOH CH3CH2ONa + H2O


Halogenation

Ethanol is not used industrially as a precursor to ethyl halides, but the reactions are illustrative. Ethanol reacts with hydrogen halides to produce haloalkane, ethyl halides such as ethyl chloride and ethyl bromide via an SN2 reaction, SN2 reaction: :CH3CH2OH + hydrogen chloride, HCl → CH3CH2Cl + H2O These reactions require a catalyst such as zinc chloride. HBr requires refluxing with a
sulfuric acid Sulfuric acid (American spelling) or sulphuric acid (Commonwealth spelling), also known as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with molecular formula H2SO4. It is a colorless, odorless and vis ...

sulfuric acid
catalyst. Ethyl halides can, in principle, also be produced by treating ethanol with more specialized Halogenation, halogenating agents, such as thionyl chloride or phosphorus tribromide. :CH3CH2OH + SOCl2 → CH3CH2Cl + SO2 + HCl Upon treatment with halogens in the presence of base, ethanol gives the corresponding haloform (CHX3, where X = Cl, Br, I). This conversion is called the haloform reaction. " An intermediate in the reaction with chlorine is the aldehyde called chloral, which forms chloral hydrate upon reaction with water: :4 Cl2 + CH3CH2OH → CCl3CHO + 5 HCl :CCl3CHO + H2O → CCl3C(OH)2H


Oxidation

Ethanol can be oxidized to
acetaldehyde Ethanal (common name acetaldehyde) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is one of the most important aldehydes, occurring widely in nature and being produced on a la ...
and further oxidized to
acetic acid Acetic acid , systematically named ethanoic acid , is a colourless liquid organic compound with the chemical formula CH3COOH (also written as CH3CO2H, C2H4O2, or HC2H3O2). Vinegar is no less than 4% acetic acid by volume, making acetic acid ...

acetic acid
, depending on the reagents and conditions. This oxidation is of no importance industrially, but in the human body, these oxidation reactions are catalyzed by the
enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules k ...
liver alcohol dehydrogenase. The oxidation product of ethanol, acetic acid, is a nutrient for humans, being a precursor to acetyl CoA, where the acetyl group can be spent as energy or used for biosynthesis.


Metabolism

Ethanol is similar to macronutrients such as proteins, fats, and carbohydrates in that it provides calories. When consumed and metabolized, it contributes 7 calories per gram via ethanol metabolism.


Safety

Pure ethanol will irritate the skin and eyes. Nausea, vomiting, and intoxication are symptoms of ingestion. Long-term use by ingestion can result in serious liver damage. Atmospheric concentrations above one in a thousand are above the European Union occupational exposure limits.


History

The ethanol fermentation, fermentation of sugar into ethanol is one of the earliest biotechnology, biotechnologies employed by humans. Ethanol has historically been identified variously as spirit of wine or ardent spirits, and as aqua vitae or aqua vita. The intoxicating effects of its consumption have been known since ancient times. Ethanol has been used by humans since prehistory as the intoxicating ingredient of
alcoholic beverage An alcoholic drink is a drink that contains ethanol, a type of alcohol produced by fermentation of grains, fruits, or other sources of sugar. The consumption of alcohol plays an important social role in many cultures. Most countries have laws re ...
s. Dried residue on 9,000-year-old pottery found in China suggests that Neolithic people consumed alcoholic beverages. The inflammable nature of the exhalations of wine was already known to ancient natural philosophers such as Aristotle (384–322 BCE), Theophrastus (c. 371–287 BCE), and Pliny the Elder (23/24–79 CE). However, this did not immediately lead to the isolation of ethanol, even despite the development of more advanced distillation techniques in second- and third-century Roman Egypt. An important recognition, first found in one of the writings attributed to Jabir ibn Hayyan, Jābir ibn Ḥayyān (ninth century CE), was that by Salt-effect distillation, adding salt to boiling wine, which increases the wine's relative volatility, the flammability of the resulting vapors may be enhanced. The distillation of wine is attested in Arabic works attributed to Al-Kindi, al-Kindī (c. 801–873 CE) and to Al-Farabi, al-Fārābī (c. 872–950), and in the 28th book of Al-Zahrawi, al-Zahrāwī's (Latin: Abulcasis, 936–1013) ''Kitāb al-Taṣrīf'' (later translated into Latin as ''Liber servatoris''). In the twelfth century, recipes for the production of ''aqua ardens'' ("burning water", i.e., ethanol) by distilling wine with salt started to appear in a number of Latin works, and by the end of the thirteenth century it had become a widely known substance among Western European chemists. Its medicinal properties were studied by Arnald of Villanova (1240–1311 CE) and John of Rupescissa (c. 1310–1366), the latter of whom regarded it as a life-preserving substance able to prevent all diseases (the ''aqua vitae'' or "water of life", also called by John the ''Aether (classical element), quintessence'' of wine). In China, archaeological evidence indicates that the true distillation of alcohol began during the 12th century Jin dynasty (1115–1234), Jin or Southern Song dynasty, Southern Song dynasties. A still has been found at an archaeological site in Qinglong, Hebei, dating to the 12th century. In India, the true distillation of alcohol was introduced from the Middle East, and was in wide use in the Delhi Sultanate by the 14th century. In 1796, German-Russian chemist Johann Tobias Lowitz obtained pure ethanol by mixing partially purified ethanol (the alcohol-water azeotrope) with an excess of anhydrous alkali and then distilling the mixture over low heat. French chemist Antoine Lavoisier described ethanol as a compound of carbon, hydrogen, and oxygen, and in 1807 Nicolas-Théodore de Saussure determined ethanol's chemical formula. Fifty years later, Archibald Scott Couper published the structural formula of ethanol. It was one of the first structural formulas determined. Ethanol was first prepared synthetically in 1825 by Michael Faraday. He found that sulfuric acid could absorb large volumes of coal gas. He gave the resulting solution to Henry Hennell, a British chemist, who found in 1826 that it contained "sulphovinic acid" (Ethyl sulfate, ethyl hydrogen sulfate). In 1828, Hennell and the French chemist Georges-Simon Serullas independently discovered that sulphovinic acid could be decomposed into ethanol. On page 368, Hennell produces ethanol from "sulfovinic acid" (Ethyl sulfate, ethyl hydrogen sulfate). Thus, in 1825 Faraday had unwittingly discovered that ethanol could be produced from
ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or H2C=CH2. It is a colorless flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene ...

ethylene
(a component of coal gas) by Acid catalysis, acid-catalyzed hydration, a process similar to current industrial ethanol synthesis.In 1855, the French chemist Marcellin Berthelot confirmed Faraday's discovery by preparing ethanol from pure ethylene. (Note: The chemical formulas in Berthelot's paper are wrong because chemists at that time used the wrong atomic masses for the elements; e.g., carbon (6 instead of 12), oxygen (8 instead of 16), etc.) Ethanol was used as lamp fuel in the United States as early as 1840, but a tax levied on industrial alcohol during the American Civil War, Civil War made this use uneconomical. The tax was repealed in 1906. Use as an automotive fuel dates back to 1908, with the Ford Model T able to run on petrol (gasoline) or ethanol. It fuels some spirit lamps. Ethanol intended for industrial use is often produced from
ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or H2C=CH2. It is a colorless flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene ...

ethylene
. Ethanol has widespread use as a solvent of substances intended for human contact or consumption, including scents, flavorings, colorings, and medicines. In chemistry, it is both a solvent and a feedstock for the synthesis of other products. It has a long history as a fuel for heat and light, and more recently as a fuel for internal combustion engines.


See also

* 1-Propanol * Butanol fuel * Cellulosic ethanol commercialization * Ethanol-induced non-lamellar phases in phospholipids * Vinyl alcohol, Ethenol * Ethynol * Isopropyl alcohol * Methanol * Rubbing alcohol * tert-Butyl alcohol * Timeline of alcohol fuel


References


Further reading

* . * * *


External links


Alcohol (Ethanol)
at ''The Periodic Table of Videos'' (University of Nottingham)
International Labour Organization
ethanol safety information



* [http://webbook.nist.gov/cgi/cbook.cgi?Name=ethanol&Units=SI National Institute of Standards and Technology] chemical data on ethanol
Chicago Board of Trade
news and market data on ethanol futures * Calculation o
vapor pressureliquid densitydynamic liquid viscositysurface tension
of ethanol
Ethanol History
A look into the history of ethanol


Industrial ethanol production process flow diagram using ethylene and sulphuric acid
{{Authority control Ethanol, Alcohol solvents Alkanols Anatomical preservation Commodity chemicals Disinfectants Hepatotoxins Household chemicals Human metabolites IARC Group 1 carcinogens Oxygenates Primary alcohols Rocket fuels Teratogens Alcohols