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In
chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during a with other . ...

chemistry
, alcohol is an
organic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during ...
that carries at least one
hydroxyl A hydroxy or hydroxyl group is a functional group with the chemical formula -OH and composed of one oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the ...

hydroxyl
functional group In organic chemistry, a functional group is a substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions re ...
(−OH) bound to a saturated
carbon Carbon (from la, carbo "coal") is a with the C and 6. It is lic and —making four s available to form s. It belongs to group 14 of the periodic table. Carbon makes up only about 0.025 percent of Earth's crust. Three occur naturally, ...

carbon
atom. The term alcohol originally referred to the primary alcohol
ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ (anatomy), ...

ethanol
(ethyl alcohol), which is used as a drug and is the main alcohol present in
alcoholic drink An alcoholic drink is a drink A drink (or beverage) is a liquid A liquid is a nearly incompressible fluid In physics, a fluid is a substance that continually Deformation (mechanics), deforms (flows) under an applied shear stress, o ...
s. An important class of alcohols, of which
methanol Methanol, also known as methyl alcohol, amongst other names, is 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 se ...

methanol
and
ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ (anatomy), ...

ethanol
are the simplest members, includes all compounds for which the general formula is CHOH. Simple monoalcohols that are the subject of this article include primary (RCHOH), secondary (RCHOH) and tertiary (RCOH) alcohols. The suffix ''-ol'' appears in the IUPAC chemical name of all substances where the hydroxyl group is the functional group with the highest priority. When a higher priority group is present in the compound, the prefix ''hydroxy-'' is used in its
IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the authoritative power over chemist ...
name. The suffix ''-ol'' in non-IUPAC names (such as
paracetamol 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 ...
or
cholesterol Cholesterol is any of a class of certain organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ (anatomy), organ Chemistry * Organic matter, matter that has co ...

cholesterol
) also typically indicates that the substance is an alcohol. However, many substances that contain hydroxyl functional groups (particularly sugars, such as
glucose Glucose is a simple with the . Glucose is the most abundant , a subcategory of s. Glucose is mainly made by and most during from water and carbon dioxide, using energy from sunlight, where it is used to make in s, the most abundant carbohydr ...

glucose
and
sucrose Sucrose is a type of sugar Sugar is the generic name for , soluble s, many of which are used in food. Simple sugars, also called s, include , , and . Compound sugars, also called s or double sugars, are molecules made of two monosacchari ...

sucrose
) have names which include neither the suffix ''-ol'', nor the prefix ''hydroxy-''.


History

The inflammable nature of the exhalations of wine was already known to ancient natural philosophers such as
Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher A philosopher is someone who practices philosophy Philosophy (from , ) is the study of general and fundamental quest ...

Aristotle
(384–322 BCE),
Theophrastus Theophrastus (; grc-gre, Θεόφραστος ; c. 371c. 287 BC), a Greek native of Eresos Eresos (; el, Ερεσός; grc, Ἔρεσος) and its twin beach village Skala Eresou are located in the southwest part of the Greek island of Le ...

Theophrastus
(c. 371–287 BCE), and
Pliny the Elder #REDIRECT Pliny the Elder#REDIRECT Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, a naturalist Natural history is a domain of inquiry involving organisms, including animals, fungus, fungi, ...

Pliny the Elder
(23/24–79 CE). However, this did not immediately lead to the isolation of alcohol, even despite the development of more advanced distillation techniques in second- and third-century
Roman Egypt , conventional_long_name = Roman Egypt , common_name = Egypt , subdivision = Province A province is almost always an administrative division Administrative division, administrative unitArticle 3(1). , country subdivision, administrativ ...

Roman Egypt
. An important recognition, first found in one of the writings attributed to
Jābir ibn Ḥayyān
Jābir ibn Ḥayyān
(ninth century CE), was that by adding salt to boiling wine, which increases the wine's
relative volatilityRelative volatility is a measure comparing the vapor pressures of the components in a liquid mixture of chemicals. This quantity is widely used in designing large industrial distillation processes. In effect, it indicates the ease or difficulty of us ...
, the flammability of the resulting vapors may be enhanced. The distillation of wine is attested in Arabic works attributed to al-Kindī (c. 801–873 CE) and to
al-Fārābī
al-Fārābī
(c. 872–950), and in the 28th book of 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., alcohol) 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 Arnaldus de Villa Nova (also called Arnau de Vilanova in Catalan language, Catalan, his language, Arnaldus Villanovanus, Arnaud de Ville-Neuve or Arnaldo de Villanueva, c. 1240–1311) was a physician and a religious reformer. He was also thought ...
(1240–1311 CE) and
John of Rupescissa :''Johannes de Rupescissa may also refer to Cardinal Jean de La Rochetaillée'' Jean de Roquetaillade (ca. 1310 – between 1366 and 1370) was a French Franciscan Alchemy, alchemist. Biography After studying philosophy for five years at Tou ...
(c. 1310–1366), the latter of whom regarded it as a life-preserving substance able to prevent all diseases (the ''
aqua vitae ''Aqua vitae'' (Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in ...

aqua vitae
'' or "water of life", also called by John the '' quintessence'' of wine).


Nomenclature


Etymology

The word "alcohol" is from the Arabic '' kohl'' ( ar, الكحل, al-kuḥl), a powder used as an eyeliner.
Al- ( ar, ٱلْـ), also Romanized Romanization or romanisation, in linguistics Linguistics is the scientific study of language A language is a structured system of communication used by humans, including speech (spoken language) ...
is the Arabic
definite article An article is any member of a class of dedicated words that are used with noun phrases A noun phrase, or nominal (phrase), is a that has a or as its or performs the same grammatical function as a noun. Noun phrases are very common , and the ...
, equivalent to ''the'' in English. ''Alcohol'' was originally used for the very fine powder produced by the sublimation of the natural mineral
stibnite Stibnite, sometimes called antimonite, is a sulfide mineral with the formula In science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), org ...

stibnite
to form
antimony trisulfide Antimony trisulfide (Sb2S3) is found in nature as the crystalline mineral stibnite and the amorphous red mineral (actually a mineraloid) metastibnite. It is manufactured for use in safety matches, military ammunition, explosives and fireworks. I ...
. It was considered to be the essence or "spirit" of this mineral. It was used as an
antiseptic Antiseptics (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") are antimicrobial, antimicrobial substances that are applied to living biological tissue, tissue/skin to reduce the possibility of infection ...

antiseptic
, eyeliner, and
cosmetic Cosmetic may refer to: *Cosmetics, or make-up, substances to enhance the beauty of the human body, apart from simple cleaning *Cosmetic, an adjective describing beauty, aesthetics, or appearance, especially concerning the human body *Cosmetic, a top ...
. The meaning of alcohol was extended to distilled substances in general, and then narrowed to ethanol, when "spirits" was a synonym for
hard liquor Liquor or spirit (also distilled alcohol) is an alcoholic drink produced by distillation of grains, fruits, or vegetables that have already gone through alcoholic fermentation. The distillation process concentrates the liquid to increase its a ...
.
Bartholomew Traheron Bartholomew Traheron (1510?–1558?) was an English Protestant writer and Marian exile. Life Born about 1510, he is said to have been a native of Cornwall Cornwall (; kw, Kernow ) is a Ceremonial counties of England, ceremonial county in ...
, in his 1543 translation of
John of Vigo Giovanni da Vigo (1450–1525) was an Italy, Italian surgeon. He studied under Battista di Rapallo, surgeon to the Saluzzo, Marquis of Saluzzo. He spent his early years of practice in Genoa and statue of him can be found in front of the old Civic h ...
, introduces the word as a term used by "barbarous" authors for "fine powder." Vigo wrote: "the barbarous auctours use alcohol, or (as I fynde it sometymes wryten) alcofoll, for moost fine poudre." The 1657 ''Lexicon Chymicum'', by William Johnson glosses the word as "antimonium sive stibium." By extension, the word came to refer to any fluid obtained by distillation, including "alcohol of wine," the distilled essence of wine. Libavius in ''Alchymia'' (1594) refers to "vini alcohol vel vinum alcalisatum". Johnson (1657) glosses ''alcohol vini'' as "quando omnis superfluitas vini a vino separatur, ita ut accensum ardeat donec totum consumatur, nihilque fæcum aut phlegmatis in fundo remaneat." The word's meaning became restricted to "spirit of wine" (the chemical known today as
ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ (anatomy), ...

ethanol
) in the 18th century and was extended to the class of substances so-called as "alcohols" in modern chemistry after 1850. The term ''ethanol'' was invented in 1892, blending "
ethane Ethane ( or ) is an Organic compound, organic chemical compound with chemical formula . At Standard conditions for temperature and pressure, standard temperature and pressure, ethane is a colorless, odourless gas. Like many hydrocarbons, ethane ...
" with the "-ol" ending of "alcohol", which was generalized as a
libfix In linguistics, a libfix is a productive Productivity describes various measures of the efficiency Efficiency is the (often measurable) ability to avoid wasting materials, energy, efforts, money, and time in doing something or in producing a d ...
.


Systematic names

IUPAC nomenclature The International Union of Pure and Applied Chemistry The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a mem ...
is used in scientific publications and where precise identification of the substance is important, especially in cases where the relative complexity of the molecule does not make such a systematic name unwieldy. In naming simple alcohols, the name of the alkane chain loses the terminal ''e'' and adds the suffix ''-ol'', ''e.g.'', as in "ethanol" from the alkane chain name "ethane". When necessary, the position of the hydroxyl group is indicated by a number between the alkane name and the ''-ol'':
propan-1-ol 1-Propanol is a primary alcohol with the formula and sometimes skeletal formula#Pseudoelement symbols, represented as PrOH or ''n''-PrOH. It is a colorless liquid and an isomer of 2-propanol. It is formed naturally in small amounts during many f ...

propan-1-ol
for ,
propan-2-ol Isopropyl alcohol (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the autho ...
for . If a higher priority group is present (such as an
aldehyde Chemically, an aldehyde is a compound containing a functional group In organic chemistry, a functional group is a substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same ...

aldehyde
,
ketone In chemistry, a ketone is a functional group with the structure R2C=O, where R can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond). The simplest ketone is acetone (R = R' = methyl) ...
, or
carboxylic acid A carboxylic acid is an organic acid that contains a carboxyl group (C(=O)OH) attached to an R-group. The general formula of a carboxylic acid is R−COOH or R−CO2H, with substituent, R referring to the alkyl, alkenyl, aryl, or other group. ...
), then the prefix ''hydroxy-''is used, e.g., as in 1-hydroxy-2-propanone (). In cases where the OH functional group is bonded to an sp2 carbon on an
aromatic ring forms of benzene (top) combine to produce an average structure (bottom) In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: the ...
the molecule is known as a
phenol Phenol (also called carbolic acid) is an aromatic forms of benzene (top) combine to produce an average structure (bottom) In chemistry, aromaticity is a property of cyclic compound, cyclic (ring (chemistry), ring-shaped), plane (geometry), p ...
, and is named using the IUPAC rules for naming phenols.


Common names

In other less formal contexts, an alcohol is often called with the name of the corresponding alkyl group followed by the word "alcohol", e.g.,
methyl A methyl group is an alkyl 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' ...

methyl
alcohol, alcohol.
Propyl In organic chemistry, propyl is a three-carbon Carbon (from la, carbo "coal") is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an elem ...

Propyl
alcohol may be or
isopropyl alcohol Isopropyl alcohol (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the aut ...
, depending on whether the hydroxyl group is bonded to the end or middle carbon on the straight
propane Propane () is a three-carbon Carbon (from la, carbo "coal") is a chemical element with the Symbol (chemistry), symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—making four electrons available to form covalen ...

propane
chain. As described under systematic naming, if another group on the molecule takes priority, the alcohol moiety is often indicated using the "hydroxy-" prefix. Alcohols are then classified into primary, secondary (''sec-'', ''s-''), and tertiary (''tert-'', ''t-''), based upon the number of carbon atoms connected to the carbon atom that bears the
hydroxyl A hydroxy or hydroxyl group is a functional group with the chemical formula -OH and composed of one oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the ...

hydroxyl
functional group In organic chemistry, a functional group is a substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions re ...
. (The respective numeric shorthands 1°, 2°, and 3° are also sometimes used in informal settings.) The primary alcohols have general formulas RCHOH. The simplest primary alcohol is methanol (CHOH), for which R=H, and the next is ethanol, for which R=CH, the
methyl group A methyl group is an alkyl derived from methane, containing one carbon atom chemical bond, bonded to three hydrogen atoms — CH3. In chemical formula, formulas, the group is often skeletal formula#Pseudoelement symbols, abbreviated ...

methyl group
. Secondary alcohols are those of the form RR'CHOH, the simplest of which is 2-propanol (R=R'=CH). For the tertiary alcohols the general form is RR'R"COH. The simplest example is
tert-butanol ''tert''-Butyl alcohol, also called ''tert''-butanol or ''t''-butanol, is the simplest tertiary alcohol upright=0.8, The bond angle between a hydroxyl group (-OH) and a chain of carbon atoms (R) In chemistry Chemistry is the scientifi ...

tert-butanol
(2-methylpropan-2-ol), for which each of R, R', and R" is CH. In these shorthands, R, R', and R" represent
substituents A substituent is one or a group of atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that ca ...
, alkyl or other attached, generally organic groups. In archaic nomenclature, alcohols can be named as derivatives of methanol using "-carbinol" as the ending. For instance, (CH)COH can be named trimethylcarbinol.


Applications

Alcohols have a long history of myriad uses. For simple mono-alcohols, which is the focus on this article, the following are most important industrial alcohols:. *methanol, mainly for the production of
formaldehyde Formaldehyde ( , also ) (systematic nameA systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance A chemical substance is a form of matter In classical physics and general chemist ...
and as a
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, ...
*ethanol, mainly for alcoholic beverages, fuel additive, solvent *1-propanol, 1-butanol, and isobutyl alcohol for use as a solvent and precursor to solvents *C6–C11 alcohols used for
plasticizer A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity Plasticity may refer to: Science * Plasticity (physics), in engineering and physics, the propensity of ...
s, e.g. in
polyvinylchloride Polyvinyl chloride (colloquial Colloquialism or colloquial language is the style (sociolinguistics), linguistic style used for casual communication. It is the most common functional style of speech, the idiom normally employed in conversatio ...
*fatty alcohol (C12–C18), precursors to
detergent A detergent is a surfactant Surfactants are compounds that lower the (or interfacial tension) between two liquids, between a gas and a liquid, or between a liquid and a solid. Surfactants may act as s, agents, , s, or s. The word "surfact ...
s Methanol is the most common industrial alcohol, with about 12 million tons/y produced in 1980. The combined capacity of the other alcohols is about the same, distributed roughly equally.


Toxicity

With respect to acute toxicity, simple alcohols have low acute toxicities. Doses of several milliliters are tolerated. For
pentanolAn amyl alcohol is any of 8 alcohols with the formula C5H12O. A mixture of pentyl, amyl alcohols (also called amyl alcohol) can be obtained from fusel alcohol. Amyl alcohol is used as a solvent and in esterification, by which is produced amyl acetate ...
s,
hexanol Hexanol may refer to any of the following isomer In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, struct ...
s,
octanol Octanols are alcohols File:Alcohol general.svg, 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) ...
s and longer alcohols,
LD50 In toxicology Toxicology is a scientific discipline, overlapping with biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular ...
range from 2–5 g/kg (rats, oral). Methanol and ethanol are less acutely toxic. All alcohols are mild skin irritants. The metabolism of methanol (and ethylene glycol) is affected by the presence of ethanol, which has a higher affinity for liver alcohol dehydrogenase. In this way methanol will be excreted intact in urine.


Physical properties

In general, the
hydroxyl group A hydroxy or hydroxyl group is a functional group with the chemical formula -OH and composed of one oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group ( ...

hydroxyl group
makes alcohols
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 clim ...
. Those groups can form
hydrogen bond A hydrogen bond (or H-bond) is a primarily electrostatic Electrostatics is a branch of physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department ...

hydrogen bond
s to one another and to most other compounds. Owing to the presence of the polar OH alcohols are more water-soluble than simple hydrocarbons. Methanol, ethanol, and propanol are
miscible Miscibility () is the property of two substances to mix in all proportions (that is, to fully dissolve in each other at any concentration In chemistry Chemistry is the study of the properties and behavior of . It is a that covers ...
in water.
Butanol Butanol (also called butyl alcohol) is a four-carbon alcohol In , alcohol is an that carries at least one (−OH) bound to a atom. The term alcohol originally referred to the primary alcohol (ethyl alcohol), which is and is the main ...
, with a four-carbon chain, is moderately soluble. Because of
hydrogen bonding A hydrogen bond (or H-bond) is a primarily Electrostatics, electrostatic force of attraction between a hydrogen Hydrogen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of ...
, alcohols tend to have higher boiling points than comparable
hydrocarbon In organic chemistry Organic chemistry is a branch of chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, prop ...
s and
ether Ethers are a class of organic compound In , organic compounds are generally any s that contain - . Due to carbon's ability to (form chains with other carbon s), millions of organic compounds are known. The study of the properties, reaction ...

ether
s. The boiling point of the alcohol ethanol is 78.29 °C, compared to 69 °C for the hydrocarbon
hexane Hexane () is an organic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior ...

hexane
, and 34.6 °C for
diethyl ether Diethyl ether, or simply ether, is an organic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, ...

diethyl ether
.


Occurrence in nature

Simple alcohols are found widely in nature. Ethanol is the most prominent because it is the product of fermentation, a major energy-producing pathway. The other simple alcohols are formed in only trace amounts. More complex alcohols however are pervasive, as manifested in sugars, some amino acids, and fatty acids.


Production


Ziegler and oxo processes

In the
Ziegler processIn organic chemistry, the Ziegler process (also called the Ziegler-Alfol synthesis) is a method for producing fatty alcohols from ethylene using an organoaluminium compound. The reaction produces linear primary alcohols with an even numbered carbon c ...
, linear alcohols are produced from ethylene and
triethylaluminium Triethylaluminium is one of the simplest examples of an Organoaluminium chemistry, organoaluminium compound. Despite its name it has the Chemical formula, formula aluminum, Al2(Ethyl group, C2H5)6 (abbreviated as Al2Et6 or TEA), as it exists as a Di ...

triethylaluminium
followed by oxidation and hydrolysis. An idealized synthesis of
1-octanol 1-Octanol, also known as octan-1-ol, is the organic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, struc ...

1-octanol
is shown: :Al(CH) + 9 CH → Al(CH) :Al(CH) + 3 O + 3 HO → 3 HOCH + Al(OH) The process generates a range of alcohols that are separated by
distillation Distillation, or classical distillation, is the process of separating the components or substances from a liquid mixture In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, ...

distillation
. Many higher alcohols are produced by
hydroformylation Hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes from alkenes. This chemical reaction entails the net addition of a formyl group (CHO) and a hydrogen atom to a carbon-carbon do ...

hydroformylation
of alkenes followed by hydrogenation. When applied to a terminal alkene, as is common, one typically obtains a linear alcohol: :RCH=CH + H + CO → RCHCHCHO :RCHCHCHO + 3 H → RCHCHCHOH Such processes give
fatty alcohol Fatty alcohols (or long-chain alcohols) are usually high-molecular-weight, straight-chain primary alcohols, but can also range from as few as 4–6 carbons to as many as 22–26, derived from natural fats and oils. The precise chain length varies w ...
s, which are useful for detergents.


Hydration reactions

Some low molecular weight alcohols of industrial importance are produced by the addition of water to alkenes. Ethanol, isopropanol, 2-butanol, and tert-butanol are produced by this general method. Two implementations are employed, the direct and indirect methods. The direct method avoids the formation of stable intermediates, typically using acid catalysts. In the indirect method, the alkene is converted to the
sulfate ester Organosulfates are a class of s sharing a common with the structure R-O-SO3−. The SO4 core is a group and the R group is any organic residue. All organosulfates are formally s derived from s and , although many are not prepared in this way. ...
, which is subsequently hydrolyzed. The direct hydration using
ethylene Ethylene (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a member of the International Science C ...

ethylene
( ethylene hydration) or other alkenes from cracking of fractions of distilled
crude oil Petroleum, also known as crude oil and oil, is a naturally occurring, yellowish-black liquid A liquid is a nearly incompressible In fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics Mech ...
. Hydration is also used industrially to produce the diol
ethylene glycol Ethylene glycol (IUPAC name In chemical nomenclatureA chemical nomenclature is a set of rules to generate systematic names for chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecula ...

ethylene glycol
from
ethylene oxide Ethylene oxide is an organic compound , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's ability to Catenation ...

ethylene oxide
.


Biological routes

Ethanol is obtained by
fermentation Fermentation is a metabolism, metabolic process that produces chemical changes in organic Substrate (chemistry), substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in ...
using
glucose Glucose is a simple with the . Glucose is the most abundant , a subcategory of s. Glucose is mainly made by and most during from water and carbon dioxide, using energy from sunlight, where it is used to make in s, the most abundant carbohydr ...

glucose
produced from sugar from the
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution Substitution may refer to: Arts and media *Chord substitution, in music, swapping one chord fo ...

hydrolysis
of
starch Starch or amylum is a polymeric A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance ...
, in the presence of yeast and temperature of less than 37 °C to produce ethanol. For instance, such a process might proceed by the conversion of
sucrose Sucrose is a type of sugar Sugar is the generic name for , soluble s, many of which are used in food. Simple sugars, also called s, include , , and . Compound sugars, also called s or double sugars, are molecules made of two monosacchari ...

sucrose
by the enzyme
invertase Invertase is an enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme con ...
into glucose and
fructose Fructose, or fruit sugar, is a ketonic simple sugar Monosaccharides (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a cou ...

fructose
, then the conversion of glucose by the enzyme complex
zymase Zymase is an enzyme Enzymes () are protein Proteins are large s and s that comprise one or more long chains of . Proteins perform a vast array of functions within organisms, including , , , providing and , and from one location to ...
into ethanol and carbon dioxide. Several species of the benign bacteria in the intestine use
fermentation Fermentation is a metabolism, metabolic process that produces chemical changes in organic Substrate (chemistry), substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in ...
as a form of
anaerobic metabolism Anaerobic respiration is respiration using electron acceptors other than molecular oxygen (O2). Although oxygen is not the final electron acceptor, the process still uses a respiratory electron transport chain. In aerobic organisms 300px, Aero ...
. This
metabolic Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life Life is a characteristic that distinguishes physical entities that have biological processes, such as Cell signaling, signaling and self-sustaining ...

metabolic
reaction produces ethanol as a waste product. Thus, human bodies contain some quantity of alcohol endogenously produced by these bacteria. In rare cases, this can be sufficient to cause " auto-brewery syndrome" in which intoxicating quantities of alcohol are produced. Like ethanol,
butanol Butanol (also called butyl alcohol) is a four-carbon alcohol In , alcohol is an that carries at least one (−OH) bound to a atom. The term alcohol originally referred to the primary alcohol (ethyl alcohol), which is and is the main ...
can be produced by fermentation processes. Saccharomyces yeast are known to produce these higher alcohols at temperatures above . The bacterium ''
Clostridium acetobutylicum ''Clostridium acetobutylicum'', ATCC 824, is a commercially valuable bacterium Bacteria (; common noun bacteria, singular bacterium) are a type of Cell (biology), biological cell. They constitute a large domain (biology), domain of proka ...

Clostridium acetobutylicum
'' can feed on
cellulose Cellulose is an organic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior ...

cellulose
to produce butanol on an industrial scale.


Substitution

Primary
alkyl halide The haloalkanes'' known as halogenoalkanes or alkyl halides) are alkane In , an alkane, or paraffin (a historical that also has ), is an . In other words, an alkane consists of and atoms arranged in a structure in which all the s are . ...
s react with aqueous or mainly to primary alcohols in
nucleophilic aliphatic substitution A nucleophilic substitution is a class of chemical reactions in which an electron-rich chemical species A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up ...
. (Secondary and especially tertiary alkyl halides will give the elimination (alkene) product instead).
Grignard reagent A Grignard reagent or Grignard Compound is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and t ...
s react with
carbonyl In organic chemistry Organic chemistry is a branch of chemistry that studies the structure, properties and reactions of organic compounds, which contain carbon in covalent bonding.Clayden, J.; Greeves, N. and Warren, S. (2012) ''Organic Chemistr ...

carbonyl
groups to secondary and tertiary alcohols. Related reactions are the and the Nozaki-Hiyama reaction.


Reduction

Aldehydes Chemically, an aldehyde is a compound containing a functional group In organic chemistry, a functional group is a substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same fu ...
or
ketone In chemistry, a ketone is a functional group with the structure R2C=O, where R can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond). The simplest ketone is acetone (R = R' = methyl) ...
s are with
sodium borohydride Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, is an inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is ...

sodium borohydride
or
lithium aluminium hydride Lithium aluminium hydride, commonly abbreviated to LAH, is an inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. However, ...

lithium aluminium hydride
(after an acidic workup). Another reduction by aluminiumisopropylates is the Meerwein-Ponndorf-Verley reduction. Noyori asymmetric hydrogenation is the asymmetric reduction of β-keto-esters.


Hydrolysis

Alkenes In chemistry Chemistry is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence ...

Alkenes
engage in an acid catalysed
hydration reactionHydration may refer to: * Hydrate In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, b ...
using concentrated sulfuric acid as a catalyst that gives usually secondary or tertiary alcohols. The and of alkenes are more reliable in organic synthesis. Alkenes react with NBS and water in halohydrin formation reaction. Amines can be converted to diazonium salts, which are then hydrolyzed. The formation of a secondary alcohol via reduction and hydration is shown: :


Reactions


Deprotonation

With a pKa, pK of around 16–19, they are, in general, slightly weaker acids than water (molecule), water. With strong bases such as sodium hydride or sodium they form Salt (chemistry), salts called alkoxides, with the general formula Alkyl, RO Metal, M+. : 2 R-OH + 2 NaH → 2 R-ONa+ + 2 H : 2 R-OH + 2 Na → 2 R-ONa+ + H The acidity of alcohols is strongly affected by solvation. In the gas phase, alcohols are more acidic than in water.


Nucleophilic substitution

The OH group is not a good leaving group in nucleophilic substitution reactions, so neutral alcohols do not react in such reactions. However, if the oxygen is first protonated to give R−OH+, the leaving group (water (molecule), water) is much more stable, and the nucleophilic substitution can take place. For instance, tertiary alcohols react with hydrochloric acid to produce tertiary
alkyl halide The haloalkanes'' known as halogenoalkanes or alkyl halides) are alkane In , an alkane, or paraffin (a historical that also has ), is an . In other words, an alkane consists of and atoms arranged in a structure in which all the s are . ...
s, where the
hydroxyl group A hydroxy or hydroxyl group is a functional group with the chemical formula -OH and composed of one oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group ( ...

hydroxyl group
is replaced by a chlorine atom by unimolecular nucleophilic substitution. If primary or secondary alcohols are to be reacted with hydrochloric acid, an activator such as zinc chloride is needed. In alternative fashion, the conversion may be performed directly using thionyl chloride.[1] Alcohols may, likewise, be converted to alkyl bromides using hydrobromic acid or phosphorus tribromide, for example: : 3 R-OH + PBr → 3 RBr + HPO In the Barton-McCombie deoxygenation an alcohol is deoxygenated to an alkane with organotin, tributyltin hydride or a organoborane, trimethylborane-water complex in a radical substitution reaction.


Dehydration

Meanwhile, the oxygen atom has lone pairs of nonbonded electrons that render it weakly Base (chemistry), basic in the presence of strong acids such as sulfuric acid. For example, with methanol: Upon treatment with strong acids, alcohols undergo the E1 elimination reaction to produce alkenes. The reaction, in general, obeys Zaitsev's Rule, which states that the most stable (usually the most substituted) alkene is formed. Tertiary alcohols eliminate easily at just above room temperature, but primary alcohols require a higher temperature. This is a diagram of acid catalysed dehydration of ethanol to produce
ethylene Ethylene (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a member of the International Science C ...

ethylene
: A more controlled elimination reaction requires the formation of the xanthate ester.


Protonolysis

Tertiary alcohols react with strong acids to generate carbocations. The reaction is related to their dehydration, e.g. isobutylene from tert-butyl alcohol. A special kind of dehydration reaction involves triphenylmethanol and especially its amine-substituted derivatives. When treated with acid, these alcohols lose water to give stable carbocations, which are commercial dyes. image:Kristallviolett Darstellung.svg, 322px, Preparation of crystal violet by protonolysis of the tertiary alcohol.


Esterification

Alcohol and
carboxylic acid A carboxylic acid is an organic acid that contains a carboxyl group (C(=O)OH) attached to an R-group. The general formula of a carboxylic acid is R−COOH or R−CO2H, with substituent, R referring to the alkyl, alkenyl, aryl, or other group. ...
s react in the so-called Fischer esterification. The reaction usually requires a catalyst, such as concentrated sulfuric acid: : R-OH + R'-COH → R'-COR + HO Other types of ester are prepared in a similar manner for example, tosyl (tosylate) esters are made by reaction of the alcohol with p-toluenesulfonyl chloride in pyridine.


Oxidation

Primary alcohols (R-CHOH) can be oxidized either to
aldehyde Chemically, an aldehyde is a compound containing a functional group In organic chemistry, a functional group is a substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same ...

aldehyde
s (R-CHO) or to
carboxylic acid A carboxylic acid is an organic acid that contains a carboxyl group (C(=O)OH) attached to an R-group. The general formula of a carboxylic acid is R−COOH or R−CO2H, with substituent, R referring to the alkyl, alkenyl, aryl, or other group. ...
s (R-COH). The oxidation of secondary alcohols (R1R2CH-OH) normally terminates at the
ketone In chemistry, a ketone is a functional group with the structure R2C=O, where R can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond). The simplest ketone is acetone (R = R' = methyl) ...
(R1R2C=O) stage. Tertiary alcohols (R1R2R3C-OH) are resistant to oxidation. The direct oxidation of primary alcohols to carboxylic acids normally proceeds via the corresponding aldehyde, which is transformed via an ''aldehyde hydrate'' (R-CH(OH)) by reaction with water before it can be further oxidized to the carboxylic acid. Reagents useful for the transformation of primary alcohols to aldehydes are normally also suitable for the oxidation of secondary alcohols to ketones. These include Collins reagent and Dess-Martin periodinane. The direct oxidation of primary alcohols to carboxylic acids can be carried out using potassium permanganate or the Jones reagent.


See also

* Enol * Ethanol fuel * Fatty alcohol * Index of alcohol-related articles * List of alcohols * Lucas' reagent, Lucas test * Polyol * Rubbing alcohol * Sugar alcohol * Transesterification


Notes


References

*


External links

{{Authority control Alcohol, Alcohols, Antiseptics Functional groups