formic acid
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Formic acid (), systematically named methanoic acid, is the simplest
carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with substituent, R referring to the alkyl, alkenyl, aryl, or other group. ...
, and has the
chemical formula In chemistry, 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, ...
HCOOH and structure . It is an important intermediate in
chemical synthesis As a topic of chemistry, chemical synthesis (or combination) is the artificial execution of chemical reactions to obtain one or several product (chemistry), products. This occurs by physics, physical and chemical manipulations usually involving o ...
and occurs naturally, most notably in some ants.
Ester In chemistry, an ester is a chemical compound, compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an Alcohol ...
s, salts and the
anion An ion () is an atom or molecule with a net electric charge, electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be po ...
derived from formic acid are called
formate Formate (IUPAC name: methanoate) is the conjugate base of formic acid. Formate is an anion () or its derivatives such as ester of formic acid. The salts and esters are generally colorless.Werner Reutemann and Heinz Kieczka "Formic Acid" in ''Ull ...
s. Industrially, formic acid is produced from
methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula CH3OH (a methyl group In organic chemistry, a methyl group is an alkyl derived from m ...
.


Natural occurrence

In nature, formic acid is found in most
ants Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Creta ...
and in
stingless bee Stingless bees, sometimes called stingless honey bees or simply meliponines, are a large group of bees (about 550 described species), comprising the tribe Meliponini (or subtribe Meliponina according to other authors). They belong in the family A ...
s of the genus ''
Oxytrigona ''Oxytrigona'' is a genus of bees belonging to the family Apidae. The species of this genus are found in Southern America. Species: *''Oxytrigona chocoana'' *''Oxytrigona daemoniaca'' *''Oxytrigona flaveola'' *''Oxytrigona huaoranii'' *''Ox ...
''.
Wood ants Wood is a porous and fibrous structural tissue found in the Plant stem, stems and roots of trees and other woody plants. It is an organic materiala natural composite material, composite of cellulose fibers that are strong in tension and emb ...
from the genus '' Formica'' can spray formic acid on their prey or to defend the nest. The puss moth caterpillar (''Cerura vinula'') will spray it as well when threatened by predators. It is also found in the
trichome Trichomes (); ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...
s of
stinging nettle ''Urtica dioica'', often known as common nettle, burn nettle, stinging nettle (although not all plants of this species sting) or nettle leaf, or just a nettle or stinger, is a herbaceous perennial plant, perennial flowering plant in the famil ...
(''Urtica dioica''). Apart from that, this acid is incorporated in many fruits such as pineapple (0.21mg per 100g), apple (2mg per 100g) and kiwi (1mg per 100g), as well as in many vegetables, namely onion (45mg per 100g), eggplant (1.34 mg per 100g) and, in extremely low concentrations, cucumber (0.11mg per 100g). Formic acid is a naturally occurring component of the
atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...
primarily due to forest emissions.


History

Some alchemists and naturalists were aware that ant hills give off an acidic vapor as early as the 15th century. The first person to describe the isolation of this substance (by the distillation of large numbers of ants) was the English naturalist
John Ray John Ray Fellow of the Royal Society, FRS (29 November 1627 – 17 January 1705) was a Christian England, English Natural history, naturalist widely regarded as one of the earliest of the English parson-naturalists. Until 1670, he wrote his na ...
, in 1671. Ants secrete the formic acid for attack and defense purposes. Formic acid was first synthesized from hydrocyanic acid by the French chemist
Joseph Gay-Lussac Joseph Louis Gay-Lussac (, , ; 6 December 1778 – 9 May 1850) was a French chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. ...
. In 1855, another French chemist,
Marcellin Berthelot Pierre Eugène Marcellin Berthelot (; 25 October 1827 – 18 March 1907) was a French chemist and Republican Union (France), Republican politician noted for the Thomsen-Berthelot principle, ThomsenBerthelot principle of thermochemistry. He synt ...
, developed a synthesis from
carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...
similar to the process used today. Formic acid was long considered a
chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A homonuclear molecule, molecule co ...
of only minor interest in the chemical industry. In the late 1960s, however, significant quantities became available as a byproduct of
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon chemical bond, bond ...
production. It now finds increasing use as a preservative and antibacterial in
livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool Wool is the textile fibre obtained from sheep an ...
feed.


Properties

Formic acid is a colorless liquid having a pungent, penetrating odor at room temperature, comparable to the related
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon chemical bond, bond ...
. Formic acid is about ten times stronger than
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon chemical bond, bond ...
. It is
miscible Miscibility () is the property of two chemical substance, substances to mix in all mixing ratio, proportions (that is, to fully dissolution (chemistry), dissolve in each other at any concentration), forming a homogeneity and heterogeneity, homoge ...
with water and most polar organic
solvent A solvent (s) (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a ...
s, and is somewhat soluble in
hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic, and their odors are usuall ...
s. In hydrocarbons and in the vapor phase, it consists of hydrogen-bonded dimers rather than individual molecules. Owing to its tendency to hydrogen-bond, gaseous formic acid does not obey the
ideal gas law The ideal gas law, also called the general gas equation, is the equation of state of a hypothetical ideal gas. It is a good approximation of the behavior of many gases under many conditions, although it has several limitations. It was first s ...
. Solid formic acid, which can exist in either of two polymorphs, consists of an effectively endless network of hydrogen-bonded formic acid molecules. Formic acid forms a high-boiling
azeotrope An azeotrope () or a constant heating 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 ...
with water (22.4%). Liquid formic acid tends to supercool.


Chemical reactions


Decomposition

Formic acid readily decomposes by dehydration in the presence of concentrated
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen ...
to form
carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...
and water: :HCO2H → H2O + CO Treatment of formic acid with
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen ...
is a convenient laboratory source of CO. In the presence of platinum, it decomposes with a release of
hydrogen Hydrogen is the chemical element with the Symbol (chemistry), symbol H and atomic number 1. Hydrogen is the lightest element. At standard temperature and pressure, standard conditions hydrogen is a gas of diatomic molecules having the chemical ...
and
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon Carbon () is a chemical element with the chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetraval ...
. :HCO2H → H2 + CO2 Soluble ruthenium catalysts are also effective. Carbon monoxide free hydrogen has been generated in a very wide pressure range (1–600 bar).


Reactant

Formic acid shares most of the chemical properties of other
carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with substituent, R referring to the alkyl, alkenyl, aryl, or other group. ...
s. Because of its high acidity, solutions in alcohols form esters spontaneously. Formic acid shares some of the reducing properties of
aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group ...
s, reducing solutions of metal oxides to their respective metal. Formic acid is a source for a formyl group for example in the formylation of methylaniline to N-methylformanilide in
toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon. It is a colorless, water (molecule), water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a met ...
. In synthetic organic chemistry, formic acid is often used as a source of
hydride In chemistry, a hydride is formally the anion of hydrogen( H−). The term is applied loosely. At one extreme, all chemical compound, compounds containing covalent bond, covalently bound H atoms are called hydrides: water (H2O) is a hydride of ...
ion, as in the Eschweiler-Clarke reaction: It is used as a source of hydrogen in
transfer hydrogenation In chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, struct ...
, as in the Leuckart reaction to make amines, and (in aqueous solution or in its
azeotrope An azeotrope () or a constant heating 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 ...
with
triethylamine Triethylamine is the chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) containing atoms from more than one chemical element held together by chemical ...
) for hydrogenation of
ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bon ...
s.


Addition to alkenes

Formic acid is unique among the carboxylic acids in its ability to participate in addition reactions with
alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon Carbon () is a chemical element with the chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—its atom making four electro ...
s. Formic acids and alkenes readily react to form formate
ester In chemistry, an ester is a chemical compound, compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an Alcohol ...
s. In the presence of certain acids, including sulfuric and
hydrofluoric acid Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colourless, acidic and highly corrosive. It is used to make most fluorine-containing compounds; examples include the commonly used pharmaceutical antidep ...
s, however, a variant of the Koch reaction occurs instead, and formic acid adds to the alkene to produce a larger carboxylic acid.


Formic acid anhydride

An unstable formic anhydride, H(C=O)−O−(C=O)H, can be obtained by dehydration of formic acid with ''N'',''N′''-dicyclohexylcarbodiimide in ether at low temperature.


Production

In 2009, the worldwide capacity for producing formic acid was per year, roughly equally divided between Europe (, mainly in Germany) and Asia (, mainly in China) while production was below per year in all other continents. It is commercially available in solutions of various concentrations between 85 and 99 w/w %. , the largest producers are
BASF BASF Societas Europaea, SE () is a German multinational corporation, multinational chemical company and the List of largest chemical producers, largest chemical producer in the world. Its headquarters is located in Ludwigshafen, Germany. The ...
, Eastman Chemical Company, LC Industrial, and Feicheng Acid Chemicals, with the largest production facilities in
Ludwigshafen Ludwigshafen, officially Ludwigshafen am Rhein (; meaning "Ludwig I of Bavaria, Ludwig's Port upon Rhine"), is a List of cities and towns in Germany, city in the German state of Rhineland-Palatinate, on the river Rhine, opposite Mannheim. With M ...
( per year, BASF, Germany),
Oulu Oulu ( , ; sv, Uleåborg ) is a List of cities and towns in Finland, city, Municipalities of Finland, municipality and a seaside resort of about 210,000 inhabitants in the region of North Ostrobothnia, Finland. It is the most populous city in no ...
(, Eastman, Finland), Nakhon Pathom (n/a, LC Industrial), and Feicheng (, Feicheng, China). 2010 prices ranged from around €650/tonne (equivalent to around $800/tonne) in Western Europe to $1250/tonne in the United States.


From methyl formate and formamide

When
methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula CH3OH (a methyl group In organic chemistry, a methyl group is an alkyl derived from m ...
and
carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...
are combined in the presence of a strong base, the result is
methyl formate Methyl formate, also called methyl methanoate, is the methyl ester of formic acid. The simplest example of an ester, it is a colorless liquid with an ethereal odour, high vapor pressure, and low surface tension. It is a precursor to many other co ...
, according to the
chemical equation A chemical equation is the symbolic representation of a chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. ...
: :CH3OH + CO → HCO2CH3 In industry, this reaction is performed in the liquid phase at elevated pressure. Typical reaction conditions are 80 °C and 40 atm. The most widely used base is
sodium methoxide Sodium methoxide is the simplest sodium alkoxide. With the formula , it is a white solid, which is formed by the deprotonation of methanol. Itis a widely used reagent in industry and the laboratory. It is also a dangerously caustic Base (chem ...
.
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 reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...
of the methyl formate produces formic acid: :HCO2CH3 + H2O → HCOOH + CH3OH Efficient hydrolysis of methyl formate requires a large excess of water. Some routes proceed indirectly by first treating the methyl formate with
ammonia Ammonia is an inorganic chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a dis ...
to give
formamide Formamide is an amide derived from formic acid. It is a colorless liquid which is miscible with water and has an ammonia-like odor. It is chemical feedstock for the manufacture of sulfa drugs and other pharmaceuticals, herbicides and pesticides, a ...
, which is then hydrolyzed with
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen ...
: :HCO2CH3 + NH3 → HC(O)NH2 + CH3OH :2 HC(O)NH2 + 2H2O + H2SO4 → 2HCO2H + (NH4)2SO4 A disadvantage of this approach is the need to dispose of the ammonium sulfate byproduct. This problem has led some manufacturers to develop energy-efficient methods of separating formic acid from the excess water used in direct hydrolysis. In one of these processes, used by
BASF BASF Societas Europaea, SE () is a German multinational corporation, multinational chemical company and the List of largest chemical producers, largest chemical producer in the world. Its headquarters is located in Ludwigshafen, Germany. The ...
, the formic acid is removed from the water by liquid-liquid extraction with an organic base.


Niche and obsolete chemical routes


By-product of acetic acid production

A significant amount of formic acid is produced as a byproduct in the manufacture of other chemicals. At one time,
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon chemical bond, bond ...
was produced on a large scale by oxidation of
alkane In organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms tha ...
s, by a process that cogenerates significant formic acid. This oxidative route to acetic acid has declined in importance so that the aforementioned dedicated routes to formic acid have become more important.


Hydrogenation of carbon dioxide

The catalytic
hydrogenation Hydrogenation is a chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions e ...
of CO2 to formic acid has long been studied. This reaction can be conducted homogeneously.


Oxidation of biomass

Formic acid can also be obtained by aqueous catalytic partial oxidation of wet biomass by the OxFA process. A Keggin-type polyoxometalate (H5PV2Mo10O40) is used as the homogeneous catalyst to convert sugars, wood, waste paper, or cyanobacteria to formic acid and CO2 as the sole byproduct. Yields of up to 53% formic acid can be achieved.


Laboratory methods

In the laboratory, formic acid can be obtained by heating
oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and chemical formula, formula . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact ...
in
glycerol Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...
and extraction by steam distillation. Glycerol acts as a catalyst, as the reaction proceeds through a glyceryl oxalate intermediate. If the reaction mixture is heated to higher temperatures,
allyl alcohol Allyl alcohol (IUPAC name: prop-2-en-1-ol) is an organic compound with the structural formula . Like many Alcohol (chemistry), alcohols, it is a water-soluble, colourless liquid. It is more toxic than typical small alcohols. Allyl alcohol is us ...
results. The net reaction is thus: :C2O4H2 → HCO2H + CO2 Another illustrative method involves the reaction between lead formate and
hydrogen sulfide Hydrogen sulfide is a chemical compound with the chemical formula, formula . It is a colorless Chalcogen hydride, chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic ...
, driven by the formation of lead sulfide. :Pb(HCOO)2 + H2S → 2HCOOH + PbS


Electrochemical production

It has been reported that formate can be formed by the electrochemical reduction of CO2 (in the form of
bicarbonate In inorganic chemistry, bicarbonate (International Union of Pure and Applied Chemistry, IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a Polyatomic ion, polyatomic anion wi ...
) at a
lead Lead is a chemical element with the Symbol (chemistry), symbol Pb (from the Latin ) and atomic number 82. It is a heavy metals, heavy metal that is density, denser than most common materials. Lead is Mohs scale of mineral hardness#Intermediate ...
cathode A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. A conventional current describes the direction in ...
at pH 8.6: : + + 2e → + 2 or : + + 2e → + If the feed is and oxygen is evolved at the anode, the total reaction is: : + → + 1/2


Biosynthesis

Formic acid is named after ants which have high concentrations of the compound in their venom. In ants, formic acid is derived from
serine Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − form un ...
through a 5,10-methenyltetrahydrofolate intermediate. The conjugate base of formic acid, formate, also occurs widely in nature. An
assay An assay is an investigative (analytic) procedure in laboratory medicine, mining, pharmacology, environmental biology and molecular biology for qualitatively assessing or quantitatively measuring the presence, amount, or functional activity of a ...
for formic acid in body fluids, designed for determination of formate after methanol poisoning, is based on the reaction of formate with bacterial
formate dehydrogenase Formate dehydrogenases are a set of enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme co ...
.


Uses


Agriculture

A major use of formic acid is as a
preservative A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by ...
and
antibacterial An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy, ...
agent in livestock feed. In Europe, it is applied on
silage Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation (food), fermentation to the point of souring, acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). Th ...
, including fresh hay, to promote the fermentation of
lactic acid Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscibility, miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as ...
and to suppress the formation of
butyric acid Butyric acid (; from grc, βούτῡρον, meaning "butter"), also known under the systematic name butanoic acid, is a straight-chain alkyl carboxylic acid with the chemical formula CH3CH2CH2CO2H. It is an oily, colorless liquid with an unple ...
; it also allows fermentation to occur quickly, and at a lower temperature, reducing the loss of nutritional value. Formic acid arrests certain decay processes and causes the feed to retain its nutritive value longer, and so it is widely used to preserve winter feed for
cattle Cattle (''Bos taurus'') are large, domestication, domesticated, Cloven hoof, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referr ...
. In the
poultry Poultry () are domestication, domesticated birds kept by humans for their egg (food) , eggs, their meat or their feathers. These birds are most typically members of the Superorder (biology), superorder Fowl, Galloanserae (fowl), especially the ...
industry, it is sometimes added to feed to kill '' E. coli'' bacteria. Use as a preservative for silage and (other) animal feed constituted 30% of the global consumption in 2009.
Beekeeper A beekeeper is a person who keeps honey bees. Beekeepers are also called honey farmers, apiarists, or less commonly, apiculturists (both from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic ...
s use formic acid as a miticide against the tracheal mite ('' Acarapis woodi'') and the ''Varroa destructor'' mite and ''Varroa jacobsoni'' mite.


Energy

Formic acid can be used in a
fuel cell A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen fuel, hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most bat ...
(it can be used directly in formic acid fuel cells and indirectly in hydrogen fuel cells). Electrolytic conversion of electrical energy to chemical fuel has been proposed as a large-scale source of formate by various groups. The formate could be used as feed to modified '' E. coli'' bacteria for producing
biomass Biomass is plant-based material used as a fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work (physics), work. The concept was originally applied ...
. Natural microbes do exist that can feed on formic acid or formate (see Methylotroph). Formic acid has been considered as a means of
hydrogen storage Hydrogen storage can be accomplished by several existing methods of holding hydrogen for later use. These include mechanical approaches such as using high pressures and low temperatures, or employing chemical compounds that release H2 upon demand ...
. The co-product of this decomposition, carbon dioxide, can be rehydrogenated back to formic acid in a second step. Formic acid contains 53 g/L hydrogen at room temperature and atmospheric pressure, which is three and a half times as much as compressed hydrogen gas can attain at 350 bar pressure (14.7 g/L). Pure formic acid is a liquid with a
flash point The flash point of a material is the "lowest liquid temperature at which, under certain standardized conditions, a liquid gives off vapours in a quantity such as to be capable of forming an ignitable vapour/air mixture". (EN 60079-10-1) The fl ...
of +69 °C, much higher than that of gasoline (−40 °C) or ethanol (+13 °C). It is possible to use formic acid as an intermediary to produce isobutanol from using microbes.


Artificial photosynthesis

In August 2020 researchers at Cambridge University announced a stand-alone advanced 'photosheet' technology that converts sunlight, carbon dioxide and water into oxygen and formic acid with no other inputs.


Soldering

Formic acid has a potential application in
soldering Soldering (; ) is a process in which two or more items are joined by melting and putting a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Unlike welding, soldering does not involv ...
. Due to its capacity to reduce oxide layers, formic acid gas can be blasted at an oxide surface in order to increase solder
wettability Wetting is the ability of a liquid to maintain contact with a solid surface science, surface, resulting from intermolecular interactions when the two are brought together. This happens in presence of a gaseous phase or another liquid phase not ...
.


Chromatography

Formic acid used as a volatile pH modifier in
HPLC High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to p ...
and
capillary electrophoresis Capillary electrophoresis (CE) is a family of electrokinetic separation methods performed in submillimeter diameter capillaries and in micro- and nanofluidic channels. Very often, CE refers to capillary zone electrophoresis (CZE), but other elect ...
. Formic acid is often used as a component of mobile phase in reversed-phase
high-performance liquid chromatography High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pa ...
(RP-HPLC) analysis and separation techniques for the separation of hydrophobic macromolecules, such as peptides, proteins and more complex structures including intact viruses. Especially when paired with mass spectrometry detection, formic acid offers several advantages over the more traditionally used phosphoric acid.


Other uses

Formic acid is also significantly used in the production of leather, including tanning (23% of the global consumption in 2009), and in dyeing and finishing textiles (9% of the global consumption in 2009) because of its acidic nature. Use as a coagulant in the production of rubber consumed 6% of the global production in 2009. Formic acid is also used in place of mineral acids for various cleaning products, such as limescale remover and toilet bowl cleaner. Some formate
esters In chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, stru ...
are artificial flavorings and perfumes. Formic acid application has been reported to be an effective treatment for
wart Warts are typically small, rough, hard growths that are similar in color to the rest of the skin. They typically do not result in other symptoms, except when on the bottom of the feet, where they may be painful. While they usually occur on the ...
s.


Safety

Formic acid has low toxicity (hence its use as a food additive), with an of 1.8g/kg (tested orally on mice). The concentrated acid is corrosive to the skin. Formic acid is readily metabolized and eliminated by the body. Nonetheless, it has specific
toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect ...
effects; the formic acid and
formaldehyde Formaldehyde ( , ) (Preferred IUPAC name, systematic name methanal) is a naturally occurring organic compound with the chemical formula, formula and structure . The pure compound is a pungent, colourless gas that Polymerization, polymerises s ...
produced as metabolites of
methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula CH3OH (a methyl group In organic chemistry, a methyl group is an alkyl derived from m ...
are responsible for the
optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve Cranial nerves are the nerves that emerge directly from the brain (including the brainstem The ...
damage, causing blindness, seen in methanol poisoning. Some chronic effects of formic acid exposure have been documented. Some experiments on bacterial species have demonstrated it to be a
mutagen In genetics, a mutagen is a physical or chemical agent that permanently changes nucleic acid, genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level. As many mutations can ca ...
. Chronic exposure in humans may cause kidney damage. Another possible effect of chronic exposure is development of a skin
allergy Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include Allergic rhinitis, hay fever, Food allerg ...
that manifests upon re-exposure to the chemical. Concentrated formic acid slowly decomposes to carbon monoxide and water, leading to pressure buildup in the containing vessel. For this reason, 98% formic acid is shipped in plastic bottles with self-venting caps. The hazards of solutions of formic acid depend on the concentration. The following table lists the
Globally Harmonized System of Classification and Labelling of Chemicals The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is an internationally agreed-upon standard managed by the United Nations that was set up to replace the assortment of hazardous material classification and labelli ...
for formic acid solutions: Formic acid in 85% concentration is flammable, and diluted formic acid is on the U.S. Food and Drug Administration list of food additives., The principal danger from formic acid is from skin or eye contact with the concentrated liquid or vapors. The U.S. OSHA Permissible Exposure Level ( PEL) of formic acid vapor in the work environment is 5 parts per million parts of air ( ppm).


See also

* Orthoformic acid * Formic acid vehicle


References


External links


International Chemical Safety Card 0485




{{DEFAULTSORT:Formic Acid Alkanoic acids Solvents Cleaning product components Organic compounds with 1 carbon atom