Formic acid 66284 221591735 2008-06-25T05:21:32Z VolkovBot 3035831 robot Adding: [[hr:Mravlja kiselina]] {{Chembox new | Name = Formic acid | ImageFileL1 = Formic-acid.png | ImageSizeL1 = 120px | ImageNameL1 = Skeletal structure of formic acid | ImageFileR1 = Formic-acid-3D-balls-B.png | ImageSizeR1 = 120px | ImageNameR1 = 3D model of formic acid | IUPACName = Methanoic acid | OtherNames = Hydrogen carboxylic acid<br/>Formylic acid<br/>Aminic acid | Section1 = {{Chembox Identifiers | SMILES = O=CO | CASNo = 64-18-6 | RTECS = LQ4900000 }} | Section2 = {{Chembox Properties | Formula = CH<sub>2</sub>O<sub>2</sub><br />HCOOH | MolarMass = 46.0254 g/mol | Appearance = Colorless, fuming liquid | Density = 1.22 g/mL, liquid | Solubility = Miscible | MeltingPt = 8.4°C (47.1°F) | BoilingPt = 100.8°C (213.3°F) | pKa = 3.744 | Viscosity = 1.57 c[[Poise|P]] at 26°C }} | Section3 = {{Chembox Structure | MolShape = [[Planar]] | Dipole = 1.41 [[Debye|D]](gas) }} | Section7 = {{Chembox Hazards | ExternalMSDS = [http://sciencelab.com/msds.php?msdsId=9924098 ScienceLab.com] | MainHazards = Corrosive; irritant;<br />sensitizer. | NFPA-H = 3 | NFPA-F = 2 | NFPA-R = 0 | FlashPt = 69°C (156°F) | RPhrases = {{R10}}, {{R35}} | SPhrases = {{S1/2}}, {{S23}}, {{S26}}, {{S45}} }} | Section8 = {{Chembox Related | Function = [[carboxylic acid]]s | OtherFunctn = [[Acetic acid]]<br/>[[Propionic acid]] | OtherCpds = [[Formaldehyde]]<br/>[[Methanol]]}} }} '''[[Formic acid]]''' (systematically called '''methanoic acid''') is the simplest [[carboxylic acid]]. Its [[formula]] is [[hydrogen|H]][[carbon|C]][[oxygen|O]]OH or CH<sub>2</sub>O<sub>2</sub>. It is an important intermediate in [[chemical synthesis]] and occurs [[naturally]], most notably in the [[venom]] of [[bee]] and [[ant]] [[stinger| sting]]s. In [[nature]], it is found in the [[sting (pain)| stings]] and [[bites]] of many [[insects]] of the order [[Hymenoptera]], mainly [[ant]]s. It is also a significant [[combustion]] product resulting from alternative fueled [[vehicles]] burning [[methanol]] (and [[ethanol]], if contaminated with [[water]]) when mixed with [[gasoline]]. Its name comes from the [[Latin]] word for ant, ''[[formica]]'', referring to its early [[isolation]] by [[the]] [[distillation]] of ant bodies. A [[chemical compound]] such as a [[salt]] from the [[neutralization]] of formic acid with a [[base (chemistry)|base]], or an [[ester]] derived from formic acid, is referred to as '''formate''' (or '''methanoate'''). The formate [[ion]] has the formula HCOO<sup>−</sup>. ==Properties== Formic acid is [[Miscibility|miscible]] with [[water (molecule)|water]] and most polar [[organic chemistry|organic]] [[solvent]]s, and somewhat soluble in [[hydrocarbon]]s. In hydrocarbons and in the vapor phase, it actually consists of [[Hydrogen bond|hydrogen-bond]]ed dimers rather than individual molecules. In the gas phase, this hydrogen-bonding results in severe deviations from the [[ideal gas law]]. Liquid and solid formic acid consists of an effectively endless network of hydrogen-bonded formic acid molecules. Formic acid shares most of the chemical properties of other [[carboxylic acid]]s, although under normal conditions it will not form either an [[acyl chloride]] or an [[acid anhydride]]. Until very recently, all attempts to form either of these derivatives have resulted in carbon monoxide instead. It has now been shown that the anhydride may be produced by reaction of formyl fluoride with sodium formate at −78°C, and the chloride by passing HCl into a solution of 1-formimidazole in monochloromethane at −60°C.{{Fact|date=October 2007}} Heat can also cause formic acid to decompose to carbon monoxide and water. Formic acid shares some of the [[redox|reducing]] properties of [[aldehyde]]s. Formic acid is unique among the carboxylic acids in its ability to participate in addition reactions with [[alkene]]s. Formic acids and alkenes readily react to form formate [[ester]]s. In the presence of certain acids, including [[sulfuric acid|sulfuric]] and [[hydrofluoric acid]]s, however, a variant of the [[Koch reaction]] takes place instead, and formic acid adds to the alkene to produce a larger carboxylic acid. Most simple formate salts are water-[[soluble]]. It is also a bi-functional compound. ==Production== A significant amount of formic acid is produced as a byproduct in the manufacture of other chemicals, especially [[acetic acid]]. This production is insufficient to meet the present demand for formic acid, and some formic acid must be produced for its own sake. When [[methanol]] and [[carbon monoxide]] are combined in the presence of a strong [[Base (chemistry)|base]], the formic acid derivative [[methyl formate]] results, according to the [[chemical equation]] :[[methanol|CH<sub>3</sub>OH]] + [[carbon monoxide|CO]] → [[methyl formate|HCOOCH<sub>3</sub>]] 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]]. [[Hydrolysis]] of the methyl formate produces formic acid: :[[methyl formate|HCOOCH<sub>3</sub>]] + [[water|H<sub>2</sub>O]] → HCOOH + [[methanol|CH<sub>3</sub>OH]] Direct hydrolysis of [[methyl formate]] requires a large excess of [[water]] to proceed efficiently, and some producers perform it by an indirect route by first reacting the methyl formate with [[ammonia]] to produce [[formamide]], and then hydrolyzing the formamide with [[sulfuric acid]] to produce formic acid: :[[methyl formate|HCOOCH<sub>3</sub>]] + [[ammonia|NH<sub>3</sub>]] → [[formamide|HCONH<sub>2</sub>]] + [[methanol|CH<sub>3</sub>OH]] :[[formamide|HCONH<sub>2</sub>]] + [[water|H<sub>2</sub>O]] + ½[[sulfuric acid|H<sub>2</sub>SO<sub>4</sub>]] → HCOOH + ½[[ammonium sulfate|(NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>]] This technique has problems of its own, particularly disposing of the [[ammonium sulfate]] byproduct, so some manufacturers have recently developed energy efficient means of separating formic acid from the large excess amount of water used in direct hydrolysis. In one of these processes (used by [[BASF]]) the formic acid is removed from the water via [[liquid extraction]] with an organic base. In the laboratory formic acid can be obtained by heating [[oxalic acid]] in anhydrous [[glycerol]] and extraction by steam distillation. Another preparation (which must be performed under a fume hood) is the acid [[hydrolysis]] of [[ethyl isonitrile]] using [[hydrochloric acid|HCl]] solution.<ref name="cohen">Cohen, Julius B.: ''Practical Organic Chemistry'' MacMillan 1930</ref> ::[[ethyl isonitrile|C<sub>2</sub>H<sub>5</sub>NC]] + 2[[water|H<sub>2</sub>O]] → [[ethyl amine|C<sub>2</sub>H<sub>5</sub>NH<sub>2</sub>]] + HCOOH The isonitrile being obtained by reacting [[ethyl amine]] with [[chloroform]] (note that the fume hood is required because of the overpoweringly objectionable odor of the isonitrile). ==Uses== The principal use of formic acid is as a [[preservative]] and [[bacterium|antibacterial]] agent in livestock feed. When sprayed on fresh [[hay]] or other [[silage]], it 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]]. In the [[poultry]] industry, it is sometimes added to feed to kill [[salmonella]] bacteria. Other uses: *It is used to process organic latex (sap) into raw [[rubber]]. *[[Beekeeper]]s use formic acid as a [[miticide]] against the Tracheal ([[Acarapis woodi]]) mite and the [[Varroa destructor|Varroa mite]]. *It is of minor importance in the [[textile]] industry and for the [[tanning]] of [[leather]]. *Some formate [[esters]] are artificial flavorings or perfumes. *It is the active ingredient in some brands of household [[limescale]] remover. *It is used in laboratories as a solvent modifier for [[HPLC]] separations of proteins and peptides, especially when the sample is being prepared for [[mass spectrometry]] analysis. *It is used by clinical pathology laboratories to disinfect [[prion]] activity in brain samples In [[organic synthesis|synthetic organic chemistry]], formic acid is often used as a source of [[hydride]] ion. The [[Eschweiler-Clarke reaction]] and the [[Leuckart-Wallach reaction]] are examples of this application. It is also used as a source of hydrogen in [[transfer hydrogenation]]. In the laboratory formic acid is also used as source for [[carbon monoxide]], which is set free by the addition of [[sulfuric acid]]. Formic acid is also a source for a [[formyl]] group for example in the [[formylation]] of methylaniline to N-methylformanilide in [[toluene]].<ref>''N-methylformanilide'', [[Organic Syntheses]], Coll. Vol. 3, p.590 (1955); Vol. 20, p.66 (1940). [http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv3p0590 Article]</ref> [[Formic acid fuel cell|Fuel cells that use modified formic acid]] are promising. ==History== As early as the 15th century, some [[alchemy|alchemists]] and [[natural history|naturalists]] were aware that ant hills gave off an acidic vapor. The first person to describe the isolation of this substance (by the distillation of large numbers of ants) was the [[England|English]] naturalist [[John Ray]], in 1671. Ants secrete the formic acid for attack and defense purposes. Formic acid was first synthesized from [[hydrocyanic acid]] by the [[France|French]] chemist [[Joseph Gay-Lussac]]. In 1855, another French chemist, [[Marcellin Berthelot]], developed a synthesis from [[carbon monoxide]] that is similar to that used today. In the chemical industry, formic acid was long considered a [[chemical compound]] of only minor industrial interest. In the late-1960s, however, significant quantities of it became available as a byproduct of [[acetic acid]] production. It now finds increasing use as a preservative and antibacterial in [[livestock]] feed. ==Safety== The principal danger from formic acid is from skin or eye contact with liquid formic acid or with the concentrated vapors. Any of these exposure routes can cause severe chemical burns, and eye exposure can result in permanent eye damage. Inhaled vapors may similarly cause irritation or burns in the respiratory tract. Since [[carbon monoxide]] may also be present in formic acid vapors, care should be taken wherever large quantities of formic acid fumes are present. The US [[Occupational Safety and Health Administration|OSHA]] Permissible Exposure Level ([[Permissible exposure limit|PEL]]) of formic acid vapor in the work environment is 5 parts per million parts of air ([[Parts per million|ppm]]). Formic acid is readily metabolized and eliminated by the body. Nonetheless, some chronic effects have been documented. Some animal experiments have demonstrated it to be a [[mutagen]], and chronic exposure may cause liver or kidney damage. Another possibility with chronic exposure is development of a skin [[allergy]] that manifests upon re-exposure to the chemical. The hazards of solutions of formic acid depend on the concentration. The following table lists the [[Directive 67/548/EEC|EU classification]] of formic acid solutions: {| class = "wikitable" ! [[Concentration]] ([[weight percent]]) ! Classification ! [[List of R-phrases|R-Phrases]] |- | 2%&ndash;10% | Irritant ('''Xi''') | {{R36/38}} |- | 10%&ndash;90% | Corrosive ('''C''') | {{R34}} |- | >90% | Corrosive ('''C''') | {{R35}} |- |} An [[assay]] 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.<ref>{{cite journal |journal= Biochem Med |date=1975 |volume=13 |issue=2 |pages=117–26 |title= Formate assay in body fluids: application in methanol poisoning |author= Makar AB, McMartin KE, Palese M, Tephly TR |doi=10.1016/0006-2944(75)90147-7 |pmid=1}}</ref> ==References== {{reflist|2}} ==External links== {{commons|Formic acid|Formic acid}} * [http://etd.rau.ac.za/theses/available/etd-09082004-124908/ Carbon monoxide as reagent in the formylation of aromatic compounds]. * [http://ecb.jrc.it/ European Chemicals Bureau]. * [http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc04/icsc0485.htm International Chemical Safety Card 0485]. * [http://www.cdc.gov/niosh/npg/npgd0296.html NIOSH Pocket Guide to Chemical Hazards]. [[Category:Formates]] [[Category:Carboxylic acids]] [[Category:Solvents]] [[ar:حمض فورميك]] [[bs:Metanska kiselina]] [[bg:Мравчена киселина]] [[ca:Àcid fòrmic]] [[cs:Kyselina mravenčí]] [[da:Myresyre]] [[de:Ameisensäure]] [[et:Metaanhape]] [[el:Μυρμηκικό οξύ]] [[es:Ácido fórmico]] [[eo:Formika acido]] [[fr:Acide méthanoïque]] [[ko:폼산]] [[hr:Mravlja kiselina]] [[id:Asam format]] [[is:Maurasýra]] [[it:Acido formico]] [[he:חומצה פורמית]] [[la:Acidum formicum]] [[lv:Skudrskābe]] [[hu:Hangyasav]] [[nl:Mierenzuur]] [[ja:ギ酸]] [[no:Maursyre]] [[nn:Maursyre]] [[pl:Kwas mrówkowy]] [[pt:Ácido metanóico]] [[ro:Acid formic]] [[qu:Sisi p'uchqu]] [[ru:Муравьиная кислота]] [[sk:Kyselina mravčia]] [[sl:Mravljinčna kislina]] [[su:Asam format]] [[fi:Muurahaishappo]] [[sv:Myrsyra]] [[th:กรดฟอร์มิก]] [[vi:Axít formic]] [[tr:Formik asit]] [[uk:Мурашина кислота]] [[zh:甲酸]]