Formic acid , systematically named methanoic acids , is the simplest carboxylic acid , and has the chemical formula H2CO2. It is an important intermediate in chemical synthesis and occurs naturally, particularly in some ants . The word “formic” comes from the Latin word for ant, formica , referring to its early isolation by distillation of ant bodies . The esters , salts and ions obtained from formic acid are called formate . Industrially, methanolFormic acid is produced from.
Property
Formic acid is a colorless liquid with a pungent, penetrating odor [5] at room temperature , comparable to that of the related acetic acid. It is miscible with water and most polar organic solvents, and is somewhat soluble in hydrocarbons. In the hydrocarbon and vapor phase, it consists of hydrogen-bonded dimers rather than individual molecules. [6] [7] Because of its tendency to hydrogen-bond, gaseous formic acids does not obey the ideal gas law. [7] Solid formic acid, which can exist in either of the two polymorphs, consists of an effectively endless network of hydrogen-bonded formic acid molecules. Formic acid forms a low boiling azeotrope with water (22.4%). Liquid formic acid tends to supercool.
natural phenomena
In nature, formic acid is found in most ants and stingless bees of the genus Oxytrigona . [8] [9] Wood ants of the genus Formica may spray formic acid on their prey or to protect the nest. Pus moth caterpillar ( Cerura vinula ) sprays it as well when threatened by predators. It is also found in the trichomes of stinging nettle ( Urtica dioica ). [10] Formic acid is a naturally occurring component of the atmosphere, mainly due to forest emissions. [11 1]
Production
In 2009, the worldwide capacity for formic acid production was 720 thousand tonnes (1.6 billion lb) per year, roughly equal to Europe (350 thousand tonnes or 770 million lb, mainly in Germany) and Asia (370 thousand tonnes or 820 million lb). million pounds). , mainly in China) while production in all other continents was less than 1 thousand tons, or 2.2 million pounds per year. [12] It is commercially available in solutions of various concentrations between 85 and 99 w/w%. [6] as of 2009The largest producers are BASF, Eastman Chemical Company, LC Industrial and Feicheng Acid Chemicals, with the largest production facilities in Ludwigshafen (200 thousand tons or 440 million pounds per year, BASF, Germany), Oulu (105 thousand tons or 230 million). . Pound, Eastman, Finland), Nakhon Pathom (N/A, LC Industrial), and Feicheng (100 thousand tons or 220 million pounds, Feicheng, China). 2010 prices ranged from about €650/tonne (equivalent to about $800/tonne) in Western Europe to $1250/tonne in the United States. [12]
from methyl formate and formamide
When methanol and carbon monoxide are combined in the presence of a strong base, the result is methyl formate, according to the chemical equation:
CH 3 OH + CO → HCO 2 CH 3
In industry, this reaction is carried out 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 methyl formate produces formic acid:
HCO 2 CH 3 + H 2 O → HCOOH + CH 3 OH
Efficient hydrolysis of methyl formate requires a large amount of water. Some routes from the first methyl form proceed indirectly by treating ammonia to give formamide, which is then hydrolyzed to sulfuric acid:
HCO 2 CH 3 + NH 3 → HC (O) NH 2 + CH 3 OH2 HC (O) NH 2 + 2 H 2 O + H 2 SO 4 → 2 HCO 2 H + (NH 4 ) 2 SO 4
One disadvantage of this approach is the need to dispose of the ammonium sulfate byproduct. This problem has prompted some manufacturers to develop energy-efficient methods for separating formic acid from excess water used in direct hydrolysis. In one of these processes, used by BASF, formic acid is removed from water by liquid-liquid extraction with an organic base.
Came chemical way
byproduct of acetic acid production
A significant amount of formic acids is produced as a byproduct in the manufacture of other chemicals. At one time, acetic acid was produced largely by the oxidation of alkanes, a process that yields the important formic acids. [ citation needed ] This oxidative pathway for acetic acid is decreasing in importance so that the above dedicated pathway for formic acids has become more important.
hydrogenation of carbon dioxide
The catalytic hydrogenation of CO 2 for formic acids has been studied for a long time. This reaction can be conducted homogeneously.
oxidation of biomass
Formic acids can also be obtained by aqueous catalytic partial oxidation of wet biomass by the OxFa process. [15] [16] A Keggin-type polyoxometalate (H 5 pv 2 Mo 10 O 40 ) converting sugars to formic acids and CO, used in wood, paper waste, or as homogeneous catalysts for cyanobacteria 2 sole byproducts In form of. Formic acids yields of up to 53% can be achieved. [ citation needed ]
laboratory methods
In the laboratory, formic acid can be obtained by heating oxalic acid in glycerol and extraction by steam distillation. [17] Glycerol acts as a catalyst, as the reaction proceeds through the glyceryl oxalate intermediate. If the reaction mixture is heated to a high temperature, allyl alcohol results. The net reaction is as follows:
C 2 O 4 H 2 → CO 2 H 2 + CO 2
Another example method involves the reaction between the lead He form and hydrogen sulfide, driven by the formation of lead sulfide.
Pb(HCOO) 2 + H 2 S → 2HCOOH + PbS
electrochemical production
It has been pointed out that Swarup may be formed by the Company of Power Shortage
2(as bicarbonate) at the lead cathode at pH 8.6:
HCO–3+ H2O + 2e – → HCO–2+ 2 Oh–
come on
CO2+ H2O + 2e – → HCO–2+ oh–
If feed CO2. Is and oxygen evolves at the anode, the total reaction is:
CO2+ oh–→ HCO–2+ 1/2 o 2
It has been proposed by various groups as a large-scale source of the format. [20] This format can be used as feed for E. coli bacteria modified to produce biomass . [21] [22] There exist natural microbes that can feed on formic acid or formate (see Methylotrophs).
Biosynthesis
Formic acids is named after ants whose venom contains high concentrations of the compound. In ants, formic acids is derived from serine via a 5,10-methylenetetrahydrofolate intermediate. [23] The conjugate base of formic acids, formate, is also found widely in nature. An assay for formic acids in body fluids, designed for the determination of formate following methanol poisoning, is based on the reaction of formate with bacterial formate dehydrogenase.
artificial photosynthesis
In August 2020 researchers at the University of Cambridge announced a stand-alone advanced ‘photosheet’ technology that converts sunlight, carbon dioxide and water into oxygen and formic acids without any other inputs. [25]
Use
A major use of formic acids is as a preservative and antibacterial agent in animal feed. In Europe, it is applied to silage, including fresh hay, to promote fermentation of lactic acid and to suppress the formation of butyric acid; This allows fermentation to take place quickly and at a lower temperature, minimizing the loss of nutritional value. [6] Formic acids inhibits some decay processes and causes feed to retain its nutritive value longer, and is therefore widely used to preserve winter feed for cattle. [26] In the poultry industry, it is sometimes added to feed to kill the E. coli bacteria. [27] [28]Use as a preservative for silage and (other) animal feed accounted for 30% of global consumption in 2009. [12]
Formic acid is also used significantly in the production of leather, including tanning (23 % of global consumption in 2009 [12] and in finishing textiles, and dyeing) (9 % of global consumption in 2009 [12] ) because from its acidic nature. Use as a coagulant in the production of rubber [6] consumed 6% of global production in 2009. [12]
Formic acids is also used in place of mineral acids for various cleaning products, [6] such as limescale removers and toilet bowl cleaners. Some formate esters are artificial flavors and perfumes.
Beekeepers use formic acids as a miticide against the hose mite ( Acarapis woodi ) and the Varroa mite mite and Varroa jacobsoni mite. [29]
The use of formic acids for warts has been reported to be an effective treatment. [30]
Formic acids can be used in fuel cells (it can be used directly in formic acids fuel cells and indirectly in hydrogen fuel cells). [31] [32]
CO. It is possible to use formic acids as an intermediary to produce isobutanol from
2The use of microbes [33] [34] [35]
Formic acid has a potential application in soldering, due to its ability to reduce oxide layers, formic acids gas can be blasted onto the oxide surface to increase solder wettability.
Formic acids is often used as a component of the mobile phase in reverse-phase high-performance liquid chromatography (RP-HPLC) analysis and separation techniques for the separation of more complex structures including hydrophobic macromolecules, such as peptides, proteins and intact viruses. goes. Particularly when combined with mass spectrometry detection, formic acids offers several advantages over the more traditionally used phosphoric acid. [36] [37]
chemical reaction
Formic acids is about ten times stronger than acetic acids. It is used as a volatile pH modifier in HPLC and capillary electrophoresis.
Formic acids is a source for the formyl group for example in the formylation of methylaniline to N-methylformanilide in toluene. [38]
In synthetic organic chemistry, formic acids is often used as the source of the hydride ion. The Eschweiler-Clark reaction and the Leuckart-Wallach reaction are examples of this application. It, or more commonly with its azeotrope triethylamine, is also used as a source of hydrogen in transfer hydrogenation.
As mentioned below, formic acid readily decomposes with concentrated sulfuric acid to form carbon monoxide.
CH 2 O 2 + H 2 SO 4 → H 2 SO 4 + H 2 O + CO
reactions
Formic acids shares most of the chemical properties of other carboxylic acids. Due to its high acidity, solutions in alcohol spontaneously form esters. Formic acid shares some of the reducing properties of aldehydes, reducing solutions of metal oxides to their respective metal. [39]
rot
Heat and especially acids decompose formic acids to carbon monoxide (CO) and water (dehydration). Treatment of formic acids with sulfuric acids is a convenient laboratory source of CO.
In the presence of platinum, it decomposes with the release of hydrogen and carbon dioxide.
CH 2 O 2 → H 2 + CO 2
Soluble ruthenium catalysts are also effective. [42] [43] Carbon monoxide free hydrogen is generated over a very wide pressure range (1–600 bar). [42] Formic acid has been considered as a means of hydrogen storage. [44] The by-product of this decomposition, carbon dioxide, can be re-hydrogenated back into 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 that of compressed hydrogen gas at 350 bar pressure (14.7 g/L). Pure formic acid is a liquid with a flash point of +69 °C, significantly higher than that of gasoline (-40 °C) or ethanol (+13 °C). [ citation needed ]
other than alkynes
Formic acid is unique among carboxylic acids in its ability to participate in addition reactions with alkanes. Formic acid and alkanes readily react to form esters. In the presence of some acids, including sulfuric and hydrofluoric acids, however, a type of Koch reaction occurs, and formic acid adds to the alkene to produce a larger carboxylic acid. [45]
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 temperatures. [46]
history
Some alchemists and naturalists were aware that ant hills release an acidic vapor as early as the 15th century. The first person to describe the isolation of this substance (by distillation of large numbers of ants) was the English naturalist John Ray in 1671. [47] [48] Ants secrete formic acid for attack and defense purposes. Formic acid was first synthesized from hydrocyanic acid by the French chemist Joseph Gay-Lussac. In 1855, another French chemist, Marcellin Berthelot, developed a synthesis from carbon monoxide similar to the process used today.
Formic acid was long considered a chemical compound of only minor interest in the chemical industry. In the late 1960s, however, acetic acid became available in significant quantities as a byproduct of production. It now finds increasing use as a preservative and antibacterial in animal feed.
Security
Formic acid has low toxicity (hence its use as a food additive), with an LD50 of 1.8 g/kg (tested orally on rats). Concentrated acid is corrosive to the skin. [6]
Formic acid is easily metabolized and eliminated by the body. However, it has specific toxic effects; Formic acid and formaldehyde produced as metabolites of methanol are responsible for optic nerve damage, leading to blindness, which is seen in methanol poisoning. [49] Few chronic effects of formic acid exposure have been documented. Some experiments on bacterial species have shown it to be a mutagen. [50] Long-term exposure in humans can cause kidney damage. [50] Another possible effect of chronic exposure is the development of skin allergies that appear upon re-exposure to the chemical.
Concentrated formic acid slowly decomposes into carbon monoxide and water, creating pressure in the vessel. For this reason, 98% formic acid is shipped in plastic bottles with self-venting caps.
The dangers of formic acid solutions depend on the concentration. The following table lists the European Union classification of formic acid solutions:
| Concentration (Weight Percentage) | classification | r phrases |
|---|---|---|
| २-१०% | Hitch ( XI ) | R36/38 |
| १०-९०% | corrosive ( C ) | R34 |
| > 90% | corrosive ( C ) | R35 |
Formic acid is flammable in 85% concentrations, and dilute formic acid is on the US Food and Drug Administration list of food additives. [51] The main danger from formic acid is contact with the skin or eyes with concentrated liquids or vapors. The US OSHA permissible exposure level (PEL) of formic acid vapor in the work environment is 5 parts per million (ppm) of air.
