Formic acid is the simplest carboxylic acid and has a formula of HCOOH. It has a pungent and penetrating odour at room temperature. It is also miscible with water and most polar organic solvents but immiscible in non-polar solvents.
Formic acid can be found in the venom of ants. It can undergo a series of organic reactions to form other relevant organic compounds, such as with alcohol to form esters, reduction to form aldehydes, decomposition to form carbon dioxide and water, and reaction with sulfuric acid to yield carbon monoxide.
1. Hydrolysis of Methyl Formate
Formic acid can be manufactured with the reaction of methanol and carbon monoxide, in the presence of a strong base such as sodium methoxide. The methyl formate formed is then hydrolyzed to yield formic acid and regenerate methanol. With the regeneration of methanol, only a catalytic amount of methanol is required for the whole manufacturing process.
CH3OH + CO → HCO2CH3
HCO2CH3 + H2O → HCO2H + CH3OH
2. By-Product of Acetic Acid Production
Formic acid is also a by-product from the manufacturing of acetic acid. When acetic acid is manufactured via the acetaldehyde oxidation method, butane is oxidized, and ethylene is hydrated via Wacker process to obtain acetaldehyde. Further oxidation of acetaldehyde yields acetic acid, with significant amount of formic acid as by-product.
Formic acid can also be formed from the hydrogenation of carbon dioxide or by heating oxalic acid in glycerol catalyst and extraction by steam distillation. Alternatively, oxidation of biomass such as sugars, wood and waste paper can yield formic acid and carbon dioxide.
Formic acid is also used as a preservative and antibacterial agent in livestock feed. In Europe, it is applied on silage to promote the fermentation of lactic acid and to suppress the formation of butyric acid. 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.
Textile & Dyeing Industry
Formic acid is used in dyeing and dye fixing, setting and retaining colors in fibers. Due to its acidic nature, it is also used as a neutralizing agent and pH adjuster in textile processing and finishing of textile, as effective and accurate pH control is required throughout the whole process of dyeing, processing and finishing.
Formic acid has a wide range of uses. It is used as a miticide, to kill tracheal mite. It is used instead of mineral acids in some cleaning products such as lime scale remover and toilet cleaners. Its esters are used in the making of perfumes. It is also used in fuel cells, but it is still under study. It is used as a coagulant in rubber production. It is used in leather tanning and production. It is also added to animal fodder in the poultry industry, as it kills the E-coli.