Description
Molecular weight: 46.03 g/mol
pH: 2-3
Formic acid, also known as methanoic acid, is the simplest carboxylic organic acid. It occurs naturally in nettles and ant venom. Formic acid is a covalent substance, but its molecules can also bond with each other by hydrogen bonds. Its reactive properties can be attributed to the presence of the carboxyl group (-COOH). It can cause corrosion, especially to metals susceptible to acids (e.g. iron, zinc, magnesium) and has a pungent odor. It also has fungicidal properties. Formic acid also has the ability to act as a reducing agent and is one of the more reactive organic acids. Due to its reducing properties, formic acid plays a role in the reduction of silver salts to metallic silver, which is used in the production of mirrors. It is also used in the feed industry, household chemicals and other areas. It is classified as a dangerous substance with the number UN 1779 according to the ADR regulations.
On an industrial scale, formic acid is most often produced during the carbonylation reaction of methanol (CH₃OH) or formaldehyde (CH₂(OH)₂)), i.e. by treating one of these substances with carbon monoxide (CO). This reaction leads to the production of methyl formate (HCOOCH₃). Methyl formate is then hydrolyzed, which produces formic acid and methanol (as a by-product), which is later regenerated. Importantly, this reaction sometimes uses a catalyst such as cobalt or rhodium. Another common method of obtaining formic acid is the hydrolysis of formamide (CH₃NO), where hydrolysis is carried out in the presence of acids or base, which leads to the production of formic acid. Sometimes, for transport or storage purposes, formic acid is converted to sodium formate using sodium hydroxide. Then, when a strong acid (e.g. sulfuric acid H₂SO₄) is added, sodium formate is converted back to formic acid.
Because it is a weak acid, methanoic acid partially dissociates in water, releasing hydrogen ions (H⁺) and formate ions (HCOO⁻). Formic acid reacts with alcohols to form esters. It also undergoes oxidation reactions in the presence of various compounds to form carbon dioxide (CO2) and water.
