Formate

Formate (also known as methanoate) is a salt or ester of formic acid. It is also an ion of formic acid. It is formed when formic acid dissolves in water (which splits into a formate anion and a hydron). The chemical formula is HCOO^- (also written as HCO₂^-) as an ion itself. Formate salts and esters are usually colourless.

Formate anion structure (the dashed line means there is a resonance). The white ball is a hydrogen atom, the red balls are oxygen atoms, and the black (or gray) ball is a carbon atom.

Formate esters

Formate esters have the chemical formula HCOOR (where R is an organic group like an alkyl or aryl group). It is made when formic acid reacts with an alcohol to make a formate ester and water.

The reaction between formic acid and ethanol gives ethyl formate and water:

HCOOH + CH₃OH ⇌ HCOOC₂H₅ + H₂O

Formate salts

Formate salts are made when formic acid reacts with a base (like sodium hydroxide).

The reaction between formic acid and sodium hydroxide gives sodium formate and water:

HCOOH + NaOH —> HCOONa + H₂O

Examples

• methyl formate: HCOOCH₃
• ethyl formate: HCOOC₂H₅
• sodium formate: HCOONa
• potassium formate: HCOOK

Related pages

• Acetate
• Carboxylate
• Carboxylic acid