Acetic formic anhydride, or ethanoic methanoic anhydride is a chemical compound with formula C3H4O3, or H3C-(C=O)-O-(C=O)H. It can be viewed as the mixed anhydride of acetic acid (H3C- (C=O)OH) and formic acid (H(C= O)OH) by removal of a molecule of water.
It can be produced by reaction between sodium formate and acetyl chloride in anhydrous diethyl ether, at 23–27 °C.Among other uses, it is a formylation agent for amines, amino acids, and alcohols, and a starting material for formyl fluoride.
Formyl acetate is a useful formylating agent for the hydroxyl, phenol, and amine groups as well as other heteroatoms; useful for the synthesis of aldehydes from aromatic Grignard reagents, for the preparation of formyl fluoride, and for the preparation of diazoacetaldehyde.
Preparative Methods of Formyl acetate: acetic formic anhydride is not comercially available. The easiest method of preparation is by the reaction of sodium formate and Acetyl Chloride in dry ether as reported by Krimen. Alternatively, Ketene and Formic Acid form the title compound at room temperature or below. Acetic formic anhydride can be prepared rapidly in situ by stirring formic acid, acetyl chloride, and Triethylamine in THF at -70 °C for 10 min. AFA is found in a mixture of formic acid (excess) with Acetic Anhydride. The mixture is more accurately described as formic acid-acetic anhydride mixture (FAM) and is also used as a formylating agent. Purification: by fractional distillation at low pressure.
Handling, Storage, and Precautions of formyl acetate: it decomposes slowly at room temperature and faster at elevated temperatures, giving acetic acid and carbon monoxide. Due to gas evolution, AFA is best stored at 4 °C in a flask fitted with a polyethylene stopper since sealed samples can explode. The compound is an eye and skin irritant and should be handled in a fume hood.
