Acetic formic anhydride is an organic compound with the chemical formula, which can be viewed as the mixed anhydride of acetic acid and formic acid. It is used on a laboratory-scale as a formylating agent.[1]
Acetic formic anhydride can be produced by reacting sodium formate with acetyl chloride in anhydrous diethyl ether between 23–27 °C.[2] It can also be prepared by the reaction of acetic anhydride and formic acid at 0 °C.
While more stable than formic anhydride, acetic formic anhydride is thermally unstable and gradually decomposes above about 60 °C, with the evolution of carbon monoxide.[3] Impurities such as pyridine or residual acid can promote this, resulting in decomposition commencing as low as 0 °C. Crude material has been successfully purified by distillation at ≤30 °C under reduced pressure.
Acetic formic anhydride is a formylation agent for amines, amino acids, and alcohols. It is also a starting material for other compounds such as formyl fluoride.[2]