What is "oxalyl chloride"

n. (context organic compound English) An organic compound with the chemical formula (COCl)₂, the diacid chloride of oxalic acid, a useful reagent in organic synthesis.

Oxalyl chloride is a chemical compound with the formula (COCl). This colourless, sharp-smelling liquid, the di acid chloride of oxalic acid, is a useful reagent in organic synthesis. It can be prepared by treating oxalic acid with phosphorus pentachloride.