Acetyl hypochlorite

Preparation, properties, and structure

Acetyl hypochlorite is reported to be produced by the reaction of acetic anhydride and dichlorine monoxide at very low temperatures:

Cl₂O + (CH3CO)₂O → 2CH₃COOCl

The liquid can be distilled at reduced pressure, however it cannot be heated, as it violently decomposes at 100 °C to acetic anhydride, oxygen, and chlorine gas, and reacts with water and alcohols. This is a problem in the Hunsdiecker reaction, as it results in a lower yield from the decomposition of this compound if using water or an alcohol as a solvent, so the reaction uses the nonpolar carbon tetrachloride instead. The compound must be stored under 0 °C in the dark, as it slowly decomposes in the presence of light or above 0 °C into methyl chloride and carbon dioxide.

This compound reacts with various metals such as zinc and mercury to produce their respective chlorides and acetates.

In modern uses, the compound is usually prepared in situ, by the reaction of mercury acetate or acetic acid and chlorine or hypochlorous acid, usually in a solvent such as carbon tetrachloride. The compound is in equilibrium with a mixture of acetic acid and hypochlorous acid.

The carbonyl oxygen and the hypochlorite ion were shown to be on the same side. The O-Cl bond was shown to be 1.70 Å, and the molecular geometry around the central carbon was trigonal planar.