Abstract��
In preparation of 1 chloropinacolone(1 chloro 3,3 dimethy1 2 butanone) by chlorination of pinacolone in methanol, the reaction mixture may vigorously bump sometimes.The reason is that the system (usually in methanol) is contaminated by small amount of water. Under this chlorination condition,water reacts with chlorine via hypochloric acid to form very unstable chloric acid. The decomposition of chloric acid results in bumping under certiain condition.Water limitation for safety operation is estimated.Observations of the impact of some metals and salts have been made. The method of predisposition of methanol and decomposition of water in it is put forward.