The reaction of bromine with cyclohexene in carbon tetrachloride. Part 1. Reactions in the absence of hydrogen bromide; presence of a scavenger

Abstract

The addition of bromine to cyclohexene in carbon tetrachloride solutions has been studied. Results are unreproducible, but when N-bromosuccinimide or N-bromophthalimide is also present to scavenge hydrogen bromide, a slower reaction, second-order in bromine, with reproducible rate constants is observed. This shows a negative overall activation energy. There may be terms in higher powers of [Br₂], but the first-order term in bromine is too small to measure. A faster second phase of the reaction begins when all the N-bromo-imide initially present has reacted with the hydrogen bromide formed in side reactions, including those leading to 3-bromocyclohexene and (from adventitious water) to 2-bromocyclohexanol, and is of order 1.5 in bromine.