Halogenation with <i>N</i>-haloamines in strong acids. II. Kinetics and rate constants

Abstract

The kinetics of the radical chain chlorination of decanoic acid by N-chlorodimethylamine and N-chloropiperidine in 2 and 4 M H 2 SO 4 in acetic acid have been examined at 30°. The rate of reaction is proportional to the decanoic acid concentration and to the square root of the rate of chain initiation. The rate controlling step for propagation involves the attack of an aminium radical on decanoic acid, and termination involves the self-reaction of two aminium radicals. The latter reaction may involve the prior, rapid deprotonation of one or both radicals. The propagation rate constant has been estimated to be in the range 7 × 10 2 to 1 × 10 4 M −1 s −1 and the termination rate constant to be in the range 6 × 10 6 to 5 × 10 7 M −1 s −1 .