Halogenation with N-haloamines in strong acids. II. Kinetics and rate constants

Authors: J. Spanswick, K. U. Ingold +1 more
Published: 15 Feb 1970
Journal: Canadian Journal of Chemistry
Volume: 48, Issue: 4, Pages: 554-560

TL;DR: The rate of reaction is proportional to the decanoic acid concentration and to the square root of the rate of chain initiation as discussed by the authors, and 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.

Abstract

The kinetics of the radical chain chlorination of decanoic acid by N-chlorodimethylamine and N-chloropiperidine in 2 and 4 M H2SO4 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 × 102 to 1 × 104 M−1 s−1 and the termination rate constant to be in the range 6 × 106 to 5 × 107 M−1 s−1.

Citations

1. Unexpected acid catalysis in reactions of peroxyl radicals with phenols.
   Luca Valgimigli, Riccardo Amorati, Silvia Petrucci, Gian Franco Pedulli, Di Hu, Jason J. Hanthorn, Derek A. Pratt +6 more
   Published: 19 Oct 2009
   Journal: Angewandte Chemie

TL;DR: Peroxyl radicals are highly reactive with phenols in the presence of weak organic acids. The reaction mechanism differs significantly from that without acid, with electron transfer from the phenol to the hydroperoxide radical being the rate-determining step.

2. Nucleophilic character of alkyl radicals. XIV. Homolytic δ‐aminoalkylation of protonated quinoxaline
   T. Caronna, Attilio Citterio, T. Crolla, M. Ghirardini, Francesco Minisci +4 more
   Published: 01 Oct 1976
   Journal: Journal of Heterocyclic Chemistry

TL;DR: In this paper, a general reaction of wide synthetic interest, involving homolytic δ-aminoalkylation of quinoxaline in an acidic medium, is described.

3. Homolytic δ-aminoalkylation of protonated quinoxaline by N-chloroamine
   Attilio Citterio, M. Ghirardini, Francesco Minisci +2 more
   Published: 01 Jan 1976
   Journal: Tetrahedron Letters

4. Synthetic Applications of the Polar Effects of the Substituents in Free-Radical Reactions
   Francesco Minisci
   Published: 01 Jan 1986

TL;DR: In this paper, the polar effects of free-radical reactions were investigated and shown to play a dominant role in free radical reactions when charged species are involved, and a charged radical is as much important as a charged substrate in determining the overall sensitivity to the polar effect.