Inter- and intramolecular mechanisms for chlorine rearrangements in trimethyl-substituted N-chlorohydantoins

Billy W. McCann, Hao Song, Hasan B. Kocer, Idris Cerkez, Orlando Acevedo, S. D. Worley

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

The antimicrobial compounds 1-chloro-3,5,5-trimethylhydantoin and 3-chloro-1,5,5-trimethylhydantoin (1 and 2, respectively) have been synthesized and examined via a joint experimental and computational study. The measured rate of loss of oxidative chlorine in the absence and presence of exposure to UVA irradiation determined 2 to be less stable than 1. An interesting migration reaction was observed during UVA irradiation that featured the production of chlorine rearrangement and dechlorinated compounds. Two novel hydrogen atom transfer reaction (HATR) mechanisms have been proposed: (1) an intramolecular process in which a hydrogen atom undergoes a series of sigmatropic shifts, and (2) an intermolecular pathway in which a radical abstracts a hydrogen atom from a neighboring molecule. Density functional theory (DFT) calculations at the UB3LYP/6-311G++(2d,p) theory level have been employed to elucidate the preferred reaction pathway. Both proposed HATR mechanisms predicted 2 to possess a lower free energy of activation, ΔG , relative to 1 in accordance with the experimental stability measurements. However, the intermolecular route had an overall lower absolute ΔG and was more consistent with measured product ratios in solution. The intermolecular reaction pathway, unlike the intramolecular route, also predicted the lack of formation of a migration product featuring a Cl covalently bonded to a methylene group at the 5-position of the hydantoin moiety, which was verified by NMR experiments.

Original languageEnglish (US)
Pages (from-to)7245-7252
Number of pages8
JournalJournal of Physical Chemistry A
Volume116
Issue number26
DOIs
StatePublished - Jul 5 2012
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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