Inter- and Intramolecular Mechanisms for Chlorine Rearrangements in Trimethyl-Substituted N-Chlorohydantoins

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• 作者：Billy W. McCann ; Hao Song ; Hasan B. Kocer ; Idris Cerkez ; Orlando Acevedo ; S. D. Worley
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：July 5, 2012
• 年：2012
• 卷：116
• 期：26
• 页码：7245-7252
• 全文大小：453K
• 年卷期：v.116,no.26(July 5, 2012)
• ISSN：1520-5215

文摘

The antimicrobial compounds 1-chloro-3,5,5-trimethylhydantoin and 3-chloro-1,5,5-trimethylhydantoin (<b>1b> and <b>2b>, 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 <b>2b> to be less stable than <b>1b>. 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 <b>2b> to possess a lower free energy of activation, 螖G^{鈥?/sup>, relative to <b>1b> in accordance with the experimental stability measurements. However, the intermolecular route had an overall lower absolute 螖G鈥?/sup> 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.}