Hydration effects on the reaction with an open-shell transition state: QM/MM-ER study for the dehydration reaction of alcohol in hot water

Hideaki Takahashi, Fumihiro Miki, Hajime Ohno, Ryohei Kishi, Suguru Ohta, Shin ichi Furukawa, Masayoshi Nakano

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

The reaction mechanism for the dehydration of 1,4-butanediol in hot water has been investigated by means of the hybrid quantum mechanical/molecular mechanical approach combined with the theory of energy representation (QM/MM-ER). We have assumed that the proton transfers along the hydrogen bonds of the water molecules catalyze the reaction, where the transition state (TS) forms a singlet biradical electronic structure. It has been revealed by the simulation that the biradical electronic state at the TS changes to zwitterionic structure in solution due to the hydration of the polar solvent. Such the electronic structure change gives rise to the substantial stabilization of the TS in hot water. As a result, the water-catalytic path becomes more favorable in aqueous solution than another possible path that proceeds without proton transfers as opposed to the reaction mechanism in the gas phase. Furthermore, the activation free energy computed by the present method is in excellent agreement with the experimental result.

Original languageEnglish
Pages (from-to)781-794
Number of pages14
JournalJournal of Mathematical Chemistry
Volume46
Issue number3
DOIs
Publication statusPublished - 2009 Aug
Externally publishedYes

Keywords

  • Free energy
  • QM/MM
  • Real-space grids
  • Theory of energy representation
  • Water solution

ASJC Scopus subject areas

  • Chemistry(all)
  • Applied Mathematics

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