Unique feature of chain reactions of thiols with quinone imines: thiols as reactants and simultaneously catalysts at the rate-determining step of chain propagation

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• 作者：V. T. Varlamov ; B. E. Krisyuk
• 关键词：Key wordsquinone imines ; thiyl radicals ; radical adduct ; isomerization ; thiophenol ; molecular catalysis ; quantum chemical calculations ; DFT/PBE and CCSD levels
• 刊名：Russian Chemical Bulletin
• 出版年：2016
• 出版时间：February 2016
• 年：2016
• 卷：65
• 期：2
• 页码：401-406
• 全文大小：290 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Chemistry
  Organic Chemistry
  Inorganic Chemistry
  Russian Library of Science
  
• 出版者：Springer New York
• ISSN：1573-9171
• 卷排序：65

文摘

The isomerization of radical adducts, formed due to the addition of thiyl radicals to the cyclohexadiene ring of quinone imine, to phenoxyl and aromatic aminyl radicals is considered by quantum chemical methods (DFT/PBE and CCSD). Isomerization via the intramolecular transfer of the highly mobile H atom of the C—H bond to the O or N atoms from the position of PhS• radical addition to the cyclohexadiene ring of quinone imine cannot virtually occur because of the high activation energy comparable or even exceeding the C—H bond dissociation energy. An alternative bimolecular mechanism involving the thiol molecule, which is inserted into the transition state thus extending it to be favorable for the reaction to occur, was proposed. After the reaction, the thiol is regenerated, i.e., acts as both the reactant and catalyst of the chain reaction of quinone imine with thiol. The reasons for the high rate of the H atom transfer via this mechanism are considered.