Radical addition reactions: factors determining the transition-state geometry

详细信息    查看全文

• 作者：E. T. Denisov
• 关键词：alkyl ; alkoxyl ; and aminyl radicals ; hydrogen atom ; acetylene ; carbonyl compound ; transition ; state geometry ; quantum chemistry ; model of intersecting parabolas ; olefin ; radical addition ; force constant of a chemical bond ; triplet repulsion ; electronegativity of atoms ; activation energy ; enthalpy of reaction
• 刊名：Russian Chemical Bulletin
• 出版年：2005
• 出版时间：April 2005
• 年：2005
• 卷：54
• 期：4
• 页码：914-923
• 全文大小：251 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

文摘

Interatomic distances in the reaction centers of the addition reactions of (i) H· to the C=C, C=O, N≡C, and C≡C bonds, (ii) ·CH₃ radical to the C=C, C=O, and C≡C bonds, and (iii) alkyl, aminyl, and alkoxyl radicals to olefin C=C bonds were determined using a new semiempirical method for calculating transition-state geometries of radical reactions. For all reactions of the type X· + Y=Z → X— Y—Z· the r # _X...Y distance in the transition state is a linear function of the enthalpy of reaction. Parameters of this dependence were determined for seventeen classes of radical addition reactions. The bond elongation, Δr # _X...Y, in the transition state decreases as the triplet repulsion, electronegativity difference between the atoms X and Y in the reaction center, and the force constant of the attacked multiple bond increase.