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The anionic chain process mechanism for reactions of perchlorofluoroethanes with nucleophiles in solution: a theoretical study
Author(s) -
Zhang ChengGen,
Huang MingBao
Publication year - 2007
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1128
Subject(s) - chemistry , exothermic reaction , solvation , endothermic process , nucleophile , polarizable continuum model , computational chemistry , exothermic process , hyperconjugation , polarizability , chain reaction , photochemistry , organic chemistry , ion , catalysis , molecule , adsorption
Anionic chain process mechanism (including reactions (1)–(4)) suggested by the experimental investigations for the reactions of nucleophile (CH 3 O − ) with perchlorofluoroethanes CF 2 ClCCl 3 ( 1 ), CF 2 ClCCl 2 F ( 2 ), and CF 3 CCl 3 ( 3 ) in solution is examined by performing calculations using the B3LYP method and the SCIPCM (self‐consistent isodensity polarizable continuum) model for simulating solution effects. The SCIPCM‐B3LYP calculations indicate that anionic species have large solvation energies and solvation energy values for different kinds of anions are quite different, which effects changes in ΔH's for the reactions in solution. Competition between anionic hyperconjugation and solvation leads to negative ΔH values for reactions (2) from 1 and 2 in solution. Reactions (3) and (4) from 1 , 2 , and 3 in solution are predicted to be exothermic or highly exothermic. Since the ΔH values for reactions (1) and (2) from 1 and 2 in solution are negative or small positive values, the reactions of CH 3 O − with 1 and 2 in solution proceed via the anionic chain process. For 3 in solution, reactions (1) and (2) are endothermic while reactions (3) and (4) are exothermic or highly exothermic. The reactions of CH 3 O − with 3 in solution may proceed via the anionic chain process. All these conclusions are in agreement with the experimental indications for reactions of nucleophiles with 1 , 2 , and 3 in solution. Copyright © 2007 John Wiley & Sons, Ltd.