Theoretical Studies on the Gas-Phase Alkylation of Delocalized Ambident Anions with Methyl Fluoride

Title
Theoretical Studies on the Gas-Phase Alkylation of Delocalized Ambident Anions with Methyl Fluoride
Authors
Lee, BS.; Kim, CK.
Keywords
INTRINSIC BARRIERS, NONPERFECT SYNCHRONIZATION
Issue Date
1999-05
Publisher
KOREAN CHEMICAL SOC
Abstract
were X, Y=CH2, O, or S, have been investigated theoretically at the MP2/6-31+G*//MP2/6-31+G* and QCISD/6-31+G*//MP2/6-31+G* levels. O- and S-alkylations (X=O and S) are more favored kinetically by Delta E-not equal = 4.6 and 9.8 kcal mol(-1) than the respective C-alkylations even though they are thermodynamically less favored by 22.4 and 6.0 kcal mol(-1) respectively. It was found that the transition structures for the C-alkylations are imbalanced due to the endoergic rehybridization of the carbon center from sp(2) to sp(3) which leads to premature bond contraction of the C-Y bond and delayed bond stretching of the C-X bond. In the O-, or S-alkylation, such endoergic process is not required since the sigma-lone pair on O or S is involved in the initial stage of alkylation. The imbalanced TSs for the C-alkylation are accompanied by higher intrinsic barriers and deformation energies.
URI
http://dspace.inha.ac.kr/handle/10505/20394
ISSN
0253-2964
Appears in Collections:
College of Natural Science(자연과학대학) > Chemistry (화학) > Journal Papers, Reports(화학 논문, 보고서)
Files in This Item:
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