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Theoretical investigation of ion pair S N 2 reactions of alkali isothiocyanates with alkyl halides. Part 1. Reaction of lithium isothiocyanate and methyl fluoride with inversion mechanism
Author(s) -
Zhu HuaJie,
Ren Yi,
Ren Jie,
Chu SanYan
Publication year - 2004
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.20213
Subject(s) - chemistry , sn2 reaction , thiocyanate , ionic bonding , ion , halide , reaction mechanism , lithium (medication) , alkali metal , isothiocyanate , alkyl , photochemistry , computational chemistry , inorganic chemistry , medicinal chemistry , organic chemistry , catalysis , medicine , endocrinology
The gas‐phase ionic S N 2 reactions NCS ‐ + CH 3 F and ion pair S N 2 reaction LiNCS + CH 3 F with inversion mechanism were investigated at the level of MP2(full)/6‐311+G**//HF/6‐311+G**. Both of them involve the reactants complex, inversion transition state, and products complex. There are two possible reaction pathways in the ionic S N 2 reaction but four reaction pathways in the ion pair S N 2 reaction. Our results indicate that the introduction of lithium significantly lower the reaction barrier and make the ion pair displacement reaction more facile. For both ionic and ion pair reaction, methyl thiocyanate is predicted to be the major product, but the latter is more selective. More‐stable methyl isothiocyanate can be prepared by thermal rearrangement of methyl thiocyanate. The theoretical predictions are consistent with the known experimental results. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005