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Reactions between protonated and neutral methanol in the gas‐phase: an ab initio molecular orbital study
Author(s) -
Bouchoux Guy,
Choret Nadège
Publication year - 1997
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(19971030)11:16<1799::aid-rcm61>3.0.co;2-4
Subject(s) - chemistry , protonation , gas phase , ab initio , computational chemistry , molecular orbital , methanol , molecule , organic chemistry , ion
Ab initio molecular orbital calculations at the MP2/6‐31G*//MP2/6‐31G* + ZPE level have been performed in order to explore the reaction between CH 3 OH 2 + and CH 3 OH. The detailed mechanism of proton transfer, CH 3 OH 2 + + CH 3 OH → CH 3 OH + CH 3 OH 2 + , and of cationic nucleophilic substitution, CH 3 OH 2 + + CH 3 OH → (CH 3 ) 2 OH + + H 2 O has been investigated. The former reaction involves a symmetric proton bound dimer, I, [CH 3 OH a ‐‐‐H b ‐‐‐H c OCH 3 ] + , in which exchange of the three hydrogens H a,b,c is allowed (critical energy ca . 50 kJ mol −1 . The nucleophilic substitution process involves two ion neutral complexes II, [CH 3 O(H)‐‐‐CH 3 OH 2 ] + , and III, [CH 3 OHC(H 3 )‐‐‐OH 2 ] + , only weakly stable toward isomerization. The methyl cation transfer II → III is calculated to require 28 kJ mol −1 . The proposed reaction profile supports and completes the previous theoretical and experimental studies on this system. © 1997 John Wiley & Sons, Ltd.