Reactions between protonated and neutral methanol in the gas-phase: an ab initio molecular orbital study

✍ Scribed by Guy Bouchoux; Nadège Choret

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 230 KB
• Volume: 11
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19971030)11:16<1799::aid-rcm61>3.0.co;2-4

✦ Synopsis

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.