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Impact of Water Molecules on the Isomerization of CH 3 S(OH)CH 2 to CH 3 S(O)CH 3 : A Computational Investigation
Author(s) -
Jia Cao,
Wang Wenliang,
Zhang Tianlei,
Gao Loujun,
Fu Feng,
Wang Danjun
Publication year - 2013
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.201300410
Subject(s) - isomerization , chemistry , reaction rate constant , catalysis , molecule , transition state theory , photochemistry , transition state , computational chemistry , kinetics , organic chemistry , physics , quantum mechanics
The isomerization of CH 3 S(OH)CH 2 to CH 3 S(O)CH 3 in the absence and presence of water has been investigated at the G3XMP2//B3LYP/6‐311+G(2df,p) level. The naked isomerization, the reaction without water, gives the high barrier height (21.56 kcal·mol −1 ). Three models are constructed to describe the water influence on the isomerization, that is, water molecules are the catalyst and the microsolvation, and water molecules act as the catalyst and microsolvation simultaneously. Our results show that the isomerization barrier heights of CH 3 S(OH)CH 2 to CH 3 S(O)CH 3 are reduced by 12.32, 11.04, and 7.80 kcal·mol −1 , respectively, when one, two, and three water molecules are performed as catalyst, in contrast to the naked isomerization. Moreover, the rate constants of the isomerization are calculated using the transition state theory with the Wigner tunneling correction over the temperature range of 240–425 K. We find that the rate constant of a single water molecule as the catalyst is 1.58 times larger than the naked isomerization at 325 K, whereas it is slower by 6 orders of magnitude when water molecule serves as the microsolvation at 325 K, compared to naked reaction. So the water‐catalyzed isomerization of CH 3 S(OH)CH 2 to CH 3 S(O)CH 3 is predicted to be the key role in lowering the activation energy. The isomerization involving water molecules acting as microsolvation is unfavorable under atmospheric conditions.