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DFT studies of homogeneous catalysis in the gas phase: Dehydration kinetics of several tertiary alcohols with hydrogen chloride
Author(s) -
Mora Jose R.,
Marquez David J.,
Marquez Edgar,
Loroño Marcos,
Cordova Tania,
Chuchani Gabriel
Publication year - 2012
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.23145
Subject(s) - chemistry , catalysis , hydrogen chloride , transition state , natural bond orbital , van der waals force , medicinal chemistry , alcohol , computational chemistry , hydrogen bond , molecule , density functional theory , organic chemistry
The mechanisms for the acid‐catalyzed gas‐phase dehydration of the tertiary alcohols 2‐methyl‐2‐propanol, 2‐methyl‐2‐butanol, and 2‐methyl‐2‐pentanol were examined at B3LYP/6‐31G(d), B3LYP/6‐31G(d,p), B3LYP/6‐31G(2d,p), B3LYP/6‐31G(2d,2p), B3PW1/6‐31G(d), B3PW1/6‐31G(d,p), B3PW1/6‐31G(2d,p), B3PW1/6‐31G(2d,2p), MPW91PW91/6‐31G(d), MPW91PW91/6‐31G(d,p), MPW91PW91/6‐31G(2d,p), and MPW91PW91/6‐31G(2d,2p) levels of theory. Calculation results suggest that the dehydration processes catalyzed by hydrogen chloride to give the corresponding olefin and water occur with the formation of Van der Waals complexes between the alcohol and hydrogen chloride. The transition states are six‐membered cyclic structures involving one molecule of HCl and one of the alcohol. These reactions appear to be molecular in nature. Analysis of the progress along the reaction coordinate, in terms of bond orders, NBO charges, and geometrical parameters suggest these reactions to be moderately polar and nonsynchronous and are dominated by the breaking of the HCl bond, together with an important cleavage of CO bond in the transition state. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2012