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The conformational behaviour of methylenecyclohexanes revisited

Title:

The conformational behaviour of methylenecyclohexanes revisited

Muchall, Heidi M. and Kamya, Petrina RN and Lessard, Jean (2003) The conformational behaviour of methylenecyclohexanes revisited. Canadian Journal of Chemistry, 81 (6). pp. 689-696. ISSN 0008-4042

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Official URL: http://dx.doi.org/10.1139/v03-083

Abstract

Conformational analyses on 2-substituted (methoxy, vinyloxy, and acetoxy) methylenecyclohexanes have been performed computationally with HF, B3LYP, PBE0, and MP2 and the 6-31G(d) basis set. The global minimum for the methoxy substituent is an axial conformer. For the vinyloxy substituent, except with PBE0, an axial conformer is determined as the global minimum. The acetoxy substituent prefers the equatorial orientation. This sequence is in keeping with the operation of an "unsaturation effect" in addition to an anomeric effect. For a full conformational analysis, torsional potentials for the substituents have been generated, which show further low-energy minima, which affect the equilibrium composition. In general, axial conformers dominate the equilibria. To reproduce the experimentally observed predominance of equatorial conformers for vinyloxy and acetoxy substituents, PBE0 has to be employed. CSGT isotropic shielding tensors at the B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level have been employed for comparison with experimentally observed 13C chemical shifts.

Divisions:Concordia University > Faculty of Arts and Science > Chemistry and Biochemistry
Item Type:Article
Refereed:Yes
Authors:Muchall, Heidi M. and Kamya, Petrina RN and Lessard, Jean
Journal or Publication:Canadian Journal of Chemistry
Date:June 2003
Funders:
  • Natural Sciences and Engineering Research Council of Canada
Keywords:conformational analysis, methylenecyclohexanes, anomeric effect, unsaturation effect
ID Code:6766
Deposited By:DANIELLE DENNIE
Deposited On:12 Jul 2010 16:51
Last Modified:08 Dec 2010 18:09
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