Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10558190 | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2005 | 9 Pages |
Abstract
1H NMR data show that an increase in the concentration of cis-3-methoxycyclohexanol (cis-3-MCH) shifts the conformational equilibrium from the 1aa conformer, stabilized by an intramolecular hydrogen bond (IAHB), to the 1ee conformer [Xee = 44% (at 0.05 mol Lâ1) to 59% (at 0.40 mol Lâ1), in CCl4], which forms intermolecular hydrogen bonds (IEHB), as confirmed by IR data. The percentage of 1ee conformer increases with the solvent polarity, from 33% (ÎGee-aa = 1.72 kJ molâ1) in cyclohexane (C6D12) to 97% (ÎGee-aa = â8.41 kJ molâ1) in DMSO. For trans-3-methoxycyclohexanol (trans-3-MCH), 1ae and 1ea conformers are almost equally present in the studied solvents, 1ae increasing from 41%, in C6D12 (ÎGae-ea = 0.84 kJ molâ1), to 49%, in DMSO (ÎGae-ea = 0.13 kJ molâ1). A value of 18.4 kJ molâ1 for the strength of IAHB in cis-3-MCH was obtained, from the theoretical data, through the CBS-4M method.
Keywords
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Paulo R. de Oliveira, Roberto Rittner,