DICYCLOHEXYLETHYLENEGLYCOL, DICYCLOHEXYLDIETHYLENEGLYCOL, DICYCLOHEXYLTRIETHYLENEGLYCOL, AND RELATED MONOSUBSTITUTED CYCLOHEXANES - CONFORMATIONAL-ANALYSIS USING LOW-TEMPERATURE C-13 AND H-1-NMR SPECTROSCOPY

Two conformations of each of the title molecules have been detected by 100 MHz C-13 NMR at 210 K. For the dicyclohexyl systems, the conforma tions are related via a single ring inversion. In each case the equato rial-axial conformer is 4.7 +/- 0.4 kJ/mol less stable than the diequa torially substituted form in CD,CI, solution. For monosubstituted mode ls, the conformational free energy (-Delta G degrees) values of the -O -CH2-CH2-OCH3, -OCH2-CH2-O-CH2-CH3, and -O-CH2-CH2-O-CH-(CH3)(2) group s have been determined to be 5.4, 6.1, and 6.1 +/- 0.2 kJ/mol, respect ively. In methanol, the latter equilibria are slightly more biased tow ards the axially substituted conformers.