H 1-NMR-spektren der alkylcycloheptanole

Abstract

The H 1-NMR spectra of alkylcycloheptanols allow a clear distinction between cis- and trans-configurations to be made. In agreement with theoretical calculations on the twist-chair form of cycloheptane the percentage of conformations with quasi-axial hydroxyl-groups in the equilibrium of conformations is higher in cis-2 and cis-4-alkylcycloheptanols than in the analogous trans compounds. In trans-3-alkylcycloheptanol the proportion of conformations with quasi-axial hydroxyl-groups is higher than in the cis-configuration. In all monoalkylsubstituted cycloheptanols (including the t-butylcycloheptanols) the conformations with quasi-equatorial hydroxyl groups prevail both in cis- and trans-configurations. In trans-3,5,5-trimethylcycloheptanol the additional geminal methyl groups give a rise in percentage of conformations with quasi-axial hydroxyl-groups to 60%.