Conformational study of methylethers of the type CH 3OCH 2R: an NMR and vibrational spectroscopic study

Abstract

Analysis of 13C NMR spectra of methylethers of the type CH 3OCH 2R, with R = CH 3 (I), CH 2CH 3 (II), CH(CH 3) 2 (III) and C(CH 3) 3 (IV) has shown that the trans form strongly predominates on the OCH, bond, the gauche forms appearing only in those cases where close contact between methyl groups can be avoided. Analysis of both 1H and 13C NMR spectra indicates that all staggered forms are populated on the CH 2R bond. In vibrational spectra, the strong Raman bands near 800 cm −1 were found to be very sensitive to conformational structure. For I, III and IV, the bands of various conformers in this range are separated, permitting Δ H to be determined.