STRUCTURAL AND DYNAMIC STUDY OF ACETALDOXIME BY MEANS OF N-14 NUCLEAR-QUADRUPOLE RESONANCE

The temperature dependence of N-14 NQR frequency, N-14 spin-lattice relaxation time, DTA and the second moment of H-1 NMR was observed for acetaldoxime. The occurrence of a minimum relaxation time near 150 K is attributed to the reorientation of the methyl group. The activation energy for this motion was found to be 9.8 kJ mol-1. Above 210 K, the relaxation is dominated by two different motions. The activation energies for these motions were found to be 10.4 and 59.6 kJ mol-1. The latter energy is considered to correspond to the reorientation of the OH group about the C = N bond. The phase transition observed at about 250 K and the fade-out phenomenon of the NQR lines near 250 K are attributable to the above motion. The Z-E isomerization could not be observed in the temperature range between 77 and 265 K.