The infrared spectra of some fixed cisoid and trunsoid ap-unsaturated ketones have been examined. It is concluded that the ratio of the integrated band intensities of the C=O and C=C stretching vibrations gives the most certain indication of the geometry of the chromophore, being low in cisoid and high in transoid structures. The effect of steric hindrance to coplanarity of the chromophore on the infrared spectra is discussed.
The infrared spectra of gaseous cyclopropene and a partially deuterated cyclopropene, and the Raman spectrum of liquid cyclopropene have been determined. The majority of the fundamentals and several overtones and combinations have been assigned. Some force constants based on a simple valence-force potential function have been calculated.
The relation between structure and N-H and G O frequencies is discussed. A band in the 14'70-1600 cm.-l region, present in all the pyrroles examined, is assigned to bond-stretching vibrations of the ring.THE infrared and Raman spectra of substituted pyrroles show some anomalies, particularly a lowering of the G O stretching frequency in carbonyl-substituted pyrroles. Although data for a number of pyrroles have been recorded1-9 comparatively little has been done to interpret the results and establish correlations. Since a number of pyrroles were available to us, their infrared spectra have been determined. The present work, however, is not a systematic study since there are not sufficient data for mono-and di-substituted derivatives.
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