b The availability of polybutadienes with widely varying structures has led to a study of the absorption of cis-1,4 addition in the 12to 16-micron region and the development of a method for unsaturation distribution using high cis-l,4, trans-l,4, and 1,2(vinyl) polymers as the only calibration standards. The cis-1,4 absorption band, at 13.5 microns in high cis polymers, varies in position and shape as the amount of cis-1,4 addition changes. An empirical function of the area of the absorption band between 12.0 and 15.75 microns was used to measure cis-1,4 addition. frans-l,4 and 1,2(vinyl) addition was measured at 10.3 and 1 1 .O microns, respectively. The method was applied successfully to a number of polybutadienes with widely varying distributions. The results indicate that this method, derived solely from polybutadienes, can be applied with confidence to polybutadienes with any unsaturation distribution. N THE polymerization of butadiene,
The infrared spectra of 2,2-dideuteropropane, 1,1,1,3,3,3-hexadeuteropropane, and octadeuteropropane are presented, together with that of propane for comparison. Complete assignments are proposed for the frequencies of the vibrations belonging to species A1 and B1, and partial assignments for the vibrations belonging to species B2, in these molecules. They show that some low frequency vibrations (below 1350 cm−1) in the deuterium substituted molecules cannot be described adequately in terms of simple group motions. The results suggest that this is true also for the corresponding vibrations in propane.
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