New x-ray crystallographic data on crystalline polymers of methyl sorbate. Conformational energy calculations for different configurational hypotheses

Conformational calculations have been performed on chains of poly(methyl sorbate) having different configurations; the results of these calculations have been compared with NMR and X-ray data obtained for two kinds of poly(methyl sorbate) recently synthesized. The polymer having a prevailingly erythro configuration has a chain axis and a conformation of minimum energy in accordance with that reported in a previous paper. The polymer having a prevailingly threo configuration has a chain axis compatible with a regular conformation of low energy having two constitutional repeating units and in accordance with the distribution of intensities in the X-ray spectra. The two ideal conformations found are compatible with the presence of configurational defects.