LAH, dechlorination with

Further confirmation of the uniformly head-to-tail structure of HERCLOR H elastomer was obtained from its carbon-13 NMR spectrum. Since no literature spectra of polyepichlorohydrin were available for comparison, the carbon-13 NMR spectra of the poly-(propylene oxideD resulting from dechlorination with LAH were also examined. Published spectra of poly(propylene oxideD with detailed peak assignments are available. 

Figure 7. Carhon-13 NMR spectra of (A) HERCLOR U elastomer and (B) the poiy(propylene oxide) obtained by dechlorination with LAH...

Figure 8 shows the carbon-13 NMR spectra of crystalline polyepichlorohydrin and the poly(propylene oxide) it yielded by dechlorination with LAH. The poly(propylene oxide) was also highly crystalline (m.p. 64 C. by DTA) and its carbon-13 NMR spectrum corresponds closely to that reported for the isotactic polymer. Thus, the single methylene peak at about 70.2 ppm. in the spectrum of crystalline polyepichlorohydrin is due to isotactic dyads. The poor resolution in this spectrum is due to low solubility of the crystalline polymer in the benzene solvent. No trace of the peaks due to polyepichlorohydrin are observable in the spectra of the poly(propylene oxide) obtained by dechlorination. In addition, the number of observable peaks does not increase as a result of the LAH treatment. This is further evidence that the dechlorination reaction results in smooth replacement of Cl with H without otherwise altering the structure of the polymer. 

HERCLOR H elastomer was readily dechlorinated by treatment with excess lithium aluminum hydride [LAH] (2.5 moles/mole of Cl) in tetrahydrofuran at SO C. Unreacted hydride was quenched with water, and the polymer samples were isolated for chlorine analyses. The observed pseudo-first-order rate constant for the disappearance of chlorine was found to be 1.9 x 10" minT under these conditions (Fig. 1). 

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