Chlorination of polyacrylonitrile and analysis of its products.

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Chlorination of polyacrylonitrile (PAN) was carried out by passing dried chlorine gas through a tetrahydrothiophene 1,1-dioxide (sulfolane) solution of PAN or a powdery mixture of PAN with sodium chloride. The chlorinated products were examined by comparison with acrylonitrile-α-chloroacrylonitrile (CAN) copolymers corresponding to α-chlorinated PANs. In solution the reaction proceeded easily below 100 °C, but due to side reactions analysis of the products was difficult. In the powdery mixture hardly any reaction took place below 100 °C, but in the range 120–140 °C, the reaction proceeded smoothly and its rate became <I>ca.</I> 2.7 times in proportion as its temperature was raised by 10 °C. The chlorinated products were investigated by means of infrared and thermal analyses. The chlorinated moiety consists mainly of α,β-dichlorinated units, which seem to result from the addition of chlorine to the double bonds produced by dehydrochlorination after β-chlorination. These chlorinated products were dehydrochlorinated at lower temperature than acrylonitrile-CAN copolymers, but in many respects they resemble each other in the behavior of thermal degradation.