Alkaline hydrolysis of polyacrylonitrile. On the reaction mechanism

Some new data were obtained about alkaline hydrolysis of a polyacrylonitril e (PAN) suspension at 75 degreesC in a water/ethanol mixture. At >95% conve rsion of nitrile groups, the hydrolyzed polymer contains approximate to 20% of amidines situated in the nearest neighborhood of carboxylate groups. Af ter complete hydrolysis of the amidines, poly[(sodium acrylate)-co-acrylami de] is formed having a Bernouli distribution of units. During the initial s tage of PAN cyclization at 25-97 degreesC, very short sequences of conjugat ed C=N bonds are formed which are much more reactive in hydrolysis than nit rile groups. These data enable us to reconsider the mechanism of alkaline P AN hydrolysis. A corresponding reaction scheme is suggested.