The Coloration of Some Benzospiran Compounds in Poly(vinyl chloride) Matrix Due to Electron Bombardment

Abstract

When 1, 3, 3-trimethylindo1inbenzopyrylspiran and its derivatives(A) in poly(vinyl chloride)(PVC)matrix was bombarded by an electron beam of medium energy(15kV), a stable yellow co1ored product(X)was formed. In contrast with the other matrices, X was the only product which showed no reversibility. Moreover, it was entirely different from the photoproduct(B)and thought to be formed by the reaction, between A and free chlorine compounds which were liberated from PVC due to bombardment. The reaction process of X followed a pseudofirst-order kinetics.By exposure to ultraviolet ray and electron. beam successively, the formation of X was accelerated. At the begginng, B, which was formed by the irradiation was quickly decayed and at the same time X was rapidly formed by the bombardment. The maximum rate constant of the formation of X in this process was about 200 times as large as that of usual bombardment. In the other matrices, the same type of product as B were formed by the bombardment. But in PVC, it would change so rapidly that we could not fond it.These phenomena suggested that X was connected with the product A having the open ring, in analogy with B. By the bombardment, various ch1orine compounds were formed which were believed to be ch1orine radicals or hydrogen chlorides, 1iberated from PVC. So X might be a reaction product between A and these liberated species.As thekinetics of the formation of X was of first-order, this reaction would be a pseudoprocess due to excess chlorine compounds in PVC.