Polymerization reactions, heavy particle

These results imply the production or modification of acid sites by irradiation, both with y-rays and with heavy particles. The site can hardly be acid, because the reactions (except in one instance) were studied between 149° and 400°, and acid was observed to have a half-life of 1 to 1.5 hour at 100°. A radiation-produced site similar to acid might be more stable in silica-alumina, but some of the above experiments were on pure silica. At —78°, irradiated silica gel catalyzed the polymerization of isobutylene (7d). Since the loss of this catalytic activity on annealing paralleled the loss in acidity, the activity is probably attributable to acid. 

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