Cavitation-induced Reactions in Pure Substituted Benzenes

The formation of polymers has been observed on exposure of pure substituted benzenes to ultrasound intense enough to cause cavitation. The products have some of the characteristics of the char obtained from low temperature pyrolysis of hydrocarbons. They are difficult to dissolve, melt above 300 °C, and give a large broad e.p.r. signal. A crude correlation between bond dissociation energy and the reaction rate suggests that the initiation reaction is a thermal decomposition in a cavitation bubble. The phenomenon is compared to radiolysis and thermal reactions.