Explosive decomposition of solid benzoyl peroxide

Abstract

The spontaneous decomposition of pellets of benzoyl peroxide (15 to 40 mg) has been investigated in the temperature range 105° to 140°C. The effects that the gaseous atmosphere, the pellet mass and the temperature have on the delay time before explosion were examined in detail. The overall activation energy E = 29 ± 3 kcal mole −1 , estimated from the variation of induction period with time by application of thermal explosion theory, agrees with that derived from kinetic investigations of the slow decomposition in solution. The exothermicity of the decomposition was found to be Δ H = 13·9z – 71·6 kcal mole −1 , where z (0 The slow isothermal decompsition was investigated in outline, the maximum reaction rate being about four times greater than for decomposition in solution. The S -shaped pressure/time curves have been explained in terms of an autocatalytic liquid phase decomposition, the liquid being formed as decomposition proceeds. The heat of formation of phenyl benzoate (Δ H f = −57 ± 3·5 kcal mole −1 ) as well as the latent heats of fusion of phenyl benzoate and benzoyl peroxide (Δ H fusion 0 = 7·0 ± 0·2 and 5·4 ± 1·2 kcal mole −1 respectively) have been determined. The phenyl-oxygen and phenyl-carbonbond strengths in phenyl benzoate are discussed.