The decomposition of benzoyl peroxide in solution at high pressures

Abstract

The rates of decomposition of solutions of benzoyl peroxide in carbon tetrachloride have been measured at temperatures of 60" C and 70" C in the pressure range 0 to 3000 kg/cm2. The results show that the decomposition at high pressures has the same mechanism as at atmospheric pressure and consists of a unimolecular decomposition into free radicals accompanied by a radical-induced chain decomposition. The effect of pressure is to decrease the rate of the unimolecular decomposition but to increase the rate of the chain decomposition.It is concluded that the effect of pressure on the rate of initiation in the peroxidecatalyzed polymerization of styrene is small and not an important factor in the large increase observed in the rate of polymerization.

Solvent Influence on Rates and Mechanisms

“…One such reaction [219] is the first-order decomposition of benzoyl peroxide in carbon tetrachloride at 70°C. One such reaction [219] is the first-order decomposition of benzoyl peroxide in carbon tetrachloride at 70°C.…”

Ethylene free radical polymerization in supercritical ethylene/CO2 mixture

“…This plateau obtained could again be consistent with a different repartition of radical species due to varying kinetics of decomposition in the presence of CO2. [30][31][32][33] Moreover, the secondary decomposition of benzoyl peroxide is unfavorable due to the unpaired electron lying in an orbital perpendicular to the ring -system (Figure 1 ; Scheme 1-(3)). Consequently, the yield remaining constant while increasing the CO2 pressure could suggest concomitant initiation processes by both benzoyl-peroxide derived carboxylic radicals and phenyl radicals in ethylene polymerization in scCO2, both processes compensating each other.…”

“…On the contrary, when CO2 is present in the reaction mixture, benzoic ester moieties along phenyl chain-ends can be evidenced by NMR spectroscopy, signifying that carboxylic radicals are either efficiently initiating or terminating the polymerization of ethylene, via transfer to initiator and radical recombination most likely. [30][31][32][33] The higher the CO2 proportion in the supercritical mixture, the higher the concentration of benzoic ester chain-ends. It is worth mentioning that the molar masses are increasing by increasing CO2 pressure.…”

Effect of triphenyl phosphite on the radical polymerization of styrene and methyl methacrylate

“…In the polymerization of St, it was also proposed that k, is reduced with increase in the viscosities of the polymerization system. [16][17][18] Because the viscosity of TPP (13.2 cP) is relatively high compared with the viscosities of MMA (0.52 cP), St (0.65 cP), and benzene (0.55 cP, 30"C), it may be considered that the viscosity of the polymerization system increases with increasing TPP concentration. Accordingly, in order to clarify the accelerating effect in these polymerization systems, the relationship between the relative rate (R,/R,, o) and the square root of the viscosity of the polymerization system was plotted as shown in Figure 6.…”