Change in the reactivity of di-tert-butyl peroxide during homolysis with an increase in the degree of conversion and pressure

It was found that the differential reactivity (k _d ) of di-tert-butyl peroxide (DTBP) in a solution of 2-methoxy-(1) and 2-ethoxytetrahydropyran (2) at 130°C and pressuresp=20 and 1000 MPa is a periodic function of the degree of conversion, arbitrarily measured by the concentration oftert-butyl alcohol (TBA) formed. The functionk _d =F(TBA]) was calculated with the spline approximation (SA) of the experimental TBA] as a function of the reaction time , giving a continuous curve of dTBA]/d as a function of . The integral reactivityk _d =G(TBA]) calculated with the kinetic equation for a first-order reaction for decomposition of DTBP in1, 2, 1 + C ₆ H ₆ and2 + C ₆ H ₆ in three segments of in the range ofp=20–1000 MPa changes differently with an increase in the degree of conversion for differentp. The volume activation effects ( ) determined by SA of the experimental lnk _d as a function ofp were calculated for close degrees of conversion, TBA]=0.1–0.14M. The as a function ofp obtained were compared with the similarly processed published data on decomposition of DTBP inn-heptane and dicumyl peroxide (DCP) in different aromatic solvents. The results were attributed to the effect of the type of packing of the solvent molecules surrounding the reacting molecule on the reactivity of the peroxide and not to the effect of radical recombination in the primary cage.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 829–837, April, 1992.