KINETIC-STUDIES ON THE DECOMPOSITION OF CUMYL HYDROPEROXIDE AND TERT-BUTYL HYDROPEROXIDE IN STYRENE CATALYZED BY MANGANESE(II) AND (III) ACETYLACETONATES

The kinetics of the decomposition of cumyl hydroperoxide (CHP) and ter t-butyl hydroperoxide (TBHP) in styrene catalyzed by manganese diacety lacetonate (MDA) and manganese triacetylacetonate (MTA) was studied. T he reactions are first-order with respect to the components in the cas e of MDA, and the reaction rate constants are as follows: K-TBHP = 1.0 6 X 10(13)exp(-83.74 kJ/mol/RT) 1 mol(-1) s(-1) (333 - 353 K); k(CHP) = 2 X 10(11) exp(-74 kJ/mol/RT) l mol(-1) s(-1) (343 - 363 K). The ini tial rate expression, V-0 k[CHP]1.5[MTA](0.5) (k= 0.17 l mol-1 s(-1), 343 K) at 0.02 < [CHP] < 0.1 mol/l is transformed into V-0 k[CHP](0)[M TA]0.5 at 0.1<[CHP] < 0.15 mol/l, k = 6.1 X 10(2)exp(-34 kJ/mol/RT) mo l-(0.5) l-(0.5) s(-1) (343 - 363 K). The yield of free radicals in the reaction CHP + MTA with mixed initiation was measured using dilatomet ry; for every 50 CHP molecules decomposed, 70 - 80 free radicals were liberated in hulk (at 384 K), which initiated the polymerization of st yrene.