Thermolabile hydrocarbons, 34. . Kinetics of the generation of 1,3‐di‐tert‐butylallyl radicals by thermal CC bond cleavage reactions

Abstract

AbstractThe title radicals were generated by thermal decomposition of (E,E)‐meso‐ and (E,E)‐(±)‐5,6‐di‐tert‐butyl‐2,2,9,9‐tetramethyl‐3,7‐decadiene (4a, b), (E)‐5‐(1,1‐dimethylethyl)‐2,2,6‐trimethyl‐6‐phenyl‐3‐heptene (6), and (E)‐5‐(diphenyl‐methyl)‐2,2,6,6‐tetramethyl‐3‐heptene (7). The activation parameters of these reactions were calculated from the rate constants which were followed over a 40°C temperature range. The enthalpies of formation of 4a, b were determined from the enthalpies of combustion and enthalpies of vaporization, those of 6 and 7 by MM2 calculation. From these data and their comparison with those of comparable saturated hydrocarbons of similar strain the radical stabilization enthalpy of the title radical RSE = 11.4 ± 1.5 kcal/mol was determined, which is in good agreement with results obtained from other model compounds (12.6 kcal/mol) previously.