ABSOLUTE RATE CONSTANTS FOR THE REACTIONS OF PRIMARY ALKYL RADICALS WITH AROMATIC-AMINES

Hydrogen abstraction from diarylamines (4-X-C6H1)(2)NH [X = H, CH3, C8 H17, CH3O, and Br] by the 2-methyl-2-phenylpropyl radical in n-dodecan e solution was investigated by thermolysis of 3-methyl-3-phenylbutanoy l peroxide in the presence of various concentrations of the amines, Th e reaction is a non-chain process in which the 2-methyl-2-phenylpropyl radical and its rearrangement product, the 2-benzylpropan-2-yl radica l, abstract hydrogen from both the solvent and the amine, Cross-dispro portionation reactions of the rearranged radical led to the formation of significant amounts of beta,beta-dimethylstyrene. Rate constants fo r hydrogen abstraction by the unrearranged, primary alkyl radical from n-dodecane (k(373K) = 3.5 x 10(3) M(-1) s(-1)), diphenylamine (k(373K ) = 1.3 x 10(6)M(-1) s(-1)), and the substituted diarylamines were det ermined fr om the product yields and the known rate constant for the r adical rearrangement. From kinetic experiments with N-deuteriodiphenyl amine the deuterium kinetic isotope effect, k(NH)/k(ND), was found to be 2.3 at 373 K.