The effect of additives on the thermal decomposition of benzoyl peroxide in benzene

Abstract

THE thermal decomposition of benzoyl peroxide in benzene1 generates benzoyloxy-, and thence phenyl, radicals. The latter react with the solvent to form phenylcyclohexadienyl radicals (I). The ensuing radical reactions lead to a complex mixture of products from which biphenyl and benzoic acid can be isolated, each in yields of up to ca. 0.5 mole/mole peroxide. Much of the remaining product is a mixture of involatile substances, arising initially from dimerisation reactions of the radical (I). Substantial modification of the product mixture is observed when the reaction proceeds in the presence of various additives. Thus small quantities of aromatic nitro-compounds result in yields of biphenyl and benzoic acid of as much as 0.9 mole/ mole peroxide, with correspondingly less involatile product.2 It has been suggested that the nitrocompounds accept a hydrogen atom from the radical (I), and transfer i t to a benzoyloxy-radical, or to a benzoyl peroxide molecule.8 Alternatively,

PH-dependent proton absorption in chymotrypsin binding. Evidence for a pH-dependent conformation change of the enzyme

“…(14) National Institutes of Health Predoctoral Fellow. (15) The authors thank Professor F. J. Kézdy for assistance with the mathematical formulation.…”

Spin Trapping

“…HO-+ OPy-CH=N(0)C4H 9 -> OPyCH(OH)-N(0)C 4 H 9 [19] Although we thought this was an outstanding feature of this spin trap other workers seemingly have not capitalized on this point. Instead this spin trap has become popular for a variety of biological applications because the life-times of the spin adducts seem to be longer in aqueous solutions than for PBN spin adducts.…”

“…The use of nitrosobenzene as a radical scavenger had also been used in one specific application by Perkins in order to sort out a misassigned EPR spectrum and provide support for an alternate mechanism of nitroxide formation (18,19). The choice of nitrosobenzene as a spin trap was further developed by Dr. Ryusei Konaka in Japan in a study of a variety of radicals produced from nickel peroxide oxidation of compounds with active hydrogens in various precursors (20,21).…”