Radical Chemistry of α-Azodiphenylcarbinols and of 2-Acetoxy-2-Methyl-5,5-Dialkyl-Δ³-1,3,4-Oxadiazolines

Abstract

<p>A series of new α-azodiphenylcarbinols was synthesized by mild deacetylation (with methyl lithium) of the corresponding azoacetates which, in turn, were prepared by reactions of either lead tetraacetate or bromine with benzophenone monosubstituted hydrazones. The chemistry of these new types of α-azocarbinols was studied in several aspects. Firstly, the kinetics of thermolysis of these compounds in carbon tetrachloride and in benzene solutions are reported, and the mechanism of the decomposition (radical chain, induced) is discussed. The effects of inhibitors on the decomposition is also examined. Secondly, the potential synthetic applicability of these compounds is illustrated by the hydroalkylation of several unsaturated compounds. Thirdly, the catalytic role of phenol in the radical chain reactions is discussed qualitatively. Fourthly, the e.s.r. spectra of nitroxides, resulting from the reactions of these compounds with nitrosobenzene, were obtained at room temperature in degassed benzene solutions. The aN and g values of these nitroxides are reported.</p> <p>Another part of the thesis describes the synthesis and chemistry of two new 2-acetoxy-2-methyl-5,5-disubstituted-Δ³-1,3,4-oxadiazolines. The thermolysis of these oxadiazolines was investigated, both in nitro-benzene and in benzene solutions. The results of kinetics are presented and a probable mechanism of the decomposition, through diazenyl radical intermediates, is examined.</p> <p>Radical intermediates are involved in the chemistry of these new azo compounds. α-Azocarbinols decompose by a radical-induced chain mechanism and their synthetic application involves chain addition. The oxadiazolines undergo unimolecular, homolytic cleavage. A review of radical chemistry presented in Chapter I, is therefore appropriate.</p>