Abstract
Reactions of organic peroxides involving three types of bond heterolysis, namely, hydrogen-oxygen, oxygen-oxygen, and alkyl-oxygen heterolysis, have been investigated; the knowledge of reactions involving hydrogen-oxygen and oxygen-oxygen heterolysis have been extended, while the occurrence of alkyl-oxygen heterolysis in peroxides, of which preliminary indications were contained in the work of Foster, has been firmly established. Hydrogen-oxygen heterolysis has been shown to occur in preratification reactions, that is, in the reactions of alkyl hydroperoxides with acyl chlorides, acid anhydrides, ketene, and ketene dimer, and in the reaction of alkyl hydroperoxides with carbonyl compounds and with ethylene oxides. In particular, it has been possible for the first time to isolate esters of l-arylalkyl hydroperoxides which, up to the present time, were thought to be too unstable to be isolated. Thus the hydrogen phthalate of dimethylphanylasthyl hydroperoxide was obtained in an analytically pure state. It has further been shown that the simple tertiary alkyl hydroperoxides, such as tert-butyl and tert-amyl hydroperoxides, may be esterified by modifications of standard methods, and a number of new peresters have been prepared. The esterification of these tertiary alkyl hydroperoxides has been shown to occur under conditions where the corresponding tertiary alkyl alcohols are inert, and the probable reasons for this difference of reactivity have been investigated. The addition of alkyl hydroperoxides to carbonyl compounds and to ethylene oxides has been extended, and conditions for the reversal of carbonyl addition have been established. Oxygen-oxygen heterolysis has been shown to occur in the acid catalysed decomposition of a number of perexy esters and certain other peroxides. It has been shown that the case of oxygen-oxygen heterolysis in peroxides is a direct function not only of the polarisation of the electrons of the O-O bond in the ground state of the molecule, but also of the relative migratory aptitudes of alpha substituents which exert a synartetic accelerating effect on the heterolysis, which is usually accompanied by rearrangement and decomposition. For the make of comparison, oxygen-oxygen homolyses occurring during the thermal decomposition of l-tert. -butyl hydrogen l-mono-perphthalate and l-tert. amyl hydrogen l-monoperphtalate has also been investigated. Alkyl-oxygen heterolysis has been shown to occur via an SN1 mechanism, the case of reaction being proportional to the relative electron-releasing ability of the group H in the peroxide molecule MOORâ€(TM). The reaction has been shown to occur in certain secondary and tertiary alkyl hydroperoxides and dialkyl peroxides containing at least one alpha aryl substituent, the function of which is to confer stability on the intermediate carbonium ion through resonance stabilisation. The presence of intermediate carbonium ions has been established by their reaction with weak nucleophile reagents such as sodium toluene n-sulphinate, active methyl and methylene groups, ures, phthslimide, and aromatic compounds whose nuclei are activated by electron releasing substituents.