Peroxides, arylsulfonyl

Thermal decomposition in three different ways, i.e. homolytic, polar and radical induced decomposition, as well as intermolecular reaction of sulfonyl peroxides are the main reactions displayed by sulfonyl peroxides. When bis(arylsulfonyl) peroxides are allowed to decompose at 25-40 °C in chloroform, homolytic 0—0 bond fission followed by hydrogen abstraction from the solvent results in the formation of the corresponding arylsnlfonic acids. Mixed acyl sulfonyl peroxides undergo complicated thermal decomposition in solution, and have been used commercially as polymerization initiators, since they provide a source of free radicals at a relatively low temperature . 

Since benzenesulfonyl peroxide was used as an initiator in polymerization reactions, it was thought that a free radical aromatic substitution of benzene by the benzenesulfonoxy radical takes place. A detailed study by Dannley and Knipple reveals that attachment of the sulfonoxy group derived from a bis(arylsulfonyl) peroxide to the aromatic ring occurs by electrophilic aromatic substitution (equation 5) °. 

Similarly to aromatic jt system, olefinic 7r-electron donors also readily react with bissulfonyl peroxides. Norbomene, when reacted with bis(arylsulfonyl) peroxides, gives a disubstituted product following Wagner-Meerwein rearrangement (equation 6). ... 

Hoffman and coworkers have extensively studied the reactions between amines and sulfonyl peroxides. When primary amines reacted with arylsulfonyl peroxides at —78 °C in ethyl acetate, A-alkyl-O-arylsulfonyl hydroxylamine derivatives were obtained (equation 8), whereas when various primary and secondary amines reacted with sulfonyl peroxides, oxidative deamination was observed. ... 

Thiophene sulfoxides and thiophene sulfones can be prepared by direct oxidation of the corresponding sulfides (Section 3.15.9.5.1) with hydrogen peroxide. 2-Thiophene sulfones are also prepared by reaction of arylsulfonyl chlorides with thiophene under mild Friedel-Crafts conditions, or by condensation of 2-thiophenesulfonyl chlorides with aromatic compounds (Section 3.14.2.4). 

Sulfonic peracids, synthesized in situ from arylsulfonyl imidazolides and hydrogen peroxide, are also efficient reagents for the epoxidation of a wide range of alkenes41. Substituents in the aryl group affect the selectivity of this reagents and this reaction occurs in an alkaline medium. 

Arylsulfonyl halides69 Hydrogen peroxide Dark product purified to give light coloured one... 

A -chlorotriazole, dinitrogen tetroxide, chromic acid, chromium trioxide/ A -arylsulfonyl oxaziridines, azaaromatic A -oxides, and aryldimethylamine oxides. Overoxidation to the sulfone, which is a complication with hydrogen peroxide and the peracids, may be minimized by use of only one equivalent of oxidant and low temperatures. Sodium metaperiodate, m-chloro-perbenzoic acid, and hydrogen peroxide in acetone are often the oxidants of choice when the convenient hydrogen peroxide-acetic acid method is unsatisfactory. When particularly mild conditions (CHCI3, 25°) are desired, the oxaziridines may be useful (no acids or bases are present). 

A two-step procedure for the oxidation of amines to hydroxylamines involves nucleophilic displacement along the peroxide bond of dibenzoyl peroxide and saponification of the intermediate O-ben-zoylhydroxylamine. Primary and secondary amines have been oxidized in this way (equation 29). Related reactions for transformation of amines to O-(arylsulfonyl)- and O-phosphinyl-hydroxylamines have been described by means of bis(arylsulfonyl) and bis(diphenylphosphinyl) peroxide, respectively 86,87... 

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