Persulphate oxidations. Part V. Oxidation of o-(arylthio)- and o-(arylsulphonyl)-benzoic acids

Abstract

Oxidation of three o-(arylthio)benzoic acids with persulphate gave diaryl 2,2′-dithiodibenzoates in low yield. Oxidation of the corresponding o-(arylsulphonyl)benzoic acids gave only traces of the expected dibenzothiophen 5,5′-dioxides, and the radicals formed on pyrolysis of bis-o-(phenylsulphonyl)benzoyl peroxide reacted with solvent but did not cyclise. Persulphate oxidation of biphenyl-2-yl hydrogen oxalate gave dibenzo[b,d]pyran-6-one but o-benzyloxybenzoic acid yielded 2-phenyl-1,3-benzodioxan-4-one.