Monohalo benzenes

Vvs SCE) one obtains equal quantities of di-, tri-, and tetrasulfides, at less negative potentials (—0.9 V), tri-and tetrasulfides are obtained almost exclusively [253]. Substituted monohalo-benzenes such as 4-bromobenzophenone and 2-chloronitrobenzene give corresponding diaryldisulfides [254-256]. The addition of Mel in the last case, resulting in methyl-(2-nitrophenyl)disulfide, allowed to suppose the process to occur via an intermediate 2-nitrophenyl disulfide anion. 

Monohalo ketones may be prepared by starting from pure diazo ketones an ethereal or benzene solution or suspension of a carboxylic acid chloride (1 mole) is added during 1-2 h to a stirred solution of diazomethane (3 moles) at 0-5°, reaction is allowed to proceed at 20-25°, the solvent is removed in a vacuum, and the product is recrystallized 1169 -chloro ketones may be formed as by-products during preparation of the diazo ketone, particularly if an insufficient excess of diazomethane is used hydrogen halide is often added directly to the ethereal solution of acid chloride and diazomethane 1170,1171 if then, for example, HBr is used, the resulting a>bromo ketone will contain... 

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