4-Chlorobenzenediazonium chloride, aryl

Stronger reducing agents than Cu1 can be used for reactions that are related to the classical Meerwein reaction. Tim salts not only catalyze the formation of aryl radicals from diazonium ions but, as shown by Citterio and Vismara (1980) and Cit-terio et al. (1982 a), in stoichiometric proportions they also reduce the primary aryl-ethane radical to the arylethyl anion, which is finally protonated by the solvent SH (Scheme 10-61). This method is the subject of a contribution to Organic Syntheses (Citterio, 1990), in which 4-(4 -chlorophenyl)buten-2-one is obtained in 65-75% yield from 4-chlorobenzenediazonium chloride and but-3-en-2-one. 

Interaction of 2-, 3- or 4-chlorobenzenediazonium salts with (9-alkyldithiocarbon-ate ( xanthate ) solutions [8] or thiophenoxide solutions [9] produces explosive products, possibly arenediazo aryl sulfides. The intermediate diazonium xanthate produced during the preparation of m-thiocresol can be dangerously explosive under the wrong conditions [8], while the reaction of 3-nitrobenzenediazonium chloride with xanthate solution at 70—75°C proceeds with near-explosive evolution of nitrogen [4]. The product of interaction of 2-chlorobenzenediazonium chloride and sodium 2-chlorothiophenoxide exploded violently on heating to 100°C, and the oil... 

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