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Australian Journal of Chemistry Australian Journal of Chemistry Society
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RESEARCH ARTICLE

Photochemical Reactions of Azo Compounds. II. Photochemical Cyclodehydrogenations of Methyl- and Dimethylazobenzenes

GM Badger, RJ Drewer and GE Lewis

Australian Journal of Chemistry 16(6) 1042 - 1050
Published: 1963

Abstract

Substituted benzo[c]cinnolines have been prepared from substituted azobenzenes by photochemical cyclodehydrogenation in 22N sulphuric acid. The reaction seems to involve a photochemical disproportionation as rearrangement products of the corresponding hydrazobenzenes were also formed. 4-Methylazobenzene gave 2-methylbenzo[c]cinnoline. 3-Methylazobenzene gave a mixture of 1- and 3-methylbenzo[c]cinnolines: and 2-methylazobenzene gave 4-methylbenzo[c]cinnoline and benzo[c]cinnoline. The latter result is noteworthy as it indicates that cyclization can proceed with elimination of a methyl substituent. Similar elimination was observed with 2,2'-dimethylazobenzene, which gave 4-methyl-benzo[c]cinnoline as well as the expected 4,7-dimethylbenzo[c]cinnoline. Photochemical cyclodehydrogenations of 4,4'-dimethylazobenzene and of 3,3'-dimethyl-azobenzene have also been studied.

https://doi.org/10.1071/CH9631042

© CSIRO 1963

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