
%0 Journal Article
%A Badger, GM 
%A Drewer, RJ 
%A Lewis, GE 
%T Photochemical Reactions of Azo Compounds. II. Photochemical Cyclodehydrogenations of Methyl- and Dimethylazobenzenes
%J Australian Journal of Chemistry
%D 1963/12/01
%V 16
%N 6
%P 1042-1050
%K 
%R https://doi.org/10.1071/CH9631042
%U https://www.publish.csiro.au/paper/CH9631042 
%X 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. 
