The Pyrolysis of 4,7-Dimethylcyclobuta-[b]naphthalene-1,2-dione; Failure to Detect Hydrogen Migration in 5,8-Dimethyl-2,3-didehydronaphthalene

Abstract

5,8-Dimethylnaphthalene-2,3-dicarboxylic anhydride (8) is not significantly decomposed on pyrolysis at 950°/0.05 mm. The corresponding cyclobutanaphthalene-1,2-dione (9) on pyrolysis at 670°/0.06mm gave 1,4-dimethylnaphthalene (17%), 1,4,7,10- tetramethyldibenzo [ b,h ] biphenylene (15) (3%), unidentified products, and much carbon. There was no evidence for hydrogen migration leading to the rearrangement of the 2,3-didehydronaphthalene (10) to the 1,2-didehydronaphthalene (11).