Unsymmetrically Substituted 1,8-Diarylanthracenes

Article abstract of DOI:10.1021/jo00356a031

Unsymmetrically substituted 1,8-diarylanthracenes where the aryl rings are m-tolyl (5), o-tolyl (6), and 2,3-dimethylphenyl (7) have been synthesized; the barriers to aryl ring rotation in these hydrocarbons were found to be 5.3, 10.4, and 16.3 kcal/mol, respectively.Addition of either an acetoxyl (14) or a methyl (15) substituent at C-9 of the dixylylanthracene gave mixtures of cis and trans isomers that also exhibited rotation of an aryl ring within the temperature range 25-120 deg C.X-ray crystal structures for the cis- (14b) and trans- (14a) 9-acetoxydixylylanthracenes demonstrated significant distortion in the geometry of the anthracene ring, permitting rotation of the aryl rings with unexpected ease in solutions at temperatures above 100 deg C.