17122-96-2Relevant articles and documents
Restricted Rotation Involving the Tetrahedral Carbon. LX. peri-Substituent Effect on the Rotational Barrier of the 9-Methyl Group in Several Trypticene Derivatives
Yamamoto, Gaku,Oki, Michinori
, p. 3550 - 3559 (1990)
Dynamic 1H NMR study was made on several 1-substituted 8,13-dichloro-9-methyltriptycenes and 8-chloro-13-fluoro-9-methyltriptycenes to examine the effect of peri-substituents on the rotational barrier of the 9-methyl group.The rotational barrier height increases in the expected order as the 1-hydrogen is repleaced by a bulkier group up to CH3, but shows a very low value when a t-butyl group is introduced into 1-position to show that destabilization of the ground state by the bulky t-butyl group exceeds that of the transition state for rotation.
Unsymmetrically Substituted 1,8-Diarylanthracenes
House, Herbert O.,Hrabie, Joseph A.,VanDerveer, Don
, p. 921 - 929 (2007/10/02)
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.
