98797-46-7Relevant academic research and scientific papers
Restricted Rotation Involving the Tetrahedral Carbon. LVI. NMR and Molecular Mechanics Studies on the Stereodynamics of 8,13-Dichloro-9-methoxy-1,4-dimethyltriptycene
Yamomoto, Gaku,Oki, Michinori
, p. 1690 - 1695 (1985)
The 400 MHz 1H NMR spectrum of the title compound at -100 deg C in dichloromethane revealed the presence of two isomers in a ratio of 88:12, which results from restricted rotation about the triptycyl-oxygen single bond.The major isomer was assigned to the ap rotamer on the basis of the low temperature 13C NMR spectrum.Dynamic NMR studies gave the activation parameters for the ap+/-sc conversion: ΔH = 11.9+/-0.5 kcal/mol (1 calth = 4.184 J), ΔS = 2.6+/-2.5 eu, ΔG200K = 11.4 kcal/mol.Results of molecular mechanics calculations on the compound are discussed.
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.
