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6643870 
Journal Article 
INTERNAL-ROTATION IN FREE MOLECULES OF STYRENE AND TRANS-STILBENE 
Grumadas, AY; , 
1990 
Yes 
Journal of Structural Chemistry
ISSN: 0022-4766
EISSN: 1573-8779 
PLENUM PUBL CORP 
NEW YORK 
31 
1 
19-24 
English 
WOS:A1990HQ34500004 
On the basis of experimental values of the Henry constant for adsorption on graphitized thermal black, a study has been made of internal rotation in free molecules of styrene and trans-stilbene. It has been shown that the potential functions of internal rotation for these molecules are similar in form and that they have a broad, flat minimum at an angle alpha between the planes of the phenyl group and the ethylene fragment from 0 to 20-degrees. The potential barriers to internal rotation in styrene are W(0-degrees) = 0.4 +/- 0.2 kJ/mole and W(90-degrees) = 15 +/- 1.2 kJ/mole; in trans-stilbene, W(0-degrees) = 0-0.3 kJ/mole, and W(90-degrees) = 9 +/- 1 kJ/mole. The equilibrium conformation of trans-stilbene has C2 symmetry, due to electrostatic interaction of the phenyl groups.