Molecular mechanics calculation of the rotational barriers of 2,2′,6-trialkylbiphenyls to explain their GC-elution behaviour

Application of molecular mechanics enabled calculation of the rotational barrier between the two atropisomers of 2,3,5′,6-tetramethyl-2′-(2-butyl)biphenyl. The calculated energy barrier, 149.4 kJ/mol, is in good agreement with the experimental value of 155 kJ/mol reported by Koopmans et al. (1996) for a similar 2,3,5′,6-tetramethyl-2′-(2-alkyl)biphenyl compound, supporting their interpretation of the GC-MS data of these compounds.