The remarkable configurational stability of ortho,ortho′-tetrafluoro substituted biphenyls: 2,2′,4,4′,6,6′-hexafluorobiphenyl-3,3′-dicarboxylic acid as a model

Optically active 2,2′,4,4′,6,6′-hexafluorobiphenyl-3,3′-dicarboxylic acid was obtained through its brucine salt. The half-life time for racemization was determined at various temperatures and the torsional barrier for racemization was calculated to be 25.4 kcal/mol. These results prove, contrary to textbook knowledge, that ortho,ortho′-tetrafluoro substituted biphenyls are resolvable.