The barrier to rotation in 2,2″-dimethyl-o-terphenyl and several 3,3″-derivatives (rotational isomers of 1,2-di-o-tolylbenzene)

Abstract

The synthesis and measurement of the barrier to rotation [Formula: see text] in 2,2″-dimethyl-o-terphenyl (62 kJ/mol) and the following 3,3″-disubstituted derivatives is described (Cl, Cl, 74 kJ/mol), (Cl, CN, 70 kJ/mol), (CM, CN 70 kJ/mol), (CHO, 75 kJ/mol). For 3,3″-bis-CH2Br, Δv, the separation of the —CH3 peaks in the 1Hmr spectrum, was too small to obtain [Formula: see text]