Rotation in biphenyls with a single ortho-substituent.
Barriers to rotation in a range up to 15.4 kcal mol(-1) were determined by dynamic NMR spectroscopy for a series of biphenyl compounds 1a-1h and 2a-2d with a single ortho-substituent. Ab initio calculations reproduce these barriers satisfactorily and indicate the ground-state conformation of these molecules. Results are discussed in terms of the contribution of individual substituents to the barrier and of the buttressing of adjacent positions in a benzene ring by substituents.
Mazzanti
Andrea
A
Department of Organic Chemistry "A. Mangini", University of Bologna, Viale Risorgimento 4, 20196-Bologna, Italy. mazzand@ms.fci.unibo.it
Lunazzi
Lodovico
L
Minzoni
Mirko
M
Anderson
J Edgar
JE