An excellent and detailed discussion of the general phenomenon of geminal chemical shift nonequivalence can be found in G. Binsch, et a/., J. Amer. Chem. SOC., 95, 175, 182, 190 (1973). To our knowledge, the only larger value was 0.6 ppm as exhibited by 1, 3-dichloro-2, 3-dimethylbutane: F. Schweinsberg and JG Traynham. Tetrahedron Lett.. 3809 (1970). M. Karplus. J. Amer. Chem. SOC., 85, 2870 (1963). Part of this absorption overlapped with ...
