UNUSUAL EFFECTS OF STERIC HINDRANCES IN NMR SPECTRA OF o,o'-DIALKYLSUBSTITUTED BENZYLIDENE DICHLORIDES

Article abstract of DOI:10.1016/S0040-4020(01)87135-0

It has been found that steric hindrances of the CHCl2 group rotation around C_Ar-CHCl2 bond in o,o'-dialkylsubstituted benzylidene dichlorides call forth a non-equivalence of the alkyls in positions 2 and 6.The non-equivalence displays in 1H and 13C NMR spectra at room temperature and at -20 deg C.At the latter temperature, the spectra of 2,4,6-trimethyl-3-chloromethylbenzylidene dichloride and bis(dichloromethyl)mesitylene indicate the presence of two conformations, the assignment of signals having accomplished for each of them.