NMR-STUDY OF N-1-N-1-DIMETHYL-N-2-ARYLUREAS

H-1, C-13 and N-15 NMR chemical shifts were measured for N-1 N-1-dimet hyl-N-2-arylureas. The absence of decoalescence of the N-1-methyl sign als in C-13 spectra down to 190 K in acetone-d(6) solution and the pre sence of two signals in solid state CP-MAS spectra indicate that the r otational barrier around the C-N-1 bond is 26-32 kJ mol(-1).