Carbon-13 N.M.R. chemical shifts and rotational barriers of para-substituted N,N-dimethylbenzamides

Abstract

The carbon-13 N.M.R. chemical shifts for a series of para-substituted N,N-dimethylbenzamides have been measured. The substituent induced ¹³C shifts have been examined by a dual substituent parameter (DSP) method using Hammett-type constants. The barriers to rotation have also been correlated with Hammett-type constants by the DSP method and related to ¹³C substituent induced shifts. Substituent effects of the bromomethyl, dibromomethyl and tribromomethyl groups have been examined by using the chemical shift and rotational barrier probes.