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.