The 13C chemical shifh of 9-substituted anthracenes and of several 9-substituted 4,5-dichloroanthracenes have been measured in deuteriochloroform. From correlations of the shifts of several of the proton-bearing carbons with the Taft dual substituent parameters, the relative distribution of polar and mesomeric effects of the 9-substituents to various ring positions has been deduced. The changes in substituent electronic effects, which result from twisting of axially ...
