
%0 Journal Article
%A Kelly, DP 
%A Spear, RJ 
%T Carbon-13 N.M.R. studies of carbocations. Determination of &#963;<sup>+</sup><sub>ortho</sub> constants from <sup>13</sup>C spectra of benzhydryl cations
%J Australian Journal of Chemistry
%D 1977/09/01
%V 30
%N 9
%P 1993-2004
%K 
%R https://doi.org/10.1071/CH9771993
%U https://www.publish.csiro.au/paper/CH9771993 
%X Carbon spectra of a range of 2- and 4-substituted benzhydryl cations have been measured in super acid at variable (low) temperatures. In the 4-substituted benzhydryl cations the chemical shift of the para carbon in the unsubstituted ring [&#948;(C4?)] proves to be an excellent probe for changes in charge density at the cationic carbon, as shown by its correlation with &#963;p+ (r 0.990). Measurement of &#948;(C4?) for the 2- substituted benzhydryl cations provides a direct measure of &#963;0+ for side-chain benzene derivatives; these values are OMe -0.59, Me -0.10, F 0.19, Cl 0.26, Br 0.29 and CF3 0.69. 
