13 C NMR study of ortho ‐, meta ‐ and para ‐ substituted phenyldiphenylamines: Substituent effect correlations

The 13 C chemical shifts of 11 substituted triphenylamines have been determined and the assignment of these resonances made using intensities, 1 H and 19 F couplings and predictions from bond additivity relationships. 13 C chemical shifts at carbons bearing the substituent and at carbons ortho to the substituent correlated reasonably well with the Q parameter. A multiple regression analysis of chemical shifts with the field and resonance parameters of Swain and Lupton and the Q parameter produced significantly better correlations than those obtained when Q was omitted for these positions. 13 C chemical shift correlations for carbons meta and para to the substituent were not significantly better than when Q was omitted. Significant correlations were obtained between field and resonance parameters and 13 C chemical shifts of C‐ o and C‐ p , and C‐ i , C‐ o , C‐ m and C‐ p of the non‐substituent bearing phenyl rings in ortho ‐ and para ‐substituted phenyldiphenylamines, respectively.