Figure 1. Plot of Hammett ρ versus i (the number of atoms between the ionizable proton and the ring carbon)

From

Comparison of Substituent Effects in Benzenes (XC5H5C), Pyridines (XC5H4N) and Phosphorines (XC5H4P) and their Protonated Species

R. Sanjeev, V. Jagannadham

World Journal of Chemical Education. 2020, 8(4), 155-162 doi:10.12691/wjce-8-4-3