The Sn Mechanism In Aromatic Compounds. Part 42. Para-substituent Effects Of Some Groups With A C=n Function Joined To The Ring. A Possible Inverse α-effect

Kinetic measurements of reactions of N3 -, OH -, or OMe- with a series of 4-chloro-3-nitro-X-benzenes were used to obtain values of Hammett substituent constants (σ -) for p-CH=NPh, 0.65 and 0.70; p-CH=NC6H 4NO2-p, 0.79; p-CH=NOH, 0.55; p-CH=+N(O -)Ph, 0.95. These values, plus those for p-N=NPh, 0.66; p-N= +N(O-)Ph, 0.62; P-CH=O, 0.93; p-C=N, 1.00; p-NO 2, 1.27, are analysed and discussed. The possible existence of an inverse α-effect is indicated.210811