Effects of ortho ‐substituents in S E 1 protonolysis of phenylmercuric chloride

The kinetics of the reactions of o ‐substituted phenylmercuric chlorides, o ‐RC 6 H 4 HgCl (R = CH 3 , H, C 2 H 5 O, CH 3 O, C 6 H 5 , F, COOC 2 H 5 , Cl, Br, CF 3 , NO 2 ), with hydrochloric acid in 80% aqueous dioxane in the presence of NaI were studied. The reactions are of the first order. The rate constant at 40°C decreases in the order of R: CH 3  > H > C 2 H 5 O > CH 3 O > C 6 H 5  > F > COOC 2 H 5  > Cl > Br > CF 3  > NO 2 . The analysis of effects of those o ‐substitutes is carried out through multiple regression of log k / k H with the corresponding inductive substituent constants σ I and the various resonance substituent constants σ   R 0 , σ R (BA), σ   R + , σ   R −and σ x , and the corresponding Swain–Lupton field effect constant $\Im $ and resonance effect constant $\Re $ . The results showed that o ‐substituent intramolecular coordination with the neighbor mercury (field effect) is the main effect in effects of o ‐substituents on rate of the S E 1 protonolysis. Copyright © 2007 John Wiley & Sons, Ltd.