Inductive effect benzene substituents

Inductive effect of substituent present on the benzene ring... 

Hammett relations used to define inductive effects of substituents in a benzene ring on dissociation constants of acids (see p. 60) can provide a systematic approach to evaluate the inductive effects of substituents on the hydrolysis of esters. The indue-... 

If the reactions of the same substituents on heteroaromatic azoles and on benzene rings are compared, the differences in the reactivities are a measure of the heteroatoms influence. Such influence by the mesomeric effect is smaller when the substituent is /3 to a heteroatom than when it is a or y. The influence by the inductive effect is largest when the substituent is a to a heteroatom. 

Fig. 4.3. Resonance, field, and inductive components of substituent effects in substituted benzenes.

Charton has recently examined substituent effects in the ortho position in benzene derivatives and in the a-position in pyridines, quinolines, and isoquinolines. He concludes that, in benzene derivatives, the effects in the ortho position are proportional to the effects in the para position op). However, he finds that effects of a-sub-stituents on reactions involving the sp lone pair of the nitrogen atoms in pyridine, quinoline, and isoquinoline are approximately proportional to CT -values, or possibly to inductive effects (Taft s a ). He also notes that the effects of substituents on proton-deuterium exchange in the ortho position of substituted benzenes are comparable to the effects of the same substituents in the a-position of the heterocycles. 

In common with a number of heterocyclic iodinations, kinetic effects are found in the iodination of indole and 2-methylindole [68AC(R)1435], When the substituent effects for the reaction are examined it is clear that any resonance effects from the fused benzene ring are only poorly relayed to the reactive 3-position, and the rates appear to be controlled by inductive effects. A 5-methyl group was more activating than 5-methoxy [69AC(R)799]. 

The influence of the inductive effects of the substituents present on both the amine nitrogen and benzene ring on the Co(II)/Co(III) redox potential is quite evident. 

Taft, R. W. and Lewis, I. C. The general applicability of a fixed scale of inductive effects. II. Inductive effects of dipolar substituents in the reactivities of m- and p-substituted derivatives of benzene. J. Am. Chem. Soc. 80, 2436 (1958). 

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