Relation between I effect and stability


If the electronegative atom is then joined to a chain of atoms, usually carbon, the positive charge is relayed to the other atoms in the chain. This is the electron-withdrawing inductive effect, also known as the -I effect.

However, some groups, such as the alkyl group, are less electron-withdrawing than hydrogen and are therefore considered as electron-releasing. This is electron-releasing character and is indicated by the +I effect. In short, alkyl groups tend to give electrons, leading to induction effect.

As the induced change in polarity is less than the original polarity, the inductive effect rapidly dies out and is significant only over a short distance. Moreover, the inductive effect is permanent but feeble since it involves the shift of strongly held σ-bond electrons and other stronger factors may overshadow this effect..


Relative inductive effects have been experimentally measured with reference to hydrogen, in decreasing order of -I effect or increasing order of +I effect, as follows:

–NH3+ > –NO2 > –SO2R > –CN > –SO3H > –CHO > –CO > –COOH > –COCl> –CONH2 > –F > –Cl > –Br > –I > –OR > -OH > –NH2 > –C6H5 > –CH=CH2 > –H

The strength of inductive effect is also dependent on the distance between the substituent group and the main group that react; the greater the distance, the weaker the effect.

Inductive effects can be measured through the Hammett equation, which describes the relationship between reaction rates and equilibrium constants with respect to substituents...

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