Inductive effect

The permanent displacement of sigma (σ) electrons along a saturated chain, whenever an

electron withdrawing or electron donating group is present, is called inductive effect.

Inductive effect could be + I effect or – I effect. When an atom or group attracts electrons

towards itself more strongly than hydrogen, it is said to possess – I effect.

For example,

When an atom or group attracts electrons towards itself less strongly than hydrogen, it is

said to possess + I effect.

For example,

Electrometric effect

It involves the complete transfer of the shared pair of π electrons to either of the two

atoms linked by multiple bonds in the presence of an attacking agent. For example,

Electrometric effect could be + E effect or – E effect.

+ E effect: When the electrons are transferred towards the attacking reagent

– E effect: When the electrons are transferred away from the attacking reagent

(a) Cl${}_3$CCOOH > Cl${}_2$CHCOOH > ClCH${}_2$COOH

The order of acidity can be explained on the basis of Inductive effect (– I effect). As the

number of chlorine atoms increases, the – I effect increases. With the increase in – I

effect, the acid strength also increases accordingly.

(b) CH${}_3$CH${}_2$COOH > (CH${}_3$)${}_2$ CHCOOH > (CH${}_3$)${}_3$ C.COOH

The order of acidity can be explained on the basis of inductive effect (+ I effect). As the

number of alkyl groups increases, the + I effect also increases. With the increase in + I

effect, the acid strength also increases accordingly.