Inductive Effect or I Effect

Inductive Effect  ( I-Effect )

Partial displacement of sigma electrons (σ- e^-s) towards more electronegative atom is called Inductive effect or I-effect.

Inductive effect is a permanent effect.

Standard

1. I-effect of C-H bond is considered as ZERO

2. C-Z bond (Where: Z is any atom/group)

a) If ZEN > CEN then-

C^+δ--->----Z^-δ  {Z gets –δ so –I effect of Z}

b) If ZEN < CEN then-

C^-δ---<----Z^+δ  {Z gets +δ so +I effect of Z}

Example:

CH₃^+δ--->---Cl^-δ   {Cl gets –δ so –I effect of Cl}

CH₃^+δ--->---OH^-δ {OH gets –δ so –I effect of OH}

CH₃-->--CH=O    {Electron withdrawing effect or –I effect of –CH=O  (-CH₃ :-Sp³ & CH=O :-SP²)}

Special point-1

*EN order of hybridized carbons

SP³ C {EN Value: 2.5} < SP² C {EN Value: 2.75} < SP C {EN Value: 3.25}  [SP C: ≈50% S Character]

Example:

1.      CH₃-->--C≡N  {-I effect of -C≡N  (-CH₃ :- Sp³C   &  -C≡N :- Sp C)}

                          Note: {Order of EN :-   C⁺  > C > C^-}

2.      CH₃-->--NH₂

3.      CH₃-->>--N⁺H₃  
                           Note: {-I effect of –N⁺H₃  >  -NH₂}

 *Order of  -I effect or electron withdrawing effect

-O⁺R₃  >  -N⁺R₃  >  –N⁺H₃   >  NO₂   >  -C≡N  >  -COOH  >  -CHO  >  Halogens  >  -OH  >     -NH₂  >  -Ph  >  -H   { -N⁺R₃  >  –N⁺H₃  solvation effect}

*Order of  +I effect or electron releasing effect

-O^-  >  -COO^-  >  -C(CH₃)₃  >  -CH(CH₃)₂  >  -CH₂-CH₃  >  -H

{C-->--OH  &  C--<--O^-}

*Partial displacement of sigma electron (σ- e^-s) is called I-effect so, it depends on distance.

I-effect decreasing as distance increasing

CH₃-->--CH₂-->>--CH₂-->>>--Cl

+δ₃          +δ₂           +δ₁             -δ     {Ʃ +δ = -δ}