In Chemistry, inductive effect refer to the permanent formation in a molecule due to the unequal sharing of σ electrons in a molecule.
- Inductive effect operate to σ-bond
- Partial charge development
- Can be neglected after 3rd Carbon atom
- Effect depend on distance
Inductive effect is the partial shifting or Displacement of σ electrons towards the more
electronegative atom . As a result partial charges are developed in a molecule.
Inductive Effect in Chloroethane:
Here Carbon is less electronegative than Chlorine so Cl will pull the shared electron pair more towards itself. As a result polarity or partial charges are developed on chlorine (partial negative )and carbon (partial positive).
Chlorine will pull the electron pair more than the carbon due to more electronegativity .Due to this the carbon becomes electron deficient bearing partial positive charge .This carbon then pull the electrons from the adjacent carbon so this effect travel and decreases with distance.
Classification of Inductive Effect:
Inductive effect is classified into following 2 types:
- Positive inductive effect (+I effect)
- Negative inductive effect (-I effect)
Difference between +I & -I Effect:
Positive inductive effect (+I effect):
When an electron donating or electron releasing group(such as alkyl group) is introduced to a carbon chain the charged is transferred through the chain. This results in a permanent dipole in a molecule where the electron donating group is called +I group and this effect is known as +I effect.
For example :
Here methyl group(CH3) is an electron donating or releasing group which increases the stability of carbocation (which is electron deficient) by donating electron. Here Methyl group is +I Group and this effect is known as +I effect.
Negative inductive effect (-I effect):
When an electronegative atom (e.g. halogen) is introduced to a chain of atoms(generally carbon atom), resulting in unequal sharing of electrons generates a positive charge which is transmitted through the chain. This results in a permanent dipole in a molecule where the electronegative atom(electron withdrawing group)holds a negative charge is called a –I group and this effect is known as –I effect(Positive inductive effect).
Here Chlorine(Cl) is an electron withdrawing group which pulls the electron pair from adjacent carbon & this carbon in turn pulls electron from the neighboring carbon ,this effect will travel and decrease (up to 3 carbon if present) . Here Chlorine is -I Group and this effect is known as -I effect (negative inductive effect).
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