Inductive Effect

Inductive Effect refers to the phenomenon wherein a permanent dipole arises in a given molecule due to the unequal sharing of the bonding electrons in the molecule. This effect can arise in sigma bonds, whereas the electromeric effect can only arise in pi bonds.
When an electron-releasing or an electron-withdrawing species is introduced to a chain of atoms (generally a carbon chain), the corresponding negative or positive charge is relayed through the carbon chain by the atoms belonging to it. This causes a permanent dipole to arise in the molecule and is referred to as the inductive effect.
An illustration describing the inductive effect that arises in a chloroethane molecule due to the more electronegative chlorine atom is provided above.
==Inductive Effect on Acidity and Basicity==
Using the inductive effect, we can predict the acidity and basicity of compounds. It can be said as a generalisation the electron withdrawing groups (EWG) increase the acidity of a compound and electron donating group decrease the acidity of a compound.
This is because, if we take the conjugate base of the acid, that is, RCOO-, if R is electron withdrawing, then the conjugate base is stabilised via delocalisation of the formed negative charge.
If R had been electron donating, then the conjugate base would be destabilised because of inter-electronic repulsions.
Thus it can be said that, +I groups decrease acidity (or increase basicity) and –I groups increase acidity (or decrease basicity) of compounds.
==Types==
===Negative Inductive Effect===
When an electronegative atom, such as a halogen, is introduced to a chain of atoms (generally carbon atoms), the resulting unequal sharing of electrons generates a positive charge which is transmitted through the chain.
This causes a permanent dipole to arise in the molecule wherein the electronegative atom holds a negative charge and the corresponding effect is called the electron withdrawing inductive effect, or the -I effect.
===Positive Inductive Effect===
When a chemical species with the tendency to release or donate electrons, such as an alkyl group, is introduced to a carbon chain, the charge is relayed through the chain and this effect is called the Positive Inductive Effect or the +I Effect
==Stability of Molecules==
The charge on a given atom and the charge on a group bonded to the atom play a strong part when determining the stability of the resulting molecule as per the inductive effect.
An example of this can be observed when a group displaying the -I effect is bonded to a positively charged atom and the positive charge on the resulting molecule is amplified, reducing its stability.
On the other hand, when a negatively charged atom is introduced to a group displaying a -I effect, the charge disparity is somewhat quenched and the resulting molecule would be stable as per the inductive effect.
When a group displaying the -I effect is bonded to a molecule, the electron density of the resulting molecule effectively reduces, making it more likely to accept electrons and thereby increasing the acidity of the molecule.
When a +I group attaches itself to a molecule, there is an increase in the electron density of the molecule. This increases the basicity of the molecule since it is now more capable of donating electrons.
Category:Organic chemistry