Question

Arrange the following elements in the order of negative inductive effect: $NH_3^ + ,N{O_2},CN,CHO,CO,COOH,CON{H_2},F,Cl,Br,I,OH,OR,N{H_2},COCl,{C_6}{H_5},H,S{O_3}H$

Answer 1

We need to know that if two atoms are bonded by covalent sigma bond, having electronegativity difference, the more electronegative atom develops a partial negative charge as it drags the bonding electron towards itself, due to its greater affinity to attract electrons. A partial positive charge develops on the less electronegative atom. This leads to a permanent dipole moment, which is known as the Inductive effect.

Complete answer:
As we know that if long chain compounds are present the inductive effect is relayed from one atom to another, but it’s effect gradually decreases with the increase in the chain size. Consider the long chain compound having an Electron withdrawing group (example -F) on the terminal position. The group acquires a partial negative charge and the carbon acquire a partial positive charge which is relayed along the chain. The inductive effect can be shown by the following diagram:
$\delta \delta {\delta ^ + }$ $\delta {\delta ^ + }$ ${\delta ^ + }$ ${\delta ^ - }$
$C - C - C - F$
$3$ $2$ $1$
When an electron donating group is present then that group will acquire partial positive charge and carbon will have negative charge which will relay along the chain. The inductive effect will be as given below:
$\delta \delta {\delta ^ + }$ $\delta {\delta ^ + }$ ${\delta ^ + }$ ${\delta ^ - }$
$C - C - C - G$
$3$ $2$ $1$
There are two types of inductive effect found:
+I effect
+I effect
If an atom or group of atoms attracts electrons towards itself to acquire a partial negative charge, the atom is called the -I group and the corresponding effect is called as negative inductive effect or the -I effect. More the electronegativity of the group, more will be the -I effect.
Also remember that neutral species are always more than charged species. In charged species, charge dispersion is very important for stability. More will be the charge dispersion more will be the stability. If the charge is static the species will become unstable.
The order of -I effect can be given as:
$- NH_3^ + > - N{O_2} > - CN > S{O_3}H > - CHO > - CO > - COOH > - COCl > - CON{H_2} > - F > - Cl > - Br > - I > - OH > - OR > - N{H_2} > - {C_6}{H_5} > H$

Note:
We need to know that the inductive effect is used to determine some important properties and these may be the acidic strength of organic acids, strength of organic bases, effect on dipole moment and bond length, and stability of carbocations, carbanions etc.