Question

Which of the following is the correct order of magnitude of $- {\text{I}}$ effect:
A.$- F > - N{O_2} > - COOH > - OC{H_3}$
B.$- N{O_2} > - F > - COOH > - OC{H_3}$
C.$- N{O_2} > - COOH > - F > - OC{H_3}$
D.$- COOH > - N{O_2} > - OC{H_3} > - F$

Answer 1

To answer this question, you should recall the concept of inductive effect. Inductive can be negative Inductive Effect or positive inductive effect depending on the electron-withdrawing or donating nature of the attached group.

Complete Step by step solution:
We can define the inductive effect as 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.
Positive Inductive Effect occurs when an attached group tends to release or donate electrons, such as an alkyl group.
Negative Inductive Effect occurs when an electronegative atom, such as a halogen, is the attached group. This results in an unequal sharing of electrons and the final result is the generation of a positive charge.
The correct order of magnitude of $- {\text{I}}$ effect is: $- N{O_2} > - COOH > - F > - OC{H_3}$

Thus, the correct option is option C.

Note: You should know the effect of Inductive Effect on Stability of Molecules. Charge over any chemical species plays a strong part when determining the stability of the resulting molecule as per the inductive effect. When an electron-withdrawing group i.e. a group displaying the $- {\text{I}}$ effect when bonded a positively charged atom and the positive charge on the resulting molecule is amplified, reducing its stability. While, on the other hand, when a negatively charged atom is introduced to a group with the same electron-withdrawing tendency the charge disparity is somewhat quenched and the resulting molecule would be stable.