Arrange the following in the increasing order of effective delocalization of negative charge in phenoxide ion:

(A) 2, 4, 6-trinitrophenol

(B) 3, 5-dinitrophenol

(C) 4-methylphenol

(D) 3-nitrophenol

The correct option is:

(C) < (D) < (B) < (A)

The correct answer is option 1. (C) < (D) < (B) < (A).

The effective delocalization of negative charge in a phenoxide ion is influenced by the presence and nature of substituents on the phenol ring. Electron-withdrawing groups enhance the stability of the phenoxide ion by withdrawing electron density from the ring, promoting better resonance stabilization of the negative charge.

Let us analyze each compound in the given options:

(C) 4-methylphenol:
Methyl (\(CH_3\)) is an electron-donating group. It releases electron density to the ring, making the negative charge less effectively delocalized. Therefore, this compound has a lower effective delocalization compared to the others.

(D) 3-nitrophenol:
Nitro (\(NO_2\)) is an electron-withdrawing group. It withdraws electron density from the ring, promoting better resonance stabilization of the negative charge. While it has only one nitro group, it is more effective in delocalizing the negative charge compared to 4-methylphenol.

(B) 3,5-dinitrophenol:
This compound has two nitro groups (\(NO_2\)), making it more effective in withdrawing electrons compared to 3-nitrophenol. The presence of two electron-withdrawing groups enhances the resonance stabilization of the negative charge.

(A) 2,4,6-trinitrophenol:
This compound has three nitro groups (\(NO_2\)) at ortho and para positions. It has the highest electron-withdrawing capacity among the options, leading to the most effective delocalization of the negative charge.

Therefore, the correct order of increasing effective delocalization of negative charge is:
\((C) < (D) < (B) < (A) \)

In summary, the more electron-withdrawing groups attached to the phenol ring, especially at ortho and para positions, the more effectively the negative charge can be delocalized, resulting in greater stability of the phenoxide ion.