Unlike phenol, 2,4-dinitrophenol is soluble in sodium carbonate solution in water because?
A. presence of two - $N O_{2}$ groups in the ring makes 2, 4 – dinitrophenol a stronger acid than phenol.
B. presence of two - $N O_{2}$ groups in the ring makes 2, 4 – dinitrophenol a weaker acid than phenol.
C. presence of two - $N O_{2}$ groups make the hydrogen bonding easier, making 2,4-dinitrophenol soluble.
D. nitro group reacts with $N a_{2} C O_{3}$ while the -OH group does not.

Question

Unlike phenol, 2,4-dinitrophenol is soluble in sodium carbonate solution in water because?
A. presence of two - $N O_{2}$ groups in the ring makes 2, 4 – dinitrophenol a stronger acid than phenol.
B. presence of two - $N O_{2}$ groups in the ring makes 2, 4 – dinitrophenol a weaker acid than phenol.
C. presence of two - $N O_{2}$ groups make the hydrogen bonding easier, making 2,4-dinitrophenol soluble.
D. nitro group reacts with $N a_{2} C O_{3}$ while the -OH group does not.

Vedantu Content Team · Accepted Answer

Hint: To solve this question you should have a basic idea regarding the structures of phenol and 2,4-dinitrophenol and about electron withdrawing groups and its effect after adding to any compound. Phenol has a benzene ring with one hydroxyl group and 2,4-dinitrophenol has two nitrogen oxide molecules more than phenol.Complete answer: Structures of phenol and 2,4-dinitrophenol are drawn below.

(2,4 – dinitrophenol)          (phenol)In 2,4 – dinitrophenol two - $N{{O}_{2}}$ groups are present. $N{{O}_{2}}$  has a strong electron withdrawing nature which increases acidity of the compound.Electron withdrawing group (EWG): An atom or group that draws electron density from neighboring atoms towards itself, usually by resonance or inductive effects.Therefore, presence of two electron withdrawing - $N{{O}_{2}}$groups in the ring makes 2,4- dinitrophenol a stronger acid than phenol.Sodium Carbonate solution is basic in nature. Hence, Stronger the acid it is easily soluble in the basic solution.Therefore, it reacts with $N{{a}_{2}}C{{O}_{3}}$solution to form sodium salt with the evolution of $C{{O}_{2}}$, thus making it soluble in$N{{a}_{2}}C{{O}_{3}}$.Hence, unlike phenol, 2,4-dinitrophenol is soluble in sodium carbonate solution in water because presence of two - $N{{O}_{2}}$groups in the ring makes 2, 4 – dinitrophenol a stronger acid than phenol.Hence, option A is the right answer.Note:Always remember, 2,4,6 – trinitrophenol > 2,4 – dinitrophenol > phenol, order of acidic nature of the compounds.Orders of electron withdrawing group is -$N{{O}_{2}}$, -$CN$,-$CHO$,-$COR$,-$COOH$,-$COOR$, -$CON{{H}_{2}}$(strongest to weakest)

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