JEE MainChemistryAmines
Consider the following transformations of phenol: Pathway 1: Phenol X Salicylaldehyde Pathway 2: Phenol Y Salicylic acid Pathway 3: Phenol Z p -Benzoquinone Identify the correct set of reagents X, Y, and Z.
Options
- AX = (i) CHCl ₃ + aq. NaOH , (ii) H ^+ ; Y = (i) NaOH , (ii) CO ₂ , (iii) H ^+ ; Z = Na ₂ Cr ₂ O ₇ + H ₂ SO ₄
- BX = (i) NaOH , (ii) CO ₂ , (iii) H ^+ ; Y = (i) CHCl ₃ + aq. NaOH , (ii) H ^+ ; Z = Na ₂ Cr ₂ O ₇ + H ₂ SO ₄
- CX = (i) CCl ₄ + aq. NaOH , (ii) H ^+ ; Y = (i) NaOH , (ii) CO ₂ , (iii) H ^+ ; Z = Na ₂ Cr ₂ O ₇ + H ₂ SO ₄
- DX = (i) CHCl ₃ + aq. NaOH , (ii) H ^+ ; Y = (i) NaOH , (ii) CO ₂ , (iii) H ^+ ; Z = Zn dust,
Correct answer
A. X = (i) CHCl ₃ + aq. NaOH , (ii) H ^+ ; Y = (i) NaOH , (ii) CO ₂ , (iii) H ^+ ; Z = Na ₂ Cr ₂ O ₇ + H ₂ SO ₄
Step-by-step solution
Pathway 1 is the Reimer-Tiemann reaction, which converts phenol to salicylaldehyde using chloroform ( CHCl ₃ ) and aqueous NaOH followed by acidification ( H ^+ ). Pathway 2 is Kolbe's reaction, which converts phenol to salicylic acid using NaOH and CO ₂ followed by acidification ( H ^+ ). Pathway 3 is the oxidation of phenol to p -benzoquinone, which requires a strong oxidizing agent like acidified sodium dichromate ( Na ₂ Cr ₂ O ₇ + H ₂ SO ₄ ). Therefore, the correct set of reagents is given in the first option.