Aldehyde reactions with selective oxidation and reduction

Steps:

• Compound X is an aldehyde, as it undergoes oxidation to carboxylic acid and reduction to primary alcohol.
• Reaction 1 oxidizes aldehyde to carboxylic acid using Tollens' reagent, which forms silver mirror and silver carboxylate, then acidified to release the acid.
• Reaction 2 reduces aldehyde to primary alcohol using NaBH4, a mild reducing agent.
• Option D matches: Tollens' followed by H+(aq) for oxidation; NaBH4 for reduction.

Why D is correct:

• Tollens' reagent (ammoniacal AgNO3) oxidizes RCHO to RCOOAg, and H+(aq) protonates it to RCOOH per the reaction RCHO + 2[Ag(NH3)2]+ + 3OH- → RCOO- + 2Ag + 4NH3 + 2H2O, followed by acidification.

Why the others are wrong:

• A: Acidified Na2Cr2O7 oxidizes to acid but Na (metal) reacts violently with water, not standard for alcohol.
• B: Hot acidified Na2Cr2O7 oxidizes aldehydes/primary alcohols to acids, but doesn't distinguish mild Tollens' oxidation.
• C: Tollens' followed by HCl(aq) may form silver chloride precipitate, complicating carboxylic acid isolation.

Final answer: D