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NEET Chemistry QUESTION #1067
Question 1
Identify the suitable reagent for the conversion of \(\text{PhCOCH}_2\text{OCH}_3\) (an ester/ketone) to \(\text{PhCH}_2\text{CHO}\) (an aldehyde):
  • (i) \(\text{NaBH}_4\), (ii) \(\text{H}^+/\text{H}_2\text{O}\)
  • \(\text{H}_2/\text{Pd-BaSO}_4\)
  • (i) \(\text{LiAlH}_4\), (ii) \(\text{H}^+/\text{H}_2\text{O}\)
  • (i) \(\text{AlH(iBu)}_2\), (ii) \(\text{H}_2\text{O}\)✔️
Correct Answer Explanation
DIBAL-H [\(\text{AlH(iBu)}_2\)] at low temperature selectively reduces esters to aldehydes by stopping at the aldehyde stage. \(\text{LiAlH}_4\) would over-reduce to alcohol and \(\text{NaBH}_4\) does not reduce esters. \(\text{H}_2/\text{Pd-BaSO}_4\) (Rosenmund) applies to acid chlorides, not esters/ketones.