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Organic conversion

Benzaldehyde to benzyl alcohol

1 step: reduction

Class 12, Chapter 8 Aldehydes, Ketones and Carboxylic Acids

  1. OH
    BenzaldehydeC₆H₅CHOAldehyde
  2. Step 1

    NaBH₄

    i

    Hydride reduction of an aldehyde gives the primary alcohol.

    Also written: conc. NaOH

    HO
    Benzyl alcoholC₆H₅CH₂OHAlcohol

Exam answer

  1. Step 1: Benzaldehyde to benzyl alcohol: NaBH₄.
Alternative routes (3)
  • Benzaldehyde → Benzoic acid → Benzyl alcohol
    1. Benzaldehyde to benzoic acid: KMnO₄, KOH, heat; then H₃O⁺.
    2. Benzoic acid to benzyl alcohol: (i) LiAlH₄ (ii) H₃O⁺.
  • Benzaldehyde → Toluene → Benzoic acid → Benzyl alcohol
    1. Benzaldehyde to toluene: Zn-Hg, conc. HCl.
    2. Toluene to benzoic acid: KMnO₄, KOH, heat; then H₃O⁺.
    3. Benzoic acid to benzyl alcohol: (i) LiAlH₄ (ii) H₃O⁺.
  • Benzaldehyde → Toluene → Benzyl chloride → Benzyl alcohol
    1. Benzaldehyde to toluene: Zn-Hg, conc. HCl.
    2. Toluene to benzyl chloride: Cl₂, UV light (or heat).
    3. Benzyl chloride to benzyl alcohol: aq. NaOH.
Why these reagents

Reagent and reason, step by step

  • Step 1: Benzaldehyde to benzyl alcohol: NaBH₄ Hydride reduction of an aldehyde gives the primary alcohol.
Questions

Benzaldehyde to benzyl alcohol: quick answers

How many steps does it take to convert benzaldehyde to benzyl alcohol?

1 step: Benzaldehyde, then benzyl alcohol.

Which named reaction is used to convert benzaldehyde to benzyl alcohol?

None of the steps has a name. They are reduction, so write the reagent and the condition for each step.

What is the reagent for step 1 of benzaldehyde to benzyl alcohol?

Benzaldehyde to benzyl alcohol: NaBH₄. Hydride reduction of an aldehyde gives the primary alcohol.

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