Organic conversion

Toluene to benzyl alcohol

2 steps: Etard reaction, then reduction

Class 12, Chapter 8 Aldehydes, Ketones and Carboxylic Acids

Alternative routes (4)

Toluene → Benzoic acid → Benzyl alcohol
1. Toluene to benzoic acid: KMnO₄, KOH, heat; then H₃O⁺.
2. Benzoic acid to benzyl alcohol: (i) LiAlH₄ (ii) H₃O⁺.
Toluene → Benzyl chloride → Benzyl alcohol
1. Toluene to benzyl chloride: Cl₂, UV light (or heat).
2. Benzyl chloride to benzyl alcohol: aq. NaOH.
Toluene → Benzaldehyde → Benzoic acid → Benzyl alcohol
1. Toluene to benzaldehyde: (i) CrO₂Cl₂, CS₂ (ii) H₃O⁺.
2. Benzaldehyde to benzoic acid: KMnO₄, KOH, heat; then H₃O⁺.
3. Benzoic acid to benzyl alcohol: (i) LiAlH₄ (ii) H₃O⁺.
Toluene → Benzoic acid → Benzoyl chloride → Benzaldehyde → Benzyl alcohol
1. Toluene to benzoic acid: KMnO₄, KOH, heat; then H₃O⁺.
2. Benzoic acid to benzoyl chloride: SOCl₂.
3. Benzoyl chloride to benzaldehyde: H₂, Pd/BaSO₄.
4. Benzaldehyde to benzyl alcohol: NaBH₄.

Why these reagents

Reagent and reason, step by step

Step 1: Toluene to benzaldehyde: (i) CrO₂Cl₂, CS₂ (ii) H₃O⁺ Etard reaction stops at the aldehyde through a chromium complex that hydrolyses.
Step 2: Benzaldehyde to benzyl alcohol: NaBH₄ Hydride reduction of an aldehyde gives the primary alcohol.

Questions

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

2 steps: Toluene, then benzaldehyde, then benzyl alcohol.

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

Etard reaction. Toluene is oxidised to benzaldehyde by chromyl chloride in CS2, followed by hydrolysis of the chromium complex.

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

Toluene to benzaldehyde: (i) CrO₂Cl₂, CS₂ (ii) H₃O⁺. Etard reaction stops at the aldehyde through a chromium complex that hydrolyses.