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Organic conversion

Ethanol to propan-2-ol

2 steps: oxidation, then addition

Class 12, Chapter 7 Alcohols, Phenols and Ethers

  1. OH
    EthanolCH₃CH₂OHAlcohol
  2. Step 1

    PCC

    i

    Pyridinium chlorochromate stops at the aldehyde; stronger oxidants go on to the acid.

    Also written: Cu

    OH
    EthanalCH₃CHOAldehyde
  3. Step 2

    (i) CH₃MgBr, dry ether (ii) H₂O

    i

    Grignard reagent plus an aldehyde other than methanal gives a secondary alcohol.

    OH
    Propan-2-olCH₃CH(OH)CH₃Alcohol

Exam answer

  1. Step 1: Ethanol to ethanal: PCC.
  2. Step 2: Ethanal to propan-2-ol: (i) CH₃MgBr, dry ether (ii) H₂O.
Alternative routes (3)
  • Ethanol → Ethanoic acid → Ethanoyl chloride → Ethanal → Propan-2-ol
    1. Ethanol to ethanoic acid: KMnO₄, KOH, heat; then H₃O⁺.
    2. Ethanoic acid to ethanoyl chloride: SOCl₂.
    3. Ethanoyl chloride to ethanal: H₂, Pd/BaSO₄.
    4. Ethanal to propan-2-ol: (i) CH₃MgBr, dry ether (ii) H₂O.
  • Ethanol → Ethanoic acid → Ethyl ethanoate → Ethanal → Propan-2-ol
    1. Ethanol to ethanoic acid: KMnO₄, KOH, heat; then H₃O⁺.
    2. Ethanoic acid to ethyl ethanoate: CH₃CH₂OH, conc. H₂SO₄ (catalyst), heat.
    3. Ethyl ethanoate to ethanal: (i) DIBAL-H (ii) H₂O.
    4. Ethanal to propan-2-ol: (i) CH₃MgBr, dry ether (ii) H₂O.
  • Ethanol → Ethanoic acid → Ethanoyl chloride → Propanone → Propan-2-ol
    1. Ethanol to ethanoic acid: KMnO₄, KOH, heat; then H₃O⁺.
    2. Ethanoic acid to ethanoyl chloride: SOCl₂.
    3. Ethanoyl chloride to propanone: (CH₃)₂Cd.
    4. Propanone to propan-2-ol: NaBH₄.
Why these reagents

Reagent and reason, step by step

  • Step 1: Ethanol to ethanal: PCC Pyridinium chlorochromate stops at the aldehyde; stronger oxidants go on to the acid.
  • Step 2: Ethanal to propan-2-ol: (i) CH₃MgBr, dry ether (ii) H₂O Grignard reagent plus an aldehyde other than methanal gives a secondary alcohol.
Questions

Ethanol to propan-2-ol: quick answers

How many steps does it take to convert ethanol to propan-2-ol?

2 steps: Ethanol, then ethanal, then propan-2-ol.

Which named reaction is used to convert ethanol to propan-2-ol?

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

What is the reagent for step 1 of ethanol to propan-2-ol?

Ethanol to ethanal: PCC. Pyridinium chlorochromate stops at the aldehyde; stronger oxidants go on to the acid.

Plan your own conversion