Organic conversion

Ethyne to ethanal

1 step: addition

Class 11, Chapter 9 Hydrocarbons

Alternative routes (4)

Ethyne → Ethene → Ethanol → Ethanal
1. Ethyne to ethene: H₂, Pd/C, quinoline.
2. Ethene to ethanol: H₂O, H⁺ (dilute H₂SO₄).
3. Ethanol to ethanal: PCC.
Ethyne → Propyne → Propene → Ethanal
1. Ethyne to propyne: (i) NaNH₂ (ii) CH₃Br.
2. Propyne to propene: H₂, Pd/C, quinoline.
3. Propene to ethanal: (i) O₃ (ii) Zn, H₂O.
Ethyne → Ethane → Chloroethane → Ethanol → Ethanal
1. Ethyne to ethane: H₂ (excess), Ni (or Pt, Pd).
2. Ethane to chloroethane: Cl₂, UV light.
3. Chloroethane to ethanol: aq. NaOH (or aq. KOH).
4. Ethanol to ethanal: PCC.
Ethyne → Ethene → Bromoethane → Ethanol → Ethanal
1. Ethyne to ethene: H₂, Pd/C, quinoline.
2. Ethene to bromoethane: HBr.
3. Bromoethane to ethanol: aq. NaOH (or aq. KOH).
4. Ethanol to ethanal: PCC.

Why these reagents

Reagent and reason, step by step

Step 1: Ethyne to ethanal: H₂O, dilute H₂SO₄, HgSO₄, 333 K Hydration of ethyne goes through an unstable enol that rearranges to ethanal (333 K).

Questions

How many steps does it take to convert ethyne to ethanal?

1 step: Ethyne, then ethanal.

Which named reaction is used to convert ethyne to ethanal?

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

What is the reagent for step 1 of ethyne to ethanal?

Ethyne to ethanal: H₂O, dilute H₂SO₄, HgSO₄, 333 K. Hydration of ethyne goes through an unstable enol that rearranges to ethanal (333 K).