Question

What is the action of the following reagents on ethanoic acid?

1) `LiAlH_4"/"H_3O^+`

2) `PCl_3 , "heat"`

3) `P_2O_5, "heat"`

Answer 1

1) \[\ce{\underset{\text{ethanoic acid}}{CH3} - COOH ->[LiAIH4IH3O+] \underset{\text{ethanol}}{CH3} -CH2-OH}\]

Ethanoic acid when treated with reducing agent like LiAlH₄ , it gives ethanol

2) \[\ce{\underset{\text{ethanoic acid}}{3CH3 - COOH} - PCI3 ->[\Delta] \underset{\text{acetylcholoride}}{3CH3COCI + H3PO3}}\]

Ethanoic acid, when treated with PCl₃, gives acetyl chloride

3) \[\ce{\underset{\text{two molecules of ethanoic acid}}{CH3COOH + CH3COOH} ⇌[P2O5][A] \underset{\text{acetic anhydride}}{(CH3 - CO)2O} + OH}\]

When two molecules of ethanoic acid heated with strong dehydrating agent P₂O₅, it removes water molecules to for acetic anhydride.