Question

How will you obtain (Give chemical equations only): (i) 4-hydroxy-4-methylpentan-2-one from propanone?
(ii) 3-hydroxybutanol from ethanol?
(iii) Butanoic acid from butanal?
(iv) Ethanoic anhydride from ethanoic acid?
(v) Phenyl ethanoic acid from benzyl alcohol?

Hint:

Aldol condensation gives β-hydroxy carbonyls; oxidation of aldehydes/alcohols always yields acids.

Answer 1

(i) 4-hydroxy-4-methylpentan-2-one from propanone:

To obtain 4-hydroxy-4-methylpentan-2-one from propanone, perform the following reaction:

\(\text{CH}_3\text{COCH}_3 \xrightarrow{\text{CH}_3\text{MgBr}} \text{CH}_3\text{COCH}_2\text{CH}_2\text{CH}_3 \xrightarrow{\text{H}_2\text{O}} \text{CH}_3\text{C(OH)CH}_3\text{CH}_2\text{CH}_3\)

(ii) 3-hydroxybutanol from ethanol:

To obtain 3-hydroxybutanol from ethanol, follow the reaction below:

\(\text{CH}_3\text{CH}_2\text{OH} \xrightarrow{\text{HCl}} \text{CH}_3\text{CH}_2\text{CHO} \xrightarrow{\text{NaBH}_4} \text{CH}_3\text{CH}_2\text{CH(OH)}\text{CH}_3\)

(iii) Butanoic acid from butanal:

To obtain butanoic acid from butanal, follow this oxidation reaction:

\(\text{CH}_3\text{CH}_2\text{CHO} \xrightarrow{\text{[O]}} \text{CH}_3\text{CH}_2\text{COOH}\)

(iv) Ethanoic anhydride from ethanoic acid:

To obtain ethanoic anhydride from ethanoic acid, use the following reaction:

\( 2 \text{CH}_3\text{COOH} \xrightarrow{\text{P}_4\text{O}_{10}} \text{CH}_3\text{COOCOCH}_3 \)

(v) Phenyl ethanoic acid from benzyl alcohol:

To obtain phenyl ethanoic acid from benzyl alcohol, perform the reaction shown below:

\(\text{C}_6\text{H}_5\text{CH}_2\text{OH} \xrightarrow{\text{[O]}} \text{C}_6\text{H}_5\text{CHO} \xrightarrow{\text{[O]}} \text{C}_6\text{H}_5\text{COOH}\)