Question

An organic compound A with molecular form C₄H₈O₂ on alkaline hydrolysis gives two compound B and C. C on acidification with dil. HCl gives D. Oxidation of B with K₂Cr₂O₇/H₂SO₄ also gives D. Identify A, B, C and D and explain all the reactions involved.

Answer 1

A – ethyl ethanoate 

B – ethanol 

C – sodium ethanoate 

D – ethanoic acid 

Esters upon alkaline hydrolysis gives back the carboxylic acid and the alcohol. The acid is initially obtained in its salt form. The reaction is called saponification.

CH₃COOH₂CH₃ (ethyl ethanoate) \(\overset{NaOH}\longrightarrow\) CH₃COONa (sodium ethanoate) + CH₃CH₂OH (ethanol)

The salt (sodium ethanoate) is treated with dil HCl to obtain the carboxylic acid.

CH₃COONa (sodium ethanoate) + HCl → CH₃COOH (ethanoic acid) + NaCl

Ethanol is oxidized to ethanoic acid in the presence of acidified potassium dichromate. Here, the acid used for acidification is H₂SO_4.

CH₃CH₂OH (ethanol) \(\overset{Acidified\,K_2Cr_2O_7}\longrightarrow\) CH₃COOH (ethanoic acid)