Question

Which of the following alternative is correct for the treatment of ketones with ethylene glycol in the presence of dry $HCl$ ?

• A. The product obtained is ethylene glycol hemi-ketal
• B. In this reaction, electrophilicity of carbonyl carbon decreases
• C. $HCl$ protonates the oxygen of the carbonyl group
• D. The product thus obtained is cyanohydrin

Answer 1

Answer: (C)

Ketones react with ethylene glycol in the presence of dry $HCl$ to form cyclic products known as ethylene glycol ketals.

In the above reaction dry $HCl$ protonates the oxygen of the carbonyl compounds and therefore, increases the electrophilicity of the carbonyl carbon facilitating the nucleophilic attack of ethylene glycol.