Chapter 17, Problem 17.35P

Interpretation Introduction

Interpretation:

Why the hydrate of cyclopropanone is stable is to be explained.

Concept introduction:

Ketones and aldehydes exhibit very similar chemical behavior because both contain a carbonyl group with alkyl groups or hydrogen atoms attached to the carbonyl carbon. However, the nucleophilic addition reactions they undergo differ noticeably both thermodynamically and kinetically. The rate of hydration and the extent of hydration at equilibrium are greater for the aldehydes than for the ketone. In a ketone, the steric repulsion from the two alkyl groups on the carbonyl carbon makes it more difficult for the nucleophile to attack. Furthermore, the bulky alkyl groups in the hydrate product overlap with the bulky OH groups, generating steric strain and decreasing stability. An aldehyde, on the other hand, has at the most one alkyl group bonded to the carbonyl carbon, so both these steric effects are diminished. However, this is not the case in cyclopropanone.