Question

Arrange the following compounds in order of increasing reactivity towards HCN :
Acetaldehyde, Acetone, Di-tertiary butyl ketone, Methyl tertiary butyl ketone.

Answer 1

The order of reactivity is linked with the steric hindrance or crowding of the groups around the carbonyl group. Greater the extent of steric hindrance, lesser will be the reactivity. The increasing order of reactivity towards HCN (or `CN^(-)` ion) is : Di-tertiary butyl ketone `lt` Methyl tertiary butyl ketone `lt` Acetone `lt` Acetaldehyde.