Arrange the following in increasing order of their reactivity towards HCN: Di-tert-butyl ketone, Acetaldehyde, Acetone.
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Solution and Explanation
Answer: Increasing order of reactivity towards HCN is: Di-tert-butyl ketone < Acetone < Acetaldehyde. Reason: di-tert-butyl ketone has two very bulky tert-butyl groups that both crowd the carbonyl carbon and push in electron density, so it is least reactive. Acetone (a ketone with two small methyl groups) is more reactive. Acetaldehyde, being an aldehyde with only one methyl group and a hydrogen, has the least crowding and the most positive carbonyl carbon, so it is most reactive.
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