21. Aldehydes and Ketones: Nucleophilic Addition

Predict the products formed when cyclohexanone reacts with the following reagents.

(a) CH₃NH₂, H⁺

Show how you would synthesize the following derivatives from appropriate carbonyl compounds.

(a)

Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents.

(c) semicarbazide and weak acid

Show a complete mechanism for this reaction.

Show how you would synthesize the following derivatives from appropriate carbonyl compounds.

(c)

What are the products of the following reactions? (A trace amount of acid is present in each case.)

a. cyclopentanone + ethylamine

b. cyclopentanone + diethylamine

What aldehydes are formed when the following amino acids are treated with ninhydrin? 

b. leucine 

c. arginine

2,4-Dinitrophenylhydrazine is frequently used for making derivatives of ketones and aldehydes because the products (2,4-dinitrophenylhydrazones, called 2,4-DNP derivatives) are even more likely than the phenylhydrazones to be solids with sharp melting points. Propose a mechanism for the reaction of acetone with 2,4-dinitrophenylhydrazine in a mildly acidic solution.

Predict the major products of the following reactions.

(a)

Propose mechanisms for the following reactions.

(b)