21. Aldehydes and Ketones: Nucleophilic Addition

Show how you would accomplish the following synthetic conversions efficiently and in good yield. You may use any necessary additional reagents and solvents.

(e)

The following reaction is known as the benzoin condensation. The reaction does not take place if sodium hydroxide is used instead of sodium cyanide. Propose a mechanism for the reaction and explain why the reaction does not occur if hydroxide ion is the base.

What are the products of the following reactions? Show all stereoisomers that are formed.

c.

d.

Show what amines and carbonyl compounds combine to give the following derivatives.

(a)

(b)

(c)

A chemist failed to generate the alcohol using the reaction shown here.

(b) How could the reaction conditions be modified to allow formation of the product?

Identify the bonds broken and formed in the following addition reaction.

(a) Would you expect this reaction to be favored based on entropy?

(b) Based on enthalpy [qualitatively]?

(c) Overall?

Propose a mechanism for the acid-catalyzed reaction of cyclohexanone with ethylene glycol to give cyclohexanone ethylene acetal.

Acetals can serve as protecting groups for 1,2-diols, as well as for aldehydes and ketones. When the acetal is formed from acetone plus the diol, the acetal is called an acetonide. Show the acetonides formed from these diols with acetone under acid catalysis.

For each compound,

1. name the functional group.

2. show what compound(s) result from complete hydrolysis.

(a)

Propose a mechanism for each of the following reactions:

b.

Show how you would synthesize octanal from each compound. You may use any necessary reagents.

(b) non-1-ene

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

(b)

What is the best set of reagents to use for the synthesis?

2.

Draw structures of the following derivatives.

(c) cyclopropanone oxime

Predict the products of the following reactions.

(c)

(d)