21. Aldehydes and Ketones: Nucleophilic Addition

Draw the products of the following reactions:

b.

Provide the chemical steps necessary for the following synthesis.

Which of the following correctly describes the synthesis of an acetal from an aldehyde ($\mathrm{acetal} a$) and a ketone ($\mathrm{acetal} b$)?

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

(b) excess CH₃OH, H⁺

There are three dioxane isomers: 1,2-dioxane, 1,3-dioxane, and 1,4-dioxane. One of these acts like an ether and is an excellent solvent for Grignard reactions. Another one is potentially explosive when heated. The third one quickly hydrolyzes in dilute acid. Show which isomer acts like a simple ether, and then explain why one of them is potentially explosive.

Hydration of an aldehyde is also catalyzed by hydroxide ion. Propose a mechanism for the reaction.

Which of the following sets of compounds are formed as the major organic products when an acetal is hydrolyzed in aqueous $H_{2}O$ and $\mathrm{HCl}$?

Which of the following are a. hemiacetals? b. acetals? c. hydrates?

1.

Propose mechanisms for the following reactions.

(a)

For each of the following reactions, identify the bonds that are broken and formed. Be sure to indicate whether the bond that is broken is a σ bond or a π bond.

(e)

Which of the following are a. hemiacetals? b. acetals? c. hydrates?

3.

There are three dioxane isomers: 1,2-dioxane, 1,3-dioxane, and 1,4-dioxane. One of these acts like an ether and is an excellent solvent for Grignard reactions. Another one is potentially explosive when heated. The third one quickly hydrolyzes in dilute acid. Propose a mechanism for the acid hydrolysis of the third isomer.

For each compound,

1. name the functional group.

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

(d)

For each compound,

1. name the functional group.

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

(e)