21. Aldehydes and Ketones: Nucleophilic Addition

Provide the chemical steps necessary for the following synthesis.

Provide the chemical steps necessary for the following synthesis.

Determine the starting materials based on the acetal group present.

Propose mechanisms for the following reactions.

(a) <IMAGE of reaction>

Draw structures of the following derivatives.

(e) acetaldehyde dimethyl acetal

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

(b) excess CH3OH, H+

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

(d) excess ethanol and acid

Alcohols combine with ketones and aldehydes to form interesting derivatives, which we will discuss in Chapter 18. The following reactions show the hydrolysis of two such derivatives. Propose mechanisms for these reactions. (a) <IMAGE of reaction>

For each compound,

1. name the functional group.

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

(d) <IMAGE>

For each compound,

1. name the functional group.

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

(e) <IMAGE>

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.

<IMAGE>

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.

<IMAGE>

(a) Simple aminoacetals hydrolyze quickly and easily in dilute acid. Propose a mechanism for hydrolysis of the following aminoacetal:

<IMAGE of reaction>

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