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Aldehydes, ketones. Required background: Structure of alkenes Nucleophilic substitution S N 1, S N 2 Essential for: 1. Carboxylic aids and their derivatives, lipids 2. Enols, enolates 3. Aminoacids, peptides 4. Carbohydrates and nucleic acids.

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Aldehydes, ketones

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Aldehydes, ketones


Required background:

Structure of alkenes

Nucleophilic substitution SN1, SN2

Essential for:

1. Carboxylic aids and their derivatives, lipids

2. Enols, enolates

3. Aminoacids, peptides

4. Carbohydrates and nucleic acids


Outline

1. Structure and physical properties of carbonyl compounds

2. Nomenclature of aldehydes and ketones

3. Preparation of aldehydes and ketones

4. Nucleophilic addition to the carbonyl group

5. Reduction of aldehydes and ketones

7. Acetals and their use in synthesis

8. Reaction of aldehydes and ketones with ammonia and primary amines

9. Enoles and enolates

10. Aldol condensation


Outline

1. Structure and physical properties of carbonyl compounds

2. Nomenclature of aldehydes and ketones

3. Preparation of aldehydes and ketones

4. Nucleophilic addition to the carbonyl group

5. Reduction of aldehydes and ketones

7. Acetals and their use in synthesis

8. Reaction of aldehydes and ketones with ammonia and primary amines

9. Enoles and enolates

10. Aldol condensation


Outline

1. Structure and physical properties of carbonyl compounds

2. Nomenclature of aldehydes and ketones

3. Preparation of aldehydes and ketones

4. Nucleophilic addition to the carbonyl group

5. Reduction of aldehydes and ketones

7. Acetals and their use in synthesis

8. Reaction of aldehydes and ketones with ammonia and primary amines

9. Enoles and enolates

10. Aldol condensation


Preparation of aldehydes and ketones

a.Oxidation of alcohols

b. Friedel-Crafts acylation

c. Hydration of alkynes

d. Ozonolysis of alkynes

e. Cleavage of glycols

Nucleophilic addition to the carbonyl group


Aldehydes are more reactive, than ketones due to the steric reasons and a larger positive charge on the carbonyl carbon in aldehydes.

Addition to C=O bonds is faster, than addition to C=C bonds due to the higher polarity of the C=O bond, but less favorable thermodynamically due to the stronger C=O bond vs. the C=C bond. Example: Cyanohydrin synthesis

Reduction of aldehydes and ketones


Outline

1. Structure and physical properties of carbonyl compounds

2. Nomenclature of aldehydes and ketones

3. Preparation of aldehydes and ketones

4. Nucleophilic addition to the carbonyl group

5. Reduction of aldehydes and ketones

7. Acetals and their use in synthesis

8. Reaction of aldehydes and ketones with ammonia and primary amines

9. Enoles and enolates

10. Aldol condensation


Examples:


Acetals and hemiacetals can be formed intramolecularly

Due to the stability of acetals toward bases and nucleophiles, they are often used as

protecting groups


Outline

1. Structure and physical properties of carbonyl compounds

2. Nomenclature of aldehydes and ketones

3. Preparation of aldehydes and ketones

4. Nucleophilic addition to the carbonyl group

5. Reduction of aldehydes and ketones

7. Acetals and their use in synthesis

8. Reaction of aldehydes and ketones with ammonia and primary amines

9. Enoles and enolates

10. Aldol condensation


Reactions of aldehydes and ketones with ammonia

and its derivatives


Examples:


Outline

1. Structure and physical properties of carbonyl compounds

2. Nomenclature of aldehydes and ketones

3. Preparation of aldehydes and ketones

4. Nucleophilic addition to the carbonyl group

5. Reduction of aldehydes and ketones

7. Acetals and their use in synthesis

8. Reaction of aldehydes and ketones with ammonia and primary amines

9. Enoles and enolates

10. Aldol condensation


Theequilibrium is strongly shifted toward the carbonyl form, especially in polar solvents


In esters, enolization is even less favorable due to stabilization of the carbonyl group.

Stabilization of the carbonyl form decreases acidity of the compound


Stabilization of the double bond (by conjugation) shifts the equilibrium toward the enol.

Enolization, catalyzed by acids


Outline

1. Structure and physical properties of carbonyl compounds

2. Nomenclature of aldehydes and ketones

3. Preparation of aldehydes and ketones

4. Nucleophilic addition to the carbonyl group

5. Reduction of aldehydes and ketones

7. Acetals and their use in synthesis

8. Reaction of aldehydes and ketones with ammonia and primary amines

9. Enoles and enolates

10. Aldol condensation


Aldol reaction (acid catalyzed)


Aldol reaction (base catalyzed)


Examples:


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