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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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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


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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


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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


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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


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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


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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


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Outline reasons and a larger positive charge on the carbonyl carbon in aldehydes.

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


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Examples: reasons and a larger positive charge on the carbonyl carbon in aldehydes.


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Acetals and hemiacetals can be formed intramolecularly reasons and a larger positive charge on the carbonyl carbon in aldehydes.

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

protecting groups


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Outline reasons and a larger positive charge on the carbonyl carbon in aldehydes.

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


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Reactions of aldehydes and ketones with ammonia reasons and a larger positive charge on the carbonyl carbon in aldehydes.

and its derivatives


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Examples: reasons and a larger positive charge on the carbonyl carbon in aldehydes.


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Outline reasons and a larger positive charge on the carbonyl carbon in aldehydes.

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


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The reasons and a larger positive charge on the carbonyl carbon in aldehydes.equilibrium is strongly shifted toward the carbonyl form, especially in polar solvents


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

Stabilization of the carbonyl form decreases acidity of the compound


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

Enolization, catalyzed by acids


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Outline equilibrium toward the enol.

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


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Aldol reaction (acid catalyzed) equilibrium toward the enol.


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Aldol reaction (base catalyzed) equilibrium toward the enol.


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Examples: equilibrium toward the enol.


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