1 20.2 20.2 Structure and Reactivity Structure and Reactivity - - PDF document

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Chapter 20: Carboxylic Acid Derivatives Chapter 20: Carboxylic Acid Derivatives -

• NAS

NAS Carboxylic acid Acyl (or acid) chloride Acid anhydride Ester Carboxamide

• All closely related and made from carboxylic acids
• most are interconvertable

20.1 20.1 – – Carboxylic Acid Derivative Nomenclature Carboxylic Acid Derivative Nomenclature Acyl Chlorides Acid Anhydrides 20.2 20.2 – – Carboxylic Acid Derivatives Carboxylic Acid Derivatives -

• Structure

Structure Extended π system – like carboxylic acids

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20.2 20.2 – – Structure and Reactivity Structure and Reactivity

• Fig. 20.2

20.2 20.2 – – Structure and Reactivity Structure and Reactivity Resonance possibilities - acid chlorides and anhydrides

Acid chlorides and acid anhydrides are not stabilized significantly by resonance – quite reactive towards nucleophiles

Resonance possibilities – esters, amides, carboxylates

Increasing delocalization leads to increasing stability and decreasing reactivity

20.2 20.2 – – Structure and Reactivity Structure and Reactivity

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20.3 20.3 – – General Mechanism for General Mechanism for Nucleophilic Nucleophilic Acyl Acyl Substitution Substitution

Tetrahedral intermediate

20.4 20.4 – – NAS Using Acid Chlorides NAS Using Acid Chlorides

Tetrahedral intermediate

20.4 20.4 – – NAS Using Acid Chlorides, e.g. Amide Synthesis NAS Using Acid Chlorides, e.g. Amide Synthesis

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20.5 20.5 – – Acyl Acyl Substitution in Carboxylic Acid Anhydrides Substitution in Carboxylic Acid Anhydrides

Acetic anhydride Maleic anhydride Synthesis of anhydrides

20.5 20.5 – – Acyl Acyl Substitution in Carboxylic Acid Anhydrides Substitution in Carboxylic Acid Anhydrides

Lab experiment

20.6 20.6 – – Sources of Esters Sources of Esters

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20.7 20.7 – – Physical Properties of Esters Physical Properties of Esters 20.10 20.10 – – Reactions of Esters Reactions of Esters

Acid-catalyzed hydrolysis Basic hydrolysis – saponification

20.11 Reactions of Esters with Ammonia and Amines 20.11 Reactions of Esters with Ammonia and Amines

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20.12 20.12 – – Thioesters Thioesters

Acetyl coenzyme A

20.13 20.13 – – Amides Amides

Hydrogen bonding

20.13 20.13 – – Amides Amides – – Structure and Synthesis Structure and Synthesis

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20.14 20.14 – – Intramolecular Intramolecular Amide Formation Amide Formation – – Lactams Lactams 20.15 20.15 – – Hydrolysis of Amides Hydrolysis of Amides – – not covering not covering 20.16 20.16 – – 20.17 20.17 – – Preparation and Hydrolysis of Preparation and Hydrolysis of Nitriles Nitriles

• Protonate nitrogen, attack C with water
• Proton transfer to nitrogen followed by enolization
• Rest of mechanism the same as the amide hydrolysis

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20.18 20.18 – – Addition of Addition of RMgX RMgX to to Nitriles Nitriles – – Not Covering Not Covering