Chapter 20: Carboxylic Acid Derivatives Chapter 20: Carboxylic Acid Derivatives - - NAS NAS Carboxylic acid Acyl (or acid) Acid anhydride chloride 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 – – Carboxylic Acid Derivatives Carboxylic Acid Derivatives - - Structure Structure 20.2 Extended π system – like carboxylic acids 1
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 20.2 – – Structure and Reactivity Structure and Reactivity 20.2 Resonance possibilities – esters, amides, carboxylates Increasing delocalization leads to increasing stability and decreasing reactivity 2
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 20.4 – – NAS Using Acid Chlorides, e.g. Amide Synthesis NAS Using Acid Chlorides, e.g. Amide Synthesis 20.4 Tetrahedral intermediate 3
20.5 – 20.5 – Acyl Acyl Substitution in Carboxylic Acid Anhydrides Substitution in Carboxylic Acid Anhydrides Synthesis of anhydrides Acetic Maleic anhydride anhydride 20.5 – 20.5 – Acyl Acyl Substitution in Carboxylic Acid Anhydrides Substitution in Carboxylic Acid Anhydrides Lab experiment 20.6 – – Sources of Esters Sources of Esters 20.6 4
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 5
20.12 – 20.12 – Thioesters Thioesters Acetyl coenzyme A 20.13 20.13 – – Amides Amides Hydrogen bonding 20.13 – – Amides Amides – – Structure and Synthesis Structure and Synthesis 20.13 6
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 – – 20.17 20.17 – – Preparation and Hydrolysis of Preparation and Hydrolysis of Nitriles Nitriles 20.16 • Protonate nitrogen, attack C with water • Proton transfer to nitrogen followed by enolization • Rest of mechanism the same as the amide hydrolysis 7
20.18 20.18 – – Addition of Addition of RMgX RMgX to to Nitriles Nitriles – – Not Covering Not Covering 8
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