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Chapter 21 The Chemistry of Carboxylic Acid Derivatives

Chapter 21 The Chemistry of Carboxylic Acid Derivatives. Carboxylic Acid Derivatives. Carboxylic acid derivative : a compound that has an acyl group bonded to an electronegative atom or substituent that can act as a leaving group in a substitution reaction

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Chapter 21 The Chemistry of Carboxylic Acid Derivatives

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  1. Chapter 21The Chemistry of Carboxylic Acid Derivatives

  2. Carboxylic Acid Derivatives • Carboxylic acid derivative: a compound that has an acyl group bonded to an electronegative atom or substituent that can act as a leaving group in a substitution reaction • can be hydrolyzed under acidic of basic conditions to give a carboxylic acid

  3. Structures of Carboxylic Acid Derivatives 21.1 Nomenclature and Classification of Carboxylic Acid Derivatives

  4. Reactions of Carboxylic Acid Derivatives • Chemistry dominated by nucleophilic acyl substitution rxns:

  5. Hydrolysis Reactions • Hydrolysis of Esters • Basic Hydrolysis (Saponification) • Acid Catalyzed Hydrolysis

  6. Basic Hydrolysis

  7. Acid Catalyzed Hydrolysis

  8. Hydrolysis of Amides • Happens under both acidic and basic conditions • Conditions harsher than those of ester hydrolysis + NH4+/NH2-

  9. Basic Hydrolysis • Acidic Hydrolysis

  10. Hydrolysis of Nitriles • Occurs in both acidic and basic environments • More extreme conditions are required compared to those of esters and amides

  11. Basic hydrolysis 21.7 Hydrolysis of Carboxylic Acid Derivatives

  12. Acidic hydrolysis

  13. Imidic acids can be viewed as the nitrogen-analogs of enols

  14. Problem • Write out the mechanism for the following rxn:

  15. Nucleophilic Acyl Substitution Reactions • The conditions for hydrolysis for these derivatives can differ considerably 21.7 Hydrolysis of Carboxylic Acid Derivatives

  16. Reactions of Acid Chlorides with Amines: Aminolysis 21.8 Reactions of Carboxylic Acid Derivatives with Nucleophiles

  17. Conversion of Acid Chlorides into Esters: Alcoholysis 21.8 Reactions of Carboxylic Acid Derivatives with Nucleophiles

  18. Reactions of Acid Chlorides with Carboxylate Salts: Preparation of Anydrides 21.8 Reactions of Carboxylic Acid Derivatives with Nucleophiles

  19. Problems • Give the products for the following rxns:

  20. Draw the mechanism for the following reaction:

  21. Reactions of Anhydrides with Nucleophiles 21.8 Reactions of Carboxylic Acid Derivatives with Nucleophiles

  22. Reactions of Esters with Nucleophiles • Transesterification: 21.8 Reactions of Carboxylic Acid Derivatives with Nucleophiles

  23. Problems • Give the products for the following rxns:

  24. Reduction Carboxylic Acid Derivatives • Reduction of Esters • LiAlH4 preferred over NaBH4

  25. -78°C, DIBAH = Diisobutyl aluminum hydride

  26. Reduction of Amides to Amines • Net effect is conversion of C=O to CH2 21.9 Reduction of Carboxylic Acid Derivatives

  27. Reduction of Amides to Amines • Note how the amide reduction differs from that of ester reduction 21.9 Reduction of Carboxylic Acid Derivatives

  28. Note that a protonolysis step with aqueous acid follows the LiAlH4 reduction • This is followed by base to free the amine

  29. 21.9 Reduction of Carboxylic Acid Derivatives

  30. 21.9 Reduction of Carboxylic Acid Derivatives

  31. Reduction of Nitriles to Primary Amines 21.9 Reduction of Carboxylic Acid Derivatives

  32. Two successive nucleophilic additions occur

  33. Intermediate imine not isolated 21.9 Reduction of Carboxylic Acid Derivatives

  34. Reduction of Acid Chlorides to Aldehydes • The Rosenmundreduction: • H2 gas over Pd on C • Poisoned with BaSO4 or quinoline • Keeps aldehyde from further reducing to alcohol

  35. Derivatives of LiAlH4 can also be used • Can also use DIBAH 21.9 Reduction of Carboxylic Acid Derivatives

  36. Problems • Draw the products for the following rxns:

  37. Reactions of Esters with Grignard Reagents • Tertiary alcohol produced • Two substituents are identical 21.10 Reactions of Carboxylic Acid Derivatives with Organometallic Reagents

  38. Reactions of Acid Chlorides Grignard Reagents 21.10 Reactions of Carboxylic Acid Derivatives with Organometallic Reagents

  39. Reactions of Acid Chlorides with R2CuLi • R2CuLi = Gilman reagent • Dialkylcuprates are less reactive than Grignard reagents • Allow rxn to stop at ketone • Only works with acid chlorides, not with other carboxylic acid derivatives

  40. Problems • Draw the product for the following rxns:

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