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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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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
Structures of Carboxylic Acid Derivatives 21.1 Nomenclature and Classification of Carboxylic Acid Derivatives
Reactions of Carboxylic Acid Derivatives • Chemistry dominated by nucleophilic acyl substitution rxns:
Hydrolysis Reactions • Hydrolysis of Esters • Basic Hydrolysis (Saponification) • Acid Catalyzed Hydrolysis
Hydrolysis of Amides • Happens under both acidic and basic conditions • Conditions harsher than those of ester hydrolysis + NH4+/NH2-
Basic Hydrolysis • Acidic Hydrolysis
Hydrolysis of Nitriles • Occurs in both acidic and basic environments • More extreme conditions are required compared to those of esters and amides
Basic hydrolysis 21.7 Hydrolysis of Carboxylic Acid Derivatives
Problem • Write out the mechanism for the following rxn:
Nucleophilic Acyl Substitution Reactions • The conditions for hydrolysis for these derivatives can differ considerably 21.7 Hydrolysis of Carboxylic Acid Derivatives
Reactions of Acid Chlorides with Amines: Aminolysis 21.8 Reactions of Carboxylic Acid Derivatives with Nucleophiles
Conversion of Acid Chlorides into Esters: Alcoholysis 21.8 Reactions of Carboxylic Acid Derivatives with Nucleophiles
Reactions of Acid Chlorides with Carboxylate Salts: Preparation of Anydrides 21.8 Reactions of Carboxylic Acid Derivatives with Nucleophiles
Problems • Give the products for the following rxns:
Reactions of Anhydrides with Nucleophiles 21.8 Reactions of Carboxylic Acid Derivatives with Nucleophiles
Reactions of Esters with Nucleophiles • Transesterification: 21.8 Reactions of Carboxylic Acid Derivatives with Nucleophiles
Problems • Give the products for the following rxns:
Reduction Carboxylic Acid Derivatives • Reduction of Esters • LiAlH4 preferred over NaBH4
Reduction of Amides to Amines • Net effect is conversion of C=O to CH2 21.9 Reduction of Carboxylic Acid Derivatives
Reduction of Amides to Amines • Note how the amide reduction differs from that of ester reduction 21.9 Reduction of Carboxylic Acid Derivatives
Note that a protonolysis step with aqueous acid follows the LiAlH4 reduction • This is followed by base to free the amine
Reduction of Nitriles to Primary Amines 21.9 Reduction of Carboxylic Acid Derivatives
Intermediate imine not isolated 21.9 Reduction of Carboxylic Acid Derivatives
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
Derivatives of LiAlH4 can also be used • Can also use DIBAH 21.9 Reduction of Carboxylic Acid Derivatives
Problems • Draw the products for the following rxns:
Reactions of Esters with Grignard Reagents • Tertiary alcohol produced • Two substituents are identical 21.10 Reactions of Carboxylic Acid Derivatives with Organometallic Reagents
Reactions of Acid Chlorides Grignard Reagents 21.10 Reactions of Carboxylic Acid Derivatives with Organometallic Reagents
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
Problems • Draw the product for the following rxns: