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Carboxylic Anhydrides, Esters and Amides. CHAPTER 11. Introduction. In this chapter, we study three classes of compounds derived from carboxylic acids; anhydrides, esters, and amides Each is related to a carboxyl group by loss of H 2 O. Anhydrides.
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Carboxylic Anhydrides, Esters and Amides CHAPTER 11
Introduction • In this chapter, we study three classes of compounds derived from carboxylic acids; anhydrides, esters, and amides • Each is related to a carboxyl group by loss of H2O.
Anhydrides • The functional group of an anhydride is two carbonyl groups bonded to the same oxygen. • The anhydride may be symmetrical (from two identical acyl groups), or mixed (from two different acyl groups).
Carboxylic Esters The functional group of an ester is a carbonyl group bonded to an -OR group.
Amides • The functional group of an amide is a carbonyl group bonded to a nitrogen atom.
Esters Esters are formed by reacting a carboxylic acid and an alcohol.
Naming Esters The first word of the name of an ester is the name of the alkyl or aromatic group (R') contributed by the alcohol. The second word is the carboxylic acid name, with the –ic acid ending changed to –ate.
REACTIONS Carboxylic Acid + Amine Amide
Amides • To name an amide, drop the suffix -oic acid from the IUPAC name of the parent acid and add –amide. O methanamide (IUPAC) HC–NH2 O propanamide (IUPAC) CH3CH2C–NH2
Naming Amides with N-Groups • If the amide nitrogen is also bonded to an alkyl group, name the group and show its location on nitrogen by N- ; or by N,N-di-. O CH3C–NHCH3N-methylethanamide (IUPAC) O CH3CH2C–N(CH3)2 N,N-dimethylpropanamide
Name the following amides: O A. CH3CH2CH2C–NH2 O B. CH3C–N(CH2CH3)2
Structure of 3-methyl pentamide Structure of N-methyl pentamide
Hydrolysis of Anhydrides • Hydrolysis is a chemical decomposition involving breaking a bond and the addition of the elements of water. • Carboxylic anhydrides, particularly the low-molecular- weight ones, react readily with water (hydrolyze) to give two carboxylic acids.
Hydrolysis of Esters • Hydrolysis of esters in aqueous acid is the reverse of Fischer esterification.
Hydrolysis of Amides Hydrolysis – the reverse of amide formation, the amide linkage is cleaved using water to produce a carboxylic acid and an amine.
Step-Growth Polymers • Step-growth polymers are formed by reaction between two molecules, each of which contains two functional groups. Each new bond is created in a separate step. • In this section, we discuss two types of step-growth polymers; polyamides and polyesters.
Polyamides • Reaction of dicarboxylic acid with diamine • Nylon, Kevlar, amino acids
Polyamides • The polyaromatic amide known as Kevlar is made from an aromatic dicarboxylic acid and an aromatic diamine.