Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Chapter 14 Carboxylic Acids, Esters, Amines, and Amides 14.3 Esters 1

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Esters Esters are found in fats and oils responsible for the aroma and flavor of bananas, oranges, and strawberries O  CH 3 —C—O—CH 3 ester group 2

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Esterification Esterification is the reaction of a carboxylic acid and alcohol in the presence of an acid catalyst to produce an ester. The main chain of an ester comes from the carboxylic acid, while the alkyl group in an ester comes from the alcohol. 3

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Esterification An example of esterification is the reaction of a ethanoic acid with 1-propanol to produce an ester called propylethanoate, responsible for the smell of pears. 4

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Write the equation for the reaction of propanoic acid and methanol in the presence of an acid catalyst. 5

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Write the equation for the reaction of propanoic acid and methanol in the presence of an acid catalyst. O  H + CH 3 —CH 2 —C—OH + H—O—CH 3 Propanoic acid Methanol O  CH 3 —CH 2 —C—O—CH 3 + H 2 O 6

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Naming Esters The name of an ester consists of two words derived from the name of the alcohol and the acid in that ester. 1.The first word indicates the alkyl part from the alcohol. 2.The second word is the carboxylate name of the carboxylic acid. 7

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Naming Esters Esters have IUPAC and common names: 8

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Guide to Naming Esters 9 What is the IUPAC name and common name of the following ester? O || CH 3  CH 2  CH 2  C  O  CH 2  CH 3

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Guide to Naming Esters 10 What is the IUPAC name of the following ester? Step 1 Write the name of the carbon chain from the alcohol as an alkyl group. O | CH 3  CH 2  CH 2  C  O  CH 2  CH 3 ethyl

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Guide to Naming Esters 11 What is the IUPAC name of the following ester? Step 2 Change the -ic acid of the acid name to -ate. O || CH 3  CH 2  CH 2  C  O  CH 2  CH 3 ethyl butanoate

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Give the IUPAC and common names of the following compound, which is responsible for the flavor and odor of pears. O  CH 3 — C—O—CH 2 —CH 2 —CH 3 12

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Give the IUPAC and common names of the following compound, which is responsible for the flavor and odor of pears. Step 1 Write the name of the carbon chain from the alcohol as an alkyl group. O  CH 3 —C—O—CH 2 —CH 2 —CH 3 propyl 13

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Give the IUPAC and common names of the following compound, which is responsible for the flavor and odor of pears. Step 2 Change the -ic acid of the acid name to -ate. O  CH 3 —C—O—CH 2 —CH 2 —CH 3 propyl ethanoate (IUPAC) propyl acetate (common) 14

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Aspirin and Salicylic Acid Aspirin is used to relieve pain and reduce inflammation is an ester of salicylic acid and acetic acid Oil of wintergreen is used to soothe sore muscles is an ester of salicylic acid and methanol 15

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Esters in Fruits Esters give pleasant fragrances and flavors to many fruits and flowers. 16

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Draw the structure of the following compounds. A. 3-bromobutanoic acid B. ethyl propionoate 17

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution A. 3-bromobutanoic acid Br O | || CH 3 —CH—CH 2 —C  OH B.ethyl propionoate O  CH 3 —CH 2 —C—O—CH 2 —CH 3 18

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Acid Hydrolysis of Esters In acid hydrolysis, an ester reacts with water to produce a carboxylic acid and an alcohol an acid catalyst is required O  H + H—C—O—CH 2 —CH 3 + H 2 O O  H—C—OH + H—O—CH 2 —CH 3 carboxylic acid alcohol formic acid ethanol 19

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Base Hydrolysis (Saponification) Base hydrolysis, or saponification, is the reaction of an ester with a strong base produces the salt of the carboxylic acid and an alcohol O || CH 3 —C—O—CH 2 —CH 3 + NaOH O  CH 3 —C—O – Na + + HO—CH 2 —CH 3 salt of carboxylic acid alcohol sodium acetate ethanol 20

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Base Hydrolysis of Fatty Acids Produces Soaps 21

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Cleaning Action of Soap A soap contains a nonpolar end that dissolves in nonpolar fats and oils, and a polar end that dissolves in water forms groups of soap molecules called micelles that dissolve in water and are washed away 22

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Learning Check Write the organic products when methyl acetate reacts with A. water and an acid catalyst B. KOH 23

Chemistry: An Introduction to General, Organic, and Biological Chemistry, Eleventh Edition Copyright © 2012 by Pearson Education, Inc. Solution Write the organic products when methyl acetate reacts with A. water and an acid catalyst O  H + CH 3 —C—O  CH 3 CH 3 —C—OH + HO—CH 3 B. KOH O O  Heat  CH 3 —C—O  CH 3 CH 3 —C—O – K + + HO—CH 3 24