Chapter 13 Carboxylic Acids, Esters, Amines, and Amides. Carboxylic Acids. Names and Sources of Some Carboxylic Acids. IUPAC Names

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1 Chapter 13 Carboxylic Acids, Esters, Amines, and Amides 13.1 Carboxylic Acids Carboxylic Acids A carboxylic acid contains a carboxyl group, which is a carbonyl group (C=) attached to a hydroxyl group ( H). is found on carbon 1 in carboxylic acids. C H hydroxyl group or CH carbonyl group 1 2 IUPAC Names Names and Sources of Some Carboxylic Acids In the IUPAC names of carboxylic acids the -e in the alkane name is replaced with -oic acid. CH 4 Methane HCH Methanoic acid Ethane CH Ethanoic acid substituents are numbered from the carboxyl carbon 1. CH CH 2 C H methylbutanoic acid 3 4 Common Carboxylic Acids Aromatic Carboxylic Acids methanoic acid (formic acid) H C H Benzoic acid is the aromatic carboxylic acid. locates substituents by numbering the ring from carbon 1 in the carboxyl group. ethanoic acid (acetic acid) C H 5 6

2 Give the IUPAC names of each compound. A. CH 2 CH B. CH CH 2 CH C. A. CH 2 CH propanoic acid B. CH CH 2 CH3-methylbutanoic acid C. 3-bromobenzoic acid C H C H Br Br 7 8 Chapter 13 Carboxylic Acids, Esters, Amines, and Amides 13.2 Properties of Carboxylic Acids Polarity of Carboxylic Acids Carboxylic acids are strongly polar. have two polar groups: hydroxyl ( H) and carbonyl (C=) Polarity of Carboxylic Acids Comparison of Boiling Points Carboxylic acids form dimers in which hydrogen bonds form between two carboxyl groups. H C C H A dimer of acetic acid Compound Molar Mass Boiling Point CH 2 C H C CH 2 CH 2 H C C H C have higher boiling points than alcohols, ketones, and aldehydes of similar mass

3 Solubility in Water Boiling Points and Solubility Carboxylic acids: form hydrogen bonds with many water molecules. Water molecules with 1-4 carbon atoms are very soluble in water Acidity of Carboxylic Acids Neutralization of Carboxylic Acids Carboxylic acids are weak acids. ionize in water to produce carboxylate ions and hydronium ions. C H + H 2 C + H 3 + Carboxylic acid salts are a product of the neutralization of a carboxylic acid with a strong base. CH + NaH C Na + + H 2 acetic acid sodium acetate (carboxylic acid salt) are used as preservatives and flavor enhancers Write the equation for the reaction of propanoic acid with A. water. Write the equation for the reaction of propanoic acid with A. water. CH 2 CH + H 2 CH 2 C + H 3 + B. KH. B. KH. CH 2 CH + KH CH 2 C K + + H

4 Chapter 13 Carboxylic Acids, Esters, Amines, and Amides 13.3 Esters Esters In an ester, the H in the carboxyl group is replaced with an alkyl group. C ester group Esterification Esterification is the reaction of a carboxylic acid and alcohol in the presence of an acid catalyst to produce an ester. H + C H + H CH 2 Write the equation for the reaction of propanoic acid and methanol in the presence of an acid catalyst. C CH 2 Ethyl acetate (an ester) + H Ester Products Write the equation for the reaction of propanoic acid and methanol in the presence of an acid catalyst. H + CH 2 C H + H Propanoic acid Methanol CH 2 C + H 2 Aspirin is used to relieve pain and reduce inflammation. is an ester of salicylic acid and acetic acid. il of wintergreen is used to soothe sore muscles. is an ester of salicylic acid and methanol. C H C C H 23 24

5 Naming Esters Naming Esters The name of an ester contains the names of the alkyl group from the alcohol. the carbon chain from the acid with ate ending. methyl ethanoate (acetate) C IUPAC: methyl ethanoate common: methyl acetate Esters are named with the alkyl group of the alcohol, and the salt (-ate) of the carboxylic acid From ethanoic acid (acetic acid) From methanol (methyl alcohol) Esters in Plants Esters give pleasant fragrances and flavors to many fruits and flowers. Give the IUPAC and common names of the following compound, which is responsible for the flavor and odor of pears. C CH 2 CH Give the IUPAC and common names of the following compound, which is responsible for the flavor and odor of pears. from 1-propanol C CH 2 CH 2 Draw the structure of the following compounds. A. 3-bomobutanoic acid B. Ethyl propionoate propyl ethanoate (IUPAC) propyl acetate (common) 29 30

6 Acid Hydrolysis of Esters A. 3-bromobutanoic acid Br CH CH 2 CH B. Ethyl propionoate CH 2 C CH 2 In acid hydrolysis an ester reacts with water to produce a carboxylic acid and an alcohol. an acid catalyst is required. H + H C CH 2 + H 2 H C H + H CH Base Hydrolysis (Saponification) Base Hydrolysis of Fatty Acids Produces Soaps Base hydrolysis or saponification, is the reaction of an ester with a strong base. produces the salt of the carboxylic acid and an alcohol. C CH 2 + NaH C Na + + H CH 2 salt of carboxylic acid alcohol 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. Write the organic products when methyl acetate reacts with A. water and an acid catalyst. B. KH

7 Write the organic products when methyl acetate reacts with A. water and an acid catalyst. C H + H Chapter 13 Carboxylic Acids, Esters, Amines, and Amides 13.4 Amines B. KH. C K + + H Amines Classification of Amines Amines are derivatives of ammonia, NH 3. contain N attached to one or more alkyl or aromatic groups. NH 2 NH N NH 2 Amines are classified as primary, secondary, or tertiary. In a primary (1 ) amine, one carbon group is bonded to the nitrogen atom. A secondary (2 ) amine has two carbon groups bonded to the nitrogen atom. A tertiary (3 ) amine has three carbon groups bonded to the nitrogen atom. H N H N H N Models of Amines The 3-dimensional models show the shapes of amine molecules with one or more alkyl groups bonded to the nitrogen atom. Naming Amines Simple amines are named as alkylamines. list the names of the alkyl groups bonded to the N atom in alphabetical order in front of amine. CH 2 NH 2 NH N CH 2 Ethylamine Dimethylamine Ethyldimethylamine 41 42

8 Give the common name and classify as primary, secondary, or tertiary. A. CH 2 CH 2 NH 2 B. CH 2 N A. CH 2 CH 2 NH 2 propylamine, 1 B. CH 2 N ethyldimethylamine, Aromatic Amines The amine of benzene is named aniline. Alkyl groups on the N use the prefix N- with alkyl name. Give the common name of each compound. A. NH CH 2 NH 2 NH 2 NH B. CH 2 N CH 2 aniline 3-chloroaniline N-methylaniline Cl C. NH Hydrogen Bonding for Amines A. NH CH 2 ethylmethylamine B. CH 2 N CH 2 diethylmethylamine The N H bond provides hydrogen bonding in 1 and 2 amines, but not in 3 amines. is not as polar as the -H bonds in alcohols. C. NH 2 aniline 47 48

9 Solubility in Water Amines with 1-6 carbon atoms are soluble in water. form hydrogen bonds with the polar -H bond in water. Consider the following compounds. 1) CH 2 CH 2 NH 2 2) CH 2 NH 3) CH 2 CH 2 A. Which compound has the highest boiling point? B. Which compound is soluble in water? Amines React as Bases Consider the following compounds. 1) CH 2 CH 2 NH 2 2) CH 2 NH 3) CH 2 CH 2 A. Which compound has the highest boiling point? 1) CH 2 CH 2 NH 2 Like ammonia, amines are weak bases in water. NH 3 + H 2 NH 4+ + H ammonium hydroxide NH 2 + H 2 NH 3+ + H methylammonium hydroxide B. Which compound is soluble in water? 1) CH 2 CH 2 NH 2 2) CH 2 NH Neutralization Forms Amine Salts Properties of Amine Salts An amine salt forms when an amine is neutralized by acid. is named by replacing the amine part of the name with ammonium, followed by the name of the negative ion. NH 2 + HCl NH 3+ Cl methylamine methylammonium chloride Amine salts are solids at room temperature. soluble in water and body fluids. the form used for drugs

10 Alkaloids Alkaloids are physiologically active nitrogencontaining compounds. obtained from plants. used as anesthetics, antidepressants, and in stimulants such as caffeine. often addictive. Cocaine Cocaine (from coca leaves ) is sold illegally as the amine salt. reacted with NaH to produce the free amine form known as crack Caffeine Nicotine Caffeine is a stimulant of the central nervous system. is found in coffee beans, tea, chocolate, and soft drinks. Nicotine increases the adrenaline level in the blood. causes addiction to tobacco. N Morphine and Codeine Morphine and codeine are alkaloids. obtained from the oriental poppy plant. used as painkillers. modified to make heroin. Write the structural formula for A. methylpropylamine B. 2-chloroaniline 59 60

11 A. methylpropylamine CH 2 CH 2 NH B. 2-chloroaniline NH 2 Cl Chapter 13 Carboxylic Acids, Esters, Amines, and Amides 13.5 Amides Amides Aromatic Amide In amides, an amino group( NH 2 ) replaces the H group of carboxylic acids. C H C NH 2 The aromatic amine is benzamide. C NH2 Benzamide Preparation of Amides Naming Amides Amides are produced by reacting a carboxylic acid with ammonia or an amine (1 or 2 ). using heat. Heat C H + NH 3 C NH 2 + H 2 Heat C H + NH 2 C NH + H 2 Amides are named as alkanamides. IUPAC replaces oic acid ending with amide. Common names replace -ic acid ending with amide. Methanamide (IUPAC) H C NH 2 Formamide (common) Propanamide (IUPAC) CH 2 C NH 2 Propionamide (common) 65 66

12 Naming Amides with N Groups An alkyl group bonded to the N atom is named as N-alkyl in front of the amide name. H C N N-methylethanamide (IUPAC) N-methylacetamide (common) H CH 2 C N CH 2 N-ethylpropanamide (IUPAC) N-ethylpropionamide (common) Give the IUPAC and common names for the following: A. CH 2 CH 2 C NH 2 H B. C N CH A. CH 2 CH 2 C NH 2 butanamide; butryamide Draw the structures of A. pentanamide. B. N-methylbutyramide. H B. C N CH 2 N-ethylethanamide; N-ethylacetamide A. pentanamide CH 2 CH 2 CH 2 C NH 2 B. N-methylbutyramide CH 2 CH 2 C NH Some Amides in Health and Medicine Urea is the end product of protein metabolism. Saccharin is an artificial sweetener. Some amides such as phenobarbital, Nembutal TM and Seconal TM are barbiturates. Acetaminophen is used to reduce fever and pain

13 Some Amides in Health and Medicine Physical Properties of Amides Amides that are primary ( NH 2 ) or secondary ( NH )form hydrogen bonds. that are primary have higher melting points than secondary. that are tertiary (no H on N) do not form hydrogen bonds and have lower melting points. all form hydrogen bonds with water. with 1-5 carbon atoms are soluble in water Hydrogen Bonding of Amides Hydrolysis of Amides C N H H C N H H Hydrogen bonding occurs between primary amides. Amides undergo acid hydrolysis to produce a carboxylic acid and an ammonium salt. base hydrolysis to produce the salt of a carboxylic acid and an amine or ammonia Hydrolysis Reactions acid hydrolysis C H + NH 4+ Cl HCl + H 2 C NH 2 NaH Write the products of the hydrolysis of N-ethylpropanamide with NaH. base hydrolysis C Na + + NH

14 Write the products of the hydrolysis of N-ethylpropanamide with NaH. CH 2 C Na + + CH 2 NH 2 79