What are carboxylic acids, esters,
amines, and amides?
A carboxylic acid contains a
carboxyl group, which
• is a carbonyl group (C=O)
attached to a hydroxyl group
(—OH).
• is found on carbon 1 in
carboxylic acids.
O

CH3 — C—OH
hydroxyl group or
CH3COOH
carbonyl group
1
How to name carboxylic acids?
IUPAC names
• Replace the -e in the alkane name with -oic acid.
CH4
methane
HCOOH
CH3—CH3 ethane
methanoic acid
CH3—COOH ethanoic acid
• Number substituents from the carboxyl carbon 1.
CH3
O
|
║
CH3—CH—CH2—C—OH
4
3
2
1
3-methylbutanoic acid
three-dimensional models
2
Some common carboxylic acids
Methanoic acid (formic acid)
O
║
H─C─OH
ethanoic acid (acetic acid)
O
║
CH3─C─OH
3
Aromatic carboxylic acids
Benzoic acid
• aromatic carboxylic acid.
benzoic acid
O
• locates substituents by
numbering the ring
from carbon 1 in the
carboxyl group.
O
O
C
C OH
OH
C OH
Cl
NH2
3-chlorobenzoic acid
4-aminobenzoic acid
4
Polarity of carboxylic acids
Carboxylic acids
• are strongly polar.
• have two polar groups:
hydroxyl (−OH) and
carbonyl (C=O).
5
Solubility in water
Carboxylic acids:
• form hydrogen bonds
with many water
molecules.
• with 1-4 carbon atoms
are very soluble in
water.
• as carbon atoms increase
in chains, solubility
decreases.
Water molecules
6
Acidity of carboxylic acids
Carboxylic acids
• are weak acids.
• ionize in water to
produce carboxylate
ions
and hydronium ions.
7
Neutralization of carboxylic acids
Carboxylic acid salts
• product of neutralization of a carboxylic acid
• with a strong base.
CH3—COOH + NaOH
CH3—COO– Na+ + H2O
acetic acid
sodium acetate
(carboxylic acid salt)
• are used as preservatives and flavor enhancers.
8
What are esters?
Esters give flowers and fruits their
pleasant fragrances and flavors.
In an ester, the H in the
carboxyl group is replaced
with an alkyl group.
not learning how to name
them!
O

CH3 — C—O —CH3
ester group
9
What is esterification?
Esterification is the reaction of a carboxylic acid
and alcohol in the presence of an acid catalyst to
produce an ester.
O

H+
CH3—C—OH + H—O—CH2—CH3
O

CH3—C—O—CH2—CH3 + H2O
ethyl acetate (an ester)
10
Ester products
Aspirin
• is used to relieve pain
and reduce
inflammation.
• is an ester of salicylic
acid and acetic acid.
O
C OH
O
O C CH3
O
Oil of wintergreen
• is used to soothe sore
muscles.
• is an ester of salicylic
acid and methanol.
C O CH3
OH
11
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
• Salt- “soap”
O
||
CH3—C—O—CH2—CH3 + NaOH
O

CH3—C—O– Na+ + HO—CH2—CH3
salt of carboxylic acid
alcohol
12
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.
13
Amines
Amines
• are derivatives of ammonia, NH3.
• contain N attached to one or more alkyl or aromatic
groups.
CH3
CH3


CH3—NH2
CH3—NH
CH3—N—CH3
NH2
14
Amines are classified as primary,
secondary, or tertiary.
• primary (1°) amine, one carbon group is bonded to nitrogen atom.
• secondary (2°) amine has two carbon groups bonded to nitrogen atom.
• tertiary (3°) amine has three carbon groups bonded to nitrogen atom.
H
|
CH3—N—H
1°
CH3
|
CH3—N—H
2°
CH3
|
CH3—N—CH3
3°
15
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.
CH3—CH2—NH2
ethylamine
CH3—NH—CH3
CH3
|
CH3—N—CH2—CH3
dimethylamine
ethyldimethylamine
16
Aromatic Amines
• The amine of benzene is named aniline.
• Alkyl groups on the N use the prefix N- with alkyl
name.
NH2
NH2
NH CH3
Cl
aniline
3-chloroaniline
N-methylaniline
17
Hydrogen bonding for amines
The N−H bond
• provides hydrogen
bonding in 1°and 2°
amines, but not in 3°
amines.
• is not as polar as the OH bonds in alcohols.
18
Solubility in water
Amines
• with 1-5 carbon atoms
are soluble in water.
• form hydrogen bonds
with the polar O-H bond
in water.
19
Amines react as bases
Like ammonia, amines are weak bases in water.
NH3 + H2O
NH4+ + OH–
ammonium hydroxide
CH3—NH2 + H2O
CH3—NH3+ + OH–
methylammonium hydroxide

forms when an amine is
neutralized by acid.
20
Properties of amine salts
Amine salts are
• solids at room
temperature.
• soluble in water and
body fluids.
• the form used for drugs.
21
Alkaloids
Alkaloids are
• physiologically active
nitrogen-containing
compounds.
• obtained from plants.
• used as anesthetics,
antidepressants, and in
stimulants such as
caffeine.
• often addictive.
22
Cocaine
Cocaine is
• sold illegally as the
amine salt.
• reacted with NaOH to
produce the free amine
form known as “crack.”
23
Caffeine
Caffeine
• is a stimulant of the
central nervous system.
• is found in coffee beans,
tea, chocolate, and soft
drinks.
24
Nicotine
Nicotine
• increases the adrenaline
level in the blood.
• causes addiction to
tobacco.
N
CH
3
25
Morphine and Codeine
Morphine and codeine are
• alkaloids.
• obtained from the
oriental poppy plant.
• used as painkillers.
• modified to make
heroin.
26
Amides
In amides,
• an amino group(–NH2) replaces the –OH
group of carboxylic acids.
• The aromatic amine is benzamide.
O
C
O
||
CH3—C—OH
O
||
CH3—C—NH2
NH2
benzamide
27
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 and Seconal
are barbiturates.
• Acetaminophen is used
to reduce fever and
pain.
28
Physical properties of amides
Amides
• that are primary (−NH2) 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.
29
Hydrogen bonding of amides
O
||
CH3—C—N—H
|
H
Hydrogen bonding occurs
between primary amides.
O
||
CH3—C—N—H
|
H
30