Transcript CH. 11-15 part 2 Chapter 14 Carboxylic Acids, Esters, Amines, and Amides 14.3 Esters.

CH. 11-15 part 2
Chapter 14 Carboxylic Acids, Esters,
Amines, and Amides
14.3
Esters
2
Esters
Esters are
• found in fats and oils
• responsible for the aroma and flavor of bananas,
oranges, and strawberries
O

CH3 —C—O—CH3
ester group
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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.
4
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.
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Naming Esters
Esters have IUPAC and common names:
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Learning Check
Give the IUPAC and common names of the following
compound, which is responsible for the flavor and odor
of pears.
O

CH3 — C—O—CH2—CH2—CH3
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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
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Esters in Fruits
Esters give pleasant fragrances and flavors to many fruits and
flowers.
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Solution
A. 3-bromobutanoic acid
Br
O
|
||
CH3—CH—CH2—COH
B.
ethyl propionoate
O

CH3—CH2 —C—O—CH2—CH3
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Base Hydrolysis of Fatty Acids Produces Soaps
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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
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Chapter 14 Carboxylic Acids, Esters,
Amines, and Amides
14.4
Amines
13
Amines
Amines
• are derivatives of ammonia, NH3
• contain N attached to one or more alkyl or
aromatic groups
CH3—NH2
NH2
CH3
CH3


CH3—NH CH3—N—CH3
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Classification of Amines
Amines are classified as primary, secondary, or tertiary:
• a primary (1) amine has one carbon group 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
|
CH3—N—H
1°
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CH3
CH3
|
CH3—N—CH3
2°
3°
|
CH3—N—H
Skeletal Structures of Amines
The skeletal structures show the shapes of amine molecules
with one or more alkyl groups bonded to the nitrogen atom.
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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
Dimethylamine
CH3
|
CH3—N—CH2—CH3 Ethyldimethylamine
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Learning Check
Give the common name of each compound.
A.
CH3—NH—CH2—CH3
B.
CH3
|
CH3—CH2—N—CH2—CH3
NH2
C.
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Properties of Amines
1 and 2 amines
• can form hydrogen bonds with
each other and water molecules
• can form hydrogen bonds, while
amines with less than six
carbons are soluble in water
because they form hydrogen
bonds with water
3 amines can only form hydrogen
bonds with water molecules
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Learning Check
Consider the compounds below:
1. Which compound cannot form hydrogen bonds with
other amines?
2. Which compound is not soluble in water?
A. CH3—CH2—CH2—NH2
B. CH3—CH2—NH—CH3
C. CH3—CH2—CH2—CH3
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Solution
Consider the compounds below:
1. Which compound cannot form hydrogen bonds with
other amines?
CH3—CH2—CH2—CH3
C is an alkane, which cannot form hydrogen bonds with
each other.
2. Which compound is not soluble in water?
CH3—CH2—CH2—CH3
C is an alkane and therefore not soluble in water.
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Neutralization Forms Amine Salts
An amine salt
• forms when amines such as those
responsible the odor in fish are
neutralized by acid such as citric acid
in lemons
• is named by replacing the amine
part of the name with ammonium,
followed by the name of the
negative ion
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Neutralization Forms Amine Salts
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Properties of Amine Salts
Amine salts are
• solids at room temperature
• soluble in water and body fluids
• the form used for drugs
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Alkaloids
Alkaloids are
• physiologically active nitrogencontaining compounds
produced by plants such as
cocaine
• compounds that are alkali-like
or have basic characteristics
like amines
• used as anesthetics, as
antidepressants, and in
stimulants such as caffeine,
and may be habit forming
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Alkaloids: Cocaine
Cocaine is extracted from plants by reacting them with
hydrochloric acid and producing cocaine hydrochloride.
When cocaine hydrochloride is treated with NaOH and
ether it is called free-basing. This reaction produces “crack
cocaine,” a free amine or free base of the amine.
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Heterocyclic Amines
A heterocyclic amine
• is a cyclic compound that contains one or more nitrogen
atoms in a ring
• typically consists of five or six atoms in the ring with one
or more nitrogen atoms
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Caffeine
Caffeine
• is a stimulant of the central nervous system
• is found in coffee beans, tea, chocolate, and soft drinks
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Nicotine
Nicotine
• increases the adrenaline level in the blood
• causes addiction to tobacco
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Morphine and Codeine
Morphine and codeine are
• alkaloids
• obtained from the oriental poppy plant
• used as painkillers
• modified to make heroin
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Solution
A. methylpropylamine CH3–CH2–CH2–NH–CH3
B. 2-chloroaniline
NH2
Cl
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Chapter 14 Carboxylic Acids, Esters,
Amines, and Amides
14.5
Amides
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Amides
Amides are derivatives of carboxylic acids in which a nitrogen
group (–NH2) replaces the –OH group of carboxylic acids.
O
||
CH3—C—OH
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O
||
CH3—C—NH2
Preparation of Amides
Amides are produced by reacting a carboxylic acid
with ammonia or a 1 or 2 amine with heat.
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Naming Amides
• For IUPAC naming, the -oic acid from the carboxylic acid
name ending is replaced with -amide
• For common names, the -ic acid from the carboxylic acid
name ending is replaced with -amide
O

H—C—NH2
methanamide (IUPAC)
formamide (common)
O

propanamide (IUPAC)
CH3—CH2—C—NH2 propionamide (common)
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Naming Amides with N Groups
An alkyl group attached to the nitrogen of an amide is named
with the prefix N-, followed by the alkyl name.
O H
 │
CH3 —C—N—CH3
N-methylethanamide (IUPAC)
N-methylacetamide (common)
O H
 │
CH3—CH2 —C—N—CH2—CH3
N-ethylpropanamide (IUPAC)
N-ethylpropionamide (common)
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Solution
A.
pentanamide
O

CH3–CH2–CH2–CH2–C–NH2
B.
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N-methylbutyramide
O

CH3–CH2–CH2–C–NH–CH3
Some Amides in Health and Medicine
• Urea is the end product of protein metabolism.
• Saccharin is an artificial sweetener.
• Some amides, such as phenobarbital (Luminal) and
pentobarbital (Nembutal), are barbiturates.
• Acetaminophen is used to reduce fever and pain.
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Some Amides in Health and Medicine
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Solubility of Amides
Amides with one to five carbon atoms are soluble in water
because they can form hydrogen bonds with water molecules.
Hydrogen bonding effects are diminished when molecules have
more than five carbon atoms, therefore reducing solubility.
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Hydrolysis Reactions
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Chapter 15 Lipids
15.1
Lipids
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Lipids
Lipids are
• biomolecules that contain fatty acids or a steroid nucleus
• soluble in organic solvents, but not in water
• named for the Greek word lipos, which means “fat”
• extracted from cells using organic solvents
• an important feature in cell membranes, fat-soluble
vitamins, and steroid hormones
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Types of Lipids
There are different types of lipids.
1. Lipids such as waxes, fats, oils, and glycerophospholipids are
esters that can be hydrolyzed to give fatty acids and alcohols.
2. Steroids are also lipids; they do not contain fatty acids and
cannot be hydrolyzed. They are characterized by the steroid
nucleus of four fused carbon rings.
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General Structure of Lipids
Lipids are naturally occurring compounds that are soluble in
organic solvents but not in water.
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Learning Check
There are two types of lipids, fatty acids and steroids. Which
type is described by the following?
A. contains a four-membered ring system
B. contains long carbon chains
C. includes triacylglycerols
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Solution
There are two types of lipids, fatty acids and steroids. Which
type is described by the following?
A. contains a four-membered ring system
steroids
B. contains long carbon chains
fatty acids
C. includes triacylglycerols
fatty acids
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Learning Check
Which of the following is NOT a characteristic of lipids?
A. may contain a carboxylic acid group
B. may contain a four-ring structure
C. soluble in water
D. mostly nonpolar
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Solution
Which of the following is NOT a characteristic of lipids?
The answer is C. Lipids are nonpolar and therefore are NOT
soluble in water.
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Chapter 15 Lipids
15.2
Fatty Acids
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Fatty Acids
Fatty acids are
• long-chain carboxylic acids
• typically 12–18 carbon atoms
• insoluble in water
• saturated or unsaturated
Olive oil contains 84% unsaturated fatty
acids and 16% saturated fatty acids.
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Saturated and Unsaturated Fatty Acids
Fatty acids can be
• saturated, with all single C–C bonds
O
OH
coconut oil, saturated fatty acid
• monounsaturated, with one double C=C bond
• polyunsaturated, with more than one double C=C bond
O
OH
palmitoleic acid, found in butter
monounsaturated fatty acid
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Properties of Saturated Fatty Acids
Saturated fatty acids
• contain only single C–C bonds and fit close together in a
regular pattern
• have strong attractions between long carbon chains
• have higher melting points and are usually solids at
room temperature
O
O
O
OH
OH
OH
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Properties of Saturated Fatty Acids
In saturated fatty acids, the molecules fit
closely together to give high melting points.
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Properties of Unsaturated Fatty Acids
Unsaturated fatty acids
• contain one or more cis
double C=C bonds
• have “kinks” in the fatty
acid chains
• do not pack closely
• have few attractions
between chains
• have low melting points
• are liquids at room temperature
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HOOC
H
H C
COOH
C
“kinks” in
chain
H
C
C
H
Properties of Unsaturated Fatty Acids
In unsaturated fatty acids, molecules cannot fit closely
together, resulting in lower melting points.
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Melting Points of Some
Saturated Fatty Acids
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Melting Points of Some
Unsaturated Fatty Acids
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Learning Check
Assign the melting points of –17 C, 13 C, and 69 C to
the correct fatty acid. Explain.
stearic acid
oleic acid
linoleic acid
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(18 carbons)
(18 carbons)
(18 carbons)
saturated
one double bond
two double bonds
Solution
Stearic acid is saturated and would have a higher melting
point than the unsaturated fatty acids. Because linoleic has
two double bonds, it would have a lower mp than oleic acid,
which has one double bond.
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stearic acid
mp 69 C
oleic acid
mp 13 C
linoleic acid
mp –17 C
saturated
most unsaturated
Prostaglandins
Prostaglandins
• are hormone-like substances produced in cells
• are also known as eicosanoids, formed from arachidonic acid,
the polyunsaturated fatty acid with 20 carbon atoms
• differ by the substituents attached to the five-carbon ring
• have many functions, such as lower or raising blood
pressure and stimulating contraction and relaxation of
uterine smooth muscle
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Prostaglandins
When tissues are injured, arachidonic acid is converted
to prostaglandins such as PGE and PGF that produce
inflammation and pain in the area.
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Prostaglandins: NSAIDs
The treatment of pain, fever, and inflammation is based
on inhibiting the enzymes that convert arachidonic acid
to prostaglandins.
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Prostaglandins: NSAIDs
Nonsteroidal anti-inflammatory drugs (NSAIDs) block
production of prostaglandins, decreasing pain and inflammation.
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Omega-3 Fatty Acids
Unsaturated fats such as those in vegetable oils and fish are
recognized as more beneficial to health than saturated fats.
Vegetables contain omega-6 acids, meaning the first double
bond occurs at carbon 6. Examples of omega-6 acids are
linoleic and arachidonic acids.
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Omega-3 Fatty Acids
Fish have high levels of omega-3 acids, meaning the first double
bond occurs at carbon 3. Examples of omega-3 acids include
linolenic, eicosapentaenoic, and docosahexaenoic acids.
Cold-water fish are a source of omega-3 fatty acids.
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Omega-3 and Omega-6 Fatty Acids
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Chapter 15 Lipids
15.3
Waxes, Fats, and Oils
Waxes are esters of long-chain alcohols and fatty acids.
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Waxes
Waxes are
• esters of saturated fatty acids and long-chain alcohols
• coatings that prevent loss of water by leaves of plants
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Fats and Oils: Triacylglycerols
Fats and oils are
• also called triacylglycerols
• esters of glycerol
• produced by esterification
• formed when the hydroxyl groups of glycerol react
with the carboxyl groups of fatty acids
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Triacylglycerols
In a triacylglycerol, glycerol forms ester bonds with three
fatty acids.
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Formation of a Triacylglycerol
In a triacylglycerol, three hydroxyl groups on a glycerol
molecule form ester bonds with the carboxyl groups of
three fatty acids.
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Melting Points of Fats and Oils
A fat
• is usually solid at room temperature
• is prevalent in meats, whole milk, butter, and cheese
An oil
• is usually liquid at room temperature
• is prevalent in plants such as olive and safflower
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Oils with Unsaturated Fatty Acids
Oils
• have more unsaturated fats
• have cis double bonds that cause “kinks” in the fatty
acid chains
• with “kinks” in the chains do not allow the triacylglycerol
molecules to pack closely
• have lower melting points than saturated fatty acids
• are liquids at room temperature
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Diagram of Triacylglycerol with Unsaturated
Fatty Acids
Unsaturated fatty acid chains
with kinks cannot pack closely.
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Percent Saturated and Unsaturated Fatty
Acids in Fats and Oils
Vegetable oils have low melting points because they have a
higher percentage of unsaturated fatty acids than do animal fats.
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