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Amides and Amines: Organic Nitrogen Compounds
Chapter 25
Amides and Amines: Organic Nitrogen Compounds
Chapter 25
Hein * Best * Pattison * Arena
Colleen KelleyChemistry DepartmentPima Community College
© John Wiley and Sons, Inc.
Version 1.0
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Chapter Outline
25.1 Amides: Nomenclature and Physical Properties
25.2 Chemical Properties of Amides
25.3 Polyamides: Condensation Polymers
25. 4 Urea
25.5 Amines: Nomenclature and Physical Properties
25.6 Preparation of Amines
25.7 Chemical Properties of Amines
25.8 Sources and Uses of Selected Amines
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Nitrogen-Containing Compounds
• The amines and amides are the two major classes of nitrogen-containing compounds.
• Amines isolated from plants form a group of compounds called alkaloids.– Quinine, caffeine
• Amides are nitrogen derivatives of carboxylic acids.– Nylon, proteins
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Amides: Nomenclature Amides: Nomenclature and Physical Propertiesand Physical Properties
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• Carboxylic acids react with ammonia to form ammonium salts.
• When heated, ammonium salts of carboxylic acids lose a molecule of water and are converted to amides:
RC
OH
O
+ NH3
RC
O-NH4+
O
RC
NH2
O
+ H2O
carboxylicacid
ammonia
ammonium salt
amide
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IUPAC Rules for Naming Amides
1. The IUPAC name is based on the longest carbon chain that includes the amide group.
2. Drop the –oic acid ending from the corresponding IUPAC acid name.
3. Add the suffix –amide.
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Naming Amides
HC
NH2
O
methanamideH3C
CNH2
O
ethanamide
CNH2
O
benzamide
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Naming Amides
• When the nitrogen of an amide is connected to an alkyl or aryl group, the group is named as a prefix preceded by the letter N:
H3CC
NHCH3
O
N-methylethanamide
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Physical Properties of Amides• Except for formamide (methanamide), a
liquid, all other unsubstituted amides are solids at room temperature.
• Many are odorless and colorless.
• Low molar-mass amides are soluble in water, but solubility decreases quickly as molar-mass increases.
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• The amide functional group is polar, and nitrogen is capable of hydrogen bonding.
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Chemical Properties Chemical Properties of Amidesof Amides
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Hydrolysis of Amides
H3CC
NH2
O
+ H2O + HCl H3CC
OH
O
+ NH4Cl
under acidic conditions:
H3CC
NH2
O
+ NaOH H3CC
O-Na+
O
+ NH3 (g)
under basic conditions:
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Polyamides: Polyamides: Condensation Condensation
PolymersPolymers
Polyamides: Polyamides: Condensation Condensation
PolymersPolymers
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Polyamides
• Polyamides are condensation polymers.
• Proteins are biological polyamides.
• Nylon-66 is a synthetic polyamide.
RC
OH
O
R'
H2C
NH
H
carboxylicacid group
amine groupR
C
O
R'
H2C
HN
+ H2O
amide linkage
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UreaUrea
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Urea• The body disposes of nitrogen by the
formation of a diamide known as urea.
• Urea is a white solid that melts at 133 C.
• It is soluble in water and therefore is excreted from the body in the urine.
H2NC
NH2
O
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Amines: Nomenclature Amines: Nomenclature and Physical Propertiesand Physical Properties
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H
NH H
ammonia
H
NH CH3
methylamineprimary amine
CH3
NH CH3
dimethylaminesecondary amine
CH3
NH3C CH3
trimethylaminetertiary amine
H
NH
cyclohexylamineprimary amine
H
NH
anilineprimary amine
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IUPAC System for Naming Amines
1. The IUPAC system names simple amines by using the name of the alkane (omitting the final –e) and adding the ending –amine.
CH3CH2NH2 ethanamine
CH3CH2CH2NH2 1-propanamine
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2. Secondary and tertiary amines are named as N-substituted primary amines by using the longest carbon chain as the parent name.
CH3
NH CH2CH2CH3
CH3
NCH3
N-methyl-1-propanamine
CH2CH3
NH3C CH2CH2CH2CH3
N-ethyl-N-methyl-1-butanamine
N,N-dimethylcylcohexanamine
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Common Names of Amines
H
NH CH2CH2CH3
propylamine
H
NH CHCH3
CH3
isopropylamine
H
NH C
CH3
CH3
H3C
tert-butylamine
NH2
aniline
N(CH3)2
N,N-dimethylaniline
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Heterocyclic Compounds• Ring compounds in which the atoms in the ring are not all alike are known as heterocyclic compounds.
•The most common heteroatoms are oxygen, nitrogen, and sulfur.
N
NNH
NHN
N
N
N
pyrrole pyridine pyrimidine purine
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Physical Properties of Amines
• Amines are capable of hydrogen bonding with water.
• They have odors:
– Methylamine and ethylamine = strong ammoniacal odor
– Trimethyamine = ‘fishy’ odor
– High molar-mass amines = obnoxious odors
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Preparation of Preparation of AminesAmines
Preparation of Preparation of AminesAmines
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Preparation of Amines
1. Alkylation of ammonia and amines
2. Reduction of amides and nitriles
3. Reduction of aromatic nitro compounds
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Alkylation of Ammonia and Amines
• The substitution of alkyl groups for hydrogen atoms of ammonia can be done by reacting ammonia with alkyl halides.
NH3+CH3Br CH3NH2+CH3Br (CH3)2NH
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Reduction of Amides and Nitriles
H3CC
NH2
O
LiAlH4 CH3CH2NH2
CH3CH2CN CH3CH2CH2NH2H2/Ni
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Reduction of Aromatic Nitro Compounds
NO2
SnHCl
NH3+Cl-
NaOH
NH2
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Chemical Properties Chemical Properties of Aminesof Amines
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Chemical Properties of Amines
1. Alkaline properties of amines
2. Salt formation
3. Formation of amides
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Alkaline Properties of Amines
CH3NH2 + H-O-H CH3NH3 + OH-+
Amines are bases and produce OH- ions in water.
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Salt Formation
• An amine reacts with a strong acid to form a salt.
CH3NH2 + H-Cl+
CH3NH3Cl-
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Formation of Amides
• Primary and secondary amines react with acid chlorides to form substituted amides.
+ (CH3CH2)2NH2Cl-
H3CC
Cl
O
+ 2 (CH3CH2)2NH2 H3CC
N(CH2CH3)2
O
+
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