1 Amines and Amides Amines Reactions of Amines Amides Reactions of Amides.
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Transcript of 1 Amines and Amides Amines Reactions of Amines Amides Reactions of Amides.
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Amines and Amides
Amines
Reactions of Amines
Amides
Reactions of Amides
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Amines
• Organic compounds of nitrogen N• Classified as primary, secondary, tertiary
CH3 CH3
CH3—NH2 CH3—NH CH3—N — CH3
1° 2° 3°
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Naming Amines
IUPAC aminoalkane Common alkylamine
CH3CH2NH2 CH3—NH —CH3
aminoethane N-methylaminomethane(ethylamine) (dimethylamine)
NH2
|
CH3CHCH3
2-aminopropane Aniline N-methylaniline(isopropylamine)
NH2 NH CH3
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Practice Naming
Give the common name and classify as primary, secondary or tertiary:
A. CH3NHCH2CH3
CH3
|
B. CH3CH2NCH3
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Solution
A. CH3NHCH2CH3
N-methylaminoethane (ethylmethylamine), 2°
CH3
|B. CH3CH2NCH3
N,N-dimethylaminoethane (ethyldimethylamine), 3°
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Reactions of Amines
• Act as weak bases in water
CH3NH2 + H2O CH3NH3+ + OH–
methylammonium hydroxide
• Neutralization with acid gives ammonium salt
CH3NH2 + HCl CH3NH3+ Cl–
methylammonium chloride
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Alkaloids
• Physiologically active nitrogen-containing compounds
• Obtained from plants• Used as anesthetics, antidepressants, and
stimulants• Many are addictive
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Nicotine
N
CH3
Nicotine, leaves of tobacco plant
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Caffeine
N
N N
NCH3
O
O CH3
CH3
Caffeine, coffee beans and tea
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Procaine
NH2N
CH3CH2
CH3CH2
CH2CH2 O C
O
Procaine (novocaine), painkiller
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Practice
Write a structural formula for
A. 1-aminopentane
B. 1,3-diaminocyclohexane
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Solution
A. 1-aminopentane
CH3CH2CH2CH2CH2-NH2
B. 1,3-diaminocyclohexaneNH2
NH2
More naming practice
• Draw:
N-methyl-N-propyl-2-aminobutane
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Solution
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Properties of Amines
• When organisms decompose, large and complex molecules such as proteins are broken down into simpler amines.
• Amines often have an unpleasant odour, such as rotting fish.
• Putrescine (1,4-diaminobutane) and Cadavarine (1,5-diaminopentane) are amines produced by bacteria when animal tissue decomposes.
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Properties cntd
• Amines have higher melting and boiling points than comparable hydrocarbons as they are more polar.
• Amines with 1-5 carbons are soluble in water. When N-H bonds are present (primary or secondary amines), hydrogen bonding can occur with water.
• The N-H bond is not as polar as the O-H bond in alcohols.
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Preparing Amines
• Preparing a Primary Amine (ammonia reacts with an alkyl halide)
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Secondary Amines
• Preparing a Secondary Amine (primary amine reacts with alkyl halide)
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Tertiary Amines
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Preparing a Tertiary Amine (secondary amine reacts with alkyl halide)
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Amides
Derivatives of carboxylic acids where an amino (-NH2) group replaces the –OH group. (CON)
O O
CH3 — C—OH CH3 — C—NH2
carboxylic acid amide
acetic acid ethanamide
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Naming Amides
Alkanamide from acid name
O
methanamide (IUPAC)
HC–NH2 formamide (common)
O propanamide (IUPAC)
CH3CH2C–NH2 propionamide(common)
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Naming Amides with N-Groups
O
CH3C–NHCH3 N-methylethanamide (IUPAC)
N-methylacetamide (common) O
CH3CH2C–N(CH3)2
N,N-dimethylpropanamide
N,N-dimethylpropionamide
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Aromatic Amides
C
O
NH2
Benzamide
C
O
NHCH3
N methylbenzamide -
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Practice
Name the following amides: O
A. CH3CH2CH2C–NH2
O
B. CH3C–N(CH2CH3)2
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Solution
O
A. CH3CH2CH2C–NH2
butanamide; butryamide (common)
O
B. CH3C–N(CH2CH3)2
N,N-diethylethanamide;
N,N-diethylacetamide
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Practice
Draw the structures of
A. Pentanamide
B. N-methylbutanamide
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Solution
A. Pentanamide O
CH3CH2CH2CH2C–NH2
B. N-methylbutanamide O
CH3CH2CH2C–NHCH3
Preparing Amides
• Carboxylic Acid + Ammonia
• Carboxylic Acid with Primary or Secondary Amine
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Reactions of Amides
Amides undergo
acid hydrolysis base hydrolysis
carboxylic acid salt of carboxylic acid
ammonium salt and an amine or ammonia
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Reactions of Amides
acid hydrolysis O
O HCl + H2O CH3COH + NH4+Cl–
CH3CNH2 O
NaOH
CH3CO– Na+ + NH3
base hydrolysis
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Practice
Write the products of the hydrolysis of
N- ethylpropanamide with NaOH.
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Solution
Hydrolysis of N-ethylpropanamide with NaOH gives the following products.
O
CH3CH2CO– Na+ + CH3CH2NH2
Properties of Amides
• Amides are weak bases and generally insoluble in water. Smaller amides are slightly soluble in water due to hydrogen bonding with NH group of amide and OH group of water.
• Amides whose N atoms are bonding to two H atoms have higher melting and boiling points than those with more alkyl groups attached due to more hydrogen bonding.
• Amide functional groups (CON) are an important linkage in proteins.
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