Transcript Lecture Notes_ch17

Chapter
Seventeen
Amines and Amides
Amines and Amides
Parachutist with a
parachute made of the
polyamide nylon.
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Chapter Seventeen | Slide 2 of 39
Nitrogen
• The four most abundant elements in organic
compounds are carbon, hydrogen, oxygen, and nitrogen
Element
Valence Electrons
Bonds for an Octet
Carbon
4
4
Hydrogen
1
1
Oxygen
6
2
Nitrogen
5
3
Chapter Seventeen | Slide 3 of 39
Amines
• Organic compounds of nitrogen N
• Classified as primary, secondary, tertiary
• NH2 = amino group
CH3—NH2
______
CH3

CH3—NH
_______
CH3

CH3—N — CH3
________
Chapter Seventeen | Slide 4 of 39
Amines and Amides cont’d
Fig. 17.1
Classification of amines is related to the number of R
groups attached to the nitrogen atom.
Chapter Seventeen | Slide 5 of 39
Naming Amines
• Classified as primary (RNH2), secondary (R2NH), or tertiary
(R3N). Different than alcohols.
R
H
R
R
N
N
N
H
primary amine
R
R
R
R
secondary amine
tertiary amine
R
R
OH R
primary ROH
H
OH R
secondary ROH
OH
R
tertiary ROH
Chapter Seventeen | Slide 6 of 39
Amines and Amides cont’d
Aniline, the simplest
aromatic amine.
Aromatic amines are
generally toxic.
Chapter Seventeen | Slide 7 of 39
Naming Primary Amines
• Identify the parent chain: the longest chain of
carbons to which the nitrogen is attached
• Replace the “-e” ending of the alkane name with “amine”
• Number the parent chain from the end closest to
the nitrogen atom
• Identify the position of the nitrogen atom with a
number
• Identify any substituents and their locations
Chapter Seventeen | Slide 8 of 39
Name the Following Amines
NH 2
NH 2
cyclohexanamine
2-propanamine
H2N
NH2
1,4-butanediamine or
1,4-diaminobutane
Chapter Seventeen | Slide 9 of 39
Naming Secondary and Tertiary Amines
• Base name involves longest carbon chain attached to
the nitrogen
– Other groups attached to the nitrogen have “N-” in front of the
substituent names
N
N-ethyl-N-methyl-ethylamine
N
N-ethyl-N-methyl-cyclohexylamine
Chapter Seventeen | Slide 10 of 39
Amines and Amides cont’d
Amine-amine hydrogen
bonding.
Chapter Seventeen | Slide 11 of 39
Amines and Amides cont’d
Low-molecular amines
are soluble in water
because of aminewater hydrogen
bonding interactions.
Chapter Seventeen | Slide 12 of 39
Amines and Amides cont’d
Ammonium ion has a
tetrahedral structure,
as does the quaternary
ammonium ion.
Chapter Seventeen | Slide 13 of 39
Amines and Amides cont’d
Fig. 17.8
Heterocyclic amines serve as “parent” molecules for
more complex amine derivatives.
Chapter Seventeen | Slide 14 of 39
Amines and Amides cont’d
Methoxyamphetamine
Isopreternol
Chapter Seventeen | Slide 15 of 39
Basicity of Amines
• Like ammonia, amines act as weak __________ in water
– _____________ are proton acceptors
• When amines react with water, the products are a
hydroxide ion and a substituted ammonium ion
– Substituted ammonium ion: an ammonium ion in which one
or more alkyl, cycloalkyl, or aryl groups have been
substituted for hydrogen atoms
CH3NH2 + H2O
CH3NH3+ + OH–
methylammonium
hydroxide
Treating an amine salt with a strong base regenerates the amine
Chapter Seventeen | Slide 16 of 39
Neutralization Forms Amine Salts
• Neutralization with _______ gives ammonium salt
CH3NH2 + HCl
CH3NH3+ Cl–
methylammonium
chloride
• Amine salts are named by replacing the “amine”
part of the name with “ammonium” followed by the
name of the negative ion
Chapter Seventeen | Slide 17 of 39
Properties of Amine Salts
• Amine salts are:
– Solid at room temperature
– Soluble in water and body fluids
– The form used for drugs
CH3
H
HO
H3C
+
N
H
CH3 Cl-
Ephedrine Hydrochloride
Ephedrine HCl
Sudafed
+
H
N
O
ClCH3
Diphenhydramine hydrochloride
Diphenhydramine HCl
Benadryl
Chapter Seventeen | Slide 18 of 39
Other Amine Salts
• Cocaine is sold illegally as an amine salt
• Cocaine is reacted with NaOH to produce the free
amine form, known as “crack”
H
ClCH3
+
N
CH 3
O
O
N
O
CH3
O
CH 3
H
H
O
O
O
O
Cocaine Hydrochloride
Cocaine (“free base”)
Chapter Seventeen | Slide 19 of 39
Amines vs. Amides
• Amides have carbonyl groups next to the nitrogen.
• Amines have alkyl groups or hydrogens bonded to
the nitrogen.
O
R
N
R2N
R
amide
R
R
amine
Chapter Seventeen | Slide 20 of 39
Classification of Amides
Classification depends on the number of alkyl groups
connected to the amide nitrogen atom
Chapter Seventeen | Slide 21 of 39
Amines and Amides cont’d
Models of the simplest
primary, secondary,
and tertiary amides.
Chapter Seventeen | Slide 22 of 39
Amines and Amides cont’d
The high boiling point
of amides are related to
the numerous amideamide hydrogen
bonding possibilities
that exist.
Chapter Seventeen | Slide 23 of 39
• Classify each as amine or amide.
amide
amine
O
NH 2
N
HN
amine
amide
amine
O
O
amide
N
N
O
amide
N
amine
N
N
O
N
amine
NH 2
amide
Chapter Seventeen | Slide 24 of 39
Amines and Amides cont’d
←CC 17. 5
Chapter Seventeen | Slide 25 of 39
Chapter Seventeen | Slide 26 of 39
Alkaloids
•
•
•
•
Physiologically active nitrogen-containing compounds
Obtained from ____________
Used as anesthetics, antidepressants, and stimulants
Many are ______________
Chapter Seventeen | Slide 27 of 39
Nicotine
Chapter Seventeen | Slide 28 of 39
Caffeine
Chapter Seventeen | Slide 29 of 39
Procaine
Chapter Seventeen | Slide 30 of 39
Preparations of Amines
• Amines can be prepared by adding an alkyl halide
to ammonia in the presence of base
• Two step process: alkylation to produce the salt; reaction with
NaOH to produce the amine
– NH3 + R-X  R-NH3+Cl– R-NH3+Cl- + NaOH  RNH2 + NaX + H2O
Chapter Seventeen | Slide 31 of 39
Preparation of Amines
– Ammonia + alkyl halide + NaOH primary amine
– Primary amine+ alkyl halide + NaOH  secondary amine
– Secondary amine+ alkyl halide + NaOH  tertiary amine
– tertiary amine + alkyl halide  quaternary
ammonium salt
Chapter Seventeen | Slide 32 of 39
Alkylation Reactions
H3N: +
R'
X
H2N
R'
H2RN: +
R'
X
HRN
R'
HR2N: +
R'
X
R2N
R'
-
X
+
R3N: + R'
X
R3N
R'
Chapter Seventeen | Slide 33 of 39
Preparation of Amides
• Amides are produced by reacting a carboxylic acid with
ammonia or an amine (primary or secondary)
– “Amidification Reactions”
– Dehydration Reaction
O
O
+
R
OH
H2N
R

+
R
H 2O
NH2
Chapter Seventeen | Slide 34 of 39
Amidification Reactions
• Ammonia + carboxylic acid  primary amide
• Primary amine + carboxylic acid 
secondary amide
• Secondary amine + carboxylic acid  tertiary
amide
Chapter Seventeen | Slide 35 of 39
Reactions of Amides
Amides undergo
acid hydrolysis
base hydrolysis
carboxylic acid
ammonium salt
salt of carboxylic acid
and an amine
or ammonia
Chapter Seventeen | Slide 36 of 39
Reactions of Amides
acid hydrolysis
O

O
HCl + H2O
CH3COH + NH4+Cl–

CH3CNH2
O
NaOH

CH3CO– Na+ + NH3
base hydrolysis
Chapter Seventeen | Slide 37 of 39
Chapter Seventeen | Slide 38 of 39
Chapter Seventeen | Slide 39 of 39