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AMIDES & AMINES
Introduction
• So far, we’ve dealt with compounds
containing C, H, and O atoms.
• Many naturally produced compounds also
contain nitrogen.
• Organic compounds that contain nitrogen
can either be called amines or amides
AMINES
• Can be thought of as ammonia (NH3), with one,
two or all three of its hydrogens substituted by
alkyl groups
• The number of substituted alkyl groups allow for
primary (10), secondary (20), and tertiary (30)
sub-classifications (similar to alcohols)
Common Names for Amines:
Text method
1. Identify the largest alkyl group attached
to the nitrogen atom as the parent alkane
2. Replace the -e at the end of the parent
alkane with the new ending –amine.
Include a position number if required
Butan-1-amine
IUPAC Names for 20 and 30
Amines
• The IUPAC names for 20 and 30 amines include
the N- prefix to denote the substituted groups on
the N atom of the amino group.
• The larger alkyl group determines the main
chain
• If the structure is a 30 amine, one group must be
considered the main chain, while the other
groups are considered branches
• Additional side chains are listed in alphabetical
order as normal
N-methylbutan-1-amine
N,N-dimethylmethanamine
5-chloro-N,N-dimethylhexan-3-amine
Properties of Amines
• N-C and N-H bonds are polar, thereby allowing
for dipole-dipole and London forces.
• In addition, N-H bonds allow for hydrogen
bonding. Note that N-H hydrogen bonds are
weaker than O-H hydrogen bonds
Preparing Amines: Substitution
Reactions
• Amines are prepared by the reaction of
ammonia with an alkyl halide (let X represent
any halogen)
AMIDES
Structure and Properties
• Contain the amide linkage as their functional
group.
O
R
C
R''
N
R'
•Structurally similar to esters.
•Amide linkage is very significant in biological systems
as the forming and breaking of these bonds give
specificity to proteins.
Naming Amides
• Locate the part of the amide that contains the
C=O group. Name the parent carboxylic acid
that this part derives from. The C=O group is
always given position number 1
• Replace the –oic acid ending of the name of
the parent acid with the suffic –amide
Ethanoic acid
2
1
ethanamide
Amide Branches
• If the amide is a 20 amide, name the alkyl
group and give it location letter N- to
indicate that it is bonded to the nitrogen
atom
• If the amide is a 30 amide, place the alkyl
groups in alphabetical order. Use location
letter N- before each group to indicate that
it is bonded to the nitrogen. If the two
groups are identical, use N,N-
Examples
Parent carboxylic chain Alkyl group
H3CH2C
O
H
C
N
CH3
H2C
N
H3C
CH3
N-methyl propanamide
N,N-diethylethanamide
C
O
CH2
H2C
CH3
N-ethyl-N-methyl butanamide
N-ethyl-N,3-dimethylbutanamide
Preparation
• Amides are made through a condensation
reaction of a carboxylic acid and a primary or
secondary amine.
• Tertiary amines can not be used as they do
not contain a hydrogen.
carboxylic acid +
O
+
H
OH
propanoic acid
H2SO4
amide + water
H2SO4
N
C
H3CH2C
1°or 2°amine
CH3
H
methylamine
methanamine
H3CH2C
O
H
C
N
+ H2O
CH3
N-methylpropanamide
Amino Acids
O
R
CH
NH2
C
OH
carbon
• Amino acids are bifunctional because they
contain both an amino group (NH2) and a
carboxyl group (COOH).
• Depending on what they are mixed with,
amino acids can act as either an acid or a
base.
• The amino and carboxyl groups are attached
to the same carbon ( carbon).
• The 20 different amino acids only differ in
their side chains (R group).