Transcript Amines and Amides

Amines and
Amides
Chapter 16
Nitrogen
• Fourth most common atom in living
systems.
• Important component of the
structure of nucleic acids, DNA, and
RNA
• Essential to the structure and
function of proteins – enzymes and
antibodies
Amine Structure
R
N
H
H
• Characterized by the presence of an
amino group (-NH2)
• One or more of the hydrogen atoms
can be replaced by an organic group.
Amines
• Organic derivatives of ammonia and, like
ammonia, they are basic.
H
N
H
H
R
N
H
H
• Amines are classified according to the
number of alkyl groups attached to the
nitrogen.
Classification of Amines
• Primary (1°) – one hydrogen replaced
H3C
N
H
H
• Secondary (2°) – two hydrogens replaced
H3C
N
CH3
H
• Tertiary (3°) – three hydrogens replaced
H3C
N
CH3
CH3
Properties of Amines
• Because nitrogen is more electronegative
than hydrogen, the N-H bond is polar.
• Hydrogen bonding can occur between
amines and water.
• Primary and secondary amines have
higher boiling points than tertiary amines
because tertiary amines cannot form
hydrogen bonds.
• Small amines (six or fewer carbons) are
soluble in water.
Naming Amines - IUPAC
• Least common system used
• Parent chain is longest continuous chain to
which the amine group is attached.
• Use a number to indicate the position of
the alkane.
• Add the prefix “amino” to the name of the
alkane.
• If a substituent is present on the nitrogen,
it is designated by the prefix N-alkyl.
Naming Amines - IUPAC
CH3NH2
CH3CH2NH2
CH3NHCH3
CH3NHCH2CH3
aminomethane
aminoethane
N-methylaminomethane N-methylaminoethane
CH3
N,N-dimethylaminomethane
CH3NCH3
Naming Amines – CA
system
• CA system – Chemical Abstracts
system
• The final –e of the parent name is
dropped and the suffix –amine is
added.
• For secondary and tertiary amines,
the prefix N-alkyl is added to the
parent compound.
Naming Amines – CA
system
CH3NH2
CH3CH2NH2
methanamine
ethanamine
CH3NHCH2CH3
CH3NHCH3
N-methylmethanamine
N-methylethanamine
CH3
N,N-dimethylmethanamine
CH3NCH3
Aromatic Amines
Aniline or
benzenamine
NH2
NH2
CH3
o-toluidine
NH2
NH2
p-toluidine
m-toluidine
CH3
CH3
Other Common Name
Amines
CH3NH2
methylamine
CH3NHCH3
dimethylamine
CH3
CH3NCH3
CH3CH2NH2
ethylamine
CH3NHCH2CH3
ethylmethylamine
trimethylamine
Amides
• Products formed in a reaction
between a carboxylic acid and an
amine.
• Contains two portions: the carbonyl
group from a carboxylic acid and the
amino group from the amine
O
R
C
NH2
Amide Bond
Properties of Amides
• Most are solids at room temperature
• Very high boiling points – hydrogen
bonding between N-H bond of one
amide and the C=O group of the
second amide
• Simpler ones are quite soluble in
water
• Unlike amines, amides are NOT
bases
Naming Amides - IUPAC
• Replace the –oic acid from the
carboxylic acid with the ending –
amide.
• Substituents on the nitrogen are
placed as prefixes and are indicated
by N- followed by the name of the
substituent.
Examples
NH2
NH2
O
Ethanamide
Acetamide
O
O
Propanamide
NH
N-methylpropanamide