Transcript Ch 16 Amines - Tennessee Wesleyan College

Ch 16 Amines
Homework problems:
16.9, 16.10, 16.21, 16.25, 16.39,
16.40
Amines
• Carbon, Hydrogen, and Oxygen are the 3
most common elements in organic
compounds
• Because of the wide distribution of amines
in the biological world, Nitrogen is the
fourth most common element.
Structure and Classification
• The functional group for amines is a
Nitrogen bonded to alkyl groups and/or
Hydrogen
N
R
R= C or H
R
R
• Amines are classified as 1o, 2o, or 3o based
on The number of alkyl groups bonded to
the Nitrogen!!
N
H
H
CH3
N
H
CH3
N
CH3
H3 C
CH3
CH3
Further Classification
• Amines are further classified as Aliphatic
or Aromatic
• Aliphatic Amines: all carbons bonded to
the nitrogen are derived from alkyl groups
• Aromatic Amines: one or more of the
carbons bonded to the nitrogen are in an
aromatic ring
Examples
N
H
CH3
H
N
N
CH3
H
CH3
NH2
H
N
CH3
H3 C
CH3
CH3
CH3
N
CH3
Heterocyclic Amines
• An amine in which the Nitrogen is a
member of a ring is classified as a
Heterocyclic Amine
• When the Nitrogen is part of a regular ring,
it is a Heterocyclic Aliphatic Amine
• When the Nitrogen is part of an aromatic
rind, it is a Heterocyclic Aromatic Amine
Examples
N
N
H
N
H
Pyrrolidine
Piperidine
Heterocyclic Aliphatic
Amines
N
Pyridine
N
N
N
Pyrimidine**
N
N
H
Purine**
Heterocyclic Aromatic Amines
* Important building blocks for the amino bases in DNA and RNA
DRUGS!!!!
• Amines are typically very important in
drugs, both legal and illegal
• See Chemical Connections 16A and 16B to
learn more!!!
IUPAC Nomenclature
• IUPAC names for 1o aliphatic amines are
derived just like alcohols, you drop the -e
from the parent name and add -amine
• Use numbers to indicate location of amino
NH2
NH2
NH2
H2 N
Aromatic Amines
• IUPAC keeps the common name Aniline:
NO 2
CH3
NH2
NH2
NH2
o
2
and
o
3
Amines
• 2o and 3o amines are named as Nsubstituted primary amines
• The largest alkyl group bonded to the
Nitrogen is taken as the parent amine
• The smaller groups are named as
substituents and their locations are indicated
with an N-
Examples
CH3
N
N
HN
CH3
CH3
Amine Salts
• When four atoms or groups are bonded to
the Nitrogen, the Nitrogen bears a positive
charge.
H
H
H
H
N
H
H
N
CH3
H
• The cation is usually associated with an
anion and presented as a salt
Naming Amine Salts
• The ending -amine is replaced by
-ammonium and the name of the anion is
added after.
H
N
H
Cl
N
H
Br
Physical Properties
• Like Ammonia, low molecular weight amines have very
sharp odors
• Amines are polar because of the difference in
electronegativity between Nitrogen and Hydrogen and also
between Nitrogen and Carbon.
• 1o and 2o amines have a Hydrogen bonded to a Nitrogen
so they are capable of Hydrogen bonding to each other
• 3o Amines do not have a Hydrogen bonded to Nitrogen so
they can not Hydrogen bond to one another.
• All classes of amines can H-Bond with water and are
therefore soluble in water!!
Reactions of Amines
• Basicity
– Due to the lone pair of electrons on the
Nitrogen, amines are weak bases and aqueous
solutions of amines are basic.
– Recall, a base is a substance that will accept a
hydrogen in a reaction.
H
N
H
H
+
H
OH
N
H
H
OH
Reactions with Acids
• Amines react completely with strong acids
to form water soluable salts.
HO
H
HO
HO
NH2
+ H-Cl
HO
Norepinephrine
(only slightly soluable in water)
H
HO
H2O
NH3
Cl
HO
Norepinephrine hydrochloride
(completely soluable in water)