chemistry 2100 lecture 7. amines amines are nitrogen-containing compounds
TRANSCRIPT
Chemistry 2100
Lecture 7
Amines
• Amines are nitrogen-containing compounds
Structure and ClassificationAmines are classified as 1°, 2°, or 3°
depending on the number of carbon groups bonded to nitrogen.
Aliphatic amine:Aliphatic amine: All carbons bonded to nitrogen are derived from alkyl groups. See the three above.
Aromatic amine:Aromatic amine: One or more of the groups bonded to nitrogen are aryl groups.NH2 N-CH3
HCH2-N-CH3
CH3
Aniline(a 1° aromatic amine)
N-Methylaniline(a 2° aromatic amine)
Benzyldimethylamine(a 3° aliphatic amine)
CH3-NH2 CH3-N-CH3
H
CH3-N-CH3
CH3
Methylamine(a 1° amine)
Dimethylamine(a 2° amine)
Trimethylamine(a 3° amine)
Structure and Classification
– Heterocyclic amine:Heterocyclic amine: An amine in which the nitrogen atom is part of a ring.
– Heterocyclic aliphatic amine:Heterocyclic aliphatic amine: A heterocyclic amine in which the ring is saturated (has no C=C bonds).
– Heterocyclic aromatic amine:Heterocyclic aromatic amine: The amine nitrogen is part of an aromatic ring.
PiperidinePyrrolidine Pyridine(heterocyclic aliphatic amines) (heterocyclic aromatic amines)
NH
NH
N N
N
Pyrimidine
N
N
Imidazole
N
N
N
N
HPurine
H
Nomenclature
IUPAC names– We derive IUPAC names for aliphatic
amines just as we did for alcohols.– Drop the final -e-e of the parent alkane and
replace it by -amine.-amine.– Use a number to locate the amino group
on the parent chain.
CH3CHCH3
NH2
NH2
H2NNH2
1,6-HexanediamineCyclohexanamine2-Propanamine
Physical PropertiesAmines are polar compounds:– Both 1° and 2° amines have N-H bonds,
and can form hydrogen bonds with one another.
– 3° Amines have no N-H bond and cannot form hydrogen bonds with one another.
CH3CH2CH2NH2 (bp 48°C) CH3CH2NHCH3 (bp 35°C) (CH3)3N (bp 3°C)
CH3CH3 (bp -88°C) CH3NH2 (bp -7°C) CH3OH (bp +65°C)
NH3 (bp -33°C) H2O (bp +100°C)
Boiling Points
OdorLike ammonia, low-molecular-weight amines have very sharp, penetrating odors.– Trimethylamine, for example, is the
pungent principle in the smell of rotting fish.
– Two other particularly pungent amines are 1,4-butanediamine (putrescine) and 1,5-pentanediamine (cadaverine).H2N NH2
1,5-Pentanediamine(Cadaverine)
NH2H2N
1,4-Butanediamine(Putrescine)
Basicity of Amines
CH3-NH
HH-O-H CH3-N-H
H
HO-H
Methylammoniumhydroxide
Methylamine(a base)
++
-: :
::
::
C6H5NH2
CH3CH2NH2Aliphatic
Ammonia
Aromatic
3.0 - 4.0
4.74
8.5 - 9.5
Class pKb Example Name
Ethanamine
Aniline
Stronger base
Weaker base
ClR N R"
H
R'
• •NR R"
R'H+ Cl -
Na + OH-
free base
ammonium salt(hydrochloride)
Ammonium Salts
(S)-(–)-nicotine
N
NCH3
H
Cl
(–)-cocaine hydrochloride
COOCH3N
O—C
O
HCH3
H
H
N
OO
NH
H
H
H
H
(–)-strychnine
NCH2CH2CH3
H
H
(S)- (+)-coniine(S)-(+)-coniine
(S)-(–)-nicotine
(–)-strychnine
(–)-cocaine hydrochloride
Alkaloids
NaNO2 + HCl (aq) O + NaCl (aq)O NH
nitrous acid
(-2 H2O)
HClOOH N N Cl NRNH2R
(1°) diazonium salt
+ N N H2O
(-HCl )OHR +
OOH NH2O
HClN ONR
R'
nitrosoamine
+(2°)
R NH
R'
H2O+
Nitrosation
NaNO2 + HCl (aq) O + NaCl (aq)O NH
nitrous acid
(-2 H2O)
HClOOH N N Cl NRNH2R
(1°) diazonium salt
+ N N H2O
(-HCl )OHR +
OOH NH2O
HClN ONR
R'
nitrosoamine
+(2°)
R NH
R'
H2O+
NaNO2 + HCl (aq) O + NaCl (aq)O NH
nitrous acid
(-2 H2O)
HClOOH N N Cl NRNH2R
(1°) diazonium salt
+ N N H2O
(-HCl )OHR +
OOH NH2O
HClN ONR
R'
nitrosoamine
+(2°)
R NH
R'
H2O+
NaNO2 + HCl (aq) O + NaCl (aq)O NH
nitrous acid
(-2 H2O)
HClOOH N N Cl NRNH2R
(1°) diazonium salt
+ N N H2O
(-HCl )OHR +
OOH NH2O
HClN ONR
R'
nitrosoamine
+(2°)
R NH
R'
H2O+
NaNO2 + HCl (aq) O + NaCl (aq)O NH
nitrous acid
(-2 H2O)
HClOOH N N Cl NRNH2R
(1°) diazonium salt
+ N N H2O
(-HCl )OHR +
OOH NH2O
HClN ONR
R'
nitrosoamine
+(2°)
R NH
R'
H2O+
NaNO2 + HCl (aq) O + NaCl (aq)O NH
nitrous acid
(-2 H2O)
HClOOH N N Cl NRNH2R
(1°) diazonium salt
+ N N H2O
(-HCl )OHR +
OOH NH2O
HClN ONR
R'
nitrosoamine
+(2°)
R NH
R'
H2O+
NaNO2 + HCl (aq) O + NaCl (aq)O NH
nitrous acid
(-2 H2O)
HClOOH N N Cl NRNH2R
(1°) diazonium salt
+ N N H2O
(-HCl )OHR +
OOH NH2O
HClN ONR
R'
nitrosoamine
+(2°)
R NH
R'
H2O+
NaNO2 + HCl (aq) O + NaCl (aq)O NH
nitrous acid
(-2 H2O)
HClOOH N N Cl NRNH2R
(1°) diazonium salt
+ N N H2O
(-HCl )OHR +
OOH NH2O
HClN ONR
R'
nitrosoamine
+(2°)
R NH
R'
H2O+
(-HCl ) 0°C
NMe2HN N Cl
N N NMe2
Butter Yellow
+
Azo Dyes
(-HCl ) 0°C
NMe2HN N Cl
N N NMe2
Butter Yellow
+
(-HCl ) 0°C
NMe2HN N Cl
N N NMe2
Butter Yellow
+
(-HCl ) 0°C
NMe2HN N Cl
N N NMe2
Butter Yellow
+
(-HCl )
+
OH
H
N N SO3H
OH
SO3HNCl N
0°C
Orange II
(-HCl )
+
OH
H
N N SO3H
OH
SO3HNCl N
0°C
Orange II
(-HCl )
+
OH
H
N N SO3H
OH
SO3HNCl N
0°C
Orange II
(-HCl )
+
OH
H
N N SO3H
OH
SO3HNCl N
0°C
Orange II
American Flag Red
NO2
NO2
Direct Blue 2BSO3H
OHNH2
HO3S
N NNN
OH NH2
SO3HHO3S
Direct Blue 2BSO3H
OHNH2
HO3S
N NNN
OH NH2
SO3HHO3S
SO3H
OHNH2
HO3S
N N OHNNNNO2N
Diamine Green B
N
CH3O
N
H
HO
H
quinine
• •
• •
• •N CH2CH2CH3
H
coniine
• •
• •
nicotine
N
N
CH3
Heterocyclic Amines
chlorophyll a
H
CH 3OOC
CH 3
N
O
H
H
CH 3 N
O
O
Mg
N
CH 3
CH
N
CH 3
CH 2CH 3
CH 2
heme
N
CH 3
CH 2
CH 2
COOH
N
CH 3
CH 2
CH 2
COOH
Fe
CH
CH 3N
CH
CH 3
N
CH 2
CH 2
nicotinamide / niacin (B3)
Morphine Codeine
Heroin
NN Cl
Hepibatidine
Poison Dart Frogs