Download Amines

Amines
By:
Dr. Siham Lahsasni
Structure and classification of amines
H
R
NH2
R
N
R
R
R N
R
R
R
+
N
R
R
Primary amine
Secondary
Tertiary
Quaternary ammonium salt
Nomenclature of Amines

Common: Listing the alkyl groups and
adding the suffix amine.

IUPAC: The amino group is considered
the substituent, and its position on the
chain is indicated by the lowest
number.
CH3
CH3
H3C
H3C NH
NH2
CH2
H3C
N
CH3
H3C
+
N
CH3
Br
-
CH3
Methyl amine
NH2
H3C
Benzyl methyl amine
CH3
Trimethyl amine
Tetramethyl
ammonium bromide
NH2
NH2
COOH
H3C
CH3
H3C
CH3
OH
3-Amino-5-methylhexane
NH2
5-Aminoheptanoic acid
NH2
NH2
OH
3-Amino-2-butanol
H3C
NH
NO 2
CH3
Aniline
o-Nitroaniline
NH2
p-Toluidine p-aminophenol
NO 2
p-nitro-N-ethylaniline
Physical properties of Amines


Because they possess a polar N-H bond,
primary and secondary amines are capable
of intermolecular hydrogen bonding: Higher
boiling points than alkanes but lower than
alcohols.
All amines are capable of forming hydrogen
bonds with water: Soluble in water.
Basicity of Amines

Amines basic because N has non bonded pair of
electrons which can be donated to an acid to form
ammonium salt.

base strength depend on the degree of substitution
(electron donating group) on N: CH3-NH-CH3 >
NH2-CH3 > NH3. Tertiary amine have the lower
basicity because the alkyl groups attached in
nitrogen.
Aliphatic amines are considerably more basic than
aromatics amines.

NH2
NH2
NH2
NO 2
>
>
NH 2
NH 2
NH 2
NO2
NH 2
NO2
<
<
<
NO 2
NH 2
NH 2
NH 2
NH 2
NH 2
Preparation of amines
1- Reduction of nitro compounds, nitriles, amides, and oximes
R
H2/Pt or Sn/HCl
NO 2
Fe/HCl or SnCl 2
R
NH2
or LiAlH 4
R
CN
O
R
C
NH2
R
CH N
H2/Pt
R
or LiAlH 4
1) LiAlH 4
2) H 3O
OH
R
+
1) LiAlH 4
2) H 3O
+
R
CH 2NH 2
CH 2NH 2
NH2
2- Alkylation of ammonia: Methods
Hoffman
R
X
+
+ -
RNH 3 X
NH3
+
H3C NH2
RNH 2
+
NaX
+
NH 4 I
+ H2O
Alkyl ammonium salt
Primary or secondary alkyl halide
CH 3I
NaOH
NH3
Ammonia
+
CH 3I
Primary amine
H3C NH CH3
CH 3NH 2
Primary amine
H3C
CH 3
NH
+
+ -
NH 4 I
Secondary amine
+
CH 3I
H3C
N
CH3
CH 3
Secondary amine
H3C
H3C N CH3
Tertiary amine
+ -
+ -
NH 4 I
+
Tertiary amine
H3C
+
CH 3I
H3C
+
N
CH3
I
-
CH 3
Tetramethylammonium iodide
CH 3
H 3C
C
NH3
+
Cl
Elimination
CH 3
H2C
C
+
NH4+Cl -
CH 3
CH 3
Tertiary alkyl halide
3- Hoffman degradation of Amides
O
R
NaOH / Br 2
C
NH2
O
O
O
OHR
RNH 2
or NaOBr
C
R
NH 2
O
NH -
C
OH-
Br 2
R
C
NHBr
N-Bromoamide
O
H2O
R
C
N
Br
-Br
R
H
N
-
R
C
N
R
R
OH
Carbanic acid non stable
C
Isocyanate
O
C
N
NH 2
+
CO2
O
4- Gabriel method
O
C
COOH
+

NH3
KOH
NH
C
COOH
O
O
Phathalimide
C
N -K+
C
+
H 2O
Potassium phtalimide
O
O
O
C
C
N -K+
+
RX
N
C
C
O
O
N-Alkyl phathalaimide
R
+
KX
5- From carbonyl groups
H
C
O
+
NH3
C
NH
H2 / Ni
C
Imine: schif f base
O
NH2
1) NH3
2) H2 / Ni
NH 2
Reactions of Amines
1- with nitraus acid HNO2
a- Aliphatic amine
R
NaNO 2
NH2
R
HCl / 0 C
+
N
N
-
X
N
N
Primary amine
+
Alcohols + alkenes
Diazonium salt
R
NH R
NaNO 2
1
HCl / 0 C
R
R
N
R
Tertiary amine
N
1
2
1
O
R
N-Nitroso alkyl amine
Secondary amine
R
N
NaNO 2
HCl / 0 C
N. R
b- Aromatic amine
NH2
+
N N
HNO 2
HCl / 0 C
Cl
N N
Nu
+
Nu
-
+
N2
Nu= CN, NO 2, I, Br, OH, OR
Cl
HO
N N
N
+
N
NaOH/ 0 C
+
OH
HCl
CH3
H3C
HN
N
O
N
HNO 2
HCl / 0 C
N-Nitroso-N-methylaniline
H3C
H3C
N
CH3
CH3
N
HNO 2
HCl / 0 C
p-Nitroso-N-ethyl-N-methylaniline
N
O
2- Acylation
O
O
R
OH+
C
R'
R'
NH 2
H
N
C
R
X
O
O
C4H9
OH+
C
Cl
H 3C
NH 2
H 3C
H
N
C
C 4H 9
3- Alkylation : Hoffman reaction
R'
R
+
X
R'
R
NH2
N
R
X-
Ag2O / H2O
Excess
R
R'
R
N
R
OH-
AgX
+
R
If R=R’=CH3
CH3
H 3C
N
CH3
CH 3
OH
-

(CH3)3N
+
CH3OH
If R’# CH3: Hoffman Elimination E2
CH2-CH 2-CH 3
H 3C
N
CH3
CH 3
OH
-

E2
(CH3)3N
+
H 2C
C
H
CH 3