Amines
: ‫ وتنقسم إلى‬NH3 ‫ من‬amines ‫تشتق‬
1° amine R-NH2.
2° amine R2NH
3 t-amine R3N
Nomenclature of amines:
A) By IUPAC system:
.amino alkane ‫ فرع في السلسلة ونسمي المركب كـ‬NH2 ‫نعتبر‬-
‫ بأن‬N ‫ نحدد بأنها متصلة بـ‬amino ‫ بـ‬alkyl ‫في حالة اتصال مجموعة‬
.N ‫ بـ‬alkyl ‫نسبق اسم‬
CH3
CH3
NH CH3
CH CH3
CH3
2-N-methyl amino propane
CH3
N
CH CH2CH3
2-N,N dimethyl amino butane
B) Common name:
.amine ‫ ثم نكتب كلمة‬N ‫ حول ذرة‬R ‫نذكر أسماء‬-
(CH3)3N
CH3CH2CH2NH2
trimethyl amine
n-propyle amine
-
Methods of preparation:
(1) From alkyl halide:
RX + NH3
RX
-HX
RNH2
-HX
o
1 amine
R2NH
RX
-HX
R3N
t-amine
2nd amine
(2) Gaberial reaction:
It can be used in synthesis of 1ry amine.
O
O
O
O
NH3
KI
NK
NH
O
Phthalic anhydride
O
O
Phthalimide
O
CH3I
N
CH3
COOH
2H2O
+ CH3NH2
COOH
O
phthalic acid
Question:
Convert phathilimide to methyl amine?
Methylamine
(3) Reduction of nitro compounds:
A- In acidic medium:
NO2
NH2
Fe/HCl
or Sn/HCl
or Zn/HCl
or H2/Pt
B- In neutral medium:
N O
NHOH
NO2
+ Zn + NH4Cl
[O]
Phenyl h ydroxy
amine
C- In alkaline medium:
Nitrosobenzene
NO2
+ Zn
2
NaOH
N N
1:1
Azobenzene
H H
N N
1:2
also
NO2
2
O
+ CH 3ONa/CH 3OH
Ph-N=N-Ph
Azooxybenzene
C) Some common names:
NH2
aniline
NH2
NH CH3
N-methyl aniline
CH3
p-toludine
Examples of heterocyclic amines.
N
pyridine
N
H
pyrrole
N
H
piperidine
N
H
indole
(4) Reductive amination:
R C O + H3N
H
- H2O
RCH=NH
Imine
H2
Pt
e.g. convert acetone to 2-aminopropane
(isopropyl amine)
RCH2NH2
Convert benzaldehyde to benzylamine
CHO
CH
H2C
NH
NH2
H2/Pt
NH3
benzaldehyde
Benzylamine
Conversion of cyclohexanol to cyclohexylamine
OH
cyclohexanol
[O]
O
cyclohexanone
NH3
NH
cyclohexanimine
H2/Pt
NH2
Cyclohexylamine
Important observation
If we cyclohexyl bromide with NH3, it loss HBr
NH3
Br
bromocyclohexane
cyclohexene
(5) From nitrile:
R
C
N
LiAlH 4
RCH2NH2
We can use the above method to increase number of carbon atoms as follow
Conversion of ethanol to
a-Ethylamine ( same number of atoms)
b-propylamine (one carbon excess)
Answer
a) CH3CH2OH
ethanol
b) CH3CH2OH
ethanol
NH3, H2/Pt
[O]
H3C CHO
CH3CH2NH2
acetaldehyde
ethanamine
PCl5
CH3CH2Cl
chloroethane
KCN
CH3CH2CN
propiononitrile
LiAlH4
CH3CH2CH2NH2
n-propylamine
(6) Hofmann degradation:
O
R C NH2
Amide
NaOBr
R-NH2
Examples
O
H3C C NH2
NaOBr
H3C NH2
acetamide
O
Ph C NH2
benzamide
Methylamine
NaOBr
Ph NH2
Aniline
This method is used for shorting chain one carbon, for example
conversion of ethanol to methylamine
CH3CH2OH
ethanol
NaOBr
[O]
H3C COOH
acetic acid
H3C NH2
Methylamine
PCl5
O
H3C C Cl
acetyl chloride
NH3
O
H3C C NH2
acetamide
- Chemical reactions of amines:
(1) Reaction with alkyl halide:
R NH2 + RX
-HX
R2NH
RX
-HX
R3N
2)acylation of amines
O
O
H
H3C C Cl
H3CH2C N C CH3
Acetyl chloride
H3CH2C NH2
(CH3CO)2O
Acetic anhydride
O
H
H3CH2C N C CH3
3) Hofmann exhaustive methylation of amines
CH3CH2CH2CH2NH2
OH
CH3CH2CH2CH2N(CH3)3
3CH3I
I
CH3CH2CH2CH2N(CH3)3

CH3CH2CH=CH2 + (CH3)3N
AgOH
1)Oxidation of aniline
NH2
NO2
CF3CO2H
trifluoroacetic acid
Nitrobenzene
Q: Show how could you differentiate between 1ry, 2nd and t-amines?
Soln.
1- Hinesberg method:
Na
R NH2
o
1 ry amine
+
Ph SO2Cl
-HCl
Benaen sulphonyl
chloride
R
NaOH
R NH SO2Ph
R N SO2Ph
soluble in NaOH
R
NH + Cl SO2Ph
R
R3 N + Cl SO2Ph
N SO2Ph
R
No Reaction
Insolub le in NaOH
2- By using nitrous acid (HNO2):
HNO2 can formed as follow
NaNO2 + HCl
HNO2 + NaCl
A) Aromatic:
1- 1ry amine
N N+Cl -
NH2
+ HNO2
2- 2nd amine
CH 3
CH 3
NH
N N O
+ HONO
N-nitrosos phenyl methyl amine
3- t-amine
R
R
R
R
N
N
+ HONO
N=O
p-Nitroso-N,N-dialkyl aniline
B) Aliphatic:
1- 1ry amine
R NH2
+ HON=O
- H2O
R OH +N 2
R-N=N-OH
2- 2nd amine
R2NH
+
HONO
R2N N O
N-nitrosos dialkyl amine
3- t- amine
R3N
+
HONO
No Reaction
Ring substitution of benzene:
NH2
NH2
Br
Br
2,4,6-tribromo aniline
+ Br2
Br
:‫ نتبع اآلتي‬aniline ‫ إلدخال مجموعة واحدة على‬:‫ملحوظة هامة‬
NH2
NHCOCH 3
+ (CH3CO)2O
(less active than aniline)
acetanilid e
acetic anhydride
O
O
NH C CH 3
NH C CH 3
NH2
H 3O +
+ Br2
Br
Br
Aromatic diazonium salts
Preparation:
NH2
N
N+Cl -
NaNO2
HCl
Chemical reactions:
(1) Sandemeyer reaction:
Cl
CuCl
+ N2
N N+Cl -
Br
CuBr
+ N2
CN
CuCN
+ N2
Benzonitrite or
cyanobenzene
.Nucleophile ‫ ويحل محلها الشق السالب‬N2 ‫الحظ أن ما يحدث هو خروج‬-
NO2
NaNO2
F
N
N+Cl -
HBF 4
I
KI
OH
HOH
:‫ إلى بنزين كاآلتي‬Ph-N=N+Cl- ‫يمكن تحويل‬
+
N N Cl + H3PO 2
Q: Convert aniline to:
1- Phenol
2- Benzene.
Question: convert toluene to 3,5-dintrotoluene
Answer
CH3
CH3
NO2
C. NHO3
(1)
CH3
C. H2SO4
NO2
CH3
CH3
Sn/ HCl
NO2
CH3
AC2O
NH2
NO2
NH2
O2 N
NaNO2
HCl
O2N
NO2
NHCOCH3
CH3
CH3
H3O
O2N
2 HNO3
2 H2SO4
NHC CH3
O
CH3
CH3
CH3
H3PO2
NO2
N N Cl
O2N
NO2
3,5-dinitro-toluene
N N
(2) Coupling reactions with phenols:
This reaction is used for preparation of dyes.
N N+Cl - +
OH
NaOH
N N
OH
OH
N N
1-Naphthol or
-Naphthol
N N
OH
OH
ONa