12th hacker series
Amines
Amines
Ammonia derivatives 3H R
N
> R
-
-
NH3
=
+ 3R
M
Fr
W
· R-NH-R
RNH2
Classification of Amines
-Tamine
zanine 3
°
annie
-
#
NRNHL N He + IR
R-NH-R
NH1z R-N-R I
R
CHz-NH-CH5
eg-cHzNth C2H5-NH-Ch2M ,Ms
C13-N-Us
Cucc3 I
Witz Chs-NH-X
C2Hj
Nomenclature
Primary Amine -
RNH2
qN-alkylamine
alkanamine
IpAce
2n -
CHy NH2
qN-methylamine
IUPAC -
methanamine
ward
root suffic suffer
alkanamine
alleane + amine >
-
a
eg-chch
it
IHPA-propan-2-amine
Naming and structures of amines
IUPAC
N -
①CH z CH2NH2 thanamine
ethylamine
OCHzHzHzNH2 propan-1 amine
n-propylamine
Or
propanomine
Hsc-E- NHL Esopropylamine propan-2-amine
·
nomenclature for secondary amine
NH M
-m
- -
-
R -
NH-R R -
NH-R
da-dialkylamine IV-alkylatkylamine
TAPAC-N-alkyl olkanamine IUPAC-N-alkylatkanamea
mething
HH- ethyl
⑨hylamine GN-ethylmethylamine
FUPAC-N-methylmethylamine
methanamine
IUPA-N-methyl ethanamics
Naming and structures of amines
&N Type
D CH3-NH-C2H5
ethyl methylamine N-methylcthanamine
② CH3-N-CH3
Trimethylamine
N
, e
-delt
de
③
HCHC-N-CH2, N
, N-diethylbutylamine N
,
N-diethy
Diethylbutan-1-amine
damine
teache
Naming of tertiary amines
R & N-triatklyamine
N-dialkylalkamine
alkanamine
-N
,
Naming and structures of amines
prop-2-en-1-amine
DHC CH-4z-NH2 Allylamne
= e
②
NH2-CH2)s -
N2 hexamethylenediamine Gnane - 1 , 6-diamine
③ Aniline Aniline
or
101 Benzenamine
Y
C3
①
/ -NHL orthotoulidine
↓,
toluidine 2-methylaniline
i
⑤
p-bromoaniline 4-bronaviline
⑤
Stones N-dimethylamitie are
N N -dime
, ,
benzenamine
benzamise
Methods of preparation of amines
Reduction of nitro compounds
nitro compound are reduced to amine by passing hydrogen gas in the
presence of finely divided nickel, palladium or platinum, and also by
reduction with metals in acidic medium. Nitroalkanes can also be
similarly reduced to the corresponding Alkanamines
wood
X X
• Reduction with iron scrap and hydrochloric acid is preferred
because FeCl2 formed gets hydrolysed to release hydrochloric acid
during the reaction.Thus, only a small amount of hydrochloric
acid is required to initiate the reaction.
Ammonolysis of alkyl halide
The reaction is carried out in a sealed tube at 373 K. The primary amine
thus obtained behaves as a nucleophile and can further react with alkyl
halide to form secondary and tertiary amine and finally quaternary
ammonium salt.
Ammonolysis has the disadvantage of yielding a mixture of primary,
secondary and tertiary amines, and also a quaternary ammonium salt.
However, primary amine is obtained as a major product by taking large
excess of ammonia. The order of reactivity of halides with amine is
RI > RESTRU
Reduction of nitriles
On nitriles reduction with lithium aluminium hydride or catalytic
hydrogenation produce primary amine . This reaction is used for
ascent of amine series. I.e, for preparation of amine containing one
carbon atom more than the starting amine
RCN
AHY RCA
Nalleg CHOU
+
Reduction of amides
Reduction of amide with lithium aluminium hydride yield amines
a
REINHL
R-C-NH
R−C− NH +2 4 [H] LiAlH 4 R−CH 2 −NH 2
Gabriel phthalimide synthesis
Gabriel synthesis is used for the preparation of primary amines.
Phthalimide on treatment with ethanolic potassium hydroxide forms,
potassium salt of phthalimide which on heating with alkyl halide, followed
by alkaline hydrolysis produces the corresponding primary amine .
Aromatic primary amine cannot be prepared by this method because aryl ha
undergo nucleophilic substitution with the anion formed by Phthalimide
Hoffmann bromamide degradation reaction
• Hoffmann developed a method for preparation of primary amines by
treating an amide with bromine in an aqueous or ethanolic solution of
sodium hydroxide. In this degradation reaction, migration of an alkyl
or aryl group takes place from carbonyl carbon of the amide to the
nitrogen atom. The Amine so formed contains one carbon less than that
present in the amide.
NOA-RNz NaCO
Na
+
R-C-NH2
+
+ Pr
Physical properties of amines
• the lower aliphatic amine are gases with fishy odour. Primary amines
with three or more carbon atoms are liquid and still higher ones are
solid. Aniline and other Arylamines are usually colourless but get
coloured in storage due to atmospheric oxidation.
• lower aliphatic amines are soluble in water because they can form
hydrogen bonds with water molecules. However, solubility decreases with
increase in molar mass of Amines due to increase in size of the
hydrophobic alkyl part. Higher amines are essentially insoluble in water.
• amines are soluble in organic solvent like alcohol, ether, and benzene.
You may remember that alcohols are more polar than amines and
form stronger intermolecular hydrogen bonds than amines
Chemical properties of amines
Basic Character of amines
• amine is being basic in nature, react with acids to form salts
Alkylation
Amines undergo alkylation on reaction with alkyl halide
Acylation
• aliphatic and aromatic primary and secondary amines react with acid
chloride anhydrides and esters by nucleophilic substitution reaction.
This reaction is known as acylation
Carbylamine reaction
• aliphatic, and aromatic primary amines on heating with chloroform
and ethanolic potassium hydroxide form isocyanides, or carbylamines
which are foul smelling substances
• Secondary and tertiary amines, do not show this reaction
- This reaction is known as carbylamine reaction or isocyanide test and is
used as a test for primary amines
RNHL+ CHUztROR-RN +- KC + Ho
Reaction with nitrous acid
• primary aliphatic amines react with nitrous acid to form aliphatic
diazonium salts, which being unstable liberate, nitrogen gas
quantitatively, and alcohols
RNA + HNOLA2 RNICER-OM + N2 + HC
HC
• aromatic amine react with nitrous acid at low temperature(273-278
K) to form diazonium salts, a very important class of compounds
used for synthesis of a variety of aromatic compounds O
NT
-
4-
NaNO+ Ha X
273-2784
Reaction with arylsulphonyl chloride
• benzenesulphonyl chloride, which is also known as Hinsberg's reagent,
reacts with primary and secondary amines to form sulphonamide
the
p-ne
82 pN
Diazonium salt
Introduction and method of preparation
• benzene diazonium chloride is prepared by the reaction of aniline with
nitrous acid at 273- 278 Kelvin
• Nitrous acid is produced in the reaction mixture by the reaction of
sodium nitrite with hydrochloric acid
• The conversion of primary aromatic amine into diazonium salt is
known as diazotisation . Due to its instability, the diazonium salt is
not generally stored and is used immediately after its preparation.
• Benzene diazonium chloride is a colourless crystalline solid
• it is readily soluble in water and stable in cold, but react with water
when warmed
• it decomposes easily in the dry state
• Benzenediazonium flouroborate is water insoluble, and stable at room
temperature
