Amines are organic compounds derived from ammonia by replacing one or more hydrogen atoms with alkyl or aryl groups. There are three main types of amines: primary, secondary, and tertiary. Amines can be prepared through several methods including reduction of nitro compounds, ammonolysis of alkyl halides, reduction of nitriles and amides, and the Hoffman bromamide degradation reaction. Amines exhibit basic chemical properties due to the lone pair of electrons on the nitrogen atom. Primary amines are the strongest bases while tertiary amines are the weakest bases. Acylation and reaction with nitrous acid are characteristic chemical reactions of amines.

1. organic
Amines
-renuha

2. WHAT ARE AMINES?
● Replacing one or more hydrogen atoms of NH3 with alkyl/aryl groups.
○ Eg:
● Amine’s hybridisation - sp3 [has three bonded pairs and 1 lone pair]
○ geometry - pyramidal

3. CLASSIFICATION
● Three types of amines :

4. NOMENCLATURE

5. NOMENCLATURE

6. Preparation of amines
1.Reduction of nitro compounds
● Nitro group [nickle/paladium/platinum in hydrogen] → Alkanamine
● Instead of Ni/Pt/Pl, Fe/Sn in the presence of HCl can be used.
○ Fe is most preferred as Fe+HCl → FeCl2
On further hydrolysis of FeCl2
, we get HCl
Since HCl is formed in the process, very little HCl is enough in the beginning.

7. Preparation of amines
2. Ammonolysis of alkyl halides
A nucleophilic reaction
● The replacement of halides by ammonia in an alkyl halide [through
nucleophilic reactions] is called ammonolysis or the breaking of C-X bond by
ammonia.
● Ammonia behaves like a nucleophile.
Disadvantage:
Gives a mixture of 1°,2°,3° and 4°.
But the major product will be 1°by
taking excess ammonia.
Order of reactivity of halides:
RI>RBr>RCl

8. A continuous process,
From 1° to 4°

9. Preparation of amines
3.Reduction of nitriles
● Nitrile in the presence of LiAlH4
or by catalytic hydrogenation [Ni/Pt in H2
]
● A step up reaction as the no of carbons increases in the product by 1.
●
2) Ni/Pt in H2

10. Preparation of amines
4. Reduction of amides
Reduction of amides ITP of LiAlH4
gives amines.

11. Preparation of amines
5. Hoffmann bromamide degradation reaction
● Formation of primary amines by treating with bromine in aqueous sol and
NaOH
● It is a step down reaction as the product will have 1 can less [the carbonyl
group migrates]

12. Physical
properties
01

13. It is slightly lesser than
alcohols as oxygen is a bit
more electronegative than
nitrogen.
Boiling point
Features of amines
Color
COlor of aniline is
COLORLESS but due to
atmospheric oxidation, it
gets colored.
Solubility
Lower amines are easily
soluble as they can form
hydrogen bonds.
The higher ones are almost
insoluble
1°>2°>3°
1°>2°>3°
Intermolecular bonding
1° has more intermolecular
H-bonding than 2°
But 3° has no intermolecular
H-bonding [due to this, bp
decreases.]
H is absent

14. States of matter
Solid
Higher primary amines
Liquid
Primary amines with 3+
carbons
Gas
Lower aliphatic amines
[Has a fishy odor]

15. Chemical properties
1. Basicity
⃞ Bronsted and lowry theory:
○ H+ acceptors → Base
○ H+ donor → acid
○ Since amines have a lone pair, they are basic in nature and behave as
lewis base [lewis theory]
■ They are soluble in water but insoluble in organic solvents
■ Reaction of amines with mineral acid to form ammonium salt
shows its basic nature.

16. Chemical properties
Aromatic amines are weaker bases than ammonia due to the ELECTRON
WITHDRAWING NATURE of the aryl gorup.
Aliphatic amines are more basic than ammonia due to +I effect [higher electron
density on nitrogen atom due to the hydrogen with the carbon atom next to N.]
↓
→
→
Higher pkb value, lower is
the basicity.
Higher the Kb value higher
is the basicity

17. basicity
In vapor/gaseous phase:
3>2>1>nh3 : due to +I effect
Why?
As there are 3 alkyl groups → more electron density and more stability.
In aqueous phase:
3 parameters:
1.I effect: 3>2>1
2.solvation: NH3>1>2>3 [lesser size-more solvtion,,h bond is more in 1]
3.steric reason: NH3>1>2>3 [1 is less bulkier.]
AQUEOUS PHASE BASICITY: 2>3>1

18. BASICITY
⃞ ARYLALKYL VS AMMONIA
○ ELECTRON WITHDRAWING GROUP → LESS BASIC
○ ELECTRON RELEASING GROUP → MORE BASIC [ELECTRON DENSITY
INCREASES]
○ AMMONIA MORE BASIC THAN ANILINE
⃞ ALKYLAMINE MORE BASIC THAN ARYLAMINE
○ Alkylamines are stronger bases than arylamines because alkyl group in
alkylamine are electron releasing but aryl group in arylamine is electron
withdrawing. Moreover, the lone pair of electrons on N in aromatic amine is
delocalised due to resonance with benzene ring

19. Chemistry evolution in our history
1 3 5 6
basicity acylation carbylamine Nitrous acid
arylsulphonyl
2 4
Electrophilic
substitution
Check tb

20. ACYLATION
● Reaction with acid chlorides/esters/acid anhydrides
● A nucleophilic substitution reaction
● One h from nh2 gets replaced by the acyl group and the
product is called amide
● A base stronger than amine is present eg pyridine
○ Removes the hcl and shifts the equilibrium forward.
● Reaction with benzyl chloride is called benzolyzation

21. carbylamines
⃞ Test for 1° amines
⃞ The presence of 2 hydrogens is important
⃞ Also called as isocyanide test as isocyanide is formed.[foul smelling]
⃞ 1° amine + koh +chcl3 gives isocyanide
⃞ 2 and 3 donrt react

22. Hinesberg’s reagent test
Product 1 Product 2 Mix Reaction
primary benzylsulphonyl 2° sulphonamide
secondary benzylsulphonyl
Forms 3°
sulphonamide
tertiary benzylsulphonyl Doesnt give the test
Used to identify/seperate 1,2 and 3° amines
Reagent is benzene sulphonyl chloride
2° sulphonamide is soluble in alkali as the h
attached to n is strongly acidic due to the
ewg sulphonyl.
3° is insoluble in alkali as it doesnt have a h
attached to n and therefore it isnt acidic

23. Text book