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PREPARATION OF AMINES
Amines can be prepared in two ways: by nucleophilic substitution of a haloalkane and by
reduction from nitriles. The preparation from a haloalkane results in a mixture of primary,
secondary and tertiary amines and their salts. The preparation from a nitrile results in the
formation of primary amines only.
a) Preparation of amines from haloalkanes
Haloalkanes react with nucleophiles. If ammonia is used as the nucleophile then amines are
formed.…read more

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So primary amines are formed by the addition of excess ammonia to a haloalkane:
RX + 2NH3 RNH2 + NH4+X
Eg
Primary amines will also be formed if haloalkanes and ammonia are mixed in a 1:1 ratio.…read more

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If any haloalkane is present after the secondary amine has been formed, it can be attacked by
the secondary amine to form a tertiary amine:
So tertiary amines are formed by reacting haloalkanes and ammonia in a 3:1 ratio or by
reacting a haloalkane with a secondary amine in a 1:1 ratio:
3RX + NH3 R3N + 3HX
R1X + R2NHR3 R1R2R3N + HX
Eg
iv) quaternary ammonium salts
If there is any haloalkane left after the tertiary amine has been formed, it will be…read more

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So quaternary ammonium salts can be made by reacting haloalkanes and ammonia in a 4:1
ratio or by reacting tertiary amines and haloalkanes in a 1:1 ratio.…read more

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BASIC PROPERTIES OF AMINES
Amines are weak bases the lone pair of electrons on the nitrogen atom can behave as a proton
acceptor. The strength of amines varies, but all react with strong acids to make alkylammonium
salts.…read more

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The hydrogen atom is slightly more electropositive than the carbon atom. This means that the
carbon atom has a slight surplus of electrons which the nitrogen atom can attract towards itself.
This effect is known as a "positive inductive effect" and it means that the N atom has an excess
of electron density:
The greater the electron density on the N atom, the more likely the lone pair is to be released
for bonding.…read more

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USES OF QUATERNARY AMMONIUM SALTS
Quaternary ammonium salts are principally used as cationic surfactants. Longchain ammonium
salts are mainly used for this purpose:
Eg
A surfactant is a substance which can be added to a liquid to reduce its surface tension.
Cationic surfactants can also be added to solids which tend to attract negative charge, such as
glass, hair and fibres. The cation helps cancel out the negative charge and hence acts as an
antistatic agent.…read more

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Summary of preparation and acidbase properties of amines
Type of reaction Mechanism
1. haloalkane primary amine Nucleophilic
substitution (required)
reagents: haloalkane and excess ammonia
conditions: heat
equation: RX + 2NH3 RNH2 + NH4X
or
reagent: haloalkane and ammonia (1:1 ratio)
conditions: heat
equation: RX + NH3 RNH2 + HX
2. haloalkane secondary amine
reagents: haloalkane and ammonia (2:1 ratio)
conditions: heat
equation: 2RX + NH3 RNHR + 2HX
or
reagents: haloalkane and primary amine
conditions: heat
equation: R1X + R2NH2 R1NHR2 + HX
3.…read more

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R1NH3Cl + NaOH R1NH2 + NaCl + H2O
R1R2NH2Cl + NaOH R1R2NH + NaCl + H2O
R1R2R3NHCl + NaOH R1R2R3N + NaCl + H2O…read more

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