General Chemistry 2 Assignment - Preparation of amine (Group 13 and 18)
• organic compounds that contain one or more nitro
functional groups: -NO2 (O-N=O)
• The O-N=O bond angle is very nearly tetrahedral
• There are 2 type of nitro compound:
zwitter ionic polar structures
A positively charged nitrogen and two
equivalent negatively charged oxygens
Preparation of amine involves nitration of the ring and subsequent
reduction of the nitro group to an amino group –NH2. In aromatic and
aliphatic nitro compounds, nitro group undergoes similar reactions.
However depending on the attachment of functional groups (aryl or
alkyl ), the reactivity may be different.
The various reduction stages of the nitro group are
The reaction involve removal of water
• In general, reduction is easily achieved either by
catalytic hydrogenation (H2 + catalyst), with
reducing metals in acid(Zinc or tin or iron or metal
salt such as SnCl2 in dilute mineral acid can also be
• For example:
• As amines can classified to be primary , secondary
and tertiary. Most primary amines can be obtained
by reduction of nitro compound
• The final product depends on the nature of the
reducing agent as well as the pH of the medium.
CH3CH2NH2 + 2H2O
CH3CH2NH2 + 2H2O
Catalytic reduction Ni or Pt/3H2
(Given by both aromatic and aliphatic nitro compound)
Reduction in acidic medium(6H)
Zn/HCl . Fe/HCl.Sn/HCl
Aliphatic nitro compounds can be reduced to aliphatic
amines using several different :
1) Catalytic hydrogenation using platinum (IV) oxide (PtO2) or
2) Iron metal in refluxing acetic acid
3) Samarium diiodide
Aromatic nitro compounds can be reduced to aromatic
amines using several different :
1) Zinc Dust and AmmoniumCatalytic
2) Catalytic ydrogenation using platinum (IV) oxide
(PtO2) or Raney nickel
•The nitro group is easily reduced by catalytic hydrogenation using Pd/C
catalyst in ethanol.
Reduction by metal in acidic solutions
• Metals (Fe, Sn and Zn) and HCl are sued for reducing a nitro group (-NO2)
to an amino group (-NH2).
Reduction with lithium aluminium hydride ,LiAlH
• Aliphatic nitro compounds are reduced to p-amines with LiAlH4.
If the reduction involve the nitro compound which have
di- and polynitro groups ,hydrogen sulfide in aqueous
or alcoholic ammonia is use for selective reduction of
one nitro group. Treating 2,4-dinitrotoluene with
hydrogen sulfide and ammonia result in reduction of
the 4-nitro group.
In the reduction of di- or polynitro aromatic compounds by gaseous H2S over a
solid catalyst,additions of CO gas promotes the formation of amino group from
all nitro groups in the molecule
•The reduction of nitro compound is highly
exothermic reaction. The heat is given out when
the nitro group is reduce and amino group being
In the laboratory,
reacting a nitro-aromatic
with a mixture of tin and
conc. hydrochloric acid
by heating under reflux
will reduce it to a
primary aromatic amine
(-NH2 directly attached
to benzene ring). In
industry , metal like iron
powder and acid are
used or a direct
reduction in the gas
phase with hydrogen or
transition metal catalyst.
C6H5NO2 + 6[H] ==> C6H5NH2 + 2H2O
2C6H5NO2(aq) + 14H+
(aq) + 3Sn(s) ==> 2C6H5NH3
(aq) + 3Sn4+
(aq) + 4H2O(l)
In nitrile reduction, a nitrile is reduced to
an amine or with a suitable chemical reagent.
Reagents for the conversion to amines
are lithium aluminium hydride( LiAlH4), Raney
nickel( Nickel catalyst),
hydrogen or diborane (B2H6).
This organic reaction is one of several nitrogen-
hydrogen bond forming reactions.
Reactions are sensitive to acidic or alkaline
conditions, which can cause hydrolysis of -CN
The reduction of nitriles using LiAlH4
LiAlH4 is more commonly
employed for the reduction of nitriles
on the laboratory scale.
Similarly, LiAlH4 reduces amides to
There are four hydrogens ("tetrahydido") around
the aluminium in a negative ion.
The "(III)" shows the oxidation state of the aluminium,
and is often left out because
aluminium only ever shows the +3 oxidation
state in its compounds.
The structure of LiAlH4 is:
In the negative ion,
one of the bonds is a co-ordinate covalent bond
using the lone pair on a hydride ion (H-)
to form a bond with an empty orbital on the aluminium.
The nitrile reacts with the lithium tetrahydridoaluminate
in solution in ethoxyethane
followed by treatment of the product
of that reaction with a dilute acid.
The reduction of nitriles using hydrogen
and a metal catalyst
The carbon-nitrogen triple bond in a nitrile can also be reduced by reaction
with hydrogen gas in the presence of a variety of metal catalysts.
Commonly quoted catalysts are palladium, platinum or nickel.
The reaction will take place at a raised temperature and pressure.
It is impossible to give exact details because it will vary from
catalyst to catalyst.
For example, ethanenitrile can be reduced to ethylamine by
with hydrogen in the presence of a palladium catalyst.
Overall, the carbon-nitrogen triple bond is reduced to give a
Primary amines contain the -NH2 group.
Reduction Of Primary
Presenter : See Teck Jia
Wong Wei Leong
Amides are a group of organic compounds derived
from ammonia (NH3).
Amide reduction in chemistry is the organic
reduction of amides.
Amides, RCONR'2, can be reduced to the amine,
RCH2NR'2 by conversion of the C=O to -CH2-
Reagents are lithium aluminium hydride and catalytic
Requires high temperature and pressure.
The main reaction product is an amine.
The nature of the amine obtained depends on the
substituent present on the original amide.
The Hofmann rearrangement is the organic reaction
of a primary amide to a primary amine with one
fewer carbon atom.
The reaction of bromine with sodium
hydroxide forms sodium hypobromite, which
transforms the primary amide into an
intermediate isocyanate. The intermediate
isocyanate is hydrolyzed to a primary amine giving
off carbon dioxide
Aliphatic & Aromatic amides are converted into
aliphatic & aromatic amines respectively.
In the preparations of Anthranilic Acid from Pthlamide.
Nicotinic acid is converted into 3-Amino pyridine.
The Symmetrical structure of α-phenyl propanamide
does not change after hofmann reaction.