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Presenters:Tan Cai YingZainab Iqbal

PREPARATION OF AMINE

Reduction of Nitro Compound

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About Nitro Compound• 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:

Nitro compound

Aromatic Aliphatic

zwitter ionic polar structuresA positively charged nitrogen and two equivalent negatively charged oxygens

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Reduction of Nitro Compound to Amine

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.

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The various reduction stages of the nitro group are given below:

The reaction involve removal of water

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Reduction of Nitro Compound• 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 used)

• For example:

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• 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

1 。 Amine

CH3CH2NH2 + 2H2O

1 。 Amine

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

Zn/NH4Cl(neutral medium)

Reducing agentCH3CH2NHOH +H2O

N-ethyl hydroxylamine

CH3CH2NO2

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Aliphatic nitro compounds can be reduced to aliphatic amines using several different reagents:

1) Catalytic hydrogenation using platinum (IV) oxide (PtO2) or Raney nickel

2) Iron metal in refluxing acetic acid3) Samarium diiodide

Aromatic nitro compounds can be reduced to aromatic amines using several different reagents:1) Zinc Dust and AmmoniumCatalytic2) Catalytic ydrogenation using platinum (IV) oxide

(PtO2) or Raney nickel

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Catalytic reduction

•The nitro group is easily reduced by catalytic hydrogenation using Pd/C catalyst in ethanol.

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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).

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Reduction with lithium aluminium hydride ,LiAlH

• Aliphatic nitro compounds are reduced to p-amines with LiAlH4.

Methylnitrobenzene Methylphenylamine

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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

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•The reduction of nitro compound is highly exothermic reaction. The heat is given out when the nitro group is reduce and amino group being form.

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Laboratory Example

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

Redox Reaction:2C6H5NO2(aq) + 14H+

(aq) + 3Sn(s) ==> 2C6H5NH3+

(aq) + 3Sn4+(aq) + 4H2O(l)

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Reduction of Nitrile compound

Presenters:Priscilla Pang Jie-YiTyo Ann Kei

PREPARATION OF AMINE

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

group.

http://en.wikipedia.org/wiki/File:Nitrile_reduction.png

The reduction of nitriles using LiAlH4

Lithium tetrahydridoaluminate, LiAlH4 is more commonly

employed for the reduction of nitriles on the laboratory scale.

Similarly, LiAlH4 reduces amides to amines.

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.

[H] means "hydrogen from a reducing agent".

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 reaction

with hydrogen in the presence of a palladium catalyst.

Overall, the carbon-nitrogen triple bond is reduced to give a primary amine.

Primary amines contain the -NH2 group.

Preparation Of Amines

Reduction Of Primary Amides

Presenter : See Teck JiaWong Wei Leong

Amide ReductionAmides 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 hydrogenation.

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.

PREPARATION OF AMINE

HOFMANN DEGRADATION OF AMIDES

PRESENTERS:MAK YONG JING

VIGNESHRAAJ

HOFMANN DEGRADATION OF AMIDES

Definition

The Hofmann rearrangement is the organic reaction of a primary amide to a primary amine with one fewer carbon atom.

Mechanism

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

CONTINUE..

1) Removal of proton from amide N

2) Formation of N-Bromo amide

3) Removal of another proton from amide N

4) Rearrangement through Migration of aryl group

5) Hydrolysis of isocyanate intermediate

6) The formation of amine

R―NH2

Amine

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.

Applications of Hofmann degradation of amides

The End

A presentation from Group 13

See Teck J ia 1001025171Wong Wei Leong 1001025884Mak Yong J ing 1001025654Vigneshraa j 1001025877

Group 18Tan Ca i Yi ng 1001025965Zai nab Iqba l 1000923191Tyo Ann Ke i 1001025268Pr i sc i l l a Pang J i e -Yi 1001025675