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Amination by reduction involves synthesis of aminesby reductive method

Amines may be defined as derivative of ammonia,where one or more of the hydrogen are replaced by

alkyl, aryl, cycloalkyl or heterocyclic groups Amines can be produced by reducing nitro, nitroso,

hydroxylamine, azoxy, azo compounds, as well asoximes, amides, nitriles, and azides.

In each case a carbon to nitrogen bond already exists.

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Examples:

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Amines are divided into three classes primary,secondary, and tertiarydepending upon the number orreplaced hydrogen in the parent substance ammonia.

!rimary amines contain two remaining hydrogen atoms

attached to ammonia "econdary amines contain one #ertiary amines have none remaining

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!rimary amines: !rimary amines are those amine in which

one hydrogen of ammonia is replaced by organicgroup $aromatic or alkyl group$%&'((.

Methyl amine Aniline

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"E%)*+A- AI*E

"econdary amines are those amine in which twohydrogen of ammonia are replaced by organic

substituents $alkyl ,aryl or aromatic(.

Di-phenylamine

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#E#IA- AI*E:

In tertiary amines, all three hydrogen atoms are replaced byorganic substituents.

Examples include:

Trimethylamie

Triphenyl amine

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Amines occur as gases $methylamine(

Amines occur as li/uids $aniline(

Amines occur as solids $0nephthylamine(

Amines are basic $alkaline to litmus( In general amines form crystalline water soluble salts

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ubber chemicals *ylon !harmaceuticals 1asoline "urfactants #extile auxiliaries !hotographic chemicals "weetening agent Agriculture chemicals !olyurethane Ink plastics

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A great variety of reduction methods have been used for thepreparation of amines etal and acid

Iron and acid is the ma2or example in this category , but other metals $tin and zinccan also be employed. 1enerally hydrochloric acid is preferred , but sulfuric acid ,acetic and formic acid can also be used.

%atalytic Involve the use of hydrogen $ or hydrogen containing gases( and a catalyst sch as

nickel , copper , platinum , palladium or molybdinum sulfide

"ulfide 3sed only for partial reduction of polynitro aromatic compounds.

Electrolytic etal and alkali

used mainly for production of azoxy , azo and hydrozo compounds

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"odium hydrosulfide "ulfite$ piria method(

#he reaction of sodium sulfite and bisulfite on an aromatic nitrocompound leads to a mixture of amine and acid

etal hydrides

"trong caustic oxidation reduction &ydrogenated /uinolines and naphthalene Metal and acid reductions are most vigorous and usually

yield amine as end products.

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%hemical and physical factors

Amount of iron used

!hysical condition of iron

Amount of water used

Amount of acid used

Effect of agitation

eaction temperature

-ield of amine.

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%onsidering iron and acid reduction, which is

mostly used. Amount of iron used:

0. 3se 4 mole of 5e per mole of nitro compound4. 3se iron in finely divided form

'. Any impurities are source of contamination

6. "ome excess /uantity of iron used say 4.7 to 7

moles per mole of reactant

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Physical condition of iron0. %lean, finally divided, soft gray, cast iron yield best results4. #he rate of reduction depend on fineness and porosity of iron

particles. Amount of water used

0. *ormally 67 moles of water per mole of nitro compound is used4. "lightly excess is better'. 3nnecessary dilution not recommended. because it reduce catalyst

concentration.

Amount of acid used:0. #he acid usually employed in the reduction process are hydrochloric

acid and sulfuric acid4. hydrochloric acid causes formation of small amount of chlorinated

amines

'. sulfuric acid causes formation of darker amines and lower yield

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Effect of agitation:0. "ince reduction process is multiphase reaction, best results is obtained

with intimate contact

4. 8ith slow mixing iron settle down therefore a double impeller typestirrer is needed

Reaction temperature:0. "tudy shows the reduction process is exothermic.

4. It is necessary to remove surplus heat while maintaining the reductionat the optimum reaction temperature.

'. #o control temperature reflux condenser are used

Yield:0. 3pto 97;