Chemistry, asked by taran8270, 1 year ago

What would be the product formed on reduction of cyano benzene.

Answers

Answered by kuruvillabc
0

Catalytic hydrogenation

The catalytic hydrogenation of nitriles is often the most economical route available for the production of primary amines.[3] Catalysts for the reaction often include group 10 metals such as Raney nickel,[4][5][6] palladium black, or platinum dioxide.[1] However, other catalysts, such as cobalt boride, also can be selective for primary amine production:

R-C≡N + 2 H2 → R-CH2NH2

A commercial application of this technology includes the production of hexamethylenediamine from adiponitrile, a precursor to Nylon 66.[7]

Depending on reaction conditions, intermediate imines can also undergo attack by amine products to afford secondary and tertiary amines:

2 R-C≡N + 4 H2 → (R-CH2)2NH + NH3

3 R-C≡N + 6 H2 → (R-CH2)3N + 2 NH3

Such reactions proceed via enamine intermediates.[8] The most important reaction condition for selective primary amine production is catalyst choice.[1] Other important factors include solvent choice, solution pH, steric effects, temperature, and the pressure of hydrogen.

Stoichiometric reductions

Reducing agents for the non-catalytic conversion to amines include lithium aluminium hydride, lithium borohydride,[9] diborane,[10] or elemental sodium in alcohol solvents.[11]

To aldehydes

Nitriles can also be reduced to aldehydes. The Stephen aldehyde synthesis uses Tin(II) chloride and hydrochloric acid to yield an aldehyde via the hydrolysis of a resulting iminum salt. Aldehydes can also form using a hydrogen donor followed by in-situ hydrolysis of an imine. Useful reagents for this reaction include formic acid with a hydrogenation catalysis[12] or metal hydrides which are used to add one mol of hydrogen to the nitrile. For example, sodium borohydride reduces nitriles in alcoholic solvents with a CoCl2 catalyst or Raney nickel.[13] Reducing agent Diisobutylaluminium hydride, or DIBAL-H, is another commonly used metal hydride. DIBAL-H acts as a proton source, adding a hydride ion to the carbon of the nitrile. The resulting imine is a relatively stable intermediate that can be hydrolzed to the aldehyde.[14]

Mechanism

The mechanism for the reduction of a nitrile to an aldehyde with DIBAL-H.

DIBAL-H is added in controlled amounts at low temperatures to achieve partial reduction of the nitrile.[15] The aluminum atom in DIBAL acts as a Lewis acid, accepting an electron pair from the nitrile. The nitrile is then reduced by the transfer of a hydride ion to the carbon of the carbon-nitrile triple bond, producing an imine. After a workup with water, the aluminum complex is hydrolyzed to produce the desired aldehyde.[16] Because the hydrolytic workup generates the aldehyde at the end, the nitrile does not undergo over-reduction.

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