Synthesis of Dipheny or Biphenyl | Dr. Bharat Baria
In this video, I have discussed six different methods for the synthesis of Diphenyl which are as follow.
1) By Fitting reaction (1863): Diphenyl is synthesized by treatment of bromobenzene and sodium in dry ethereal solution.
2) From Aryl Magnesium Halide: Another example of Fitting reaction includes reaction between phenylmagnesiumbromide and bromobenzene in presence of small amount of metal halides like CoCl2, NiCl2, FeCl3 etc. to give diphenyl.
3) By Ullman reaction (1903): Aryl Iodides are heated with copper powder in a sealed tube, to give diphenyl in about 80 %.
4) By Busch’s Method (1936): (Reaction between Bromobenzene and hydrazine)
Biphenyl is prepared by refluxing an alkaline ethanolic solution of bromobenzene with hydrazine in the presence of palladium catalyst on CaCO3 support.
5) From Diazonium salt: Diazotization reaction of aniline and NaNO2 in the presence of H2SO4 forms benzenediazonium hydrogensulphate which on warming with ethanol in presence of copper powder gives diphenyl.
Furthermore, diphenyl is also obtained from benzidine. Benzidine is diazotized with NaNO2 & hydrochloric acid, to form diazonium salt which on treatment with hypophosphorous acid (H3PO2) yields diphenyl.
6) From benzene: On a large scale, diphenyl is prepared by passing benzene vapours in presence of moisture through a red hot Iron tube (1000-1100 °C) packed with pumice. This reaction is inter-molecular dehydrogenation reaction proceeds through free radical mechanism.
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