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IUPAC name 4,4'-diaminobiphenyl
Other names Benzidine
Molecular formula C12H12N2
Molar mass 184.25
CAS number 92-87-5
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Benzidine is the trivial name for 4,4'-diaminobiphenyl, a carcinogenic aromatic amine which has been used as part of a test for cyanide and also in the synthesis of dyes. It has been linked to bladder cancer and pancreatic cancer.

In common with benzidine some other aromatic amines such as 2-aminonaphthalene have been withdrawn from use in almost all industries because they are so carcinogenic.

In the past a common test for blood used benzidine but this has largely been replaced by tests using phenolphthalein / hydrogen peroxide and luminol. An enzyme in blood causes the benzidine to be oxidized to a polymer which is blue coloured. The test for cyanide uses similar chemistry to give the blue colour.

Benzidine is a known human carcinogen. [1]

Benzidine rearrangement

In a classic rearrangement reaction called the benzidine rearrangement benzidine is formed by reaction of the 1,2-diphenylhydrazine (PhNHNHPh) with acids. One plausible reaction mechanism has both hydrazine nitrogen atoms protonated after which a sigmatropic reaction takes place [2].


  1. ^ Link
  2. ^ Advanced Organic Chemistry third edition Jerry March ISBN 047185472-7
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Benzidine". A list of authors is available in Wikipedia.
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