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(organic chemistry)
NH2C6H4C6H4NH2 An aromatic amine with a melting point of 128°C; used as an intermediate in syntheses of direct dyes for cotton.



4,4’-diaminodiphenyl, an organic compound.

Clear, lustrous crystals that darken in air and under the influence of light because of oxidation. Melting point Tm= 128° C; boiling point Tb = 400°C. It is readily soluble in alcohol and ether; it is an aromatic diamine. It forms salts with solutions of organic and inorganic acids—for example, with HC1, a dichlorhydrate, and with H2 SO4, a monosulfate. Benzidine is obtained by the isomerization of hydrazobenzene under the action of mineral acids. Benzidine was first obtained by this method by N. N. Zinin in 1845. It is an important intermediate product in the production of azo dyes. It is also widely used in analytical chemistry for the qualitative and quantitative determination of various cations and anions that oxidize benzidine to colored compounds (to yellow in a strongly acidic medium and blue in a neutral medium). Benzidine is a carcinogenic substance; its maximum permissible concentration in air is 1 mg/m3.

References in periodicals archive ?
To assess the two screening tests, the researchers periodically obtained urine samples between 1991 and 1997 from 1,788 Chinese men and women who had worked with benzidine dyes in clothing factories during the 1970s.
Chemical Common exposure sources 1,3-Butadiene Gasoline, vehicle exhaust, tobacco smoke, heating of some cooking oils Acrylamide Cooked food, tobacco smoke, water-treatment by-products, some consumer products Aromatic amines I: Uncured or newly finished polyurethane foam, TDA and TDIs spray-in insulation, sealants and coatings, some breast implants Aromatic amines II: Hair and textile dyes; used in the production benzidine and of paints, printing inks, liquid crystal aniline dyes, displays, and inkjet and laser printers, and combustion products, in the food industry other Benzene Gasoline, vehicle exhaust, tobacco smoke, solvents Halogenated organic Dry cleaning, spot remover, glues, degreasers, solvents (e.
Of these workers, 514 (21%) men and 287 (13%) women were exposed to [beta]-naphthylamine or benzidine.
Diamino benzidine was the substrate developed as a chromogen.
Patent Number 5,153,222, titled "Method of Treating Pulmonary Hypertension with Benzidine Prostaglandins," was originally scheduled to expire on October 6, 2009.
Pyromellitic dianhydride (PMDA) and benzidine (BZD) are also commercially available, and were used as received.
2] treatment was installed at the Bofors Nobel Superfund Site, located near Muskegon, MI (USA), for the decomposition of hazardous wastewaters containing benzene, toluene, chlorobenzene, tetrachloroethane, benzidine, etc.
This test is based diazotized benzidine derivatives with pinocembrin, pinobanksin, pinosylvin and pinosylvin monomethyl ether, phenolic constituents in the pine heartwood.
cyclophosphamide, benzo(a)pyrene, and benzidine in male, female, pregnant female, and fetal mice.
1 followed by horseradish peroxidase-conjugated streptavidin (GE Healthcare) and 3,3',5,5'-tetramethyl benzidine (Kirkegaard & Perry Laboratories) as the substrate.
After similar washing, a tetra-methyl benzidine substrate (Zymed Laboratories, San Francisco, CA) was added and incubated for 15 min at room temperature.
The poly(amic acid) (PAA) was prepared by combining pyromellitic dianhydride (PMDA) and benzidine in DMAc at room temperature [19].