Synthesis of benzidine (4,4′-diaminobiphenyl)

Preparation of benzidine

Preparation of benzidine (4,4'-diaminobiphenyl)

Preparation of benzidine (4,4′-diaminobiphenyl)

105 g of sodium hydroxide are dissolved in 300 ml of water. To this solution a mixture of 50 ml methanol, and 100 g of nitrobenzene are added. The reaction flask is fitted with a reflux condenser and the zinc dust, which must have been passed through a fine sieve, is added in small portions. It is very important that the reaction flask should be thoroughly well stirred after each addition portion of zinc, and, indeed, throughout the experiment. After addition of zinc dust a vigorous reaction take places and the mixture boils. The mixture is kept boiling by successive additions of zinc. Quick addition of zinc dust should be avoided in order to prevent foaming. The brown color gradually disappears, and when the reduction is complete the contents of the flask should appear grayish white. If this effect is not produced at this stage, additional portion of zinc dust may be added, and the flask heated till reduction is complete. The reaction mixture is cooled, diluted with distilled water, ice added, and the reaction mixture carefully acidified with hydrochloric acid, not allowing the temperature to rise above 15° C. The hydrazobenzene separates out in crusts, which are easily separated from the liquid, and any zinc remaining undissolved is separated by pouring the reaction mixture through a porcelain funnel without paper. The separated hydrazobenzene is additionally washed with water. Then hydrazobenzene is converted into benzidine by boiling with 300-400 ml of water and adding concentrated hydrochloric acid gradually as long as HCl is absorbed. Finally, the hydrochloric acid solution is allowed to boil for a few minutes longer and the solution of benzidine hydrochloride is filtered. To the filtrate sulfuric acid is added, to precipitate the benzidine as sulfate. This is filtered, washed, and boiled with dilute NaOH solution. The solution of the benzidine base is filtered, and the benzidine crystallizes out on cooling, which is filtered, and dried yielding 20-30 g of final product. Further purification is performed by crystallizing from hot water. Benzidine crystallizes from hot water in large silky plates which melt at 122° C.

The Synthetic Dyestuffs and the Intermediate Products from which They are Derived, by J. C. Cain, 208-209, 1905





InChI Key


Canonical SMILES


MeSH Synonyms

benzidine, benzidine acetate, benzidine dihydrochloride, benzidine hydrochloride, benzidine monosulfate

Depositor-Supplied Synonyms

BENZIDINE, 92-87-5, 4,4′-Diaminobiphenyl, biphenyl-4,4′-diamine, p-Diaminodiphenyl, 4,4′-Bianiline, Benzidin, Benzidina, Benzydyna, p,p’-Diaminobiphenyl, Fast Corinth Base B, 4,4′-Biphenyldiamine, 4,4′-Diaminodiphenyl, p,p-Bianiline, p,p’-Dianiline, 4,4′-Biphenylenediamine, 4,4′-Diphenylenediamine, 4-(4-aminophenyl)aniline, [1,1′-Biphenyl]-4,4′-diamine, Benzioine, Benzidine base, p-Benzidine, C.I. Azoic Diazo Component 112, p,p’-Bianiline, RCRA waste number U021, Benzidin [Czech], Benzydyna [Polish], Benzidina [Italian], 4,4′-Diamino-1,1′-biphenyl, 1,1′-Biphenyl-4,4′-Diamine, NCI-C03361, Benzidine (and its salts), RCRA waste no. U021, NSC 146476, Biphenyl, 4,4′-diamino-, CCRIS 71, HSDB 948, CI Azoic diazo component 112, C.I. 37225, CHEBI:80495, HFACYLZERDEVSX-UHFFFAOYSA-N, (1,1′-Biphenyl)-4,4′-diamine, EINECS 202-199-1, UN1885, BRN 0742770, CI 37225, AI3-00140, DSSTox_CID_137, DSSTox_RID_75390, DSSTox_GSID_20137, 4-(4-aminophenyl)phenylamine, CAS-92-87-5, Bensidine, di-phenylamine, [1,1′-Biphenyl]-4,4′-diamine, hydrochloride (1:2), [1,4′-diamine, Biphenyl,4′-diamino-, 4.4′- diaminobiphenyl, Biphenyl,4,4′-diamino-, WLN: ZR DR DZ, Oprea1_312205, SCHEMBL29021, biphenyl -4,4′-ylenediamine, MLS002303016, 48504_SUPELCO, ARONIS24425, B1883_SIGMA, B3503_SIGMA, BIDD:GT0832, CHEMBL15901, UNII-2X02101HVF, 531-86-2 (monosulfate), 46080_RIEDEL, AC1L1O17, IFLab1_004231, BIPHENYL,4,4′-DIAMINO, STOCK6S-90151, 12115_FLUKA, CTK3I6733, Benzidine [UN1885] [Poison], 21136-70-9 (sulfate), 531-85-1 (di-hydrochloride), MolPort-000-630-151, 14414-68-7 (hydrochloride), 2X02101HVF, HMS3091M16, Benzidine [UN1885] [Poison], [4-(4-aminophenyl)-phenyl]-amine, ALBB-005944, Tox21_202359, Tox21_300405, ANW-44091, BBL013163, KM3148, NSC146476, SBB060240, STK317796, ZINC00265747, 36341-27-2 (unspecified acetate), AKOS000118878, AKOS016402822, CCG-202856, LS-1939, MCULE-2044272330, NSC-146476, UN 1885, IDI1_009986, NCGC00091340-01, NCGC00091340-02, NCGC00091340-03, NCGC00254474-01, NCGC00259908-01, 4′-Amino[1,1′-biphenyl]-4-ylamine #, AJ-18574, AK-46852, AN-42627, AN-45628, BC676915, CJ-02628, SC-65115, SMR000033596, T991, ZB009977, DB-057341, TC-132836, B0045, ST24046012, ST45137851, C16444, 4-13-00-00364 (Beilstein Handbook Reference), A844372, AC-907/25014310, I14-6066, 3B3-019366, BENZIDINE (SEE ALSO BENZIDINEDIHYDROCHLORIDE 531-85-1), 46310-07-0, 56481-94-8, InChI=1/C12H12N2/c13-11-5-1-9(2-6-11)10-3-7-12(14)8-4-10/h1-8H,13-14H

Removed Synonyms

Diphenylamine, Benzidine acetate, benzidine monosulfate, BENZIDINE DIHYDROCHLORIDE, Benzidine hydrochloride, CID7111, C029876, 531-85-1, 14414-68-7

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