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IUPAC name
Other names
o-Tolidine; Orthotolidine; Diaminoditolyl; Diaminotolyl; Bianisidine; Tolidine blue; 3,3'-Dimethylbenzidine; 4,4'-Bi-o-toluidine
119-93-7 YesY
Jmol-3D images Image
KEGG C14443 YesY
PubChem 8413
Molar mass 212.29 g·mol−1
Density 1.23 g/cm3
Melting point 129 °C (264 °F; 402 K)
Boiling point 300.5 °C (572.9 °F; 573.6 K)
1.3 g/L
Main hazards potential carcinogen[2]
R-phrases R45 R22 R51/53
S-phrases S53 S45 S61
Flash point 244 °C (471 °F; 517 K)
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

2-Tolidine (o-tolidine) is an organic compound with the chemical formula (C6H4(CH3)NH2)2. Several isomers are known; the 3-tolidine derivative is also important commercially. It is a colorless compound although commercial samples are often colored. It is slightly soluble in water. It forms salts with acids, such as the hydrochloride, which is commercially available.

2-Tolidine can be produced by a benzidine rearrangement from a hydrazine derivative derived from 2-nitrotoluene.[3]

(CH3C6H4)2N2H2 → (C6H3(CH3)NH2)2


2-Tolidine is a commercially important aromatic amine used mainly for dye production.[4]

Pigment Yellow 16, a derivative of o-tolidine

It has also for the production of certain elastomers. 2-Tolidine is an intermediate for the production of soluble azo dyes and insoluble pigments used particularly in the textile, leather and paper industries. 2-Tolidine was widely used as a reagent or indicator in analytical, clinical and forensic chemistry, such as in the analytical determination of gold.


2-Tolidine is toxic and possibly carcinogenic. It is listed as an IARC Group 2B carcinogen, meaning it is "possibly carcinogenic to humans". Animal studies have shown that animals exposed to tolidine developed tumors in the liver, kidney, and mammary glands.[5]


  1. ^ Record of ortho-Tolidin in the GESTIS Substance Database of the IFA, accessed on 6.6.2008
  2. ^ "NIOSH Pocket Guide to Chemical Hazards #0618". National Institute for Occupational Safety and Health (NIOSH). 
  3. ^ Noller, Carl R.: Textbook of Organic Chemistry, Springer Verlag, 1960
  4. ^ K. Hunger. W. Herbst "Pigments, Organic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2012. doi:10.1002/14356007.a20_371
  5. ^ CDC - NIOSH Pocket Guide to Chemical Hazards