3,3'-Dichlorobenzidine

3,3'-Dichlorobenzidine[1]
Names
Preferred IUPAC name
3,3′-Dichloro[1,1′-biphenyl]-4,4′-diamine
Other names
4-(4-Amino-3-chlorophenyl)-2-chloroaniline
4,4′-Diamino-3,3′-dichlorobiphenyl
o,o'-Dichlorobenzidine
3,3′-Dichlorobiphenyl-4,4′-diamine
3,3′-Dichloro-4,4′-biphenyldiamine
3,3′-Dichloro-4,4′-diaminobiphenyl
Identifiers
CAS Number
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.001.918
KEGG
PubChem CID
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C12H10Cl2N2/c13-9-5-7(1-3-11(9)15)8-2-4-12(16)10(14)6-8/h1-6H,15-16H2 checkY
    Key: HUWXDEQWWKGHRV-UHFFFAOYSA-N checkY
  • InChI=1/C12H10Cl2N2/c13-9-5-7(1-3-11(9)15)8-2-4-12(16)10(14)6-8/h1-6H,15-16H2
    Key: HUWXDEQWWKGHRV-UHFFFAOYAF
SMILES
  • Clc2cc(c1ccc(N)c(Cl)c1)ccc2N
Properties
Chemical formula
 C12H10Cl2N2
Molar mass 253.13 g/mol
Appearance Gray or purple crystalline solid
Melting point 132 to 133 °C (270 to 271 °F; 405 to 406 K)
Boiling point 402 °C (756 °F; 675 K)
Solubility in water
 0.07% (15°C)[2]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Potential carcinogen[2]
NIOSH (US health exposure limits):
PEL (Permissible)
 carcinogen[2]
REL (Recommended)
 Ca[2]
IDLH (Immediate danger)
 Ca [N.D.][2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)
Infobox references

3,3'-Dichlorobenzidine is a chlorinated aromatic amine derived from benzidine. It is widely used in the production of diarylide yellow pigments used in the production of printing inks.[3] Its use in the production of dyes has been largely discontinued because of concerns about carcinogenicity.

Properties and the market

3,3'-Dichlorobenzidine is a crystalline solid soluble in alcohol, benzene, diethyl ether, and glacial acetic acid, but difficultly soluble in dilute hydrochloric acid and water.[4] It exists in gray-to-purple needle-like crystals.[4] Commercial powder samples may also be light-brown or violet.[5]

This compound is often confused with its dihydrochloride salt, even in scientific literature.[4] 3,3'-Dichlorobenzidine dihydrochloride is sparingly soluble in water and readily soluble in alcohol. It is marketed in the form of a colorless to pale gray crystalline powder. Both the commercial 3,3'-dichlorobenzidine and its hydrochloride usually contain 5 to 30% of water.[5]

The so-called urethane quality 3,3'-dichlorobenzidine is anhydrous and free of hydrochloric acid.[5] However, some sources dispute the very existence of the free base on the market and believe the dihydrochloride salt to be the only form available commercially.[4]

Preparation and reactions

3,3'-Dichlorobenzidine is prepared in two steps from 2-nitrochlorobenzene. The first step involves reduction with zinc in base to afford 2,2'-dichlorodiphenylhydrazine. This intermediate undergoes the benzidine rearrangement to afford 3,3'-dichlorobenzidine.[5]

Aqueous solutions of 3,3'-dichlorobenzidine degrade in light to monochloro derivative. It undergoes chlorination (for example in water treatment plants) to give the tetrachloro derivative.

The most widely practiced reaction of 3,3'-dichlorobenzidine is its double diazotization. This bis(diazo) intermediate is then coupled to derivatives of acetoacetylaminobenzene (CH3C(O)CH2C(O)NHAr). In this way, the diarylide commercial yellow pigments are produced: Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Orange 13, Pigment Yellow 81, and Pigment Yellow 83.[3]

Structure of Pigment Yellow 12, which is derived from dichlorobenzidine.[6]

Safety

3,3'-Dichlorobenzidine is considered a carcinogen.[1] This compound has been shown to increase the incidence of tumors in animals.[7] Because it is structurally similar to benzidine, a known carcinogen, it is believed that it may share a similar mechanism in causing bladder cancer in humans.[7]

References

  1. ^ a b Dichlorobenzidine - Compound Summary, PubChem.
  2. ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0191". National Institute for Occupational Safety and Health (NIOSH).
  3. ^ a b K. Hunger; W. Herbst (2012). "Pigments, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a20_371. ISBN 9783527303854.
  4. ^ a b c d "3,3′-Dichlorobenzidine and Its Dihydrochloride" (PDF). National Toxicology Program, Department of Health and Human Services. Retrieved 6 December 2025.
  5. ^ a b c d Schwenecke, H.; Mayer, D. (2005). "Benzidine and Benzidine Derivatives". Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_539. ISBN 9783527303854.
  6. ^ Barrow, Michael J.; Christie, Robert M.; Lough, Alan J.; Monteith, Jean E.; Standring, Paul N. (2000). "The Crystal Structure of C.I. Pigment Yellow 12". Dyes and Pigments. 45 (2): 153–160. doi:10.1016/S0143-7208(00)00017-6.
  7. ^ a b "3, 3'-Dichlorobenzidine". U.S. Environmental Protection Agency, Integrated Risk Information System. 7 March 2011. Accessed 3 May 2011.
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