2,4-Dinitrochlorobenzene

Preparation and reactions

DNCB is produced commercially by the nitration of p-nitrochlorobenzene with a mixture of nitric and sulfuric acids. Other methods afford the compound less efficiently include the chlorination of 1,3-dinitrobenzene, nitration of o-nitrochlorobenzene and the dinitration of chlorobenzene.

By virtue of the two nitro substituents, the chloride in DNCB is particularly susceptible to nucleophilic substitution, at least relative to simple chlorobenzene. In this way, the compound is a precursor to many other compounds. For example, the chloride can be replaced by iodide easily.

Reaction of DNCB with ammonia gives 2,4-dinitrochloroaniline, again a versatile precursor.

DNCB is as a substrate in glutathione S-transferase, relevant to activity assays.

Safety

DNCB induces a type IV hypersensitivity reaction in almost all people exposed to it, so it is used medically to assess the T cell activity in patients. This is a useful diagnostic test for immunocompromised patients. It can also be used to treat warts.

DNCB can cause contact dermatitis.

References

References

1. "1-Chloro-2,4-dinitrobenzene".
2. Gerald Booth. (2007). "Nitro Compounds, Aromatic". Wiley-VCH.
3. "Synthesis of 1-chloro-2,4-dinitrobenzene - F. Ullmann, Verlag S. Hirzel Leipzig, 1908".
4. J. F. Bunnett, R. M. Conner. (1960). "2,4-Dinitroiodobenzene". Organic Syntheses.
5. F. B. Wells, C. F. H. Allen. (1935). "2,4-Dinitroaniline". Organic Syntheses.
6. Norman Kharasch, Robert B. Langford. (1964). "2,4-Dinitrobenzenesulfenyl Chloride". Organic Syntheses.
7. (1974). "Glutathione S-transferases. The first enzymatic step in mercapturic acid formation". J Biol Chem.
8. "Treating warts". Harvard Medical School.
9. (1986). "The effect of altering area of application and dose per unit area on sensitization by DNCB". Br. J. Dermatol..