2,4-Dinitrochlorobenzene

2,4-Dinitrochlorobenzene (DNCB) is an organic compound with the chemical formula (O₂N)₂C₆H₃Cl. It is a yellow solid that is soluble in organic solvents. It is an intermediate for the industrial production of other compounds.^[2]

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.^[3]

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.^[4][5][6]

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

DNCB is as a substrate in glutathione S-transferase, relevant to activity assays.^[7]

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.^[8]

DNCB can cause contact dermatitis.^[9]