2-Nitrochlorobenzene is an organic compound with the formula ClC₆H₄NO₂. It is one of three isomeric nitrochlorobenzenes.^[1] It is a yellow crystalline solid that is important as a precursor to other compounds due to its two functional groups.

Nitrochlorobenzene is typically synthesized by nitration of chlorobenzene in the presence of sulfuric acid:

C₆H₅Cl + HNO₃ → O₂NC₆H₄Cl + H₂O

This reaction affords a mixture of isomers. Using an acid ratio of 30% nitric acid, 56% sulfuric acid and 14% water, the product mix is typically 34-36% 2-nitrochlorobenzene and 63-65% 4-nitrochlorobenzene, with only about 1% 3-nitrochlorobenzene.^[1]

2-Nitrochlorobenzene can be reduced to the 2-chloroaniline with Fe/HCl mixture, the Bechamp reduction.^[1]

2-Nitrochlorobenzene, like its isomers, is reactive toward nucleophiles, resulting in chloride substitution. With polysulfide, it reacts to give di-orthonitrophenyl disulfide:^[2]

2 O₂NC₆H₄Cl + Na₂S₂ → (O₂NC₆H₄S)₂ + 2 NaCl

Similarly, it reacts with sodium methoxide to give 2-nitroanisole.

Substitution of chloride by fluoride is also practiced commercially to convert 2-nitrochlorobenzene to 2-fluoronitrobenzene. The Halex process uses potassium fluoride in polar solvents like sulfolane :

O₂NC₆H₄Cl + KF → O₂NC₆H₄F + KCl

2-Nitrochlorobenzene is useful because both of its reactive sites can be utilized to create further compounds that are mutually ortho. Its derivative 2-chloroaniline is a precursor to 3,3’-dichlorobenzidine, a precursor to dyes and pesticides.