Nitrobenzene is an organic compound with the chemical formula C6H5NO2. Nitrobenzene is a water-insoluble pale yellow oil with an almond-like odor. It freezes to give greenish-yellow crystals. Although occasionally used as a flavoring or perfume additive, nitrobenzene is highly toxic in large quantities and is mainly produced as a precursor to aniline. In the laboratory, it is occasionally used as a solvent, especially for electrophilic reagents.