Toluene is a colorless, water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a CH3 group attached to a phenyl group. Toluene is a very good solvent because, unlike water, it can dissolve many organic compounds. In many commercial products, toluene is used as a solvent that is present in paint thinners, nail polish remover, glues, and correction fluid.