Toluene or methylbenzene is a clear, water-insoluble organic liquid, used as paint thinner and organic solvent. It is an aromatic hydrocarbon.
The methyl group makes toluene around 25 times more reactive than benzene in electrophilic aromatic substitutions. The addition of a halogen in the presence of UV light will yield benzyl halides. Reaction with potassium permanganate yields benzoic acid.
Toluene is liquid at standard conditions, with a characteristic sweet, solvent-like smell. It is less dense than water, with a density of 0.87 g/mL. Toluene melts at -95 °C and boils at 111 °C. It is insoluble in water, but miscible with many organic solvents. Toluene exhibits iridescence.
Toluene is available at hardware as paint thinner, sometimes mixed with other hydrocarbons, depending on the product. Fractional distillation can be used to distill the components.
There are a few ways to prepare toluene. One method involves the methylation of benzene with a methyl halide, such as methyl chloride in the presence of anhydrous aluminium chloride. Since toluene is less toxic than benzene, this is a good way, albeit consuming, to eliminate benzene.
Toluene vapors can cause headaches, dizziness, nausea, so work should be performed in a fume hood or outside. Toluene is less toxic and carcinogenic than benzene, meaning it can be used as a substitute for benzene as a solvent.
Toluene is less volatile than other hydrocarbons, but due to its strong smell it's best to store it in closed bottles, and kept in a solvent cabinet.
Burning toluene will release soot, so it's best to dispose of it using Fenton's reagent.