Toluene (or toluol) is an organic aromatic solvent found in paint and some degreasing products. Toluene is a colorless liquid with a benzene-like odor and a flash point below 73 F (class 1B flammable). Toluene can enter the body through inhalation and exposure to high airborne concentrations and can cause neurological impairment similar to intoxication. Skin absorption is another way toluene can enter the body. Toluene will dissolve fats and oils in the skin to produce drying and cracking. All operations involving the use of toluene shall be performed outdoors whenever possible. In all cases, the use of toluene will require proper ventilation, including exhaust systems as appropriate for indoor exposures.
Toluene shall not be used for cleaning equipment except where essential to pavement marking and sign shop operations.
- The main chemical use of toluene is to make benzene and xylenes using a number of technologies. In the hydrodealkylation (HDA) process, toluene and hydrogen are reacted to make benzene only. A toluene disproportionation (TDP) plant will convert toluene to benzene and xylenes while there are selective toluene disproportionation (STDP) processes that produce a paraxylene-rich stream. The transalkylation (TA) process takes toluene and C9 aromatics to produce xylenes.
- Toluene is also used as a solvent but this application is expected to continue to weaken because of environmental and health regulations restricting solvent emissions. The definition of solvent end use and quality varies around the world. In most industrialised countries, solvent grade toluene is a high quality stream where purity is essential as environmental exposure levels must be quantified.
- Toluene is consumed in the manufacture of toluene diisocyanate (TDI) which is used in the manufacture of polyurethane flexible foams used in upholstery, mattresses and automotive seats. Smaller uses for TDI include polyurethane elastomers and coatings.
- Other minor chemical uses include the manufacture of phenol, caprolactam, nitrobenzene, benzoic acid and benzyl chloride.
- In non-chemical uses, toluene is used in large quantities as an octane booster in gasoline but most of that portion is not removed from refinery streams