Toluene

Toluene, also known as methylbenzene, is an aromatic hydrocarbon with the formula C7H8. It is a colorless, highly flammable liquid with a sweet, distinctive odor. Toluene is soluble in many organic solvents but has limited solubility in water. It is classified as a volatile organic compound released by various industrial processes and, to a lesser extent, natural sources.

Industrially, toluene is produced chiefly as part of the BTX aromatics stream obtained in petroleum refining. It is also found in trace amounts in crude oil and in emissions from volcanic activity. In refinery processes, toluene is recovered from streams that also contain benzene and xylenes and is distributed for a range of downstream uses.

Major uses of toluene include its role as a versatile solvent for paints, coatings, inks, adhesives, and degreasers. It is a key feedstock for the production of benzene derivatives such as toluene diisocyanate, which is used to make polyurethane foams, as well as benzoic acid and various alkylated aromatics. Historically, toluene has been nitrated to form nitro compounds including TNT, reflecting its role in the development of energetic materials.

Safety and environmental considerations: toluene is flammable, and its vapors can form explosive mixtures with air. Acute exposure can affect the central nervous system, causing headaches, dizziness, and confusion; long-term exposure may impact liver and kidney function. It is regulated with occupational exposure limits by many authorities. Environmentally, toluene is a VOC that can volatilize from air, water, and soil; it is typically biodegradable and subject to treatment in air and water systems, but spills should be contained to limit ecological impact.