Toluene, which is also known as toluol, is a colourless solution which smells a little like paint thinner. Its main uses are as a raw material for industry, and as a solvent – it can dissolve paint, rubber, ink, and adhesives. But how is toluene made?
How is Toluene Made?
Low levels of toluene are found in crude oil, and naturally in the tolu tree. It is a by-product of coke from coke, and of gasoline production with a catalytic reformer or steam cracker. Small quantities of toluene are also a by-product of styrene manufacture.
Making Toluene Through Catalytic Reforming
Toluene is made through catalytic reforming by passing a hydrocarbon mixture over a dehydrogenation catalyst. Hydrocarbon gases are removed, and an aromatic-rich fraction is obtained from the reformate. Toluene is then produced through distillation or solvent extraction (which is the more usual method). It is also possible to produce benzene and xylene isomers through solvent extraction or distillation at different stages of the process.
Making Toluene Through A Steam Cracker
Increasingly, toluene is made by a process of steam cracking liquid hydrocarbons such as naphtha and gas oil. The hydrocarbon being used must be hydrogenated before extracting the toluene as it is unstable.
Making Toluene In The Lab
Making toluene in the lab is very expensive but it can be done in a student demonstration, for example. Toluene can be synthesised by mixing methyl chloride and benzene in the presence of aluminium chloride or other Lewis acid.
What Is Toluene Used For?
Toluene has many uses, especially as an effective solvent. It also has a variety of applications in the lab, as well as various industrial uses.
- Solvent: Toluene is a common solvent in paint, thinners, adhesives, and nail polish, as well as numerous other products.
- Fuel: Toluene, along with benzene and xylene, acts as an octane booster for internal combustion engines when added to gasoline.
- In the lab: You can use toluene to make carbon nanomaterials
- Polystyrene kits: Toluene is used as a fine cement for polystyrene kits
- Coolant: As it has good heat transfer properties, toluene has been used as a coolant in nuclear reactors
- Cocaine extraction: Toluene is used to remove cocaine from coca leaves, in order for the leaves to be used to make fizzy drinks
The Toxicology of Toluene
We can all be exposed to toluene in small amounts, especially in vehicle-heavy areas or when using paint or nail polish.
Inhaling toluene, especially on a regular basis, can cause you to feel tired and weak – it almost feels similar to drinking too much alcohol as you can become confused, forgetful and nauseated. Whether or not toluene does this to you depends how much you inhale, over how long a period, and how many times you are exposed.