Industrial and Laboratory Methods to Prepare Toluene

As a chemical distributor in Florida, some of our clients use toluene. Toluene is a clear, sweet-smelling liquid occurring naturally in pine oil. It is referred to as an aromatic hydrocarbon – a hydrocarbon with alternating double- and single-bonded rings. Toluene is used as a solvent and as a feed stock, a selected naphtha fraction. In the past, toluene (C6H5CH3) was manufactured primarily by distilling coke from coal. Recently dozens of new methods have been tested and proven worthy. While many approaches are specific to a manufacturer, others are utilized worldwide. Each process includes the final step of separating the isomers of benzene, xylene, and toluene via distillation or solvent extraction.

  • Fractional distillation - Crude oil consists of several components of different sizes, weights and boiling temperatures. To separate the components, use varied boiling points.

  • Azeotropic distillation – an azeotrope is two or more liquids that cannot be separated by simple distillation. Currently, two processes for separating toluene involve using an aqueous solution of methyl ethyl ketone and water, or using methanol.

  • Extractive distillation – A non-volatile substance is added to the components being separated to create an appreciable concentration of components.

  • Solvent extraction – A solvent with a high selectivity for aromatics that works in a reasonable temperature range, such as sulfur dioxide or aqueous diethylene glycol, works in a two-phase system to release toluene.

  • Reformation of naphtha in the presence of a catalyst (catalytic reforming method) - A mixture abundant in aromatic hydrocarbons is superheated and a catalyst is added, thereby dehydrogenizing the mixture. Light hydrocarbon gases are released and toluene is extracted from the center of the core.

  • Steam cracking of liquid hydrocarbons – Steam cracking occurs when larger hydrocarbons are broken down into smaller components. Naphtha, or flammable hydrocarbon molecules, contains copious amounts of aromatic compounds. Both pyrolysis gasoline and toluene are derived from steam cracking naphtha.

  • Friedel-Crafts reaction – Methyl chloride and anhydrous aluminum chloride react; benzene is added as the raw material to produce toluene.

  • Wurtz-Frittig reaction – Bromebenzene and methyl bromide react in the presence of sodium metal in a dry ether solution to produce toluene.

  • Decarboxilation reaction – Soda lime and sodium toluate are heated in a decarboxylation reaction.

  • Distillation of cresol and zinc dust – Cresol, distilled in the presence of zinc, produces toluene.

Toluene is a useful solvent in a variety of applications, including as a fuel additive to increase octane ratings, manufacturing cosmetics, as a solvent in cleaning agents and adhesives, manufacturing dyes in inks, and manufacturing polymers for plastic bottles and polyurethane. With its myriad uses and forms of manufacture, toluene will surely be a chemical used for years to come. Contact your chemical distributor in Florida Bell Chem today to find how easy it is for your company to order toluene.