Oxidation of methylbenzene (toluene)

One way to avoid the over-production of propanone associated with the cumene oxidation process, is to use a different reaction to produce phenol. About 5% of phenol is produced using the oxidation of methylbenzene (toluene), a process sometimes called the Dow and California Research Process.

This is a two-step process
diagram: methylbenzene to benzoic acid to phenol

The advantage of the oxidation of methylbenzene is that it produces no propanone co-product and also very few impurities. It has a high theoretical atom economy, a high yield, and produced far less waste than the cumene oxidation process.

At present, however, the process is up to 3 to 4 times more energy intensive than the cumene oxidation process, and so it is not widely used.

Atom Economy

The balanced equation for the process is:

This process has an atom economy of 60.1% if phenol is the only useful product, which is a further improvement on the previous processes.

The fact that this process is not widely used reflects the fact that atom economy is, however, only one of many factors that must be taken into account.

diagram: comparison of waste generated

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