Phenol from Benzoic Acid

The action of a copper salt converts benzoic acid to phenol. The copper, reoxidized by air, functions as a real catalyst. The Lummus process operates in the vapor phase at approximately 250°C. Phenol yield of 90% is possible:

In the Lummus process (Figure 1.1), the reaction occurs in the liquid phase at approximately 220–240°C over Mg²⁺ + Cu²⁺ benzoate.

Figure 1.1. The Lummus benzoic-acid-to-phenol process.

Magnesium benzoate is an initiator, with the Cu²⁺ reduced to Cu¹⁺. The copper (1) ions are reoxidized to copper (II) ions.