GB824631A - Production of phenols from aromatic carboxylic acids - Google Patents

Abstract

A process for preparing phenolic compounds comprises bringing a monocarboxylic acid of the benzene series in which the carboxyl group is attached to the ring and where there is at least one unsubstituted position ortho to the carboxyl group on the ring and where any other substituents are substantially inert to the oxidizing action of cupric oxide and are selected from phenyl, alkyl, alkoxy, nitro and halogen, into contact with an oxidizing agent consisting essentially of cupric oxide under atmospheric or superatmospheric pressure at a temperature of at least 200 DEG C. but below a temperature at which destructive carbonization takes place and in the absence of elemental oxygen, until oxidation and decarboxylation of the acid has occurred, if necessary releasing the pressure and finally recovering the so-produced free phenol from the reaction medium. An oxidation and decarboxylation reaction is considered to take place so that the product contains the hydroxy group ortho to the original carboxyl group. A preferred embodiment consists of heating benzoic acid with at least an equivalent amount of cupric oxide at 250-280 DEG C. and displacing the phenol from the reduced copper body by passing a stream of inert gas, e.g. steam, through it at 275-500 DEG C. A further embodiment comprises bringing in sequence a solid mass comprising cupric oxide, preferably in a multiple zone moving bed reactor system, into contact with benzoic acid at 200-400 DEG C. until substantial reduction of the cupric oxide has occurred, then into contact with an aqueous medium preferably liquid water, to strip phenol from the reduced mass, then into an oxidizing zone to convert the reduced mass to cupric oxide and finally repeating the cycle and recovering the phenol from the aqueous medium. The phenol may also be recovered from the reduced copper mass by steam stripping. The cupric oxide oxidant may be promoted with cobaltic oxide if desired. The phenolic products obtained from various acids are specified.