SELECTIVE HYDROXYLATION OF PHENOL OR PHENOLIC ETHERS

摘要

Phenols, and related aromatic compounds, phenolic ethers, can be hydroxylated selectively using hydrogen peroxide in the presence of an amorphous or microcrystalline zirconium phosphate catalyst in a solvent containing an aliphatic carboxylic acid. The process is particularly suitable for phenol itself, and advantageously employs a partially dehydrated microcrystalline catalyst obtained by heating an hydrated microcrystalline zirconium phosphate for example at about 100 DEG C. A convenient reaction temperature is 50 to 90 DEG C, and convenient solvent is acetic acid. In an improved method of producing the catalyst, zirconium phosphate is precipitated from an aqueous phosphoric acid solution of zirconium oxychloride in the presence of a cationic phase transfer agent such as an alkylpyridinium salt or tetraalkylquaternary ammonium salt or a nonionic surfactant such as an alcohol ethoxylate.