Metal ion catalysis in the hydroxyalkylation of phenol with glyoxylic acid

Abstract The hydroxyalkylation reaction of phenol with glyoxylic acid in aqueous medium is found to be homogeneously catalyzed by various metal ions. Catalysis with M II ions results in a reaction product with an ortho/para ratio of 0.2 to 1.1, whereas catalysis using higher valent cations, because of their ability to form mixed complexes with phenol and glyoxylic acid, affords a reaction product with an ortho/para ratio of 1.3 to 28. The catalyzed Cannizzaro reaction of glyoxylic acid was observed as a side‐reaction. Addition of a suitable inert ligand, e.g. oxalic acid or NTA, is shown to decrease the ortho/para ratio and to suppress the Cannizzaro reaction. The coordination of glyoxylic acid and its hydrate with several cations has been studied by NMR techniques and a mechanism of the catalyzed hydroxyalkylation and Cannizzaro reaction is proposed.