Metal ion catalysis in the hydroxyalkylation of phenol with glyoxylic acid

Article abstract of DOI:10.1002/recl.19881070326

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 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 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.