Alkyl or omega-hydroxyalkyl para-hydroxymethyl-benzoate prodn - by electrochemical reduction of dialkyl or dihydroxy-alkyl terephthalate

摘要

Prodn. of alkyl or omega-hydroxyalkyl (pref. CH3) esters of p-hydroxymethylbenzoic acid by electrochemical reduction of dialkyl or dihydroxyalkyl terephthalates (pref. dimethyl terephthalate) dissolved or suspended in an electrolyte soln. in an electrolysis cell are sepd. into a cathodic and an anodic compartment is improved in that a dialkyl or dihydroxyalkyl terephthalate is cathodically reduced in a catholyte contg. a tetraalkylammonium salt as an electrolyte at pH >3 and a current density of 2-50 A/dm2, in a cell provided with solid electrodes and a porous diaphragm. High purity p-hydroxymethylbenzoic acid esters used as inters. in the mfr. of polyesters are produced with high selectivity. The method can also be applied to ring-substd. derivs., and to m- and o-hydroxymethylbenzoic acid esters.