Prepn. of P-aminophenol from nitrobenzene - by electrolysis in sulphuric acid soln. without solvent using solid-polymer-electrolyte electrode and rotating disc electrodes

摘要

p-Aminophenol (I) is produced from nitrobenzene (II) by electrolysis of a soln. of 1.5-3M H2SO4 and 0.5-2M (II), contg. no solvent or setting agent, in the negative electrode space using, as working electrodes, a solid-polymer-electrolyte electrode (SPE electrode) and a rotating electrode consisting of several disc-shaped electrodes (RDE). The RDE is made of graphite, Cu, Bi-coated graphite, Cu amalgam or Bi-coated Cu, and the SPE electrode is of SPE-Cu-Bi, SPE-Cu or SPE-Bi; current density of the RDE electrode is 20-200 mA/cm2, and current density of the SPE electrode is 1/5-1/100 that of the RDE electrode; electrolysis temp. is 80-95 deg.C and the RDE electrode rotates at 300-3600 r.p.m.; positive electrode is Pb-Ag or DSA (Ti/IrO2); electrolysis is stopped when there is an increase in the potential at the negative electrode w.r.t. a reference electrode. USE/ADVANTAGE - Provides an electrochemical process for the prod. of (I) from (II) in high yield with the greatest possible reduction in the formation of by-prods., in the absence of solvents and wetting agents.