4 aminophenol

Paracetamol, chitosan and cerium nitrate (Ce(NO₃)₃·6H₂O) were obtained from Sigma-Aldrich Chemicals (St. Louis, Mo, USA). Zinc acetate (Zn(C₂H₃O₂)₂·2H₂O), glassy carbon microspheres (GCMs, particle size 0.4–12 micron), 4-aminophenol and paraffin oil were obtained from Alfa Aesar (Ward Hill, MA). Standard stock solutions were prepared separately by dissolving Paracetamol and p-aminophenol in anhydrous ethanol and kept in darkness at 4 °C. Phosphate buffer solutions (PBS, 0.2 M) of pH 2.0–8.0 were prepared from orthophosphoric acid and its salts and used as a supporting electrolyte in the current study. All aqueous solutions were freshly prepared with doubly-distilled water from a Millipore system (Milli-pore Inc., 18.2 MΩ cm).

4-Aminophenol was obtained from Alfa Aesar Co., Inc. 4,4′-Biphenol, 2-(2-(2-chloroethoxy)ethoxy)ethanol, diethyl acetamidomalonate, potassium iodide (KI) and tetrabutyl orthotitanate (Ti(OⁱPr)₄) were supplied by TCI Development Co., Ltd. Ethyleneglycol dimethyl ether was supplied by Aladdin Bio-Chem Technology Co., Ltd. Sodium nitrite (Na₂NO₃), methanol (CH₃OH), phenol, hydrochloric acid (HCl, 36%), potassium carbonate (K₂CO₃), N,N-dimethylformamide (DMF), dichloromethane (CH₂Cl₂), chloroform were (CHCl₃), tetrahydrofuran (THF) and dioxane were purchased from Sinopharm. DMF was dehydrated before use. All other reagents were commercial grade and used as received.