title: Photocatalytic degradation of paracetamol: intermediates and total reaction mechanism.
abstract: The advanced oxidation of paracetamol (PAM) promoted by TiO(2)/UV system in aqueous medium was investigated. Monitoring this reaction by HPLC and TOC, it was demonstrated that while oxidation of paracetamol is quite efficient under these conditions, its mineralization is not complete. HPLC indicated the formation of hydroquinone, benzoquinone, p-aminophenol and p-nitrophenol in the reaction mixtures. Further evidence of p-nitrophenol formation was obtained following the reaction by UV-vis spectroscopy. Continuous monitoring by IR spectroscopy demonstrated the breaking of the aromatic amide present in PAM and subsequent formation of several aromatic intermediate compounds such as p-aminophenol and p-nitrophenol. These aromatic compounds were eventually converted into trans-unsaturated carboxylic acids. Based on these experimental results, an alternative deacylation mechanism for the photocatalytic oxidation of paracetamol is proposed. Our studies also demonstrated IR spectroscopy to be a useful technique to investigate oxidative mechanisms of pharmaceutical compounds.
authors.affiliation: Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Av. Manuel Nava #6, San Luis Potosí, S.L.P., 78290, Mexico.
authors.forename: Edgar
authors.initials: E
authors.lastname: Moctezuma
authors.forename: Elisa
authors.initials: E
authors.lastname: Leyva
authors.forename: Claudia A
authors.initials: CA
authors.lastname: Aguilar
authors.forename: Raúl A
authors.initials: RA
authors.lastname: Luna
authors.forename: Carlos
authors.initials: C
authors.lastname: Montalvo
mesh_terms: D000082:Acetaminophen / Q000737:chemistry* / Q000528:radiation effects; D002244:Carbon / Q000032:analysis; D002264:Carboxylic Acids / Q000737:chemistry; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D010777:Photochemistry; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D014025:Titanium / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: D002264:Carboxylic Acids; C009495:titanium dioxide; D000082:Acetaminophen; D002244:Carbon; D014025:Titanium