CENTRO DE INVESTIGACION Y DESARROLLO EN CIENCIAS APLICADAS "DR. JORGE J. RONCO"
Unidad Ejecutora - UE
congresos y reuniones científicas
Oxidation of alcohols using aqueous hydrogen peroxide asssted by pyridinium salt-Keggin heteropolyacid
P. TUNDO, G. ROMANELLI, P. VILLABRILLE, C. CÁCERES, P. VÁZQUEZ
Conferencia; 1st International IUPAC Conference on Green Chemistry; 2006
The oxidation of alcohols plays an important role in organic synthesis and since carbonyl compounds are widely used as intermediates both industrial and laboratory. In oxidation processes, the use of a number of non-environmental oxidants is very common, although other compounds are sought that are not detrimental to the environment. In the context, during the last years very useful procedures involving hydrogen peroxide (H2O2) as oxidant and a catalyst have been developed to promote oxidations of organic substrates, due to the effective oxygen-content, low cost, safety in storage and operation and environmentally friendly character of H2O2. On the other hand, this work address as execute the principles of green chemistry, between them: the use of catalysts and not stoichiometric reagents and increase energy efficiency, principally. Catalysts are used in small amounts and can carry out a single reaction many times and run chemical reactions at ambient temperature. When the Keggin heteropolyacids (HPA) are used as catalysts, it is facilite these objectives. The present work investigates the influence of pyridine salts, with Keggin structure for the selective oxidation of sulfides to sulfoxides or sulfones, it varing to reaction conditions, with H2O2 hydrogen peroxide. The pyridine (Py) salts from H4PMo11VO40, H5PMo10V2O40, H9PMo6V6O40 acids obtained by V substitution in the structure of H3PMo12O40 were synthesized. They were characterized by FT-IR and the variation of their acid properties and that of their original acids was determined by titration with n-butylamine. Vibrational spectrum of primary structure Keggin was modified when Mo+6 atoms were substituted by V+5atoms. The performance of different catalysts on 1-phenilethanol oxidation was studied. The effect of the amount of used hydrogen peroxide was studied in function of conversion time. The different alcohols were used for the oxidation reaction and it was observed that the selectivity depends of initial alcohol. The benzilic alcohols produce excellent yields and with other alcohols, the performance of oxidation reaction is low using the same catalyst.