INVESTIGADORES
ROMANELLI Gustavo Pablo
congresos y reuniones científicas
Título:
Multiphase oxidation of alcohol and sulfides with hydrogen peroxide catalyzed by heteropolyacids
Autor/es:
P. TUNDO, G. ROMANELLI, P. VÁZQUEZ
Lugar:
Dresden, Alemania
Reunión:
Conferencia; 1st International IUPAC Conference on Green Chemistry; 2006
Institución organizadora:
IUPAC
Resumen:
In this work we reported a multiphase catalytic system consisting of hydrocarbon solvent (isooctane), aqueous phase, phase-tranfer (PT) agent (Aliquat 336), diluted hydrogen peroxide and Keggin heteropolyacid catalyst, afford the efficient oxidation of benzylic and secondary alcohols at 70°C, in moderate time reaction. The reaction gives very good yields. Similarly sulfides give sulfoxide or sulfone depending of hydrogen peroxide concentration, at room temperature with high yields and selectivity. The result of the preliminary investigation on the multiphase oxidation of 1-phenylethanol and thioanisol as models substrates on the effects of various parameters on the oxidations of alcohol and sulfides are given. The following heteropolyacid were used as catalyst: H3PMo12O40, H3PW12O40, H4SiMo12O40, H6PAlMo11O40, H4PMo11VO40 and H5PMo11Al0.5V0.5O40. H6PAlMo11O40 gave rise to the very high yields for 1-phenylethanol oxidation. In fact after a reaction time of 7 hours 99 % of yield of acethophenone. Benzyl alcohol was oxidized selectively to benzaldehyde. Larger excesses of hydrogen peroxide over the substrate lead only small amounts of benzoic acid. The thioanisol oxidation in multiphase system under optimized conditions (room temperature and 1:1.1 molar ratio of substrate:hydrogen peroxide is found to be ideal for complete conversion of sulfide in sulfoxide. Large excesses of hydrogen peroxide gave de corresponding sulfone.
As conclusion, multiphase system is an excellent medium for the oxidation of benzylic and secondary alcohols to the corresponding carbonyl compounds and sulfides to the corresponding sulfoxide or sulfone with dilute hydrogen peroxide, employing Keggin heteropolyacid as catalyst, under multiphase condition (Aliquat 336). This metodology is characterized by high yields and selectivities.
