INCAPE   05401
INSTITUTO DE INVESTIGACIONES EN CATALISIS Y PETROQUIMICA "ING. JOSE MIGUEL PARERA"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Síntesis de iononas por ciclización de pseudoionona sobre catalizadores de heteropoliácido soportado sobre sílice
Autor/es:
V.K. DÍEZ; C.R. APESTEGUÍA,; J.I. DI COSIMO
Lugar:
Búzios, Brasil
Reunión:
Congreso; 15º Congreso Brasilero de Catálisis y 5º Congreso de Catálisis del Mercosur; 2009
Resumen:
The liquid-phase cyclization of pseudoionone to ionones (a, b, g) was studied on silica-supported heteropolyacid (HPA) catalysts containing between 19 and 59 % HPA. The density, chemical nature and strength distribution of the surface acid sites were determined by adsorbing and monitoring by temperature-programmed desorption and infrared spectroscopy probe molecules such as NH3 and pyridine. The pseudoionone conversion to ionones increased with the Brønsted acid site density. The highest ionone yield, 79 %, was obtained on a 59 wt. % HPA/SiO2 catalyst at 383 K and is comparable to the best values reported in literature for the homogeneously-catalyzed reaction using sulfuric acid.  The ionone isomer distribution was modified by varying both the temperature and the reaction time.  A reaction mechanism was postulated in which ionone isomers (a, b, g) are primary products, but g-ionone is isomerized to a-ionone while b-ionone is not converted in the other isomers.