INVESTIGADORES
DIEZ veronica Karina
artículos
Título:
Kinetic and mechanistic study of the synthesis of ionone isomers from pseudoionone on Brønsted acid solids
Autor/es:
V.K. DÍEZ; C.R. APESTEGUÍA; J. ISABEL DI COSIMO
Revista:
CATALYSIS TODAY
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2017 vol. 296 p. 127 - 134
ISSN:
0920-5861
Resumen:
The kinetics of the liquid-phase synthesis of a-, b- and g-ionones from pseudoionone was studied on Brønsted acid solids. Four silica-supported tungstophosphoric acid catalysts containing different heteropolyacid loadings, as well as a silica-supportedtriflic acid sample and a commercial resin (Amberlyst 35W) were tested in abatch reactor at 343-383 K under autogenous pressure. The final composition of the ionone isomer mixturedepended on the catalyst acidic properties and operational conditions. The reaction pathways leading to the three ionone isomers were elucidated by postulating a heterogeneousLangmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic model. First order rateexpressions, participation of a single Brønsted acid site in each reaction stepand a cationic cyclic intermediate shared by the three ionone isomers were themain model assumptions. It was found that a-, b- and g-ionones form directly from pseudoionone bycyclization. However, the final concentration of a- and b-ionones is enhanced in consecutive pathwaysinvolving the isomerization of g-ionone. The relative importance of theisomerization steps and the selective formation of a- or b-ionone depend on the Brønsted acid site strength andreaction temperature.
