OBTENCIÓN DE PRODUCTOS DE QUÍMICA FINA MEDIANTE ACILACIÓN DE GUAIACOL

MARDELLY KATERYNE MONTAÑEZ-VALENCIA; CRISTINA LILIANA PADRÓ; MARÍA EUGENIA SAD

Coimbra

Congreso; XXVI CICAT; 2018

The acylation of guaiacol with acetic acid in gas phase using different acid catalysts was studied at 523 K employing different acid catalysts (HPA/SiO2, HBEA, HZSM-5, NaZSM-5, ZnZSM-5 y SiO2/Al2O3). The effect of the contact time on guaiacol conversion and products distribution was evaluated. For all catalysts studied, the reaction was highly selective towards the O-acylation product (2-acetoxyanisole)which is used like flavoring in additives for foods. On HPA/SiO2 catalyst was obtained the highest selectivity towards 2-acetoxyanisole due to the predominant presence of acidic sites of the Brønsted nature. On ZSM5 catalysts was obtained the highest selectivity towards acetovanillone product(C-acylation product) which is widely used in the pharmaceutical industry.Catechol is produced towards demethylation and disproportion of guaiacol and its  formation was promoted on HBEA, HZSM-5 y ZnZSM-5 and in minor extent on SiO2/Al2O3 and NaZSM-5.  the highest selectivity towards veratrole was favored on the catalysts that have large pores such as HBEA and the mesoporousSiO2/Al2O3. The formation of acylanting agent( acylium ion) can occur indifferently by interaction of acetic acid with Lewis or Brønsted acid sites. The form of adsorption of guaiacol (parallel to the surface whether it interacts on Brønsted sites or vertical whether it does with Lewis sites) conditions the distribution of products.