Activity, selectivity and stability of Zn-exchanged NaY and ZSM5 zeolites for the synthesis of o-hydroxyacetophenone by phenol acylation

<strong>Study of the effect of solvent and different Lewis acids in one pot multicomponent microwave assisted reaction for the chemoselective generation of </strong><strong>1.4-thiazepan-3-ones and 4-tiazolidinones.</strong>

“…Previously, we performed the corresponding determination of the surface area of the zeolites by the BET method [11]. b See reference [12].…”

Evaluation of Fe- and Cr-containing clinoptilolite catalysts for the production of camphene from α-pinene

“…The infrared spectra of adsorbed ammonia on ion-exchanged clinoptilolites showed that 0.4Cr-CL and 0.7Fe-CL clinoptilolite samples tend to exhibit greater Bronsted acidity than raw clinoptilolite. The spectra for 0.7Fe-CL and 0.4Cr-CL zeolite samples exhibit more intense absorption bands at $1420 cm À1 as compared to that of Raw-CL, which revealed the presence of higher amounts of Brønsted acid sites on the exchanged clinoptilolites [37]. Additionally, ammonia adsorption on Bronsted acid sites is more extensive on 0.7Fe-CL than that of 0.4Cr-CL.…”

“…5, IR spectra obtained for all catalysts are similar and showed that there is not any significant change in the hydroxyl region which means that the ion-exchange process carried out mostly by replacing the counter ions (Na + , K + , Ca 2+ or Mg 2+ ) present on the zeolite structure, not by the replacement of OH groups. This means that protonic sites are not involved in the exchange with Fe 3+ and Cr 3+ ions [37]. It is noteworthy that the effect of Fe 3+ and Cr 3+ -exchange is also indicated by the widening of the 1000-1200 cm À1 band showing the incorporation of new cationic species into the zeolite structure [38].…”

Zncl2@MWCNTs nanocomposite as an efficient and reusable catalyst for direct regioselective ortho C-acylation of phenolic compounds under solvent-free and microwave conditions

“…The known Friedel-Crafts reaction via Lewis acid catalyst suffers from the formation of undesired p-substituted products, especially when bulky acyl groups need to be introduced. The synthesis of some ketones with sulfur and nitrogen as functional groups is also limited in this method (17,18). The use of new hybrid Lewis acid catalysts in achieving clean reactions with good selectivity and performance under the better reaction conditions has yet to be investigated.…”