Manifestation of zeolitic pore characteristics of modified montmorillonite in oxazole synthesis by propargylation and cycloisomerization reactions

作者：Venkatesha N J; Bhat Y S^*; Prakash B S Jai

来源：Applied Catalysis A: General , 2015, 496: 51-57.

DOI：10.1016/j.apcata.2015.02.036

• Montmorillonite
• Phenoldisulfonic acid
• Propargylation
• Cycloisomerization
• Zeolitic pore

Zeolitic micropores are found to be developed on montmorillonite clay by treatment with phenoldisulphonic acid (PDSA). The micropores developed have the ability to enhance the cycloisomerization of the alkynylamide to form oxazole product. Pore characteristics by surface measurement techniques and acidity by pyridine adsorption using FT-IR were evaluated. Surface measurements showed significant increase in the surface area, acidity and the micropore volume but neither of them correlated well with the cycloisomerization activity. Variation in Bronsted and Lewis acidity and pore volume by surface coverage using Bronsted (B) and Lewis (L) acid compounds, caused variation in cycloisomerization activity. Best correlation with the amount of oxazole formed was observed when volume accessibility factor (VAF), a product of micropore volume and ratio of B to L acidity were considered. Based on this, a reaction scheme for cycloisomerization is proposed involving both B and L sites within the micropores.

• 出版日期2015-4-25