Fun ctionalize d nano sil ica as an e fficient c atalyst for Synthesi s of chrom ene derivatives by m ulti-comp onent rea ctions

Base- catalyzed condensation and addition reactio ns are in dustrially important i n the production of dr ugs, fragrances and chemical inter mediates [ ۱]. In such systems, s everal difficu lt issues arise, of which we may address to the isolation o f the products, the corr osive nature of the reaction mixtur e and formation of larg e amounts of waste materials. Therefore, improved synthesis routes in terms of pr oduct purity, yield, and minimal waste formatio n are highly desirable. Solid acid catalysts have been extensively studied and applied in numerous reacti ons so far [۲]; however, solid base catalysts have not been e xtensively s tudied [۳]. These heterogeneous catalysts are k nown to suppress side reactions which include self-conden sation and oligomerization, resulting in better selectivity and product yield. This means cost and energ y savings for the downs tream separ ation and purification of the produ ct. It also avoids the co mplex neutralization and separati on steps needed to recover the ho mogeneous base catalysts from the reaction mixture. The recovered solid catalysts can be readily regen erated for fur ther use.

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Key words: Homogeneous base catal yst ، Nano silica ، Am inoethyl piperazine ، Multi-comp onent conde nsation