Boric Acid-Functionalized Fe3O4@SiO2 as a Novel Superparamagnetically Recoverable Nano Catalyst for Mukaiyama-Aldol Reaction

Document Type: Research Paper

Authors

1 Chemistry Department,Tarbiat Modares University

2 Chemsitry Department, Tarbiat Modares University

3 Chemistry Department, Tarbiat Modares University

Abstract

We have reported the fabrication of boric acid incorporated into surface of magnetite nanoparticles. The catalyst was characterized using spectroscopic, magnetic and thermal techniques (FT-IR, SEM, XRD, ICP, VSM and TGA). It catalyzed Mukaiyama aldol reaction of a ketene silyl acetal type nucleophile ((1-methoxy-2-methylprop-1-enyloxy) trimethylsilane), and various aldehydes (aromatic, aliphatic, α,β-unsaturated), in acetonitrile and the yields were in the range of 45-98%. Magnetic Fe3O4-boric acid was multi-functional. The Fe3O4 core of the catalyst made easy separation and recycling while its boric acid portion catalyzed Mukaiyama aldol reaction. Nano size nature of the catalyst increased its activity in a way that boric acid, which is a weak Lewis acid, functioned similar to a more strong one like BF3. Boric acid functionality had the advantage of being moisture insensitive, economically reasonable and environmentally friendly. Furthermore Fe3O4@ SiO2@Boric acid was magnetically recovered via an external permanent magnet and was reused at least 6 times with a negligible change in its activity.

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