Green synthesis of pyranopyrazoles using Tungestic acid/Zr bio-based MOF as an efficient heterogeneous catalyst

Document Type : Original Paper

Authors

1 Department of Chemistry, Khouzestan Science & Research Branch, Islamic Azad University, Ahvaz, Iran

2 Department of Science, Payame Noor University (PNU), 19395-4697, Tehran, Islamic Republic of Iran

3 Department of Polymer Engineering, Shiraz Branch, Islamic Azad University, Shiraz, Iran

4 Department of Chemistry, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran

Abstract

This reported work aims to fabricate an eco-friendly Zr bio-based MOF as a new magnetic nanocatalyst based on the immobilization of tungstic acid onto new design robust, cost-effective, green and scalable Zirconium-L-aspartate amino acid metal-organic framework (MOF)-grafted L-(+)-tartaric acid stabilized magnetite nanoparticles (Fe3O4/Tart-NPs) was successfully prepared by two successive hydrothermal method. This catalyst was characterized by FT-IR, XRD, FE-SEM and TGA-DTA  analysis. This catalyst is outstanding to prepare l ‐ (4 ‐ phenyl) ‐ 2,4 ‐ dihydropyrano [2,3 ‐ c] pyrazole derivatives in aqueous media due to the open metal sites, high and steady proton conductivity in the zirconium-MOF, MIP-202(Zr), MOF and also due to Brønsted acid properties of tungstic acid. This acidic catalyst can easily be extracted by an outward magnetic field after completion of the reaction without any deactivation or selectivity loss. The products were characterized by spectroscopic analysis (1HNMR,13CNMR and also  FTIR). The optimized reaction conditions and a possible reaction mechanism is outlined.

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