Sulfonic acid functionalized metal–organic framework (S-IRMOF-3): a novel catalyst for sustainable approach towards the synthesis of acrylonitriles?

RSC Advances Pub Date: 2019-05-21 DOI: 10.1039/C9RA01012B

Abstract

A sulfonic acid functionalized metal–organic framework (S-IRMOF-3) has been synthesized by dropwise addition of chlorosulfonic acid (0.5 mL) in IRMOF-3 (1 g) containing 20 mL of CHCl3 at 0 °C under simple stirring. The catalyst was applied in Knoevenagel condensation of various aromatic and hetero-aromatic aldehydes forming acrylonitrile derivatives. The catalyst was characterized thoroughly by using FT-IR, XRD, 13C MAS NMR, SEM, EDX, elemental mapping, TEM, BET, NH3-TPD and TGA/DTA techniques. The presence of characteristic bands at 1694 cm?1, 1254–769 cm?1 and 1033 cm?1 in the FT-IR spectrum, 2θ ? 6.7° and 9.8° in the XRD pattern and δ = 31.79, 39.55, 129.61, 131.46 (4C, CH), 133.54, 140.07 (2C), 167.71, 171.47 ppm (2C, 2C[double bond, length as m-dash]O) in the solid state 13C MAS NMR spectrum confirmed the successful formation of catalyst. This new eco-friendly approach resulted in a significant improvement in the synthetic efficiency (90–96% yield), high product purity, and minimizing the production of chemical wastes without using highly toxic reagents for the synthesis of acrylonitriles with selectivity for (Z)-isomer. Steric interactions seem to have an influence on the control of the Z-configurational isomers. By performing DFT calculations, it was found that the (Z)-isomer 3a is stabilized by 1.64 kcal mol?1 more than the (E)-isomer. The catalyst could be reused for five consecutive cycles without substantial loss in catalytic activity.

Graphical abstract: Sulfonic acid functionalized metal–organic framework (S-IRMOF-3): a novel catalyst for sustainable approach towards the synthesis of acrylonitriles
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