Synthesis of Nano Magnetite Fe3O4 Based Vanadic Acid: A Highly Efficient and Recyclable Novel Nano-catalyst for the Synthesis of 4,4’-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ols)

Nano magnetic Fe3O4 based vanadic acid [MNPs@VO(OH)2] (average diameter 20–26 nm) has been synthesized by grafting VOCl3 on the Fe3O4 surface nanoparticles as a retrievable supporter to produce novel heterogeneous reusable solid acid with dual ability (Bronsted and Lewis acid) followed by stirring in the air. The resultant material was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) analysis and energy-dispersive X-ray spectroscopy (EDX). Significantly, the as-prepared [MNPs@VO(OH)2] exhibits a high catalytic activity in the synthesis of 4,4’-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols). Additionally, the newly synthesized heterogeneous solid acid catalyst can be reused for several times without apparent loss of its catalytic activity. This work is licensed under a Creative Commons Attribution 4.0 International License

One-pot three-component synthesis of 4,4-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) using silica vanadic acid as heterogeneous and recyclable catalyst with dual ability

Silica vanadic acid (oxo-vanadium has been supported on silica) with Lewis and Bronsted acid site is introduced as an efficient, reusable, and heterogeneous catalyst for tandem Knoevenagel–Michael reaction of two equivalents of 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one with various aromatic aldehydes for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol)s at room temperature. The present methodology offers several advantages over existing methodologies, such as excellent yields, short reaction time, simple procedure, easy work-up, mild reaction conditions, and synthesis of wide range of products. This procedure gave the products in excellent yields within very short reaction times over other vanadium(V) compounds. Also this catalyst can be reused six times without appreciable loss of its catalytic activity

A green non-acid-catalyzed process for direct N=N–C group formation: comprehensive study, modeling, and optimization

The aim of this work is to introduce, model, and optimize a new non-acid-catalyzed system for a direct N=N–C bond formation. By reacting naphthols or phenol with anilines in the presence of the sodium nitrite as nitrosonium (NO+) source and triethylammonium acetate (TEAA), a N=N–C group can be formed in non-acid media. Modeling and optimization of the reaction conditions were investigated by response surface method. Sodium nitrite, TEAA, and water were chosen as variables, and reaction yield was also monitored. Analysis of variance indicates that a second-order polynomial model with F value of 35.7, a P value of 0.0001, and regression coefficient of 0.93 is able to predict the response. Based on the model, the optimum process conditions were introduced as 2.2 mmol sodium nitrite, 2.2 mL of TEAA, and 0.5 mL H2O at room temperature. A quadratic (second-order) polynomial model, by analysis of variance, was able to predict the response for a direct N=N–C group formation. Predicted response values were in good agreement with the experimental values. Electrochemistry studies were done to introduce new Michael acceptor moieties. Broad scope, high yields, short reaction time, and mild conditions are some advantages of the presented method