Efficient Solvent Free Knoevenagel Condensation Over Vanadium Containing Heteropolyacid Catalysts

Viswanadham, Balaga; Pedada, Jhansi; Chary, Komandur V. R.; Friedrich, Holger B.; Singh, Sooboo

doi:10.1007/s10562-015-1646-9

Cited by 35 publications

(29 citation statements)

References 30 publications

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“…From Raman spectra (Fig. 3), the pure PMA shows typical Keggin ion bands at 987, 880, 603 and 245 cm -1 which were assigned to M-O t , Mo-O b -Mo, Mo-O c -Mo and Mo-O a , respectively [4]. In the case of fresh and regenerated Cu-PMA catalysts, these bands are retained, further illustrating that these catalysts retained the Keggin ion structure.…”

Section: Fourier Transform Infrared and Raman Spectroscopymentioning

confidence: 89%

“…2 [4]. There is a shift in these bands for the fresh and regenerated Cu-PMA catalysts located at 1057, 957, 886, 754 cm -1 which is minimal, suggesting that the Keggin ion of heteropolyacid is intact after copper exchange.…”

Section: Fourier Transform Infrared and Raman Spectroscopymentioning

confidence: 93%

“…1. These patterns showed diffraction peaks at 8.2°, 9.1°, 26.5°and 28.8°and were assigned to the characteristic diffraction peaks of Keggin ion structure [4]. There was a significant decrease in the intensity of characteristic peaks once copper was incorporated into the phosphomolybdic acid.…”

Section: Xrd Studiesmentioning

confidence: 97%

“…In addition, metal promoted hydroxyapatites showed superior catalytic performance for this reaction [22,24]. In studies conducted by Viswanadham et al [4] and Khorasani and co-workers [25], using vanadium substituted phosphomolybdic acid and phosphotungstic acid catalysts respectively, it was shown that the reaction proceeds via the attacking of a proton on the carbonyl oxygen lone pair. In the view of several researchers, heteropolyacid catalysts were found to be robust, easily recyclable and showed better catalytic properties than other catalysts.…”

Section: Introductionmentioning

confidence: 97%

“…As a result, heteropolyacid catalysts can be reused after activation or without activation, leading to a more economically sustainable process under solvent free conditions [3]. Heteropolyacid catalysts are used in several reactions such as oxidation and acid catalyzed transformations [4][5][6][7][8][9][10][11]. Among these reactions, the Knoevenagel condensation reaction is an important C-C bond forming reaction and its products are extensively used as intermediates in the manufacture of perfumes, pharmaceuticals and polymers [12,13].…”

Section: Introductionmentioning

confidence: 99%

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The Role of Copper Exchanged Phosphomolybdic Acid Catalyst for Knoevenagel Condensation

et al. 2016

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Cu exchanged heteropolyacid catalysts were synthesized by ion exchange method and characterized using various physico-chemical techniques such as X-ray diffraction (XRD), FT-IR, Raman, BET surface area, temperature programmed desorption (TPD) of ammonia, 31 P NMR, pyridine adsorbed FT-IR spectroscopy, ICP-AES and STEM analysis. XRD diffractograms shows crystallites of heteropolyacid, while FT-IR and Raman spectra indicate that the Keggin ion is retained in the catalysts. 31 P NMR, ammonia TPD and pyridine adsorbed FT-IR spectra results suggest that acidity decreases once Cu was incorporated in the heteropolyacid catalyst. For the Knoevenagel condensation reaction, the Cu exchanged phosphomolybdic acid (Cu-PMA) exhibits better catalytic performance than the phosphomolybdic acid (PMA) catalyst and this is related closely with the structural and acidic properties of the catalyst. Graphical Abstract NC CN R O H CuPMA CN NC R O H CuPMA CN NC R H H Keywords Cu exchanged PMA Á Bi-functional Á Raman spectroscopy Á TPD Á Py-FTIR Á 31 P NMR Á Acidity

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Section: Fourier Transform Infrared and Raman Spectroscopymentioning

confidence: 89%

Section: Fourier Transform Infrared and Raman Spectroscopymentioning

confidence: 93%

Section: Xrd Studiesmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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The Role of Copper Exchanged Phosphomolybdic Acid Catalyst for Knoevenagel Condensation

et al. 2016

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Elucidating the Role of Addenda and Hydrogen Atoms on the Acidity of Heteropolyacid to Produce Butyl Levulinate as a Green Diesel Additive

Ahmad,

Znad,

Ahmad

2024

Advanced Sustainable Systems

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The present study explores the synthesis of butyl levulinate (BL), a green diesel additive, using vanadium‐incorporated Keggin phosphomolybdic acid (HPVM) catalysts. This study highlights the effect of addenda and hydrogen atoms on HPVM catalysts for BL production, thereby elucidating a correlation between addenda atoms, HPVM acidity, and BL yield. The catalysts are characterized using Raman spectroscopy, FTIR, XRD, ammonia‐TPD, SEM‐EDX, and ICP‐OES techniques to determine their structural properties, acidity, and elemental composition. Reaction parameters, including time, temperature, catalyst concentration, stirring rate, and solvent volume, are systematically evaluated to optimize the conversion of levulinic acid (LA) to BL. A significant BL yield (>96%) is obtained using 25 wt.% H4PMo11VO40 (H4PVM) catalyst at 100 °C in 40 min. Kinetic analysis unveiled a pseudo‐first‐order reaction mechanism for BL synthesis with activation energies of 66.73, 68.81, and 71.19 kJ.mol−1 for H4PMo11VO40 (H4PVM), H5PMo10V2O40 (H5PVM), and H6PMo9V3O40 (H6PVM) catalysts, respectively. Additionally, thermodynamic parameters, such as enthalpy of activation (ΔH*), entropy of activation (ΔS*), and Gibbs free energy of activation (ΔG*), are determined. Overall, this study highlights the complex interplay between acidity, activation energy, and BL yield, emphasizing the significance of the number of vanadium addenda atoms in catalyst performance.

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Pd nanoparticles Incarcerated in Aluminium Oxy‐Hydroxide: An Efficient and Recyclable Heterogeneous Catalyst for Selective Knoevenagel Condensation

Göksu

Gültekin

2017

ChemistrySelect

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Knoevenagel condensation between aryl aldehyde derivatives with malononitrile was successfully achieved using commercially available Pd/AlO(OH) nanoparticles (0.5 wt% Pd) in an aqueous medium. All benzylidenemalononitrile (BMN) derivatives were obtained promptly (8‐60 min) with high selectivity and yields of over 99 % in a mixture of H2O/MeOH (v/v=1/2) at room temperature. Moreover, when benzoyl chloride derivatives were utilized instead of aryl aldehyde derivatives, medium amounts of the expected products were yielded. Before the reaction and after five reuses, characterization of the Pd/AlO(OH) nanoparticles was carried out via X‐ray diffraction and scanning electron microscopy analysis. The BMN derivative characterization was accomplished using the 1H NMR and 13C NMR spectra. In order to optimize the reaction conditions, the parametric effects of the solvent type and catalyst amount were examined. Consequently, the PdAlO(OH) NPs were used for the first time in the Knoevenagel condensation. A novel, practical and eco‐friendly process was developed for Knoevenagel condensation in the presence of Pd/AlO(OH) nanoparticles.

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Efficient Solvent Free Knoevenagel Condensation Over Vanadium Containing Heteropolyacid Catalysts

Cited by 35 publications

References 30 publications

The Role of Copper Exchanged Phosphomolybdic Acid Catalyst for Knoevenagel Condensation

The Role of Copper Exchanged Phosphomolybdic Acid Catalyst for Knoevenagel Condensation

Elucidating the Role of Addenda and Hydrogen Atoms on the Acidity of Heteropolyacid to Produce Butyl Levulinate as a Green Diesel Additive

Pd nanoparticles Incarcerated in Aluminium Oxy‐Hydroxide: An Efficient and Recyclable Heterogeneous Catalyst for Selective Knoevenagel Condensation

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