Solvent-Free Knoevenagel Condensation over Cobalt Hydroxyapatite

Pillai, Manoharan Karuppiah; Singh, Sooboo; Jonnalagadda, Sreekantha B.

doi:10.1080/00397910903531714

Cited by 24 publications

(10 citation statements)

References 19 publications

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“…It has, therefore, been of considerable interest in areas such as biomaterials [1], adsorbents [2] and catalysis [3]. HAP has been used as a precious/transition metal catalyst support in a variety of reactions including: oxidation of alcohols [4], methane [5] and CO [6]; selective reduction of NOx over copper [7] and silver [8] impregnated HAP; Claisen-Schmidt condensation [9]; Michael addition [10]; Heck [11]; Knoevenagel condensation [12]; and the Diels-Alder reaction [13].…”

Section: Introductionmentioning

confidence: 99%

Effects of surfactant on morphology, chemical properties and catalytic activity of hydroxyapatite

Hajimirzaee

Chansai

Hardacre

et al. 2019

Journal of Solid State Chemistry

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Hydroxyapatite (HAP) was synthesised in the presence of surfactants and tested as a catalyst in CO oxidation. XRD confirmed that the characteristic HAP crystal phase was practically unaffected by the addition of surfactant. The surfactant altered both the Ca/P ratio and particle size of HAP. Catalyst tests showed that the activity of HAP increased for preparations using TWEEN, PEG and PVA. The temperature for 50% conversion, T50, values decreased from 340 °C for unmodified HAP, to 320 °C for TWEEN and to 315 °C for both PEG and PVA. This enhanced activity is rationalised by the higher BET surface areas and acid site densities in the surfactant-modified preparations: these increased from 52 m 2 g-1 for HAP to 69, 76 and 68 m 2 g-1 , and from 101 μmoles g-1 for HAP to 110, 170 and 126 μmoles g-1 for TWEEN, PEG and PVA, respectively. These findings demonstrate that HAP i.e. without the addition of precious metals to either the surface or framework, is an active CO catalyst and that the straightforward inclusion of surfactant during preparation can optimise the catalytic performance.

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Section: Introductionmentioning

confidence: 99%

Effects of surfactant on morphology, chemical properties and catalytic activity of hydroxyapatite

Hajimirzaee

Chansai

Hardacre

et al. 2019

Journal of Solid State Chemistry

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“…Earlier, hydroxyapatites were used as supports in a many studies [24][25][26][27][28]. Recently, our group has also successfully used cobalt, iridium and platinum hydroxyapatites as catalysts for solvent-free Knoevenagel condensation reactions of aldehydes with esters, resulting in good yields [29,30]. In this communication we report the synthesis of Fe, Co or Sr containing hydroxyapatites and their characterization by various techniques, to determine their potential as support materials.…”

Section: +mentioning

confidence: 99%

Synthesis of thermally stable metal substituted hydroxy apatites for the selective oxidation of light paraffins

Singh¹,

Jonnalagadda²

2012

Bull. Chem. Soc. Eth.

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ABSTRACT. Hydroxyapatite and a series of hydroxyapatite-type compounds containing Co, Fe or Sr were synthesized by co-precipitation and characterized by ICP-OES, BET, IR, Raman spectroscopy, powder and in-situ XRD, SEM, TEM, TPR, TPD and TGA. In-situ XRD and TGA studies indicate that the materials are able to maintain their structure at temperatures reaching 900 °C. The TPD data indicated that acidic sites of varying strengths were present in all the three hydroxyapatites. From SEM, the surface of the materials consisted of an agglomeration of irregular plate-like particles. The catalytic activity of the compounds was investigated in the oxidation of n-pentane and n-hexane. The conversion of the feed and composition of the products were largely influenced by changes in the temperature and flow rates. For n-pentane, the products consisted of lower hydrocarbons and oxygenated compounds, carbon oxides and very small amounts 1,3-pentadiene, furan and furfural. Low conversions of n-hexane were obtained for all the tested catalysts and selective products were the hexene isomers and some aromatics.

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“…Hydroxyapatites, which have both acidic and basic sites, proceeds by either of the two pathways mentioned [22]. 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.…”

Section: Introductionmentioning

confidence: 95%

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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Solvent-Free Knoevenagel Condensation over Cobalt Hydroxyapatite

Cited by 24 publications

References 19 publications

Effects of surfactant on morphology, chemical properties and catalytic activity of hydroxyapatite

Effects of surfactant on morphology, chemical properties and catalytic activity of hydroxyapatite

Synthesis of thermally stable metal substituted hydroxy apatites for the selective oxidation of light paraffins

The Role of Copper Exchanged Phosphomolybdic Acid Catalyst for Knoevenagel Condensation

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