Modified hydroxyapatite with sodium nitrate: an efficient new solid catalyst for the Claisen–Schmidt condensation

Sebti, Saı̈d M.; Solhy, Abderrahim; Tahir, Rachid; Smahi, Abdellatif

doi:10.1016/s0926-860x(02)00273-9

Cited by 45 publications

(29 citation statements)

References 41 publications

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“…The primary HA phase was prepared by wet method with diammonium hydrogen phosphate [(NH 4 ) 2 HPO 4 ] and calcium nitrate tetrahydrate [Ca(NO 3 ) 2 ·4H 2 O] with a Ca/P ratio of 1.67 18, 22, 23. A long time of vigorous stirring was necessary as it was helpful to contribute to the formation of HA crystals.…”

Section: Methodsmentioning

confidence: 99%

Effect of sintering on porosity, phase, and surface morphology of spray dried hydroxyapatite microspheres

Wang

Zhu

et al. 2008

J Biomedical Materials Res

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This article deals with the effect of sintering temperature on the physical and chemical characteristics of hydroxyapatite microspheres (HAMs) obtained by spray drying method. A set of specimens were sintered in a conventional furnace at 500-1100 degrees C. The surface morphology, phase composition, size distribution, specific surface area, and porosity were characterized by scanning electron microscope, X-ray diffractometer, laser diffraction particle size analyzer, and specific surface area analyzer, respectively. The results indicated that at 800 degrees C, hydroxyapatite crystals began to grow and were sintered together, which caused a drastic decrease in both the specific surface area and the pore volume. Great changes took place on the surfaces of HAMs during sintering. When the samples were sintered at the temperature of 500 and 600 degrees C, no obvious changes can be found on the surfaces of the samples, but at 800 degrees C, open-micropore surfaces came forth. Besides, the dispersibility of the samples decreased at high temperature (1100 degrees C) because small particles tended to aggregate together.

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Section: Methodsmentioning

confidence: 99%

Effect of sintering on porosity, phase, and surface morphology of spray dried hydroxyapatite microspheres

Wang

Zhu

et al. 2008

J Biomedical Materials Res

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“…Furthermore, we have tested the sodium-modified phosphate Na/NP [99] and Na/HAP [100], and the lithiummodified natural phosphate Li/NP [101]. In this case, the best condition was 2.5 mmol of substrates, 0.1 g of catalyst and 1-3 mL of methanol at room temperature.…”

Section: -2 Claisen-schmidt Condensationmentioning

confidence: 99%

Phosphates: New Generation of Liquid-Phase Heterogeneous Catalysts in Organic Chemistry

Sebti¹,

Zahouily²,

Lazrek³

et al. 2008

COC

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This two part review looks at the uses of phosphate based heterogeneous catalysts for a range of synthetic organic reactions. Many different phosphates are known and have been tested as catalysts in a wide range of reaction types, either as catalysts, or in combination with other species such as zinc chloride or KF. The first section deals with the wide variety of phosphates which have been utilized in organic chemistry, while the second focuses more tightly on catalysts derived from naturally occurring phosphates. In all cases, efficient reactions can be achieved and in many reactions, significant solvent effects have been noted. Of benefit is the fact that relatively benign solvents such as lower alcohols and water are often the most effective.

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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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Modified hydroxyapatite with sodium nitrate: an efficient new solid catalyst for the Claisen–Schmidt condensation

Cited by 45 publications

References 41 publications

Effect of sintering on porosity, phase, and surface morphology of spray dried hydroxyapatite microspheres

Effect of sintering on porosity, phase, and surface morphology of spray dried hydroxyapatite microspheres

Phosphates: New Generation of Liquid-Phase Heterogeneous Catalysts in Organic Chemistry

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

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