Synthesis and characterization of nanocrystalline hydroxyapatite and its catalytic behavior towards synthesis of 3,4‐disubstituted isoxazole‐5(4H)‐ones in water

Abstract

In the present work, the nanocrystalline particles of hydroxyapatite (HAp) using an easy alkoxide‐based sol–gel technique including triethyl phosphate [PO (OC2H5)3] and Ca (NO3)2·4H2O as P and Ca precursors have been synthesized. The sample characterization was performed by X‐ray diffraction, Fourier transform‐infrared analysis, scanning electron microscopy, thermal analysis (thermogravimetric analysis/differential thermal analysis), and elemental analysis of energy‐dispersive X‐ray analysis. It is interesting that single phase of HAp was obtained at a low firing temperature of 500°C. Modified Scherrer equation as the Williamson−Hall method was applied for the measurement of crystallite size distributions and micro‐strain of the sample. The determined crystallite size by complementary technique of transmission electron microscopy has good consistency with those obtained from the Scherrer formula. Moreover, we reported the one‐pot synthesis of 3,4‐disubstituted isoxazole‐5(4H)‐ones through the aqueous solution reaction of three components of ethyl acetoacetate, hydroxylamine hydrochloride and various aromatic aldehydes at room temperature. This protocol offers several advantages, including a simple work‐up procedure, very short reaction times (under 25 min), in accordance with the principles of green chemistry, recyclability, excellent yields (87–98%) and environmentally friendly.

Conversions of Cement bypass waste to Nano-hydroxyapatite exploited in water purification

“…2(b) and Table 1. The major diffraction peaks of Kiln-HA were appeared at 2θ = 25.8°, 31.4°, 49.4° and 53.4° (Khawar et al, 2019;Maleki et al, 2019). The crystallite size of the hydroxyapatites studied ranged from 14.85 to 25.72 nm, placing them in the Nano-scale, according to previous research (Abo-El-Enein, 2017).…”

“…3 (a-d). In the case of Kiln-HA1, Kiln-HA2, and Kiln-HA3 samples, the (SEM) photos seemed to be in the shape of a star or coral reefs, while Kiln-HA4 was sheet-like in appearance.Other hydroxyapatite materials have been observed to have a similar morphology (Barakat et al, 2008;Maleki et al, 2019). According to the EDX analysis, the examined materials mostly include P, Ca, O, and H, with trace levels of additional elements including Mg, Fe and Ti Fig.…”

Polycaprolactone Microsphere‐Encapsulated Fluconazole‐Loaded Zinc Oxide and Hydroxyapatite Nanocomposites for Enhanced Biological Performance

“…This outcome prescribes that ZnO and HAp crystals are stoichiometric in nature in both the synthesized ZnO and HAp powder and the FCZ-ZnO-HAp-PCL nanocomposite (Figure 5C). [33,34] The antibacterial activity of the ZnO, FCZ-ZnO-HAp and FCZ-ZnO-HAp-PCL composites was first investigated qualitatively well and disc diffusion agar methods (Figure 6). The ZnO NPs, FCZ-ZnO-HAp and FCZ-ZnO-HAp-PCL composites with three different concentrations (10 μg/mL, 30 μg/mL and 100 μg/ mL) were tested in order to investigate the composite component effects on the antibacterial activities against G À ve, Escherichia coli (E. coli) and gram G + ve, Staphylococcus aureus (S. aureus).…”

Eco-friendly synthesis of chromeno[4,3-b]chromenes with a new photosensitized WO3/ZnO@NH2-EY nanocatalyst

“…In the extension of our previous studies on the development of green synthetic protocols to achieve important heterocyclic compounds [57][58][59] and to recognize the extensive applications of chromene derivatives, herein, we report a simple and convenient new method to synthesize different substituted chromeno [4,3-b]chromene derivatives by means of a green LED through the multicomponent condensation of aryl aldehydes, 1,3cyclohexanedione, and 4-hydroxylcoumarin, using an EYsupported nanocomposite (WO 3 /ZnO) as a green heterogeneous nanocatalyst under solventless conditions (Scheme 1).…”