Abeer Nasser Al-Romaizan

We report a sealed-tube-assisted one-pot oxidative aromatization of in situ-generated dihydropyrazolo[1,5-a]pyrimidine intermediates to afford polymethoxylated pyrazolo[1,5-a]pyrimidine derivatives using sodium persulfate in ethanol, utilizing the Mg-Al hydrotalcite (Mg-Al HT) as a solid base catalyst. Dihydropyrazolo[1,5-a]pyrimidine intermediates are firstly produced efficiently by an aza-Michael addition followed by a cyclocondensation sequence under sealed tube condition performed by Q-tube instrument and subsequently aromatized in situ utilizing sodium persulfate as a sustainable oxidant in a true one-pot fashion. Subsequent treatment of the catalyst-containing reaction mixture with sodium persulfate under sealed-tube heating afforded the corresponding aromatized products. Control experiments showed that the oxidation was enhanced under ambient-air conditions, while appreciable conversion was retained after nitrogen purging. This integrated operation is kinetically advantageous: direct addition of persulfate to the crude reaction mixture provides the target pyrazolo[1,5-a]pyrimidines in up to 91–92% isolated yield within 10 min, whereas oxidation of isolated intermediates under otherwise identical conditions requires longer reaction times. Optimized conditions utilize merely 3 mol% Na₂S₂O₈, yielding the necessary pyrazolo[1,5-a]pyrimidines with an isolated yield of up to 91% within 10 min, demonstrating superior efficiency and environmental compatibility compared to N-bromosuccinimide and selenium dioxide. The approach accommodates various aminopyrazoles with polymethoxy chalcone, facilitating quick access to a limited collection of purine-mimetic heterocycles with possible therapeutic relevance. The methodology tolerates the recyclable Mg–Al hydrotalcite catalyst and the use of ethanol as a benign solvent, aligning the overall process with the principles of sustainable chemistry through reduced energy input, low oxidant loading, and minimized waste generation.

An efficient, economical, and green, sustainable synthesis of fused azines using Mg-Al hydrotalcite under a high-pressure Q-Tube reactor has been developed. This reaction proceeds through the aza-Michael addition of α,β-unsaturated ketone with different aminoazoles. This method offered excellent yields in a short reaction time that economically saved energy in addition to the protocol showing the reuse of the catalyst seven times without losing its catalytic activity.

For the creation of adaptable carbonyl compounds in organic synthesis, the oxidation of alcohols is a crucial step. As a sustainable alternative to the harmful traditional oxidation processes, transition-metal catalysts have recently attracted a lot of interest in acceptorless dehydrogenation reactions of alcohols. Here, using well-defined, air-stable palladium(II)–NHC catalysts (A–F), we demonstrate an effective method for the catalytic acceptorless dehydrogenation (CAD) reaction of secondary benzylic alcohols to produce the corresponding ketones and molecular hydrogen (H₂). Catalytic acceptorless dehydrogenation (CAD) has been successfully used to convert a variety of alcohols, including electron-rich/electron-poor aromatic secondary alcohols, heteroaromatic secondary alcohols, and aliphatic cyclic alcohols, into their corresponding value-added ketones while only releasing molecular hydrogen as a byproduct.

Ultrasound-assisted synthesis of novel pyrazoles using Ni-Mg-Fe LDH as a catalyst in cyclopentyl methyl ether (CPME) is introduced. Different LDHs were tested as a catalyst for the synthesis of pyrazoles via a 1,3-dipolar cycloaddition reaction. Among them, Ni-Mg-Fe LDH was the superior catalyst for this reaction. This protocol offered high yields, a short reaction time, and a green solvent, and with the reuse of this catalyst six times with the same activity, it could be regarded as an ecofriendly, greener process. The NiMgFe LDH catalyst with the smallest particle size (29 nm) and largest surface area showed its superior efficacy for the 1,3 dipolar cycloaddition rection and can be successfully used in up to six catalytic cycles with little loss of catalytic activity. A plausible mechanism for this reaction over the Ni-Mg-Fe LDH is proposed.

Here, we report the fabrication of nZVI by the wet chemical technique in the presence of ethanol using ferric iron and sodium borohydride as the reducing agents under ambient conditions. The obtained nZVI particles are mainly in a zero-valent oxidation state and do not undergo significant oxidation for several weeks. The structural and morphological parameters of nZVI were investigated by using UV, XRD, SEM, EDX, TEM, and DLS analysis. The optical nature, bandgap energy, and absorption edge were all revealed by the UV–visible spectrum. The phase development and crystallinity of nZVI particles were shown by the XRD pattern. The morphological investigation revealed that the nanoparticles were spherical with an average size of 34–110 nm by using ImageJ software, and the elemental analysis was analyzed using EDX. Furthermore, the catalytic treatment performance of domestic wastewater was evaluated in terms of pH, COD (chemical oxygen demand) solubilization, total solids (TS), volatile solids (VS), phosphorous, and total nitrogen (TN) reduction under aerobic and anaerobic operating conditions. The effluent was subjected to a process evaluation with a different range (100–500 mg/L) of nZVI dosages. The COD solubilization and suspended solids reduction were significantly improved in the anaerobic condition in comparison to the aerobic condition. Furthermore, the effect of nZVI on phosphorous (PO₄³⁻) reduction was enhanced by the electrons of iron ions. The high concentration of nZVI dosing has a positive impact on COD solubilization and phosphorous removal regardless of the aeration condition with 400 mg/L of nZVI dosage.