Sulfonated Honeycomb Coral (HC-SO3H): a new, green and highly efficient heterogeneous catalyst for the rapid one-pot pseudo-five component synthesis of 4,4′-(aryl methylene) bis(3-methyl-1H-pyrazol-5-ol)s

Microwave-driven oleic acid esterification over chlorosulfonic acid-treated hydroxyapatite: synergism for intensified biodiesel production

Treating hydroxyapatite (HAP) with sulfonic acid without structural destruction remains challenging owing to the sensitivity of HAP to acidic pH. In this work, natural derived HAP was prepared using natural phosphate via a dissolution/precipitation process. Notwithstanding the challenge, the prepared HAP was treated with three concentrations of chlorosulfonic acid in dichloromethane to prepare HAP-S1, HAP-S2 and HAP-S3 depending on the acid content under carefully controlled conditions. The treatment of HAP with the lowest acid concentration led to the preservation of the apatite framework with surface modification of sulfonic acid groups. As the acid concentration increased, HAP, CaHPO4 and CaSO4 were obtained. A further increase in the acid concentration led to the formation of CaSO4 with the coexistence of Ca(H2PO4)2·H2O. Subsequently, the catalytic activity of HAP-S1 was evaluated in oleic acid esterification under microwave irradiation, resulting in a yield of up to 87% under optimized conditions of 10 wt% of catalyst to oleic acid weight, 10 : 1 methanol to oleic acid molar ratio, and 40 min reaction duration under microwave irradiation at 150 °C. The activity of HAP-S1 was attributed to the active S[double bond, length as m-dash]O and S-O-H functional groups, and a possible mechanism of acid-catalyzed esterification is proposed. The catalyst was also tested in the transesterification reaction of rapeseed oil, achieving a conversion of 40.2% after 60 min reaction duration under microwave irradiation. Furthermore, the catalyst was evaluated in a two-step esterification reaction to investigate its activity towards acidified feedstocks. Results showed that after two successive runs, acidity was reduced by 79.6% with a total FAME yield of 40.13%. The obtained results indicate that this catalyst, being an acid catalyst, is more suitable for direct esterification.

Poly(aniline-co-melamine)@MnFe2O4 nanocatalyst for the synthesis of 4,4′-(arylmethylene) bis (1H-pyrazole-5-ol) derivatives, and 1,4- dihydropyrano[2,3-c]pyrazoles and evaluation of their antioxidant, and anticancer activities

In this work, magnetic poly(aniline-co-melamine) nanocomposite as an efficient heterogeneous polymer-based nanocatalyst was fabricated in two steps. First, poly(aniline-co-melamine) was synthesized through the chemical oxidation by ammonium persulfate, then the magnetic nanocatalyst was successfully prepared from the in-situ coprecipitation method in the presence of poly(aniline-co-melamine). The resulting poly(aniline-co-melamine)@MnFe₂O₄ was characterized by FTIR, FESEM, XRD, VSM, EDX, TGA, and UV-vis analyses. The catalytic activity of poly(aniline-co-melamine)@MnFe₂O₄ was investigated in the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazole-5-ol) derivatives, and new alkylene bridging bis 4,4′-(arylmethylene)bis(1H-pyrazole-5-ol) derivatives in excellent yields. The yield of 1,4-dihydropyrano[2,3-c]pyrazoles, 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol), yields, and new alkylene bridging bis 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol) derivatives were obtained 89%–96%, 90%–96%, and 92%–96%, respectively. The poly(aniline-co-melamine)@MnFe₂O₄ nanocatalyst can be recycled without pre-activation and reloaded up to five consecutive runs without a significant decrease in its efficiency. In addition, the antioxidant activity of some derivatives was evaluated by DPPH assay. Results showed that the maximum antioxidant activity of 4,4′-(arylmethylene)bis(1H-pyrazole-5-ol) derivatives and 1,4-dihydropyrano[2,3-c]pyrazoles were 75% and 90%, respectively. Furthermore, 4,4′-(arylmethylene)bis(1H-pyrazole-5-ol) derivatives and 1,4-dihydropyrano[2,3-c]pyrazoles showed good potential for destroying colon cancer cell lines. Consequently, the poly(aniline-co-melamine)@MnFe₂O₄ nanocomposite is an excellent catalyst for green chemical processes owing to its high catalytic activity, stability, and reusability.

Waste-to-wealth transition: application of natural waste materials as sustainable catalysts in multicomponent reactions

Application of natural waste materials as sustainable catalysts in multicomponent reactions.

Polyethylene glycol-bonded triethylammonium l-prolinate: a new biodegradable amino-acid-based ionic liquid for the one-pot synthesis of bis(pyrazolyl)methanes as DNA binding agents

[PEG-TEA]LP, as a new biodegradable ionic liquid catalyst, was successfully synthesized, characterized, and applied to the one-pot pseudo-five-component synthesis of bis(pyrazolyl)methanes.

ZnII doped and immobilized on functionalized magnetic hydrotalcite (Fe3O4/HT-SMTU-ZnII): a novel, green and magnetically recyclable bifunctional nanocatalyst for the one-pot multi-component synthesis of acridinediones under solvent-free conditions

Herein, the catalytic activity of a novel synthesized Fe₃O₄/HT-SMTU-Zn^II nanocatalyst, in the green and efficient synthesis of acridinediones, is described.

Cu(ii)-grafted SBA-15 functionalized S-methylisothiourea aminated epibromohydrin (SBA-15/E-SMTU-CuII): a novel and efficient heterogeneous mesoporous catalyst

The catalytic activity of novel synthesized SBA-15/E-SMTU-Cu^II nanocatalyst was investigated for the green, one-pot, pseudo five-component synthesis of tetrahydropyridine derivatives.