Sonochemical synthesis of methyl-4-(hetero)arylmethylene isoxazole-5(4H)-ones using SnII-montmorillonite

Tin exchanged montmorillonite K10 (Sn^II-Mont K10) was prepared by ion exchange between SnCl₂ and montmorillonite K10. The Sn^II-Mont K10 was characterized by X-ray diffraction, scanning electron microscope and energy-dispersive X-ray spectroscopy. The synthesized Sn^II-Mont K10 was used as a recoverable solid catalyst for synthesis of 3-methyl-4-arylmethylene isoxazole-5(4H)-ones via one-pot multicomponent cyclocondensation of hydroxylamine hydrochloride, ethyl acetoacetate and benzaldehyde derivatives in water under ultrasound irradiations. The yields of products were obtained 87–96%. The remarkable advantages of this method are a low-cost and eco-friendliness catalyst, rapid completion of the reactions, and avoidance of using organic solvents, excellent yield and mild conditions.     

Catalytic performance in 4-nitrophenol reduction by Ag nanoparticles stabilized on biodegradable amphiphilic copolymers

Biodegradable copolymers have received much more attention in the last decades due their potential applications in the fields related to environmental protection, medicine, agriculture, and the chemical processes. Silver nanoparticles (Ag NPs) were prepared via reduction of silver nitrate (AgNO₃) using biodegradable amphiphilic copolymers in aqueous solution. The micelles were constructed from the amphiphilic copolymer composed of poly(2-ethyl-2-oxazoline) and poly(ε-caprolactone). The Ag NPs with a diameter of 10–15?nm were found to show a comparable high catalytic activity toward the reduction of 4-nitrophenol (4-NP) in the presence of an excess amount of NaBH₄. The synthesized Ag NPs-loaded copolymer exhibits high catalytic activity for the reduction of 4-NP to 4-aminophenol.     

Ni ion-containing immobilized ionic liquid on magnetic Fe3O4 nanoparticles: An effective catalyst for the Heck reaction

In this work, we synthesized Ni²⁺-containing 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride ionic liquid on magnetic Fe₃O₄ nanoparticles. The catalytic activity of these novel nanocomposites was finally evaluated for the Heck reaction at 100 °C, and can be reused after washing without loss in activity. The immobilized ionic liquid catalysts proved to be effective and easily separated from the reaction media by applying an external magnetic field. This procedure has many obvious advantages compared to those reported in the previous literature, including avoidance of the use of the expensive Pd catalysts, mild reaction conditions, high yields, and simplicity of the methodology.