Sulfonic acid-functionalized ordered nanoporous Na+-montmorillonite (SANM): A novel, efficient and recyclable catalyst for the chemoselective N-Boc protection of amines in solventless media

Magnetically Recoverable Silica-Decorated Ferromagnetic-Nanoceria Nanocatalysts and Their Use with O- and N-Butyloxycarbonylation Reaction via Solvent-Free Condition

Silica-decorated ferrite nanoparticles, a new kind, coated with ceric ammonium nitrate (CAN), have been prepared successfully by simple coprecipitation techniques. Powder X-ray diffraction spectroscopy (PXRD), Fourier transform-infrared spectroscopy (FT-IR), field emission-scanning electron microscope (FE-SEM), wavelength-dispersive X-ray spectroscopy (WDX), energy-dispersive spectroscopy (EDS), inductive coupled plasma-optical emission spectroscopy (ICP-OES), and thermogravimetric analysis (TGA) techniques were used to characterize these nanoparticles. The catalysts are further studied for catalytic activity in solvent-free conditions. Importantly, these nanoparticles have been collected from the reaction mixture using an external magnet and recycled up to minimum of 15 cycles with no substantial loss of catalytic characteristics.

Sulfonyl-bridged (copper-immobilized nickel ferrite) with activated montmorillonite, [(NiFe2O4@Cu)SO2(MMT)]: a new class of magnetically separable clay nanocomposite systems towards Hantzsch synthesis of coumarin-based 1,4-dihydropyridines

In this study, the synthesis of a new class of magnetic clay-based nanocomposites by bridging of sulfonyl groups between copper-immobilized nickel ferrite (NiFe₂O₄@Cu) and activated montmorillonite is described. Synthesis of the clay nanocatalyst was carried out via the activation of montmorillonite by ClSO₃H to afford sulfonated montmorillonite. The modified montmorillonite was then reacted with copper-layered nickel ferrite to afford the magnetic clay nanocomposite [(NiFe₂O₄@Cu)SO₂(MMT)]. Next, the characterization of porous materials was carried out using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller and vibrating sample magnetometer analyses. The obtained results showed that the clay nanocomposite containing a sulfonyl-bridge has a large surface area and magnetic properties versus the prepared one without the sulfonyl groups as (NiFe₂O₄@Cu)(MMT). The nanostructured clay had excellent catalytic activity towards the Hantzsch synthesis of coumarin-based 1,4-dihydropyridines via one-pot and three-component condensation of 4-hydroxycoumarin, aromatic aldehydes and ammonia. All reactions were carried out in water as a green and economic green solvent within 10–45 min to affords 1,4-DHPs in high to excellent yields. Reusability of the clay nanocomposite was investigated for six consecutive cycles without significant loss of catalytic activity. Based on this study, therefore, sulfonated montmorillonite could be considered an excellent support for the immobilization of magnetic materials.

In this study, the synthesis of a new class of magnetic clay-based nanocomposites by bridging of sulfonyl groups between copper-immobilized nickel ferrite (NiFe₂O₄@Cu) and activated montmorillonite is described.

ChemoselectiveN-tert-butyloxycarbonylation of amines in glycerol

The operational simplicity, cleaner reaction, rapid reaction convergence, functional group tolerance, excellent yield, high selectivity, catalyst-free feature and solvent recyclability are the distinct advantages of this protocol. This makes the protocol feasible, economical and environmentally benign.

Efficient one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones catalyzed by a new heterogeneous catalyst based on Co-functionalized Na+-montmorillonite

A facile and efficient solvent-free protocol for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones by using Co@imine-Na⁺-MMT as a new, environmentally friendly and reusable heterogeneous catalyst is reported.

Introduction of a new ionic liquid solid acid based on clay as an efficient, recyclable and thermally stable catalyst for organic transformations

Ammonium hydrogen sulfate based ionic liquid immobilized on Na⁺–montmorillonite (AHS@MMT) was prepared via anchoring ammonium hydrogen sulfate propyltriethoxysilane onto sodium montmorillonite by covalent bonds.

Introduction of taurine (2-aminoethanesulfonic acid) as a green bio-organic catalyst for the promotion of organic reactions under green conditions

Taurine (2-aminoethanesulfonic acid), a semi-essential amino acid that exists in the human body and numerous other living creatures, is used as a green bio-organic catalyst for the promotion of the Knoevenagel reaction between aldehydes and malononitrile.

(CTA)3[SiW12]–Li+–MMT: a novel, efficient and simple nanocatalyst for facile and one-pot access to diverse and densely functionalized 2-amino-4H-chromene derivatives via an eco-friendly multicomponent reaction in water

A simple, facile and highly efficient one-pot synthesis of a pharmaceutically interesting diverse kind of functionalized 2-amino-4H-chromene is reported.

A waste to wealth approach through utilization of nano-ceramic tile waste as an accessible and inexpensive solid support to produce a heterogeneous solid acid nanocatalyst: to kill three birds with one stone

Waste minimization through the utilization of cost-effective, available, and nontoxic nano-ceramic tile wastes for the heterogenization of sulfuric acid.