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A new strategy for a catalytic C−C bond forming cascade reaction comprising acetal hydrolysis and Knoevenagel condensation is presented here. The heterogeneous nanocatalyst is prepared by immobilizing an ionic liquid on the surface of highly monodisperse silica nanoparticles. This work is the first example of showing that there is no need to use bifunctional acid‐base catalysts for a cascade reaction including the hydrolysis of benzaldehyde dimethyl acetal to benzaldehyde and the subsequent Knoevenagel condensation of the resulting benzaldehyde with malononitrile. It is shown here that these reactions can proceed smoothly with a mono‐functional heterogeneous catalyst that contains a neutral ionic liquid. It has been proposed that such a neutral ionic liquid can "switch on" to an acidic catalyst in conjunction with water. The selected ionic liquid has potentially biodegradability characteristics, which is an important issue to achieve a sustainable catalyst. The simple procedure for preparing both the ionic liquid and the monodisperse silica nanoparticles provides opportunities for a large‐scale synthesis of the catalyst. This work introduces a breakthrough in the design and synthesis of heterogeneous catalysts for acid/base catalyzed cascade organic reactions. [ABSTRACT FROM AUTHOR]

• A protic pyridinium protic ionic liquid framework in Pechmann synthesis of coumarins. • Stability and efficiency of PMO-Py-IL in catalyzing reactions over several runs. • The ionic nature of PMO-Py-IL enhances mixture polarity leading to higher yields. • PMO-Py-IL provides a simple, eco-friendly method for coumarin synthesis. Oxygen-containing heterocycles hold diverse uses in biology and organic chemistry. Herein, a method utilizing a functionalized pyridinium protic ionic liquid framework (PMO-Py-IL) was developed for the solvent-free Pechmann synthesis of coumarins from phenols and ethyl or methyl acetoacetate. High to excellent product yields were obtained under the investigated conditions. PMO-Py-IL remained stable and reactive across multiple reaction runs (up to 12 times), showcasing its stability and efficiency. The ionic nature of the catalyst can increase the polarity of the reaction mixture, leading to improved solubility of reactants and facilitating their interaction. This ultimately stabilizes the intermediates and accelerates the reaction, resulting in higher yields of the desired product. This can further speed up the reaction and increase the yield of the desired product. The proposed approach provides an efficient, simple and easy work-up methodology for coumarin synthesis, with outstanding nanocatalyst's reusability, offering environmental and economic advantages. [Display omitted] [ABSTRACT FROM AUTHOR]

• Preparation of benzimidazoles from o-phenylenediamine and benzaldehyde derivatives. • Pyridinium protic ionic liquid-supported periodic mesoporous organosilica as catalyst. • Products obtained in excellent yields (>90 %) in water under mild reaction conditions. • PMO-Py-IL exhibited excellent reusability (at least ten reaction cycles). A highly efficient protocol is herein reported for the preparation of benzimidazole compounds from o-phenylenediamine and various benzaldehyde derivatives in the presence of heterogeneous pyridinium protic ionic liquids supported on periodic mesoporous organosilica (PMO) in water. The synthesis of three novel benzimidazole derivatives is also reported. The proposed approach successfully afforded products in good yield under mild reaction conditions. PMO-Py-IL exhibited excellent catalyst activity and reusability for at least ten reaction cycles with no significant activity loss. [Display omitted] [ABSTRACT FROM AUTHOR]

A Brønsted acidic, ionic liquid containing, heteropolyanion functionalized polysiloxane network was formed by self-condensation of dodecatungstophosphoric acid and a zwitterionic organosilane precursor containing both imidazolinium and sulfonate groups. The resulting hybrid material POS-HPA-IL was investigated as a catalyst for the selective esterification of dicarboxylic acids. [ABSTRACT FROM AUTHOR]

• Copper N-heterocyclic carbene complex (Cu-NHC@Pyrm-OMS) is immobilized on highly ordered mesoporous organosilica. • (Cu-NHC@Pyrm-OMS) is an efficient catalyst for oxidation of alcohols to carbonyl compounds under mild conditions. • The Cu-NHC@Pyrm-OMS nanocatalyst is highly selective for oxidation of primary alcohols to aldehydes with high yield. • The Cu-NHC@Pyrm-OMS nanocatalyst has a broad substrate scope under green reaction conditions. • The Cu-NHC@Pyrm-OMS nanocatalyst is recyclable for at least ten times. A highly ordered organic-inorganic hybrid nanomaterial containing copper N-heterocyclic carbene complex (Cu-NHC@Pyrm-OMS) was synthesized and characterized using various techniques including FTIR, MAS NMR, XRD, TGA, SEM, and TEM. Cu-NHC@Pyrm-OMS nanomaterial is highly efficient heterogeneous system towards the selective oxidation of primary and secondary alcohols to corresponding aldehydes and ketones under mild conditions. Moreover, the supported copper nanocatalyst exhibited outstanding stability and could be reused at least ten times, remaining almost unchanged from initial activity. This work has focused on sustainable and green chemistry that use recoverable nanocatalyst, clean oxidant and aqueous media. [Display omitted] [ABSTRACT FROM AUTHOR]

• Polysiloxane acidic ionic liquids containing pyridinium trifluoroacetate salts is an efficient catalyst for protection of carbonyl compounds as 1,3-dithianes. • The catalyst is highly chemoselective for thioacetalization of aldehydes in the presence of ketones • The catalyst has a broad substrate scope under green reaction conditions. • The catalyst is reusable for at least 12 times. Dithioacetals are a well-known class of organic compounds as both protecting group for the carbonyl compounds and valuable synthons for organic synthesis. Polysiloxane acidic ionic liquids containing pyridinium trifluoroacetate salts (PMO-Py-IL) as organic-inorganic hybrid nanomaterial was studied for the transformation reaction of dithiols to aldehydes and ketones. Cyclic dithiacetals were obtained in excellent yield under mild reaction conditions. PMO-Py-IL nanocatalyst also demonstrated to be an efficient catalyst in chemoselective dithiacetalization of aldehydes in the presence of ketones. The catalyst could be separated and reused in several reaction runs without any remarkable reduction in its catalytic activity. Mild reaction conditions, short reaction time, cost effectiveness, eco-friendly nature with high chemoselectivity, and ease of isolation of the product make the present procedure sustainable and effective. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Protic pyridinium-based ionic liquid nanomaterial was successfully synthesized. • Supported protic ionic liquid showed high efficiency in esterification of free fatty acid to biodiesel. • Development of an eco-friendly and feasible method for sustainable biodiesel production. • Recycled supported protic ionic liquid can be reused up to ten times. Polysiloxane acidic ionic liquids containing pyridinium trifluoroacetate salts (PMO-Py-IL) were synthesized from pyridine containing organosilane precursors. Characterization by SEM, XRD, TGA, and nitrogen porosimetry confirmed that both pyridinium cation and trifluoroacetate anion were successfully incorporated within the organosilica network. The resulting organic-inorganic hybrid nanomaterial (PMO-Py-IL) was studied as nanocatalyst in free fatty acids esterification into biodiesel-like compounds. Remarkably, the synergistic hydrophilic/hydrophobic effect of pyridinium and trifluoroacetate ionic liquid in the well-ordered channels of PMO-Py-IL nanomaterial enhanced the activity toward sustainable biodiesel-like esters production. More importantly, PMO-Py-IL nanocatalyst also exhibited an exceptional activity and stability. The catalyst could be easily separated to reuse at least in ten reactions runs preserving almost intact its catalytic activity under otherwise identical conditions to those employed for the fresh catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ionic Liquid containing tungstate polysiloxane network (PMO-IL-WO 4 2 -). • Self-condensation of tungstic acid and zwitterionic organosilane precursor. • PMO-IL- WO 4 2- highly active in the selective aerobic oxidation of alcohols. • Broad substrate scope for reliable aerobic oxidation reactions. • Outstanding stability for at least ten reactions run. A Brönsted acidic Ionic Liquid containing tungstate anion functionalized polysiloxane network (PMO-IL-WO 4 2 -) was synthesized by simple self-condensation of tungstic acid and zwitterionic organosilane precursor possessing both imidazolium and sulfonate groups. Characterization by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), thermal gravimetric analysis TGA, nitrogen porosimetry, solid-state NMR spectroscopy and elemental analysis confirmed that both imidazolium cation and tungstate anion of zwitterion are successfully incorporated inside the organosilica framework. The catalytic activity of resulting hybrid PMO-IL- WO 4 2- material was studied in the selective aerobic oxidation of primary and secondary alcohols using an atmospheric pressure of air in pure water. Due to the ionic liquid-based charged surface containing hydrophilic sulfonic acid and tungstate group, the synergistic hydrophilic/hydrophobic and redox effect of PMO-IL-WO 4 2 - as water-friendly catalyst facilitates and enhances the activity and selectivity toward the target oxidative products in water and proved to have a particularly broad substrate scope for reliable aerobic oxidation reaction. Furthermore, the catalyst showed outstanding stability and could be easily separated and reused at least ten reactions run under the same conditions as fresh catalyst without any loss of catalytic activity and product selectivity. [ABSTRACT FROM AUTHOR]