LiHSO₄/SiO₂ as a New, Efficient and Reusable Catalytic System for the Chemoselective Conversion of Aldehydes to Acylals under Solvent‐Free Conditions

Abstract

A highly efficient, green and expeditious solvent-free method is described for the chemoselective conversion of aldehydes to the corresponding acylals in excellent yields, using acetic anhydride in the presence of catalytic amount (20 mol%) of silica-supported LiHSO4. Ketones does not react under these reaction conditions. LiHSO4/SiO2can be recovered and reused without any significant loss of its catalytic activity.

Sulfonated polyethylene glycol (PEG-OSO3H) as a polymer supported biodegradable and recyclable catalyst in green organic synthesis: recent advances

“…40 Here, PEG-OSO 3 H acts as a catalyst and can be recovered and reused eight times without apparent loss of its catalytic activity. 48 The best results were obtained, when 1.67 mol% of the catalyst was used. The recovered catalyst was dried under vacuum condition at 40 C and reused.…”

One-pot synthesis of multisubstituted imidazoles under solvent-free conditions and microwave irradiation using Fe3O4@SiO2–imid–PMAnmagnetic porous nanospheres as a recyclable catalyst

“…As it was shown inTable 1, solvent free condition at 110 ºC During the past two decades many investigations have established the critical role of microwave irradiation in the rate acceleration of diverse chemical reactions 31. The size distribution of these is centered at a value of 55 nm.…”

Alum-Catalyzed Domino Synthesis of 12-Substituted-8,9,10,12-tetrahydrobenzoxanthen-11-ones Under Solvent-Free Conditions

“…[9] Several methods are known in the literature for the preparation of tetrahydrobenzoxanthenones. Among them, the most widely used is a one-pot, multicomponent condensation of dimedone, substituted aldehydes, and naphthols in the presence of catalysts such as InCl 3 =P 2 O 5 , [10] [Et 3 N-SO 3 H]Cl, [11] p-toluenesulfonic acid=ionic liquid, [12] dodecatungstophosphoric acid, [13] iodine, [14] HClO 4 =SiO 2 , [15] proline triflate, [16] Sr(OTf) 2 , [17] H 14 [NaP 5 W 30 O 110 ], [18] CuSO 4 =SiO 2 , [19] thiamine hydrochloride, [20] tetra(n-butyl)ammonium fluoride, and cerric ammonium nitrate. [21] However, most of these methods suffer from one or more of the drawbacks such as unsatisfactory yields, long reaction times, lack of general applicability, use of expensive catalysts, halogenated and volatile solvents, tedious experimental procedures, and poor compliance with the green chemistry protocols.…”