in recent years, zinc oxid nanotubes have attracted much attention. the direct use of , zinc oxidnanotubes modified by sio2 as recoverable catalysts for organic reactions is very rare. the catalystswere characterized by xrd. the average particle size of zno catalysts is 57 nm and there are highdensitydefects on nanotubes surfaces . a simple and efficient method for the imidazol derivativessynth...

nano-silica supported boron trifluoride (bf3.sio2) is an efficient, reusable and eco-friendly catalyst for chemoselective thioacetalization of aldehydes and ketones. so, this catalyst was applied for transthioacetalization of acetals and acylals into their corresponding 1,3-dithiolanes or 1,3-dithianes  in good to excellent yields. the reactions were carried out at room temperature under solven...

ammonium monovanadate (nh4vo3) has been devoted as an efficient, commercially available, eco-friendly and reusable catalyst for the synthesis of bis(indolyl)methanes (bims), oxindole derivatives and also michael adducts of indoles at 50 °c under solvent-free conditions. the reusability of this solid acid catalyst in addition with its selectivity has also been examined.

the reaction of 3-chloropropyl boehmite nanoparticles with caffeine and sulfuric acid afforded bnps-3-propyl-imidazolopyridinium hydrogen sulfate [bnps-caff]hso4 as a new bnps-supported ionic liquid (il) catalyst. [bnps-caff]hso4 proved to be an efficient heterogeneous catalyst for the synthesis of pyrazolopyranopyrimidines via a one-pot four-component reaction of hydrazine hydrate, ethyl aceto...

cobalt hydrogensulfate is an efficient catalyst for the condensation of β-naphthol, aromatic aldehydes and 5,5-dimethyl-1,3-cyclohexanedione at 120 °c to afford 9,9-dimethyl-12-phenyl-8,10,11,12-tetrahydro-9-h-benzo[a]xanthen-11-one derivatives in high yields. also, polycondensation reactions of phenols with phthalic anhydride were carried out in the presence of cobalt hydrogensulphate under so...

a  convenient  and  efficient  one-pot  four-component  synthesis  of  1,  2,  4,  5-tetrasubstituted  imidazoles  using  nano  tio2  as  a  recyclable  catalyst  is  reported.  the results  show  that  the  methodology  has  several  advantages  such  as  low  loading  of catalyst,  excellent  yield,  short  reaction  time,  operational  simplicity  and  solvent-free conditions.

nano-sbcl5.sio2 and sbcl5.sio2 are bench-top catalysts which are reusable, readily available, versatile andefficient for promotion of many acid catalyzed organic reactions. these catalysts do not need specialprecautions for preparation, handling or storage, and they can be stored at an ambient temperature for monthswithout losing their catalytic activity. 4-dihydropyrimidin-2(1h)-ones(thiones) ...

1,2-Diketones have been reacted in one-pot method with 1,2-diamines at room temperature with ZnO nanoparticles as a catalyst. ZnO nanoparticles as an available and reusable catalyst is used for the synthesis of Quinoxalinein improved yields.

Palladium on charcoal serves as an efficient and reusable solid supported catalyst for the Sonogashira coupling of aryl chlorides with terminal acetylenes in the presence of a bulky, electron-rich biphenyl type ligand (XPhos), without copper co-catalyst.

Deprotection of various phenols from their respective methoxymethyl ethers using an heteropolyacid catalyst was studied. The catalyst was the Wells-Dawson heteropolyacid, used both in bulk or supported on silica. Yields were high to quantitative after less than one hour reaction time and the catalyst was easily recoverable and reusable.