Cobalt(II) Chloride Hexahydrate as an Efficient and Inexpensive Catalyst for the Preparation of Biscoumarin Derivatives

Abstract

Cobalt(II) chloride hexahydrate (CoCl 2 ⋅6H 2 O) has been found to be an efficient catalyst for the one-pot synthesis of biscoumarin derivatives through a combination of aromatic aldehydes and 4-hydroxycoumarin in aqueous media at 70 ∘ C. Several types of aromatic aldehyde, containing electron-withdrawing groups as well as electron-donating groups, were used in the reaction and in all cases the desired products were synthesized successfully. The present approach offers remarkable advantages such as short reaction times, excellent yields, straightforward procedure, easy purification, environment friendliness, and low catalyst loading.

Tannic acid: An Efficient Catalyst for the Synthesis of Bis-(4-hydroxycoumarin-3-yl)methanes

“…These compounds are also utilized as urease inhibitors 3 . A number of methods have been reported for the synthesis of these compounds in the presence of various catalysts like molecular iodine like molecular iodine 4 , tetrabutylammonium bromide (TBAB) 5 Manganous chloride (MnCl2 _ 4H2O) 6 sodium dodecyl sulfate(SDS) 7 , tetrabutylammoniumhexatungstate ([TBA]2[W6O19]) 8 , sulfated titania(TiO2/SO4) 9 , ruthenium(III) chloride hydrate (RuCl3⋅nH2O) 10 , Cobalt(II) chloride hexahydrate 11 , tungstate sulfuric acid 12 , NaHSO4.SiO2/ Indion 190 resin 13 , Fe3O4 nanoparticles 14 Nano TiO2@KSF 15 Boron Sulfonic Acid 16 . Although various procedures are reported for the synthesis of bis-(4hydroxycoumarin)methanes, disadvantages including low yields of products, long reaction times, nonrecyclable catalyst, use of an excess of reagents or catalysts, and harmful and corrosive solvents.…”