Wells-Dawson heteropolyacid

Zeolite Y, Envirocat EPZG," CAN, silica gel, Montmorillonite clay K 10 or KSF, InBrs/polyethylene glycol, " Fe2(S04)3-xH20, " Well-Dawson heteropolyacid,CBr4, SnCL 21120,NaHS04, polyethylene glycol. ... 

Fosfotungstic and fosfomolybdic Wells-Dawson heteropolyacids, HgPjWisOgj-xHjO and HgPjMoigOgj.xHjO, respectively, were synthesized through ion exchange with a higher yield (-90%) than the conventional organic route (-70%). 

Bennardi, D.O., Romanelh, G.P., Jios, J.L., Autino, J.C., Baronetti, G.T., Thomas, H.J. 2008. Synthesis of snbstituted flavones and chromones using a Wells-Dawson heteropolyacid as catalyst. ARKIVOC (xi) 123-130. 

Park DR, Park S, Choi JH, Song IK (2010) Acidity of group 5 metal (V, Nb, Ta)-substituted Keggin and Wells-Dawson heteropolyacid (HPA) catalysts and their application to esterification of acetic acid with ethanol. Catal Lett 135 269-274... 

Aguirre et al. were able to conclude that the acetate species are spectators in the decomposition of acetic anhydride on a Wells-Dawson heteropolyacid [23], The acetate species were present in the time-resolved ATR-Fourier transform infrared spectroscopy (FT IR) spectra but disappeared in all phase angles of the demodulated spectra. Aguirre et al. were also able to identify key intermediates. 

In general, the structure of the heteropolyacids possesses a certain contribution of microporosity, and the pseudoliquid behavior that allows the adsorption of alcohol on the external surface and within the tertiary structure of heteropoly compounds (see Table 5.1). The abnormally high Ns of the fosfomolybdic Wells-Dawson acid is attributed to the presence of ethanol derived species, modifying the pore structure of the HPA. In fact, previous investigations demonstrated that the number of surface acid sites is directly influenced by the hydration water because fiilly... 

Gharib A, Jahangir M, Seheeren JHW (2010) A method for catalytic synthesis of convenient thioxanthone crown ethers using Wells-Dawson, H [P2W,j0 j] and Preyssler Hj lNaPjWjjOjjii], heteropolyacid catalysts. Bulg Chem Commun 42 214-221... 

Heravi MM, Bakhtiari K, Bamohairam FF, Tehrani M (2007) Wells-Dawson type heteropolyacid catalyzed synthesis of quinoxaUne derivatives at room temperature. Monatsh Chem 138 465 67... 

H6P2W18O62 I8H2O, a Wells-Dawson type heteropolyacid, has been effectively exploited as a catalyst for a three-component one-pot S5mthesis of [l,2,4]triazolo/benzimidazolo-quinazolinone derivatives [49] (Scheme 29). Condensation of 2-aminobenzimidazole and 3-amino 1,2,4-triazole, as amine sources, with dimedone and different aldehydes in the presence of this green and reusable catalyst in refluxing acetonifrile affords the heterocycles in good yields. 

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