Silica-supported heteropolyacids as catalysts in alcohol dehydration reactions

Catalysts based on Keggin-type heteropolyacids supported on silica were pre pared for their use in dehydration of alcohols in liquid phase. Species pre sent in the catalysts were characterized by diverse physicochemical techniq ues, disclosing that both molybdophosphoric and tungstophosphoric acids are found with their primary Keggin structure intact. Their catalytic behavior was studied in the dehydration of alcohol of interest for the production o f intermediary compounds for fine chemical industries. Specifically, the de hydration of 1,2-diphenylethanol, 1-(3,4-dimethoxyphenyl)-2-phenylethanol a nd cholesterol was studied. It was obtained a process for the direct dehydr ation of cholesterol. It was found that the catalysts are very active and s elective, also allowing an easy separation from the reaction medium. The sa me catalysts were used several times without appreciable loss of catalytic activity and after the reaction they showed physicochemical properties simi lar to those of the original catalysts. (C) 2000 Elsevier Science B.V. All rights reserved.