Alcohols dimethyl sulfoxide-phosphorus pentoxide

Secondary and tertiary alcohols can be dehydrated in dimethyl sulfoxide when heated to 160 -185°C for 14-16 hr to give olefins in yields of 70-85% [6]. The solution is diluted with water, extracted with petroleum ether (30°-60 C), dried, and then distilled. Other acid catalysts that have been reported for dehydration of alcohols are anhydrous or aqueous oxalic [7, 8], or phosphoric acid [9], and potassium acid sulfate [10,11]. In addition, acidic oxides such as phosphorus pentoxide [10-12] and acidic chlorides such as phosphorus oxychloride or thionyl chloride [13] have been reported to be effective as catalysts for the dehydration reaction. 

---