Synthesis of cyclic ethers by cyclodehydration of 1, n -diols using heteropoly acids as catalysts

Abstract

Heteropoly acids were used as catalysts for cyclodehydration of various 1, n -diols. Cyclodehydration of butane-1,4-diol, pentane-1,5-diol and hexane-1,6-diol catalysed by H 3 PW 12 O 40 gave tetrahydrofuran, tetrahydropyran and oxepane, respectively. Cyclodehydration of diethylene glycol, triethylene glycol, diethylene glycol monomethyl ether and polyethylene glycol 200 catalysed by H 3 PW 12 O 40 gave 1,4-dioxane. In particular, cyclodehydration of hexane-1,6-diol gave an excellent yield of oxepane (80%). The selectivity exhibited by the H 3 PW 12 O 40 catalyst was even better than that exhibited by other reported catalyst systems for similar cyclodehydration reactions.