Metal(IV) phosphates as solid acid catalysts for selective cyclodehydration of 1,n-diols
Metal(IV) phosphates of tin, zirconium and titanium are applied, for the first time, as catalysts for selective cyclodehydration of butane-1,4-diol to tetrahydrofuran in high yields. Tin(IV) phosphate showed highest activity among the three, and was used as a catalyst for cyclodehydration of various 1,n-diols. Cyclodehydration of butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol and diethanolamine gave tetrahydrofuran, tetrahydropyran, oxapane and morpholine, respectively. Cyclodehydration of diethylene glycol, triethylene glycol, diethylene glycol monomethyl ether, polyethylene glycol 200 and polyethylene glycol 300 gave 1,4-dioxane.