Cyclic ethers prodn from alpha, omega diols - by dehydration in aq soln contg hydrogen halide and a salt

Process for prodn. of cyclic ethers from alpha,omega-diols or mono- or diesters of these made by treatment with an acid, comprises treating the alpha,omega-diol (ester) which is capable of forming a cyclic ehter by splitting off water on an acid, with (a) a dil, hydrogen halide acid or an aq. acid with a dissociation constant in water of >=1.10-6, or with a cpd. which forms such acids in aq. soln., and (b) a salt, whereby either (a) and/or (b) gives halide anions. Simple process giving high yields of cyclic ether with min. by-prod. formation. In a typical process, butanediol-1, 4 is converted into tetrahydrofuran.