miscible with water such solvents include cyclic ethers such as 2 5 dihydrofuran tetrahydrofuran dioxane and tetrahydropyran ethers such as alkyl ethers of alkylene glycols and polyalkylene glycols ketones such as acetone lactones of hydroxy organic acids such as butyrolactone organic acids such as acetic acid and propionic acid monoalcohols such as methanol ethanol and 2 ethylhexanol glycols such as ethylene glycol and 1 3 propylenediol and the like where it is desirable to use a mutual solvent system for the cis 1 4 dihalobutene 2 and water it is generally preferred to employ 2 5 dihydrofuran as the solvent for the sake of convenience and simplicity optionally the process can be carried out in the presence of a phase transfer agent to accelerate the transfer of water to the organic phase of the first stage hydrolysis reaction in the absence of a phase transfer agent contact of the cis 1 4 dihalobutene 2 with water proceeds slowly limiting the usefulness of the procedure as a viable commercial synthesis for tetrahydrofuran employing a phase transfer agent the hydrolysis stage herein proceeds at a much faster rate providing an economically efficient route to tetrahydrofuran phase transfer agents useful in the hydrolysis stage include quaternary ammonium or phosphonium salts in which the anion is halide hydroxide sulfate bisulfate phosphate and the like and the alkali metal tetraphenyl boron compounds some specific phase transfer agents which can be used herein with good results are tetradecyltrimethylammonium bromide tetradecyltributylammonium bromide and sodium tetraphenyl boron the reaction conditions for the first stage hydrolysis reaction are.