A method for the preparation of sevoflurane which comprises (a) providing a liquid mixture of (CF.sub.3).sub.2CHOCH.sub.2Cl, hydrogen fluoride, and an amine and (b) reacting the mixture, to form (CF.sub.3).sub.2CHOCH.sub.2F.

Fluoromethyl fluoropropyl ethers, e.g. CHF.sub.2 --O--CH.sub.2 CF.sub.2 CF.sub.3 and CHF.sub.2 --O--CF.sub.2 CHFCF.sub.3, useful for antipsychotic treatment by inhalation sufficient to induce therapeutic convulsions.

Fluoromethyl fluoropropyl ethers, e.g. CHF.sub.2 --O--CH.sub.2 CF.sub.2 CF.sub.3 and CHF.sub.2 --O--CF.sub.2 CHFCF.sub.3, useful for antipsychotic treatment by inhalation sufficient to induce therapeutic convulsions.

The method of removing fluorinated olefin byproduct formed during the synthesis of a fluoromethylhexafluoroisopropyl ether product or the like comprises: adding ammonia or an amine to the mixture to react with the fluorinated olefin byproduct, and thereafter distilling the fluoromethylhexafluoroisopropyl ether product to remove it from the byproduct.

Sodium or potassium fluoride has been found to efficiently fluorinate the chloro atom adjacent the ether oxygen in chloro-fluoro organic ethers. The reaction proceeds efficiently without added solvent at an elevated temperature and pressure.