Anaquest, Inc.

The Boc Group, Inc.

Boc, Inc.

Ohmeda Pharmaceutical Products Division Inc.

Gerald G Vernice

Chialang Huang

Leonid A Rozov

Donald F Halpern

Fernando Quiroz

Palmer W Townsend

An improved process for the production of isoflurane is disclosed. Isoflurane is formed by the exhaustive chlorination of 2,2,2-trifluoroethyl difluoromethyl ether with chlorine gas. The reaction mixture, preferably without purification or refining, is treated with UV light in the presence of isopropanol to reduce 1,1-dichloro-2,2,2-trifluoroethyl difluoromethyl ether, the other major component thereof, to isoflurane. Isoflurane is thereby obtained in yields of at least 80%.

Preparation of isoflurane

A process for the preparation of highly purified optical isomers of desflurane, i.e. 2-(difluoromethoxy)-1,1,1,2-tetrafluoroethane, is described wherein the highly purified opposite optical isomer of iso-flurane is reacted with bromine trifluoride in the cold, preferably in the presence of a solvent. A preferred solvent is bromine. The highly purified positive isomer of desflurane is advantageous over the negative isomer or the racemate.

Preparation of purified optical isomers of desflurane

An improved preparation of desflurane, 1,2,2,2-tetrafluoroethyl difluoromethyl ether utilizing hexafluoropropene epoxide as a starting material. Hexafluoropropene epoxide is advantageous in that it is relatively inexpensive and is environmentally acceptable.

Synthesis of desflurane

Fluoromethyl 1,1,1,3,3,3-hexafluoro-2-propyl ether is prepared by reacting bromine trifluoride and methyl 1,1,1,3,3,3-hexachloro-2-propyl ether or chloromethyl 1,1,1,3,3,3-hexachloro-2-propyl ether. The mixed fluorochloro ether intermediates having the formula of ##STR1## (wherein x+y=3, a+b=3, and Z=H Cl, or F) are converted to fluoromethyl 1,1,1,3,3,3-hexafluoro-2-propyl ether by reactions with bromine trifluoride.

Method for the preparation of fluoromethyl

A continuous process is disclosed for preparing 2,2,2-trifluoroethanol from 2-halo-1,1,1-trifluoroethane, preferably 2-chloro-1,1,1-trifluoroethane. In the process, 2-halo-1,1,1-trifluoroethane, a carboxylic acid salt and an hydroxylated compound such as water are continuously provided to a reaction mixture in a reactor. The 2-halo-1,1,1-trifluoroethane, the carboxylic acid salt and the hydroxylated compound are reacted therein at a reaction pressure at or above the autogenously developed pressure and at a reaction temperature of from about 223.degree. C. to about the critical temperature of the hydroxylated compound. At least a portion of the reaction product mixture is continuously withdrawn from the reactor and unreacted 2-halo-1,1,1-trifluoroethane is separated therefrom. The separated unreacted 2-halo-1,1,1-trifluoroethane is recycled as part of the 2-halo-1,1,1-trifluoroethane provided to the reaction mixture. The 2,2,2-trifluoroethanol is recovered from the reaction product mixture.

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Nutley, NJ, United States of America

Gerald G Vernice