Purification of desflurane containing R-123

Abstract

A process for preparing 2-difluoromethoxy-1,1,1,2-tetrafluoroethane (desflurane) comprising the following steps: (a) providing a first mixture comprising desflurane and 2,2-dichloro-1,1,1-trifluoroethane (R-123); (b) adding water to the first mixture to form a second mixture; and (c) fractionally distilling the second mixture to yield a desflurane product purer in R-123 than said the mixture. Also described is a purified desflurane product prepared by the process, and intermediate products comprising water added to a mixture of desflurane and R-123.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to the purification of 2-difluoromethoxy-1,1,1,2-tetrafluoroethane (desflurane), which is a well known inhalation anesthetic.[0003]2. Description of Related Art[0004]U.S. Provisional Application No. 60 / 643,301 describes a process for the preparation of desflurane by reaction of 2-chloro-2-difluoromethoxy-1,1,1-trifluoroethane (isoflurane) with hydrogen fluoride (HF) over a fixed bed catalysts. This process has a number of advantages in that it is greener than previous processes, highly efficient and adaptable to a continuous process.[0005]Even though this process also yields desflurane of a purity well within the specifications for anesthetic grade desflurane, the product contains a very small amount of 2,2-dichloro-1,1,1-trifluoroethane (R-123) as a by-product. Since R-123 and desflurane have similar boiling points (27° C. ) and 23° C., respectively) it is not easy to separate the R-123 fr...

AI Technical Summary

Problems solved by technology

Since R-123 and desflurane have similar boiling points (27° C. ) and 23° C., respectively) it is not easy to separate the R-123 from the desflurane by distillation.