Synthesis of partly-fluorinated ethers: reaction of perfluoroalkoxyethylene or perfluorobenzene derevatives with various alcohols

Abstract

Fluoroorganic compounds have attracted a great deal of interest due to their peculiar physical and biological properties. Accordingly, development of a synthetic method for the preparation of fluoroorganic compounds with typical characteristics has become an important issue in fluoroorganic chemistry.’ Perfluorinated trialkylamines and dialkyl ethers have been particularly focused on since they are characterized not only by low freezing points, high volatility, improved electrophysical and thermophysical characteristics but also by an excellent lubricating property .’ Moreover, some of perfluorinated organic compounds are also useful as an oxygen-canying liquid in biology and medi~ine.~ These fluoroogranic compounds have been prepared from hydrocarbon precursors either by electrochemical fluorination4 or by direct fluorinationS with Fz. Unfortunately, those synthetic methodologies provide only low yields of the desired products due to the occurrence of destructive products. On the other hand, fluorination with other chemicals usually requires hazardous and/or expensive fluorinating reagents. It is noteworthy, however, that perfluorination of partly-fluorinated starting materials gives better yields of the desired products because of the lower degree of the destruction process and the easiness of control of fl~orination.~” Moreover, several by-products obtained from polymerization of tetrafluoroethylene or hexafluoroepoxypropylene can be used as starting materials in the synthesis of more complex partly-fluorinated organic compounds,* For example, a,a,o-trihydroperfluorinated alcohols, H(CF2CF2),CH20H, n = 1-4, which are the by-products in the synthesis of polytetrafluoroethylene might be a good and cheap starting material for the synthesis of partly-fluorinated organic compound^.^^'^^^^ The fluorinated alcohols .have been applied to the reaction with 2,3,4,5,6-pentafluorostyreneMaH’2, decafluoroazobenzene/CsF l 3 or decafluoro-mdimethylbenzene/NaOH 4. In this paper we would like to publish a simple and convenient method for the synthesis of partlyfluorinated alkyl aryl ethers by using a polyfluorobenzene derivative (octafluorotoluene (1) or hexafluorobenzene (2)) and a,a,o-trihydroperfluorinated alcohols. The reaction of octafluorotoluene with a,cc,otrihydroperfluorinated alcohols, H(CF2CFz),CH20H, n = 1-4 in acetonitrile (or DMF) in the presence of an equimolar amount of KOH provides the fluorinated alkyl aryl ethers 3 8 (Scheme 1).