US 5,672,767 AGranted

Process for preparing polyether compounds

AssigneeBNFL Fluorochemicals Ltd.

InventorsRichard Dickinson Chambers, Andrew Keith Joel

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Abstract

A process for the preparation of a perfluoropolyether having a general formula: ##STR1## as defined hereinbefore, which process includes the direct fluorination with elemental fluorine of a polyether having a general formula: ##STR2## as defined hereinbefore, wherein the fluorination is carried out in the presence of a solvent which is an ether having at least one substituent R.sub.F, wherein R.sub.F is a fluorinated hydrocarbon group. The said solvent ether is preferably a fluorinated volatile ether. The said solvent ether preferably has at least two groups R.sub.F which may be the same or different groups. Each group R.sub.F preferably has from two to four carbon atoms and at least two fluorine atoms. The said solvent ether may be an alicyclic ether having from 3 to 5 carbon atoms in its alicyclic ring. The intermediate polyether of formula (2) may be prepared by a process in which an appropriate straight-chained or cyclic polyether is reacted with an appropriate fluoroalkene in the presence of a sensitising medium and ultra-violet radiation is applied to energise the medium and promote multiple fluorination.

Claims12

Dependent claims

In a process for the preparation of a perfluoropolyether having the formula:

##STR27## wherein R.sup.6 to R.sup.14 each represents a fully fluorinated hydrocarbon group, x is an integer and each of y and z is zero or an integer, and the sum of x, y and z is at least 2 and not greater than 100, which process includes direct fluorination with elemental fluorine of a polyether having the formula:
##STR28## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 each represent substituted or unsubstituted hydrocarbon groups, which groups may differ, R.sub.F.sup.1, R.sub.F.sup.2, R.sub.F.sup.3, and R.sub.F.sup.4 each represent fluorine-containing hydrocarbon groups containing at least two carbon atoms and at least two fluorine atoms, which groups may differ, or the combination R.sup.1 --R.sub.F.sup.1 or the combination R.sup.5 --R.sub.F.sup.4 or both represent a fluorine-containing alkyl or alkenyl group, x is an integer and each of y and z is zero or an integer, and the sum of x, y and z is at least 2 and not greater than 100,
the improvement wherein the fluorination is carried out in the presence of a solvent which is a fluorinated ether having at least one substituent R.sub.F group, wherein R.sub.F is a fluorinated hydrocarbon group, and wherein under the reaction conditions fluorination of the solvent takes place at the same time as the fluorination of the polyether (2).

Dependencies are inferred from the claim text.