Patent GB-894892-A (GB)
Title: Polyfluorocyclobutanones and their production
IPC: C08G2/00
Filed: 1959-02-27
Abstract: The invention comprises polymers of perfluorocyclobutanone and copolymers of perfluorocyclobutanone (for preparation see Group IV(b)) with carbonyl and thiocarbonyl compounds, particularly with perfluoro- and o -hydroperfluoro-aldehydes and ketones.  The polymers contain <FORM:0894892/IV (a)/1> units. Polymerization may be effected in the presence of an initiator known for anionic polymerization, e.g. an alkali metal halide, cyanide or carboxylate, a quaternary ammonium salt, a long chain quaternary (e.g. sulphonium) salt or an arylphosphine. An organic solvent may be used, e.g. an ether or amide, temperature from liquid nitrogen temperature to room temperature may be used, preferably below -50 DEG  C.  Examples describe the preparation of homopolymers of perfluorocyclobutanone and of a copolymer with thiocarbonyl difluoride.  Polyvinyl acetate is plasticized or dissolved by polyfluorocyclobutanones of formula <FORM:0894892/IV (a)/2> wherein X and Z, which can be alike or different, are fluorine, chlorine or bromine, and the Y's are pairwise hydrogen or fluorine.  Perfluorocyclobutanone and 2-chloro-pentafluorocyclobutanone are specifically mentioned. Polyvinyl alcohol is waterproofed and rendered insoluble in water by treatment with gaseous or liquid polyfluorocyclobutanones as defined above.ALSO:The invention comprises polyfluorocyclobutanones and their hydrates and hemiketals of formulae <FORM:0894892/IV (b)/1> respectively, where the X's which may be the same or different are fluorine, chlorine or bromine, the Y's are pairwise hydrogen or fluorine and R is monovalent hydrocarbyl.  The compounds in which Y is hydrogen may be prepared by the cycloaddition of ketene and the appropriate difluoroperhaloethylene (F2C=CX2), generally in the vapour phase at 200 DEG C.-700 DEG C. and at substantially atmospheric pressure, or by the ozonolysis and subsequent catalytic hydrogenation under anhydrous conditions of the corresponding 3, 3 - difluoro - 2, 2 - dihalo - 1 - methyl - enecyclobutane <FORM:0894892/IV (b)/2> This reaction is generally carried out in the presence of an alcohol giving the hemiketal which may be dealcoholated by means of a strong dehydrating agent such as P2O5. The ozonolysis is generally carried out at temperatures between ambient and that of solid CO2 or lower, the hydrogenation at ambient to 50 DEG C. and the dealcoholation at ambient to 100 DEG C.-150 DEG C.  The cyclobutanones in which the Y's are fluorine may be prepared by heating the corresponding 1, 3, 3, 4, 4 - pentafluoro - 2, 2 - dihalo - 1 - hydrocarbyloxycyclobutane <FORM:0894892/IV (b)/3> with a strong acid; the product generally consists at least in part of the polyfluorocyclobutanone hydrate which may be converted to the ketone by means of a strong dehydrating agent such as P2O5.  All the liquid phase reactions may be effected in an organic solvent such as a hydrocarbon or fluorinated hydrocarbon.  The hydrates and the hemiketals may be prepared from the cyclobutanones by reaction with water or alcohols.  The products may be used to waterproof plastics and as plasticisers (see Groups IV (a) and VIII). Perfluorocyclobutanone may be obtained by heating polymers thereof (see Group IV (a) for the latter).  On treating the polyfluorocyclobutanones in which Y is hydrogen with water, HF is eliminated and the ring opened to give 4,4-difluorotetrolic acid. 2,2,3,3-Tetra-fluorocyclobutanone reacts with glass to give 4,4-difluoro-2-butynoic acid (4,4-difluorotetrolic acid) and SiF4. The ketones in which Y is fluorine give the corresponding tetrafluorodihalocyclopropanes on irradiation with ultra-violet light (Example 4, perfluorocyclopropane from perfluorocyclobutanone).  The hydrates and hemiketals in which Y is fluorine give the corresponding tetrafluorodihalobutyric acids on base hydrolysis (Example 4: 4H-hexafluorobutyric acid by dimethyl sulphate/K2CO3 on the methyl hemiketal of perfluorocyclobutanone).  3, 3 - Difluoro - 2, 2 - dihalo - 1 - methylene - cyclobutanes used as starting materials are prepared by the reaction of allene (or an allyl ester followed by dehydroacyloxylation by heating of the resulting acyloxymethyl-3,3-difluoro-2,2-dihalocyclobutane) and a difluoroperhaloethylene F2C=CX2.  1, 3, 3, 4, 4 - Pentafluoro - 2, 2 - di - halo-1-hydrocarbyloxycyclobutanes are prepared by the cycloaddition (generally at elevated temperature, e.g. 125 DEG C.-200 DEG C., under antogenous pressure) of a perfluorovinyl ether F2C=CFOR and a difluoroperhaloethylene F2C=CX2; the perfluorovinyl ether is obtained by reacting an alkali metal alkoxide with tetrafluoroethylene. Specification 620,296 is referred to.