PERFLUOROACETAL AND PERFLUOROKETAL COMPOUNDS AND USE THEREOF IN THERMAL SHOCK TESTING

Abstract: Perfluorinated gem-alkylenedioxy compounds, viz., perfluoroacetal and ketal compounds, which can contain chlorine, useful, for example, as liquid heat transfer media such as thermal shock fluid and vapor phase soldering fluid, made by direct fluorination of their perfluorinateable precursors.

Description: PERFLUOROACETAL AND PERFLUOROKETAL COMPOUNDS AND USE THEREOF IN THERMAL SHOCK TESTING This application is a continuation-in-part of U. S. Patent applications Serial No. 07/250,384, filed September 28, 1988, and Serial No. 07/278,958, filed December 2, 1988. This invention relates to perfluoroacetals and perfluoroketals, their preparation, and to their use as liquid heat transfer media, e.g. in inducing a thermal shock to an article, such as an electronic component or device, for test purposes. Thermal shock testing is used to determine the effect, if any, of rapid and extreme temperature changes on electronic components, for example those used in aircraft which in seconds must be able to ascend from desert heat into stratospheric sub-zero cold. This testing is a type of quality control screening or evaluation used to select or eliminate those electronic components which would probably be susceptible to failure in actual use when subjected to high and/or low temperature extremes. The electronic component to be tested is alternately heated far above ambient temperature and cooled far below ambient temperature to induce a thermal shock and then visually inspected and/or performance-tested for defects that may result from the thermal shock, e.g. electrical conductivity anomalies due to cracks and other failures in the components. One common method of heating and cooling an article for thermal shock testing involves the use of immersion fluids. Inert fluorochemical immersion fluids are generally recognized as the most suitable liquids for thermal shock testing because of their excellent thermal stability and compatibility with electronic circuit and electronic circuit package materials. Commercially available fluorochemical liquids which SUBSTITUTESHEET are useful as heat transfer testing liquids include those electronic liquids sold under the trademark FLUORINERT, which are described, for example, in trade bulletin Y-IERTR(131)NP1 of the 3M Company. In the case where the thermal shock testing is carried out at two widely different temperatures, e.g. 150°C and -65°C, two different testing liquids generally have been required, one being a heating liquid with a boiling point in excess of the temperature of the heating bath and one being a cooling liquid with a low viscosity at the temperature of the cooling bath. According to U. S. Government Military Standard 883-1011.6, November 29, 1985, a perfluorinated liquid composition, FLUORINERT Electronic Liquid FC-40, having a boiling point at about 155°C, has approval as the heating liquid for thermal shock testing up to 150° C, and a perfluorinated liquid composition, FLUORINERT Electronic Liquid FC-77, having a boiling point of about 97° C and a low viscosity at -65° C, has approval as the cooling liquid. However, it has been found that after extended use, losses of portions of these liquids often occur when some of the low boiling cooling bath liquid is unavoidably carried over, on the surfaces of the electronic component, into the heating bath where the liquid that was carried over is volatilized. Furthermore, viscosity increases in the cooling bath, caused by carry-over of heating bath liquid into the cooling bath during extended use, often result in forming a cooling liquid mixture that is not as efficient as the original cooling liquid for rapid cooling of the electronic component under test. The cooling liquid mixture formed after extended use by carry-over may then have to be separated, e.g. by distillation, into two liquids for re-use. A liquid mixture of perfluoropolyethers sold under the trademark GALDEN has been described as useful as a single thermal shock liquid, i.e. a liquid used for both the heating and cooling baths. The GALDEN R fluids are described in a trade bulletin of Montedison S.p.A. on "GALDEN R PERFLUORINATED FLUIDS" as a mixture of linear low SUBSTITUTESHEET molecular weight polymers said to have the structure CF,-[(0-CF(CF, )-CF, ) (O-CF, ) JO-CF, . The GALDEN* perfluorinated fluid sold as D02TS has been found to have a boiling point of 165°C and viscosities of 231 centistokes (cs) and 1075 cs at -70°C and -80°C, respectively. However, the lower molecular weight components of such fluids can boil off from the heating bath and the remaining higher molecular weight components can lead to increased viscosity in the cooling bath. Measures can be taken to narrow the molecular weight distribution of the polyether mixture prior to use as a single thermal shock fluid, e.g. by control of the polymerization conditions and/or distillation of the product, but these measures may be difficult and may not be wholly effective or economically practical. Various other perfluoropolyethers, useful as thermal shock fluids in the testing of electronics, are the mixtures of random structures and molecular weight distributions disclosed in European Patent Application No. 86105359.3 (Montedison S.p.A.) published April 24, 1985 as Publication No. 0203348. Although European Patent Application No. 82303332.9 (the Green Cross Corp.), published April 4, 1983, as Publication No. 0077114, broadly discloses preparation of certain perfluorochemicals by fluorination of partially fluorinated ketals and acetals, there is no enabling disclosure of the latter. And U. S. Patent No. 4,760,198 (Bierschenk et al . ) discloses certain copolymers of difluoromethylene oxide and tetrafluoroethylene oxide, inclusive of some perfluoroacetals, those copolymers being mixtures of a plurality of molecular species of perfluoropolyethers with a broad range of molecular weights, some of the species having a random internal structure and all of the species having inert terminal groups, viz., random distribution of methyl or ethyl. Briefly, in one aspect, this invention provides a perfluorinated gem-alkylenedioxy composition which can be SUBSTITUTESHEET normally liquid and which consist or consist essentially of one or a mixture of perfluorinated gem-alkylenedioxy compounds, viz., perfluoroacetal or perfluoroketal compounds, having 6 to 100, and preferablyl at least 12, c e.g. 12 to 50, carbon atoms, which are useful, for example, as lubricants, hydraulic fluids, liquid heat transfer media such as thermal shock fluid and vapor phase soldering fluids, and in numerous other applications in which an inert, nonflammable, oxidatively stable fluid is , (j required. The low molecular weight perfluoropolyethers of the present invention have many useful applications in the electronics industry. Fluorocarbon fluids are useful as coolants and insulators in high-voltage electronic equipment, as immersion medium for leak testing, as heat 15 transfer agents for vapor phase soldering, as fluids for direct cooling of electronic devices and as thermal shock fluids. A broad class of perfluorinated gem-akylenedioxy compounds of this invention can be presented by the 20 general formula: Y-O-C-O-Y' Λ R 2 25 wherein Y and Y' are the same or different and are selected from the group consisting of perfluoroalkyl, perfluoroalkyleneoxyalkyl and perfluoropoly(alkyleneoxy)alkyl wherein one or more but 30 preferably not all of the fluorine atoms may be halogen atoms other than fluorine, e.g. chlorine; wherein R and R 2 are the same or different and are selected from the group consisting of -F, -Cl, -CF 2 Cl, -CFCl 2 , -CCl 3 , and perfluoroalkyl of 1 to 10 carbon atoms wherein one or more of the fluorine atoms but preferably not all may be halogen atoms other than fluorine, e.g., chlorine and wherein the perfluoroalkyl group may contain one or more ether oxygen atoms. Where Y and Y' are perfluoro- BSTITUTESHEET poly(alkyleneoxy)alkyl , the polyether of formula I may be an atactic or isotactic polymer or a block copolymer each having up to 50 carbon atoms; examples of such polyethers are Y-0-CF 2 -OY and Y-0-CF( CF 3 )-0-Y wherein each Y is the same, i.e., the same perfluoropoly( alkyleneoxy)alkyl group. Formula I can be considered as embracing two types of fluorinated ethers: (1) perfluoroacetals, when one of R and 2 is a halogen, e.g. fluorine (a subclass of perfluoroacetals being perfluoroformals, when both R χ and R 2 are halogen, e.g. fluorine); and (2) perfluoroketals, when both of R χ and R 2 are other than halogen, viz., perhaloalkyl , which can contain oxygen. In another embodiment of formula I, when Y or Y' have 20 or fewer carbon atoms and χ is fluorine then R 2 is a group other than -CF 3 or -CF 2 Cl. In another aspect, this invention provides a normally liquid, perfluoroacetal composition which is useful, for example, as a thermal shock testing fluid. The composition can consist or consist essentially of a saturated perfluoro-1,l-bis(alkyloxy)alkane compound as the single molecular species in the composition (and such composition is hereafter on occasion referred to for brevity as a "single molecular perfluoroacetal composition" or "unimolecular" composition or fluid). Said compound (hereafter referred to on occasion as a perfluoroacetal compound) thus has a perfluoro-1, 1-alkylenedioxy moiety, -0-CF-0-, but can have another perfluoro-1,1-alkylenedioxy moiety, provided it is separated from the other by at least two catenary carbon atoms of a perfluoroalkylene moiety. In another aspect, this invention provides a normally liquid, perfluoroacetal composition which consists or consists essentially of a mixture of two or more such compounds (and such composition is hereafter referred to on occasion for brevity as a "mixed perfluoroacetal composition") of discrete, non-random molecular weights, said compounds preferably being those having complementary properties, SUBSTITUTESHEET for example, boiling points and pour points each within respective narrow ranges, desired for a particular use of the composition, e.g. for use as a heat exchange medium. Unless otherwise stated or apparent, the term "perfluoroacetal composition" as used herein means that consisting or consisting essentially of one or a mixture of said compounds, that is, the term is used in a generic sense to cover the single molecular and the mixed perfluoroacetal compositions of this invention. The perfluoroacetal compound can have one or a few, e.g. 2 or 3, chlorine atoms, each of which is bonded to carbon atoms other than those carbon atoms to which an ether oxygen atom is bonded; stated otherwise, the compound can have 1, 2, or 3 carbon-bonded chlorine atoms in place of 1, 2 or 3 carbon-bonded fluorine atoms of the alkyloxy moieties if the carbon atoms to which the chlorine atoms are bonded are other than those to which the ether oxygen atoms are bonded. The perfluoroacetal composition, which is liquid at ambient conditions, e.g. 20°C at 740 Torr, generally has a boiling point greater than 20°C, preferably a boiling point of at least 40°C, and more preferably a boiling point greater than 125°C, e.g. 180°C, and can have a boiling point as high as 300° C. Generally the. perfluoroacetal compound has at least 6 carbon atoms, and can have as many as 24 carbon atoms or even up to 30 carbon atoms, but preferably the compound has at least 12 carbon atoms, e.g. 12 to 17 carbon atoms. Where a perfluoroacetal compound is a chlorine-containing perfluoroacetal compound, its effect on the boiling point of the perfluoroacetal composition will be approximately the same as that of a perfluoroacetal compound which does not contain chlorine atoms and has a higher carbon content. Generally, one chlorine atom will have about the same effect on boiling point as 1.5 to 2 carbon atoms. A particularly useful property of the perfluoroacetal composition of this invention is its wide liquid range, meaning it is normally liquid over a wide temperature SUBSTITUTESHEET range; in fact, some of them can be considered as having exceptionally wide liquid ranges. A feature of the perfluoroacetal compositions of this invention is that the perfluoroacetal compound or compounds thereof are each of c well-defined, definite, certain, and known structure of a non-random nature and with fixed carbon, fluorine, and oxygen ratios and of a definite (or particular or distinct) molecular identity. In the mixed perfluoroacetal compositions, specific molecular 0 structures and amounts of each compound in the mixture are features which can be completely predetermined and the mixture made by mixing or blending selected single molecular perfluoroacetal compositions or the mixture made as such as a reaction product of the corresponding 5 precursor mixture of acetals. These features are in contrast to those perfluoropolyether chemicals which are polymeric or oligomeric in nature and have a distribution of molecular weights, those which have a random structure, or those which are a random mixture of compounds. The o control over the nature of the single molecular perfluoroacetal compositions of this invention is a feature which means that their physical properties, particularly their low temperature viscosity and their discrete boiling point, are invariable under conditions of 5 use, for example where in use as a thermal shock fluid some of such single molecular weight perfluoroacetal composition is lost through volatilization. Some of the mixed perfluoroacetal compositions can have these advantages if the perfluoroacetal compounds in the mixture 0 are judiciously selected, for example by empirically selecting those with the desired boiling points and low temperature viscosities. The above-described features of the compositions of this invention advantageously contribute to their 5 usefulness as heat exchange liquids, such as thermal shock testing fluids. The perfluoroacetal compositions also have utility as hydraulic fluids, as pump fluids for corrosive environments, and as fluids for vapor-phase SUBSTITUTESHEET condensation heating for soldering and polymer-curing applications. Their low temperature viscosities are especially low compared with the viscosities of prior art perfluorinated polyether fluids which have a distribution of molecular weights and compositions. These low viscosities render the perfluoroacetal compositions of this invention especially effective, particularly in comparison with the prior art fluids, as heat transfer media at low temperatures. In another aspect of this invention, the perfluoroacetal and perfluoroketal compositions are prepared by direct fluorination of their perfluorinateable, saturated or unεaturated acetal or ketal precursors which can be fluorine-free or partially-fluorinated and chlorine-free or partially chlorinated. ("Perfluorinateable" means the acetal or ketal precursor contains carbon-bonded hydrogen atoms which are replaceable with fluorine and any carbon-carbon unεaturation in the precursor can be saturated with fluorine.) The resulting perfluoroacetal or perfluoroketal compounds can be made with the same number and spatial arrangement of carbon atoms as the precursors thereof. The fluorination can be carried out at a temperature between -80° C and +150° C or at moderate or near ambient temperatures, e.g. -20°C to +50°C, preferably between -10° C and +40° C, with a stoichiometric excess of fluorine gas, which is preferably diluted with an inert gas, such as nitrogen, helium, argon, perfluoromethane, or sulfur hexafluoride, to minimize or avoid hazards and to control the amount of heat generated upon initial contact of the precursor with the fluorine. Due to the extreme exothermicity of the reaction, the fluorination must be carried out slowly unless provisions have been made for rapidly removing the heat of reaction. Submersion of the reactor in a cooled liquid bath is usually adequate for achieving commercially acceptable rates of reaction. It can be carried out in a reactor containing an ultraviolet radiation source or in the dark. Using the preferred TESHEET temperature range, it is not necessary to have an ultraviolet light source since the fluorine is sufficiently reactive. If an ultraviolet light source is used, however, a wavelength between 250 and 350 n is preferred. When the reactor is irradiated with an external light source, a transparent window is needed which does not react with either fluorine or hydrogen fluoride. A quartz lens coated with a thin film of fluorinated ethylene-propylene copolymer works well. The fluorination is preferably carried out in an oxygen- and water-free environment and can be carried out in the presence of solid, particulate scavenger, such as sodium fluoride, for the hydrogen fluoride by-product generated. Alternatively, the fluorination can be carried out in an inert liquid, such as a fluorocarbon or chlorofluorocarbon liquid, as a reaction medium, or carried out with the use of both the scavenger and the inert liquid. The fluorination is preferably carried out by using fluorine diluted with inert gas to directly perfluorinate precursor acetal in the inert liquid (and, for operational advantages, in the absence of a hydrogen fluoride scavenger and without requiring UV illumination) at a temperature and inert gas flow rate sufficient to volatilize hydrogen fluoride by-product and enable its removal from the fluorination zone as it is generated, said flow rate preferably being, for example, at least 4 or 5 times as much as the flow rate of the fluorine gas per se . The yields of the perfluoroacetals by this preferred technique are surprisingly high in light of the belief heretofore that the precursor acetals were in a sense fragile and not susceptible to direct fluorination unless low temperatures and/or hydrogen fluoride scavengers were used during fluorination to slow the reaction and minimize fragmentation and other yield-reducing phenomena. A class of perfluoroacetal compositions of this invention is that whose members consist or consist essentially of one or of a mixture of perfluorinated SUBSTITUTESHEET acetal compounds which fall within the following representational general formula: Rf(ORf)'x 0-(R*f0) Rf II wherein: R and R f are each independently selected from the group consisting of C χ to C 8 , preferably C χ to C 6 , linear or branched perfluoroalkyl, C χ to C 8 , preferably C χ to C 6 , linear or branched chloroperfluoroalkyl, and unsubstituted or lower alkyl-substituted perfluorocycloalkyl or chloroperfluorocycloalkyl wherein the lower alkyl substituent has 1 to 4 carbon atoms and the number of ring carbon atoms in the cycloalkyl is 4 to 6, preferably 5 or 6; R^ , R^ , and R f are each independently selected from the group consisting of C 2 to C 4 linear or branched perfluoroalkylene and C 2 to C 4 linear or branched chloroperfluoroalkylene; each R f is independently a fluorine atom or perfluoroalkyl with 1 to 4 carbon atoms, and is preferably perfluoromethyl or, more preferably a fluorine atom; x and w are each independently an integer of 0 to 4; y is an integer of 1 to 6, preferably 1 to 3; z is an integer of 0 or 1; and the total number of carbon atoms in said compound can be 6 to 30, preferably at least 12, e.g. 12 to 17, and more preferably 13 to 14 because of the extremely low viscosity at low temperatures, e.g. less than about 300 centistokes at -70 C C, coupled with high boiling point, e.g. above about 175° C, that the compositions have when the total carbon atoms are 13 or 14. (The term "chloroperfluoro-" is used herein to describe a perfluoro moiety in which 1 or 2 fluorine atoms are replaced in a sense by chlorine atoms, e.g. as in the case of ClC 2 F 4 - or -CF 2 CF(CF 2 Cl)-. ) The perfluoroacetal compositions preferably have a boiling point in the range of 160° C to 250° C, and more preferably in the range of 175° C to 200° C. The perfluoroacetal compounds of this invention contain at least one perfluoro-1,1-alkylenedioxy unit, SUBSTITUTESHEET e.g. -OCF(R j )0- in formula II, which can be located approximately at the center of the perfluoroacetal molecule, but a perfluoroacetal compound can contain two perfluoro-1 , 1-alkylenedioxy units separated by at least two catenary carbon atoms of a perfluoroalkylene moiety and each of the units located at approximately the center of a different molecular half of the compound. Here, "approximately at the center" means having about the same number, plus or minus about one, of perfluoroalkyleneoxy units on each side of the molecule (in the case of a single alkylenedioxy unit) or molecular half (in the case of two such units). The acetals having one perfluoro-1,1-alkylenedioxy unit which is centrally located are generally more easily prepared because their precursors are readily available materials. A particularly useful subclass of the perfluoroacetal compositions of this invention is that whose members consist or consist essentially of one or a mixture of two or more perfluoroacetal compounds falling within the following representational general formula: Cn F 2 ,n x + 1 1(OCmF 2 ,m )' a-OCF[(CF2, )p F]0-(Cm ,' F,2 m ,'0)b. Cn ,' F,2n ,' ^ +l . Ill wherein: each n and n' is independently an integer of 1 to 6, each m and m' is independently an integer of 2 to 4, a and b are each independently an integer of 0 to 4, and p is 0 or 1 (if p is 0 then the central moiety is -0CF 2 0- and if it is 1 then the central moiety is -0CF(CF 3 )0-) , each said compound preferably having 13 to 14 total carbon atoms, said composition having a viscosity at -70°C of less than about 300 centiεtokeε, preferably lesε than about 200 centistokeε. In another aspect, thiε invention alεo provides a method of transferring heat from an article, εuch as an electronic component or device, to a cooling liquid, the method compriεing directly contacting the article with an above-deεcribed perfluoroacetal compoεition of thiε invention. SUBSTITUTESHEET Thiε invention further provides a method of inducing, a thermal shock to an article, such as an electronic component or device, for example for purposeε of testing the integrity or soundness of the article as described earlier herein, the method comprising the following stepε: a) heating a first bath of a heating liquid to a temperature above ambient temperature; b) cooling a second bath of a cooling liquid to a temperature below ambient temperature; and c) sequentially: i) immersing the article in an initial bath which is one of said first and second baths and allowing sa article to come to the temperature of said initial bath before removing said article from said initia bath, and ii) then immersing said article in the other of said first and second baths and allowing said article t come to the temperature of said other bath before its removal therefrom; wherein said liquids are inert, thermally stable, perfluorinated liquids, at least one of which is, but preferably both are, a perfluoroacetal composition of this invention, more preferably the version which is a single molecular perfluoroacetal composition. When a prior art fluorochemical made up of a mixture molecular weights is used as a single thermal shock fluid, the lower molecular weight components of such fluid can bo off from the heating bath and the remaining higher molecul weight components can lead to increased viscosity through pollution or contamination of the cooling bath. The εingl molecular perfluoroacetal composition of this invention, which is essentially a εingle perfluoroacetal compound, do not have these disadvantages of prior art fluids (which ha a distribution of molecular weights). The version of the perfluoroacetal composition of thiε invention which iε a mixture of perfluoroacetal compoundε alεo can overcome the disadvantageε if each of the compoundε in the mixture have the εame or about the same boiling point, e.g. boiling poi within a 10 to 15°C range, and viεcosity, e.g. viscosities -70°C of up to 300 cs, necessary to maintain the desired ba temperatures. The perfluoroacetal compositions and perfluoroketal compositions of thiε invention may be prepared from their hydrogen-containing, saturated or unsaturated, non-fluorinated or partially-fluorinated, non-chlorinated o partially-chlorinated hydrocarbon analog acetals and ketalε which are perfluorinateable by direct fluorination. Althou the perfluorinated products may contain small amountε of fluorinated materials having one or a few residual hydrogen atoms, the perfluoroacetal and perfluoroketal compoεitionε thiε invention are, except for any chlorine content, eεsentially fully-fluorinated, i.e. perfluorinated, with a residual carbon-bonded hydrogen content of generally lesε than about 0.4 mg/g, usually lesε than 0.01 mg/g, and preferably less than about 0.1 mg/g, e.g. 0.01 to 0.05 mg/g This residual hydrogen content can be lowered or essentiall completely removed (as well as traces of undeεired carboxyl acid derivatives such as terminal acyl fluoride groups resulting presumably from chain degradation reactions) upon treating at elevated temperature, e.g. at 150°C or higher, e.g. 175°C or even 260°C, the fluorinated product with fluorine, for example fluorine diluted with an inert gas su aε nitrogen, such treatment being referred to hereinafter o occasion aε the "polishing" finishing technique. In one direct fluorination process (the "solids fluorination technique") used to prepare the perfluoroaceta and perfluoroketal compositions of this invention, the precursor acetal or ketal starting material is contacted wi fluorine diluted with an inert gas, such as helium or, preferably, nitrogen, at low initial concentrations of fluorine of about 5 to 25 volume %, preferably about 10 to volume %, and at low initial temperature, which is preferab -20°C to 0°C. As the fluorination reaction proceeds, the fluorine concentration can be maintained conεtant or gradually increased up to 50 volume % or even up to 100 volume %, and the reaction temperature is increased, e.g. t SUBSTITUTESHEET 40°C-60°C, and such conditions can be maintained until the precursor iε perfluorinated. The precurεor is fluorinated the presence of a hydrogen fluoride scavenger, such as potassium fluoride or, preferably, sodium fluoride. The c scavenger may be in particulate form such as pelletε or, preferably, powder. Such a perfluorination technique iε described in U. S. Patent 4,755,567 (Bierschenk et al.), which deεcription iε incorporated herein by reference. Generally, εufficient scavenger is utilized such that all o 0 the hydrogen fluoride by-product generated in the perfluorination process is scavenged. Scavenger: precursor weight ratios of from about 1:1 to about 20:1 have been fou useful in fluorinating the precursor acetals or ketalε. Using this method, the precursor may be mixed with or coate 5 on the scavenger and the mixture fluorinated in a fluorination apparatus such aε a stationary metal tube reactor, a rotating drum reactor, or a fluidized bed reacto this technique generally giving yields of about 15 to 30 mo % of the deεired perfluoroacetal or perfluoroketal o compound(s). Typical reaction times to obtain such yields vary from about 24 hours to about 48 hours, depending upon the reactor system utilized. Another method of fluorination (the "liquids fluorination technique") that can be used to make the 5 perfluoroacetal and perfluoroketal compositions of this invention involves making a very dilute dispersion, emulsio or, preferably, solution of the precursor acetal(ε) or ketal(ε) in a liquid reaction medium, which is relatively inert to fluorine at the fluorination temperatures used, t 0 concentration of the starting material thus being relativel low so aε to more easily control the reaction temperature. The reaction mixture can also contain or have diεperεed therein a sufficient quantity of hydrogen fluoride scaveng such aε sodium fluoride or potassium fluoride to complex w 3 all of the hydrogen fluoride formed. The scavenger:precur weight ratio can be, for example, from about 0.5:1 to 7:1. The reaction mixture can be vigorously agitated while the fluorine gas is bubbled through it, the fluorine preferabl SUBSTITUTESHEET being used in admixture with an inert gas, εuch aε nitroge at a concentration of about 5 to 50 volume %, more prefera about 10 to 25 volume %, and being maintained in stoichiometric excess throughout the fluorination, e.g. up 15 to 40%, or higher, depending on the particular starting material and the efficiency of the equipment used, such as the stirrer. Yieldε generally in the range of about 30-77 mol %, and, with experience, aε high as 65 to about 80 mol of the perfluoroacetal or perfluoroketal product may be achieved by this method. Suitable liquids useful aε reacti media are chlorofluorocarbons such as Freon TM 113 ' , 1,1,2-trichlorotrifluoroethane, and Freon™ 11, fluorotrichloromethane, and chlorofluoroethers εuch aε 2,5,5-trichloroperfluoro-2-butyl tetrahydrofuran, perfluoro-biε(chloroethyl)ethe , and perfluorinated polyepichlorohydrin liquidε, which media generally will function aε good εolventε for non-fluorinated precursors, a Fluorinert™ electronic liquids FC-75, FC-72, and FC-40, perfluoroalkanes such as perfluoropentane and perfluorodecalin, perfluoropolyethers εuch as Krytox™ and Fomblin™ , perfluoroalkanesulfonyl fluorideε such as perfluoro-1,4-butanedisulfonyl fluoride and perfluorobutanesulfonyl fluoride, and the perfluoroacetal compoεitionε of thiε invention, and this latter group of media, i.e., perfluoroalkanes, etc., generally will functio well as εolventε for some precursors or as reaction media f forming disperεions of other precursors. Mixtures of such liquids can be used, e.g. to get good disperεion of precurs and intermediate reaction products. The reaction media are conveniently used at atmoεpheric preεεure. Lower molecular weight emberε of the above claεses of reaction media can alεo be uεed, but elevated preεεureε are then required to provide a liquid phaεe. The fluorination reaction iε generally carried out at a temperature between about -10°C +50°C, preferably between about -10°C to 0°C if a hydrogen fluoride εcavenger iε used, and if such scavenger iε not used, between about 0°C to 150°C, preferably about 0°C to 50°C, most preferably about 10°C to 30°C, the temperature SUBSTITUTESHEET being εufficient to volatilize the hydrogen fluoride by-product and with the aid of the inert gas, flowing at a sufficient rate, cause the purging of the by-product from t fluorination reactor as it is generated. At these temperatures, the liquidε utilized as reaction media do not react appreciably with the diluted fluorine and are essentially inert. The reaction medium and other organic subεtanceε may to εome extent be preεent in the gaεeouε reactor effluent, and a condenser may be used to condense t gaseouε reaction medium and εuch εubεtanceε in the effluent and permit the condensate to return to the reactor. The condenser should be operated so as to minimize or prevent t return to the reactor of hydrogen fluoride by-product (whic would have an adverεe effect on yield of perfluorinated product if allowed to remain in the reactor during fluorination). The return of the hydrogen fluoride can be minimized or prevented by εelective condenεation of the organic materials while allowing the hydrogen fluoride to pass through the condenser, or by total condenεation into a εeparate veεεel of both hydrogen fluoride and the organic materialε followed, if deεired, by εeparation of the hydrog fluoride aε the upper liquid phaεe and the return of the lower liquid phaεe. The reaction may be carried out in a batch mode, in which all of the precurεor iε added to the liquid prior to fluorination to provide a precurεor concentration of up to about 10% by weight, and the fluorine-containing gaε then bubbled through the precurεor-containing liquid. The reaction can also be carried out in a semi-continuous mode, in which the precurs is continuously pumped or otherwise fed neat, or aε a dilut εolution or dispersion or emulsion in a suitable liquid of the type used aε a reaction medium, into the reactor, e.g. a rate of about 1 to 3 g/hr into 400 mL of liquid reaction mixture, aε fluorine iε bubbled through, e.g. at a fluorine flow rate of about 40 to 120 mL/ in and an inert gaε flow rate of about 150 to 600 mL/min. The fluorination can alεo be carried out in a continuouε manner: the precurεor (eithe neat or dissolved or dispersed in a suitable liquid of the BSTITUTESHEET type uεed as a reaction medium to form a solution or emulsion) being continuously pumped or otherwise fed into t reactor containing the reaction medium as the fluorine-containing gas is introduced, aε deεcribed above, and the εtream of unreacted fluorine, hydrogen fluoride gaε and inert carrier gaε being continuously removed from the reactor as is a stream of liquid comprising perfluorinated product, incompletely fluorinated precursor, and inert liqu reaction medium, and the necessary separations being made t recover the perfluoroacetal composition, and, if desired, with recycling of the unreacted fluorine and the incomplete fluorinated precursor. In a liquids fluorination technique, an alternative method for fluorinating the precursorε which are inεoluble the liquid fluorination medium involveε adding a εolvent to the precursor which allows limited solubility of precurεor the liquid fluorination medium. For clarity of illustratio 1,1 ,2-trichlorotrifluoroethane has been selected aε the liquid fluorination medium; however, other highly fluorinat εolventε can also be used. Typically, a mixture containing one part precursor, one part solvent and one part 1 , 1 , 2-trichlorotrifluoroethane will give a homogeneous solution. A solvent is εelected which readily diεsolves th precurεor. Often it iε poεεible to chooεe a εolvent which will conεume little, if any, of the fluorine gas. Trifluoroacetic anhydride, trifluoroacetic acid, chloroform 1,1 ,2-trichloroethylene and 1 ,1 ,2-trichloroethane work especially well. The solution of precursor, solvent and 1, 1,2-trichloro trifluoroethane iε metered into a vigorously stirred fluorination reactor. As the precurεor solution contacts t 1 ,1 ,2-trichlorotrifluoroethane in the reactor, an emulsion formed. The resulting precursor droplets are in most caεeε εufficiently εmall that they react quickly with the fluorin gaε with negligible εide reactionε. The amount of inert liquid medium in the reactor can be maintained at a constan level by addition of recycled or fresh liquid. The perfluorinated product from the batch mode generally will SUBSTITUTESHEET have significant residual hydrogen, e.g. about 7 mg/g, whereas the perfluorinated product made by the continuous o semi-continuous mode will generally have lesε reεidual hydrogen, e.g. leεs than 0.1 mg/g. In general, the continuouε addition of precurεor iε preferred and provideε higher yield, better product quality, and more efficient us of fluorine, though the batch mode has similar advantageε i the "polishing" finishing step is used. Due to the extremely high exothermicity of the fluorination reaction, a cooled liquid or ice bath is generally employed in order that acceptable rateε of reacti may be achieved. When the reaction iε complete, the reacto iε purged of fluorine and the reactor contentε are removed. In the εolidε fluorination technique, the reactor contentε can be mixed with Freon 113 or Fluorinert FC-72 εolvent, th reεulting εlurry filtered, and the εolvent stripped, e.g. b vacuum distillation, to provide crude perfluorinated produc Where the fluorination is carried out by the liquidε fluorination technique in the preεence of a hydrogen fluori εcavenger, the εpent εcavenger can be separated by filtrati or decantation from the liquid reactor contents and the latter then distilled to separate the reaction medium from the crude perfluorinated product. Where the fluorination i carried out by the liquidε fluorination technique without uεing the εcavenger, the reaction product mixture can be distilled to recover the perfluorinated product. The crude perfluorinated product can be treated with a base, e.g. sodium hydroxide, to remove acid and hydride impurities or treated, e.g. at a temperature above 150° C, b the polishing finishing technique to remove hydrogen and ac impurities and the εo-treated product diεtilled. The order of theεe purification steps can be varied to obtain best reεultε. The precurεor acetalε uεed for preparation of the perfluoroacetal compoεitionε of thiε invention can be prepared in a variety of wayε by reaction of alcohol(ε) wi appropriate co-reactantε. Symmetrical acetalε reεult upon heating two moleε of a εingle alcohol with an aldehyde, e. SUBSTITUTESHEET formaldehyde, under acid catalysiε, with removal of water during the reaction, aε illuεtrated in Equation 1. R' c 2R0H + R'CHO —> ROCHOR + H- 0 E . 1 Lower acetals can be converted to higher ones by heating with the higher alcohol under acid catalysis, as 0 illustrated in Equation 2. R" R" 2ROH + ROCHOR' —> ROCHOR + 2R'0H Eq. 2 5 A third route, to εymmetrical acetalε, aε illuεtrated in Equation 3, involveε baεic conditionε and iε uεeful for hindered or acidic alcohols in which the above acid-catalyz equilibria are unfavored. Under phase transfer catalysis, a mixture of NaOH, or preferably KOH, and the alcohol displace 0 chloride from methylene chloride. 2ROH + 2KOH + CH 2 C1 2 —> ROCH 2 OR + 2KC1 +2H 2 O Eq. 3 The preferred route to asymmetric acetals requireε prior 5 formation of the alpha-chloroalkyl derivative of one alcohol and subsequent reaction with the second alcohol under baεic conditions, aε illustrated in Equations 4 and 5. 0 ROH + R'CHO + HC1 —> RO rCHCl + H 2 O Eq. 4 ROCHC1 + R"OH + KOH —> ROCHOR" + KCl +H 0 Eq. 5 5 This latter reaction is also the preferred method to prepare precurεorε containing two alkylenedioxy unitε. Another route to aεymmetric acetal iε the reaction of a SUBSTITUTESHEET vinyl alkyl ether with an alcohol under acid catalyεiε, aε illuεtrated in Equation 6. ROH + CH 2=CH0R' —> RO ϊC L H-OR' Eq. 6 Thiε route of Equation 6 can alεo be uεed to prepare precurεors containing two alkylenedioxy units, as illustrated in Equation 7. CH 3 2ROH + CH 2 =CHO-R-OCH=CH 2 —> ROCHO-R-OCHOR Eq. " The other methods illustrated in Equations 1-3 can be used for preparing those precursors with two of such units, although yields are lower due to competing oligomerization. In the schemeε illuεtrated in above Equationε 1 to 7, mixtures of alcoholε, aldehydeε, and/or acetalε can be uεed aε reactantε to prepare mixtures of precursorε that are fluorinated to make perfluoroacetal compoεitionε of thiε invention which are mixtureε of perfluoroacetal compoundε. Thus, the procesε of Equation 1 can be modified by use of two different alcohols, aε illuεtrated in Equation 8. R" R" 4ROH + 4R'OH + 4R"CHO —> 2ROCHOR' + ROCHOR + RO rCHOR' + 4H 2 0 Eq. Exampleε of alcoholε which can be used in the above illustrated schemeε are monhydridic alcoholε, εuch as methoxyethanol, ethoxyethanol, butoxyethanol, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol butyl ether, tetraethylene glycol methyl ether. SUBSTITUTESHEET tetraethylene glycol ethyl ether, tetraethylene glycol butyl ether, pentaethylene glycol methyl ether, pentaethylene glycol ethyl ether, pentaethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol butyl ether, tripropylene glycol methyl ether, tripropylene glycol ethyl ether and tripropylene glycol butyl ether. Uεeful precurεor acetalε for converεion by direct fluorination to the perfluoroacetalε of thiε invention include each of thoεe in the following liεt of materialε and mixtures of 2, 3, or more thereof: CH 3 (CH 2 ) 5 0CH 2 0(CH 2 ) 5 CH 3 CH 3 (CH 2 ) 3 OCH 2 0(CH 2 CH 2 0) 2 ( CH 2 ) 3 CH 3 CH 3 (CH 2 ) 6 OCH 2 0(CH 2 6 CH π 3 CH 3 (CH 2 ) 2 (0CH 2 CH 2 ) 3 0CH 2 0(CH 2 CH 2 0) 3 ( CH 2 ) 2 CH 3 CH =CHCH, (OCH, CH, ) , OCH, 0( CH, CH, 0 ) -- CH, CH=CH- CH 2 =CHCH 2 0(CH 2 ) 3 0CH 2 0(CH 2 ) 3 OCH 2 CH=CH 2 SUBSTITUTE SHEET CF 3 CHFCF 2 0(CH 2 ) 3 0CH.,0(CH-, ) 3 OCF 2 CHFCF 3 CH, (CH, ), (OCH,CH, KOCH ,0(CH_ CH,0), ( CH, ) , CH. CF, CHFCF,OC,H £ OCH,OC,H c OCF,CHFCF, and CH 3 [OC 3 H 6 ] 2 OCH 2 0[C 3 H 6 0] 2 CH 3 (where C 3 H g can be either -CH 2 CH- or -CHCH 2 - or a mixture of both) CH, CH, C1CH 2 CH 2 OCH 2 CH 2 OCH 2 OCH 2 CH 2 OCH 2 CH 2 Cl CH 3 ( CH 2 ) 3 OCH 2 CH 2 OCH 2 OCH 2 CH., 0 ( CH 2 ) 3 CH 3 CH 3 (CH 2 ) 3 (0CH 2 CH 2 ) 2 OCH 2 0(CH 2 CH 2 0) 2 (CH 2 ) 3 CH 3 CH 3 ( CH 2 ) 3 OCH 2 OCH 2 C-CCH., OCH 2 O ( CH., ) 3 CH 3 CH 3 CH 2 ( OCH 2 CH 2 ) 2 OCH 2 O ( CH., CH 2 O ) 2 CH 2 CH 3 CH 3 (CH 2 ) 2 (OCH 2 CH 2 ) 2 OCH 2 0(CH 2 CH 2 0) 2 ( CH 2 ) 2 CH 3 1 CH 3 OCH 2 CH 2 OCH 2 ( 0CH 2 CH 2 ) 3 OCH 2 OCH 2 CH 2 OCH 3 CH 3 CH 2 0CH 2 CH 2 OCH 2 ( OCH 2 CH 2 ) 3 OCH 2 OCH 2 CH 2 OCH 2 CH 3 CH 3 CH 2 OCH 2 CH 2 OCH 2 ( OCH 2 CH 2 ) 2 OCH 2 OCH 2 CH 2 OCH 2 CH 3 CH 3 OCH 2 CH 2 OCH 2 O ( CH 2 CH 2 O ) 2 ( CH 2 ) 3 CH 3 CH 3 CH 2 ( OCH 2 CH 2 ) 2 OCH 2 O ( CH 2 ) 5 CH 3 CH 3 CH 2 OCH 2 O ( CH 2 CH 2 O ) 3 ( CH 2 ) 3 CH 3 CH 3 ( CH 2 ) 3 OCH 2 CH. OCH ( CH 3 ) OCH 2 CH 2 O ( CH 2 ) 3 CH 3 CH 3 ( CH 2 ) 3 OCH 2 CH 2 OCH ( CH., CH 2 CH 3 ) OCH 2 CH 2 O ( CH 2 ) 3 CH 3 BSTITUTE SHEET ( CH 3 ) 3 COCH 2 CH 2 OCH 2 OCH 2 CH 2 OC ( CH 3 ) 3 C 3 H 7 0CH 2 CH 2 OCH ( CH., Cl ) OCH 2 CH 2 OC 3 H, CH 3 OCH 2 CH 2 OCH 2 CH ( CH 3 ) OCH 2 OCH ( CH 3 ) CH 2 OCH 3 CH 3 CH 2 OCH 2 CH ( CH 2 Cl ) OCH 2 OCH ( CH 2 Cl ) CH 2 OCH 2 CH 3 CH 3 CH 2 OCH 2 CH 2 OCH 2 CH 2 OCH 2 OCH 2 CH 2 0 ( CH 2 ) 3 CH 3 C 7 F χ 5 CH 2 OCH 2 OCH 2 C 7 F χ 5 C 3 F 7 CH 2 OCH 2 CH 2 OCH 2 OCH 2 CH 2 OCH 2 C 3 F 7 Representative examples of the perfluoroacetal compounds of this invention include the perfluorinated counterparts of the precursor acetalε liεted above. Where the precursors have unsaturation, the corresponding perfluoroacetals thereof are saturated. The perfluoroacetal compositions of this invention generally have surpriεingly low viεcoεitieε at low temperatureε compared with the viεcoεitieε of commercial GALDEN R perfluoropolyether immerεion fluidε of comparable molecular weight, which commercial fluids contain a distribution of molecular compoεitionε. Theεe low viscositieε render the perfluoroacetal compoεitionε of this invention especially effective, particularly in comparison with the prior art fluids, aε heat tranεfer media at low temperatureε. A preferred utility for the perfluoroacetal compoεitionε of thiε invention iε in cooling an article to a temperature below ambient, e.g., a temperature far below ambient temperature, εuch aε -65° C' Such cooling may take place aε part of a thermal εhock method which can be uεed to temper or test a material. An especially preferred utility is use in the thermal shock method of this invention, which is preferably carried out in accordance with Condition B or C of U.S. Military Standard MIL-STD-883C, Notice 4, method 1011.6, SUBSTITUTESHEET incorporated herein by reference, with a perfluoroacetal composition of this invention subεtituted for both of the fluids specified in that procedure. The thermal shock method may alεo be carried out using two thermal shock liquidε, one being a conventional electronic testing fluorochemical liquid which may be used in either of the two baths, and the other being a perfluoroacetal composition of this invention which is used in the remaining bath. Examples of suitable conventional liquids include the inert, perfluorinated organic compounds available from 3M as FLUORINERT™ Electronic Liquidε deεcribed in product bulletin No. 98-0211-2267-0(161)NPI iεεued February 1986. The thermal εhock method of thiε invention uεing a εingle thermal shock liquid can be carried out, for example, aε follows in accordance with MIL-STD-883-1011.6, Condition C. The article, such aε an electronic component or device to be teεted, can be preconditioned by being immerεed in a heated bath of a perfluoroacetal composition °f this invention at an elevated temperature between 150°C and 160° C for a minimum of 5 minutes. Immediately upon concluεion of the preconditioning period, the article iε tranεferred to a cooled bath of the perfluoroacetal composition at a temperature between about -65° C and -75°C. The article is held at the low temperature for 5 minutes, at the end of which time it must itself reach -65° C, and it is then transferred back to the heated bath of the perfluoroacetal composition. The article remains at the high temperature for 5 minutes. Transfer time from the high temperature bath to the low temperature bath and from the low temperature bath to the high temperature bath is lesε than 10 εecondε. The duration of the teεt iε generally about 15 complete cycles, where one cycle consiεtε of immerεion in and removal from the heated bath of the perfluoroacetal compoεition and immerεion in and removal of the article from the cooled bath of the perfluoroacetal compoεition. After completion of the final cycle of a thermal εhock teεt, an external viεual TITUTESHEET examination of the article is generally performed without magnification or with a magnifying viewer. Typical effects of thermal shock on defective articles include cracking and delamination of subεtrateε or wafers, opening of terminal sealε and caεe seams, and changes in electrical conductivity due to moisture or to mechanical displacement of conductors or insulating materialε. The electronic performance of the electronic components can be determined and compared with the electronic performance of the article prior to thermal shock testing. In an alternative thermal shock method of thiε invention uεing two thermal εhock liquidε, a perfluoroacetal compoεition of thiε invention can be placed in the heating bath of a thermal εhock apparatuε and a different perfluorinated, inert liquid, εuch aε a conventional, perfluorinated, inert thermal εhock teεting liquid, e.g., FLUORINERT FC-77, is placed in the cooling bath. In this alternative method, the manipulative stepε and conditionε uεed can be the εame as those described above for the single thermal shock method. Aε the alternative thermal shock method is practiced, the perfluoroacetal composition, when carried over into the cooling bath, will generally not raiεe the viεcoεity of the cooling bath to the extent that a conventional thermal εhock heating liquid, e.g., FLUORINERT FC-40, doeε over extended use. In another alternative thermal shock method of this invention using two thermal shock liquids, a perfluoroacetal composition of this invention can be placed in the cooling bath of a thermal shock apparatus and a different perfluorinated, inert liquid, such aε a conventional, perfluorinated, inert, thermal shock testing liquid, e.g., FLUORINERT FC-40, is placed in the heating bath. In this alternative method, the manipulative steps and conditions used can be the εame aε thoεe described above for the single thermal shock method. As the thermal shock method is practiced, the perfluoroacetal compoεition of thiε invention, when carried over into the heating SUBSTITUTESHEET bath, will generally not volatilize from the heating bath to the extent that a conventional thermal εhock cooling liquid, e.g. FLUORINERT FC-77, doeε over extended use. While the methods of this invention of inducing a thermal shock can be applied to almost any article which is im ersible in the bathε uεed in the method, the methodε are preferably uεed to induce a thermal εhock in an electronic device or component to evaluate the electronic component's reεponεe to the thermal εhock. Exampleε of electronic componentε and deviceε include integrated circuits, integrated circuit assemblies, micro-electronic componentε and deviceε, ceramic and plastic carriers for electronic chipε, and aεsemblies of micro-electronic componentε, e.g., integrated circuitε, tranεiεtorε, diodeε, reεiεtors, capacitors, and the like. Apparatus suitable for performing a thermal shock teεt are available from many manufacturers, e.g., Blue M Engineering, Blue Island, IL; Cincinnati Sub-zero Products, Inc., Cincinnati, OH; Maruberi, Santa Clara, CA; Ransco Induεtrieε, Oxnard, CA; Standard Environmental Systems, Inc., Totowa, NJ; and Thermodynamic Engineering, Inc., Camarillo, CA. Each of these apparatus possesεeε particular featureε and makes different demands on the fluid, especially in the cold bath. While some bathε in εuch apparatuε can tolerate a higher cold bath viscoεity than otherε (e.g., at a cold bath temperature of -65°C), otherε tolerate a maximum in viεcoεity of about 600 cε at -70° C. Preferred perfluoroacetal compoεitions used in this invention have cold bath viscoεitieε below the above value and thuε have general utility in εuch apparatuε. Thiε variability in apparatus apparently relates to the obεervation that fluid in the vicinity of the cooling coilε or panelε of the apparatuε tendε to be εomewhat cooler (e.g., -80°C or -85°C) than the εet temperature of the cold bath and, aε a reεult, problemε in maintaining the εet point can occur due to thickening of thiε fluid and/or due to the formation of an inεulating coating on the coil. For prior art fluidε and, by inference, many of SUBSTITUTESHEET the fluidε of thiε invention which have low viεcosity at -70°C, but not at -85°C, this can be overcome by increased mechanical agitation. However, in order for a fluid to be most useful in heat transfer applications, good fluidity, i.e., low viscoεity, at temperatureε aε low aε -85°C iε eεpecially deεirable. Single molecular weight perfluoroacetal compoεitionε of thiε invention offer an advantage over fluidε which contain higher molecular weight componentε which can εelectively congeal on cooling coilε and alεo have the advantage that thermal or mechanical loεεeε in use do not change the composition (and, therefore, propertieε) of that volume or reεidual amount remaining. The deεign characteriεticε and εpecificationε for a number of commercially available ' apparatuε are deεcribed in a product bulletin of Ransco Industrieε, Oxnard, CA, entitled "Thermal Shock Temperature Cycling, Product Bulletin 7000 Serieε". Minor amountε of optional componentε may be added to the perfluoroacetal compoεitionε, e.g., thermal stabilizers, dyes, etc., to impart particular deεired propertieε. The perfluoroacetal compoεitionε of thiε invention can alεo be aε additives for other inert fluorochemical liquidε, uεed, for example, aε thermal εhock fluidε, hydrauli'c fluidε, heat exchange media, and other working fluidε, to modify or adjust their viscoεitieε or pour pointε. Thiε invention iε further illuεtrated by the following exampleε, but the particular materialε and ' amountε thereof recited in these examples, as well aε other conditions and details, should not be construed to unduly limit thiε invention. The pour pointε given in the exampleε below were eεtimated by firεt immerεing a thermometer in a εample of diεtilled liquid product contained in a glaεε vial and then placing the vial in a liquid nitrogen or dry ice bath to cool the εample to a εolid, glaεεy εtate. The vial waε then allowed to warm εlowly and the temperature at which complete fluidity was SUBSTITUTESHEET attained waε noted and recorded aε the pour point. The viεcoεity in theεe exampleε waε meaεured by conventional means using a Weεcan viscometer timer and Cannon-Fenεke viεcometer tubeε, aε described in ASTM D446-74 (reapproved ,- in 1979). Stable low temperatureε for the viscosity measurements were achieved using Fluorinert FC-75 as the bath medium; the temperature of the perfluoroacetal composition was measured with a reεident thermocouple. 0 EXAMPLES Example 1 A cylindrical braεε reactor (about 7.5 cm in diameter and about 30 cm long, with a εealed bottom and a removable 5 head) waε fitted with a copper tube through the head reaching to within about 5 cm of the bottom aε the gaε inlet and a hole in the head waε fitted aε the exit. An intimate mixture of 30.0 g (0.139 mol) bis(n-hexyloxy)methane (prepared by the procedure Q described in Example 7 using methylene chloride as a source of the formal moiety) and 210 g (5.0 mol) NaF powder was placed in the reactor, which was then installed horizontally in a water-ethylene glycol bath and rotated at about 20-30 rpm. Fluorine and nitrogen were mixed 5 prior to entry. The bath was cooled to -l7°C and the gas mixture of 60 mL/min fluorine and 240 mL/min nitrogen was begun. An exotherm of abouat 2 to 5°C was registered by an internal thermocouple. After 22 hr, the exotherm was <1°C and the temperature was increased by 10-15°C 0 increments over the next 8 hrs to 55° C. At hour 25, the nitrogen was reduced to 120 mL/min and, at hour 29, to 60 mL/min. The fluorine was stopped at the 30th hr. The resulting white powder (364.2 g) waε combined with 7.0 g of condenεate from a cooled trap (containing dry ice) in c line after the condenser and was washed three times with 500 mL Freon 113. The combined Freon 113 waεhingε waε stripped on a rotary evaporator at lesε than 25° C. The reεidue, 72.4 g, waε distilled on a short path to 19.4 g (19%) of 88% pure perfluoro-biε(n-hexyloxy)methane (εtructure confirmed by fluorine nuclear magnetic resonance and gas chromatography-masε εpectrometry) , having a boiling range of 120-130° C/60 Torr, a pour point of -70°C, and a viεcoεity greater than 2000 cε at -85°C. 47.4 g of higher-boiling materialε waε alεo isolated. Examples 2, 3, and 4 Using the fluorination technique of Example 1 and formals prepared by the methylene chloride route of Example 7, three perfluoroacetal compositionε were made: Ex. 2, perfluoro-bis ( cyclohexyloxy)methane, having a boiling range of 105-130°C/60 Torr and a pour point of -45°C, was prepared from bis(1 ,1-cyclohexyloxy)methane : Ex. 3, perfluoro-bis(2, 4-dichlorocyclohexyloxy)methane, having a boiling point of 150° C/40 Torr and a pour point of -25°C, waε prepared from biε( 2, 4-dichlorophenoxy)- methane: and Ex. 4, [n-C. F g (OC 2 F. ) 2 0] 2 CF 2 , having a boiling point of 130-155°C/25 Torr, a pour point of -75°C, and a viεcoεity greater than 2000 cs at -85°C, was prepared from the corresponding hydrocarbon acetal. Example 5 A mixture of 130.2 g (1.0 mol) isooctyl alcohol, 92 ml (1.05 mol) CH 3 OCH 2 OCH 3 , and 1 g p-tolueneεulfonic acid waε stirred at reflux for 18 hr. The internal temperature was now 60° C. Gas-liquid chromatography showed 30% unreacted isooctyl alcohol, 41% preεumed 1-iεooctyloxy-l-methoxy methane, and 13% biε( iεooctyloxy)methane, the latter aε three distinct peaks on the SE-52 chromatographic column. The reflux condenser was removed and the mixture was heated for 3 hr. The temperature rose rapidly to 220° C. Gas-liquid chromatography now showed 13% isooctyl alcohol, 2% 1-isooctyloxy-l-methoxy methane, and 84% bis( isooctyloxy)- methane. The p-toluene εulfonic acid was neutralized with Na 2 C0 3 and the filtered product was distilled to 102.3 g (75%) of pure biε( iεooctyloxy)methane , bp 110-120° C/0.8 Torr. Perfluoro-biε( iεooctyloxy)methane , having a boiling SUBSTITUTESHEET range of 120-140° C/60 Torr and a pour point of -40° C, waε prepared from the above-prepared biε( iεooctyloxy)methane uεing the fluorination technique of Example 1. Example 6 In a 250 ml glass flask, a solution of 20.3 g (0.025 mol) biε(l,l-dihydroperfluorooctyloxy)methane (prepared from the alcohol by the method of Example 7 uεing methylene chloride) in 80 mL Fluorinert FC-75 was treated with 8.0 g (0.154 mol) NaF. The mixture was flushed with nitrogen and chilled in an ice bath to 10° C. A slow feed (approximately 50-100 mL/min) of 9% fluorine in nitrogen was maintained over about 40 hr, uεing approximately 18 g fluorine. Gaε-liquid chromatography and mass spectrometry showed two productε in a 5:1 ratio, the larger being perfluoro-biε(perfluoro-octyloxy)methane (920 mol wt) and the εmaller being monohydrido derivative(ε) thereof. Filtration and distillation gave a main cut of 10.2 g, bp 140-145°C/40 Torr, melting point -10°C. Gas-liquid chromatography showed two main iεomers and a minor amount of the monohydrideε. The total yield including other fractionε waε approximately 13g (56%). Example 7 A mixture of 1645 g (13.9 mol) 2-butoxyethanol, 225 g (7.5 mol) paraformaldehyde, 2.0 g p-tolueneεulfonic acid, and 1.5 literε toluene waε εtirred at reflux under a Dean-Stark trap, with εteady evolution of water. After 16 hr, 10 g more paraformaldehyde was added and, at 18 hr, 20 g of 37% formaldehyde waε added, in attemptε to force the reaction to completion. Converεion, aε determined by gaε-liquid chromatography waε greater than 95% and the mixture waε cooled, washed with water containing a few grams NaOH, and the toluene allowed to evaporate. The residue was distilled, yielding 1430 g (83%) of biε(2-butoxyethoxy)methane, bp 100-110°C at 0.5 Torr. Biε(2-butoxyethoxy)methane waε alεo prepared from methylene chloride and 2-butoxyethanol aε followε. A mixture of 590.9 g (5.0 mol) 2-butoxyethanol, 1120 g (20 mol) KOH, 3 g Adogen™ 464 quaternary ammonium salt, and 1 TITUTESHEET liter tetrahydrofuran waε εtirred for 30 min. The temperature roεe to 45°C. Careful addition of 750 ml (11.5 mol) methylene chloride and continued εtirring at 55° C for 18 hr gave complete conversion of the alcohol to r bis( 2-butoxyethoxy)methane . The mixture was filtered with additional methylene chloride and distilled, yielding 552 g (96%) bis(2-butoxyethoxy)methane, bp 106°C/0.25 Torr, which iε a product equivalent to that prepared above using formaldehyde as the source of the formal moiety, -OCH 2 0-. 0 A 600 mL Parr reactor of Monel metal waε equipped with a 0.6 cm diameter Monel™ metal gaε feed line (for premixed fluorine and nitrogen) with itε outlet being about 2.5 cm from the bottom of the reactor, a 0.15 cm diameter nickel organic feed line with itε outlet being 5 about 7.5 cm below the top of the reactor, and a condenser cooled by the same bath aε the jacket. The condenser was a 50 cm long straight double-tube construction, the inner tube having a diameter of about 1.2 cm and the outer tube having a diameter of about 2.5 cm. Gases from the reactor o a r e cooled aε they flow through the inner tube by ethylene-glycol-water flowing in the annulus between the tubeε. Thiε reactor waε charged with 450 mL Freon 113 and 105 g (2.5 mol) NaF. The reactor waε purged with nitrogen (175 mL/min) for 1 hr while εtirring at 3°C. Fluorine waε 5 introduced into the nitrogen εtream at 35 mL/min. After 15 min, a solution of 15.7 g (0.063 mol) of the above prepared bis(2-butoxyethoxy)methane diluted to 200 mL with Freon 113 waε placed in a εyringe pump and addition of the reεulting εolution was started at 9.2 mL/hr. The 0 additionε were maintained over the next 22 hr and after the organic addition waε complete the fluorine addition waε continued for 15 min more. The NaF and NaHF 2 were filtered from the reaction product mixture, waεhed well with Freon 113, which waε εtripped at less than 25°C on a 5 rotary evaporator, and the combined filtrate and washingε were diεtilled, yielding 26.0 g (55%) of perfluoro-biε-( 2- butoxyethoxy)methane, which waε 95% pure as determined by gaε-liquid chromatography. Thiε perfluoroacetal product SUBSTITUTESHEET had a boiling range of 100-110°C/40 Torr, boiling point of 183°C, pour point of -95°C, and viscosities of 147 cs, 504 cs, and 858 cs at -70°C, -80°C, and -85°C, respectively. (In another run, the product had viscoεitieε of 117 cs and c 690 cs at -70°C and -85°C, respectively). Traceε of acid fluoride and hydrideε (0.02 mg/g) were preεent (aε found by infra-red and proton nuclear magnetic reεonance analyεes). The perfluoroacetal product waε purified by εtirring it with hot, aqueouε KOH (25%) for 18 hrε, then 0 waεhing the εeparated product with water and drying the waεhed product over εilica gel. In another run, the distilled residue was purified by bubbling into it for 5 hrs at 175°C a mixture of fluorine diluted with nitrogen. Both purification procedureε gave colorlesε, odorleεε, 5 thermally stable perfluoro-bis(2-butoxyethoxy)methane. The thermal stability waε determined by heating the purified product with aqueouε εodium acetate for 22 hrε. at 180°C in a closed, stainleεε εteel tube and εubεequently analyzing the aqueouε layer for released 0 fluoride ion, low fluoride ion content being indicative of thermal stability. In a similar fluorination at -5°C (uεing a condenεer temperature of about -5°C), bis(2-butoxyethoxy)methane precursor was fed into the reactor as an undiluted liquid 5 to the mixture of NaF and Freon 113. In another variation of the fluorination, the precursor diluted in Freon 113 was fed to a mixture of 15.7g NaF in Freon 113 and the fluorination carried out at -3°C with the condenser at -3°C (resulting in 51% yield). 0 In another variation of the fluorination, the precursor diluted in Freon 113 was fed to a mixture of NaF and Freon 113 at -10°C (resulting in 42% yield compared to eεεentially no yield in a run when no NaF waε uεed). In these runs, the condenser temperature was set at -25° C. 35 In another variation of the fluorination, the precurεor waε fed (diluted in Freon 113) to a mixture of Freon 113 and NaF at 18° C with the condenεer εet at -25°C (reεulting in 50% yield compared to a yield of 77% from a run where no NaF was used). Another run without NaF at 0°C gave a 65% yield. In another variation, the precursor waε fed undiluted into Fluorinert FC-72 at 18°C (58% yield), and in another, fed diluted in Freon 113 into a εlurry of NaF and Fluorinert FC-75 at 18°C and in another, fed diluted in Freon 113 into perfluoro-bis( 2-butoxyethoxy)methane at 18°C. In theεe runε, the condenεer waε εet at -25°C. In another variation, the precurεor waε fed undiluted into Fluorinert FC-75 at 70°C (55% yield) and in another run, fed undiluted into Fluorinert FC-87 at 20°C (42% yield). In theεe runε, the condenεer waε εet at about -25°C. In another variation, the reactor waε charged initially with 15.7 g biε( 2-butoxyethoxy)methane , 105 g NaF, and 400 mL Freon 113 and cooled to -8°C with the condenser set at -8°C. A flow of 30 mL/min F 2 and 120 mL/min 2 waε continued for 20.5 hourε. The crude product waε iεolated as above. H-nmr analyεiε εhowed the product contained 7.1 mg H/g liquid, correεponding to an average compoεition of C χ 3 H 5 F 23 0 4 . Gaε-liquid chromatography εhowed little perfluoroacetal; instead the analysis revealed a serieε of many εmall peaks at retention times intermediate between thoεe of the perfluoroacetal and the hydrocarbon acetal precurεor. In a 200 mL vessel of Monel metal equipped with a water-cooled condenser, 25.0 g of the crude product was exposed to a gas flow of 20 mL/min F 2 and 80 mL/min N 2 for 0.5 hr at 50° C, then 2.6 hr at 100°C, 1.6 hr at 150°C, and 2.0 hr at 175°C. Distillation of the residue (16.4 g) yielded 12.7 g (41%) of perfluoro-biε-( 2-butoxyethoxy)methane . H-nmr indicated it contained 0.3 mg H/g liquid. Perfluoro-biε( 2-butoxyethoxy)methane waε alεo prepared by the εolid fluorination technique of Example 1, the yield of the product being about 20%. Example 8 A mixture of 150 g (1.5 mol) n-hexanol and 122 g (1.5 mol, 37%) formalin was treated with 140 g HCl gas over 3 SUBSTITUTESHEET hr. The resulting chloromethyl hexyl ether (172 g, 73%) was used directly. A mixture of 147.4 g (1.1 mol) 2-(2-ethoxyethoxy)ethanol, 130 g (1.3 mol), and 275 mL acetonitrile was heated to 65°C and the above chloromethyl c hexyl ether was added slowly, followed by refluxing overnight. Gas-liquid chromatography indicated 12% unreacted R0CH 2 C1 and another 14 g of the alcohol was added. After an additional hour, the mixture was cooled, waεhed with water, and the product waε dried in methylene 0 chloride over Mg 2 S0 4 and distilled to 205.6 g (75%) 3 ,6 ,9 ,11-tetraoxaheptadecane, bp 126°C/0.5 Torr. The tetraoxaheptadecane, prepared aε deεcribed above, waε fluorinated by the liquidε fluorination technique of Example 7 at about -5°C in the preεence of NaF to produce 5 C.F 13 OCF.O(C 2 F 4 0) 2 C 2 F 5 , which had a boiling range of 75-88°C/ll Torr, boiling point of 170°C, viεcoεities at -70 and -85° C of 237 cs and >2500 cs, respectively, and pour point of -80°C. Examples 9-27 0 Using the liquids fluorination technique of Example 7 at about -5°C in the presence of NaF, different perfluoroacetal compositionε, each containing a εingle perfluoroacetal compound listed below (except aε indicated) together with properties of the composition, 5 were prepared from corresponding precursor acetals (made by the routes illustrated by Equationε 1, 2, or 3 or by Equationε 4 and 5, εupra) which were εaturated except aε noted. .9. CF 3 (CF 2 ) 3 0CF 2 0(C 2 F 4 0) 2 (CF 2 ) 3 CF 3 , boiling range of 0 100-120°C/46 Torr, boiling point of 173°C, pour point of -90°C, and viεcoεitieε at -70°C and -85°C of 148 cε and >2000 cε, reεpectively. 35 10. (cyclo-C 6 F 11 0) 2 CF 2 , boiling range of 100-120°C/20 Torr, pour point of -60°C, made from diphenoxymethane. BSTITUTESHEET 11. (cyclo-C 6 F χl CF 2 0) 2 CF 2 , boiling range of 95-115° C/10 Torr, pour point of -60°C, and viscoεity at -70°C of >2000 cs, made from dibenzyloxymethane . 12. [CF 3 (CF 2 ) 2 (OC 2 F 4 ) 3 0] 2 CF 2 , boiling range of 110-125° C/8 Torr. 13. [CF 3 (0-iεoC 3 F 6 ) 2 0] 2 CF 2 , boiling at 120°C/35 Torr, pour point of -75°C, and viεcoεity of 1111 cε at -70°C. 14. (C1C 2 F 4 0C 2 F 4 0) 2 CF 2 , boiling range of 155-170° C/740 Torr, and viεcoεitieε of 55 cε and 398 cε at -70°C and -85°C, reεpectively. 15. [C 2 F 5 (0C 2 F 4 ) 2 0] 2 CF 2 , boiling range of 100-110° C/60 Torr, boiling point of 176°C, pour point of -85°C, and viεcoεitieε of 106 cε, 469 cε, and 1531 cε at -70°C, -80°C, and -85°C, reεpectively. 16. [CF 3 (CF 2 ) 2 (OC 2 F 4 ) 2 0] 2 CF 2 , boiling at 120°C/35 Torr, pour point of -85°C, and viscosities of 429 cs and >2000 cs at -70°C and -85°C, reεpectively. 17. CF 3 OC 2 F 4 OCF 2 (OC 2 F 4 ) 3 OCF 2 OC 2 4 OCF 3 , boiling at 115° C/30 Torr, pour point of -95°C, and viscosities of 162 cs and 1500 cs at -70°C and -85°C, respectively. 18. CF 3 OC 2 F 4 OCF 2 0(C 2 F 4 0) 2 (CF 2 ) 3 CF 3 , boiling at 90°C/40 Torr, pour point of -85°C. 19. C 2 F 5 OC 2 F 4 OCF 2 (OC 2 F 4 ) 3 OCF 2 OC 2 F 4 OC 2 F 5 , boiling at 120-140°C/40 Torr. 20. C 2 5 OC 2 F 4 OCF 2 (OC 2 F 4 ) 2 OCF 2 OC 2 F 4 OC 2 F 5 , boiling range of 90-110°C/15 Torr, boiling at 190° C/740 Torr, and viεcoεities of 274 cs and 2375 cε at -70°C and -85°C, SUBSTITUTE SHEET reεpectively. 21. CF 3 (CF 2 ) 3 (OC 2 F 4 ) 3 OCF 2 OC 2 F 5 , boiling range of 70-90°C/15 Torr, boiling point of 165°C, and j. viεcoεitieε of 120 cε and 750 cε at -70°C and -85°C, reεpectively. 22. (n-C 7 F 15 0) 2 CF 2 , boiling range of 125-140°C/24 Torr, boiling point of 211°C, and melting point of -50°C. 0 23. [ (CF 3 ) 2 CFCF 2 OC 2 F 4 0] 2 CF 2 , boiling range of 70-110° C/25 Torr, and viεcoεitieε of 240 cε and 1015 cε at -70°C r and -80° C, respectively. 24. [ (CF 3 ) 3 C0C 2 F 4 0] 2 CF 2 , boiling range of 80-88° C/17 5 Torr, boiling point of 183° C, and pour point of -80°C, and viscosity of 2600 cs at -70°C. 25. [CF 3 (CF 2 ) 3 0C 2 F 4 0] 2 CFCF 3 , boiling range of 85-95° C/40 Torr, and viscoεitieε of 180 cε and 2504 cε at -70°C 0 and -80°C, reεpectively. 26. An approximately equimolar mixture of (C 2 F 5 OC 2 F 4 OC 2 F 4 0) 2 CF 2 and (C 4 F g OC 2 F 4 0) 2 CF 2 , made by 5 fluorination of a mixture of 11.2g and 10.Og of the respective hydrocarbon precurεorε, boiling at 178°C and having a viεcoεity of 104 cs and 395 cs at -70°C and -80° C, respectively. 0 27. A ternary mixture of approximately one part (C 2 F 5 OC 2 F 4 OC 2 F 4 0) 2 CF 2 , one part (C 4 F p OC 2 F.0) 2 CF 2 , and two parts C 4 F g OC 2 F 4 OCF 2 OC 2 F 4 OC 2 F 4 OC 2 F 5 , made by fluorination of the reaction product of an equimolar 35 mixture of C 2 H 5 OC 2 H 4 OC 2 H 4 OH and C 4 H g OC 2 H 4 OH with formaldehyde, εaid fluorinated mixture boiling at 179°C and having viεcoεities of 87 cs and 340 cs at SHEET -70°C and -80°C, reεpectively. Example 28 Four hundred g butoxyethoxyethanol (2.5 mol), 48 g paraformaldehyde (1.6 mol), 300 ml benzene and 5 g ion exchange reεin (acid form) were placed in a 1 liter εtirred flaεk. A water separator attached to a reflux condenser was used to collect the water produced aε the alcohol and aldehyde reacted. After approximately 6 hr, the reaction was complete and the solution was filtered to remove the resin. Vacuum distillation of the solution to 120°C gave 414 g of a product (99% yield) which was esεentially free of benzene and unreacted starting materials. The hydrocarbon product was fluorinated in a 22-liter stirred tank reactor which contained 6 liters of 1,1,2- trichl ' orotrifluoroethane and 1300 g εodium fluoride powder. A gaε diεperεion tube in the bottom of the reactor provided an inlet for the fluorine and nitrogen gaεeε. The hydrocarbon reactant (275 g) waε diluted with 1,1,2-trichlorotrifluoroethane, in a separate vesεel, to give a total volume of 700 ml. Thiε solution was metered into the fluorination reactor over a 20-hour period. The reactor temperature was maintained at 0°C with external cooling throughout the reaction while the fluorine flow was set at a leval 10% higher than that required to theoretically replace all of the hydrogens on the material entering the reactor. Upon completion of the reaction, the fluorine waε turned off and the reactor waε removed from the low temperature bath and purged for 30 min with nitrogen (2 literε/min) to remove the unreacted fluorine. Filtration of the reaction product followed by distillation to remove the 1 ,1 ,2-trichlorotrifluoroethane gave 642 g of a highly fluorinated fluid (80% yield). Treatment of the fluid at 260°C with 30% fluorine for several hours gave a perfluorinated fluid, b.p. 226.5°C, having an elemental analysiε and F-nmr spectra consiεtent with the following εtructure: SUBSTITUTESHEET CF 3 CF 2 CF 2 CF 2 0CF 2 CF 2 OCF., CF 2 0CF 2 OCF 2 CF 2 0CF 2 CF 2 0CF 2 CF 2 - CF 2 CF 3 Example 29 A mixture of 400 g triethylene glycol monoethyl ether (2.2 mol), 48 g paraformaldehyde (1.6 mol), 150 ml toluene, and 10 g of an acid ion exchange reεin waε refluxed for 6 hr in a 1 liter flaεk equipped with a water separator and reflux condenser. Filtration of the product followed by diεtillation gave a quantitative yield of the deεired product. Fluorination of 201 g of the material in a εtirred liquid fluorination reactor containing 6 literε of 1,1,2-trichlorotrifluoroethane and 1055 g εodium fluoride gave 401 g fluid in an 18 hr reaction at 0°C. Diεtillation of the crude product mixture gave 355 g of perfluorinated fluid, bp 217° C, the elemental analyεiε and F-nmr εpectra of which waε conεiεtent with the following structure : CF 3 CF 2 0CF 2 CF 2 0CF 2 CF., OCF., CF 2 OCF., OCF., CF 2 0CF 2 CF 2 OCF., - CF 2 OCF 2 CF 3 Example 30 Into a 1 liter flaεk were placed 600 g triethylene glycol butyl ether (2.91 mol), 74 g paraformaldehyde (2.46 mol), 150 ml benzene and 10 g of an acidic ion exchange reεin. The mixture waε refluxed for 5 hr aε water waε removed aε the water/benzene azeotrope. Filtration of the product and removal of the benzene by diεtillation gave a 90% yield of the ether product. The product (259 g) waε diluted with 400 ml 1 ,1,2-trichlorotrifluoroethane and waε εlowly metered into a 10°C reactor containing 5.7 literε of 1,1 , 2-trichlorotrifluoroethane and 1200 g εodium fluoride powder. A fluorocarbon fluid (660 g, 88.7% yield) waε obtained following filtration and removal of the 1,1,2-trichlorotrifluoroethane. Fluorination of the fluid at 220°C with 30% fluorine for 12 hr followed by SUBSTITUTESHEET diεtillation gave a 60% yield of a fluid, bp 262°C, whoεe F-nmr εpectra waε conεiεtent with the following εtructure: CF 3 CF 2 CF 2 CF 2 OCF 2 CF 2 0CF 2 CF 2 OCF 2 CF 2 OCF 2 OCF 2 CF 2 OCF 2 CF 2 - OCF 2 CF 2 OCF 2 CF 2 CF 2 CF 3 Example 31 Into a εtirred 1 liter flaεk equipped with a water εeparator were charged 350 g tetraethylene glycol butyl ether (1.40 mol), 35 g paraformaldehyde (1.18 mol), 200 ml benzene, and 10 g ion exchange reεin. The mixture waε refluxed until the water production ceaεed. Filtration of the product followed by removal of the light fractionε by vacuum distillation to 140°C gave 343 g of a light yellow fluid. A 306 g εample of the fluid waε diluted with 450 ml of 1 ,1, 2-trichlorotrifluoroethane and εlowly pumped into a -6°C reactor over a 23 hr period. The reactor contained 1450 g of sodium fluoride powder (to react with the hydrogen fluoride formed during the reaction) and 6 liters of 1 ,1, 2-trichlorotrifluoroethane . Filtration of the product followed by distillation gave 736 g of fluid. Treatment of the latter fluid at 250°C with 30% fluorine gave a clear, odorleεs fluid which upon diεtillation gave a 52% yield of a material having a bp of 296.7° C and a F-nmr εpectra conεiεtent with the following εtructure: CF 3 CF 2 CF 2 CF 2 CF 2 CF 2 OCF 2 CF 2 OCF 2 CF 2 OCF 2 CF 2 OCF., OCF 2 CF 2 - OCF 2 CF 2 OCF 2 CF 2 OCF., CF 2 OCF., CF 2 CF 2 CF 3 Exampl e 32 A mixture of 300 g tripropylene glycol methyl ether (6.46 mol), 33.7 g paraformaldehyde (1.12 mol), 150 ml benzene, and 3 g ion exchange reεin waε refluxed for 6 hr in a 1 liter flaεk equipped with a water εeparator and reflux condenεer.. Filtration of the product followed by vacuum diεtillation of the light fractionε gave 166 g of a product with a boiling point above 150° C at 0.05 mm Hg. SUBSTITUTESHEET Fluorination of 145 g of the diεtilled material, diεεolved in 450 ml 1,1,2-triclιlorotrifluoroethane, in a εtirred fluorination reactor containing 6 literε of 1,1,2- trichlorotrifluoroethane and 700 g of εodium fluoride gave 244 g of a fluorocarbon product in a 20 hr reaction at -3°C. Diεtillation of the product gave 180 g of the perfluorinated fluid: CF,0(iso-C,F,0),CF, (O-iso-C, F, 3 OCF 3 where the hexafluoropropylene oxide units are attached randomly in a hea rd-to-head, head-to-tail and tail-to-tail fashion. The perfluorinated fluid had a bp of 260.0°C and its F-nmr spectra was conεiεtent with the foregoing εtructure. Example 33 A mixture of 600 g diethylene glycol and 30 g potaεεiu hydroxide waε heated to 160° C in a 1 liter flaεk. Acetylene gas was bubbled through the solution as It was rapidly εtirred. The raction was stopped after 48 hr and the product was extracted with water several times to remove any unreacted diethylene glycol. The product, a divinyl ether of diethylene glycol, was recovered by distillation (bp 196° C) in about an 80% yield. A 1 liter flaεk cooled to -10° C was charged with 250 g triethylene glycol ethyl ether and a catalytic amount of methanesulfonic acid. To thiε solution was added εlowly 100 g diethylene divinyl ether. Following the addition, the flaεk waε εlowly warmed to room temperature over a 3 hr period. The product waε diεtilled to 150° C at 0.05 mm Hg to remove any unreacted εtarting materialε. The product from the above reaction can be fluorinated at 20° C uεing the procedureε outlined in Example 28 to give a perfluorinated fluid of the following structure: CF 3 CF 2 0(CF 2 CF 2 0) 3 CF(CF 3 )0(CF-, CF 2 0) 2 CF(CF 3 )0- (CF 2 CF 2 0) 3 CF 2 CF 3 SUBSTITUTESHEET Example 34 A mixture of 400 g triethylene glycol ethyl ether (2.24 mol), 258 g acetaldehyde diethylacetal (1.39 mol), 300 ml benzene, and 10 g acidic ion exchange reεin was refluxed in a 1 liter stirred flaεk equipped with a continuous extractor to remove the by-product ethanol from the refluxing benzene. The solution waε refluxed for 6 hr, then filtered and placed in a rotary evaporator to remove the benzene εolvent. The product waε fluorinated in a 22 liter εtirred tank which contained 5.7 literε of 1 ,1,2-trichlorotrifluoroethane and 1100 g εodium fluoride powder. The hydrocarbon, 219 g, waε diluted to a volume of 700 ml with 1,1,2-trichlorotrifluoroethane . The εolution waε εlowly pumped into the fluorination reactor, which waε held at -5°C, over a period of 28 hr. The fluorine flow waε εet at a level approximately 10% higher than that required to react with all of the organic entering the reactor. Filtration of the crude reactor product followed by diεtillation yielded 224 g of a clear fluid with an F-nmr εpectra conεiεtent with the following εtructure : CF 3 CF 2 OCF 2 CF 2 OCF 2 CF 2 OCF 2 CF 2 OCF ( CF 3 ) OCF 2 CF., 0- CF 2 CF 2 OCF 2 CF 2 OCF 2 CF 3 Example 35 In a run very εimilar to Example 34, 400 g dipropylene glycol monomethylether (2.70 mol) waε reacted with 159.5 g acetaldehyde diethylacetal ( )1.35 mol) in benzene with an acid catalyεt. Fluorination of 250 g of the material afforded 480 g of a perfluorinated fluid having the following εtructure: CF 3 0-i εo-C 3 F 6 0- i εo-C 3 F β OCF ( CF 3 ) i εo-C 3 F g O- i εo-C 3 F g OCF 3 Example 36 SUBSTITUTE SHEET Butoxyethoxyethanol (400 g, 2.47 mol) waε reacted with 130 g polymeric chloroacetaldehyde in 150 ml benzene to give a fluid which distilled at 190° C at approximately 1 torr. The product (266 g) waε mixed with 500 ml, 1,2-trichlorotrifluoroethane and pumped into a 15-liter fluorination reactor containing 5.7 liters 1, 1,2-trichlorotrifluoroethane and 1150 g sodium fluoride powder. Fluorine, diluted with approximately four volumeε of nitrogen, waε metered into the 0° C reactor at a rate approximately 10% greater than that required to react εtoichiometrically with the polyether. The organic feed rate waε εet to allow complete addition in approximately 23 hr. Filtration of the product and removal of the 1,1,2-trichlorotrifluoroethane via a diεtillation gave a fluorocarbon product which waε further purified by a 12 hr fluorination at 200°C with 40% fluorine. Approximately 520 g of fluid waε recovered with approximately 50% being a material with a bp of 245.5° C and a F-nmr εpectra conεiεtent with the following εtructure: CF 3 CF 2 CF 2 CF 2 OCF 2 CF., OCF., CF 2 OCF ( CF., Cl ) OCF 2 CF., OCF., CF., 0- CF 2 CF 2 CF 2 CF 3 Example 37 Chloroacetaldehyde dimethyl acetal (124 g, 1 mol), 1,3-dichloro-2-propanol (258 g, 2 mol) and 5 g ion exchange reεin were mixed in a 1 liter εtirred flaεk. The mixture was heated to allow the methanol formed in the reaction to slowly diεtill from the flaεk. Approximately 70 ml of methanol waε recovered over a 6 hr period. The remaining εolution waε vacuum-diεtilled and the fraction (120 g, 38% yield) boiling between 100° C and 145° C at 2 mm Hg waε collected. The fluid as shown by F-nmr and elemental analyseε to have the following structure: (C1CH 2 ) 2 CHOCHOCH(CH 2 Cl ) 2 CH 2 C1 UBSTITUTESHEET The above acetal (210 g), diluted with a εmall amount of chloroform and 1 ,1,2-trichlorotrifluoroethane, was metered over a 14 hr period into a 22°C fluorination reactor containing 5.7 liters of 1 , 1 , 2-trichlorotri- fluoroethane . The crude product was further treated with 30% fluorine at 200°C for several hours to give 197 g (57% yield) of clear fluid with a bp of 202°C and a F-nmr spectra consiεtent with the following εtructure: (CF 2 C1) 2 CF0CF0CF(CF 2 C1) 2 CF 2 C1 Example 38 Into a 1 liter εtirred flaεk containing 300 ml benzene were placed 516 g 1,3-dichloro-2-propanol (4 mol), 120 g paraformaldehyde (4 mol) and 10 g ion exchange reεin. The mixture was refluxed aε the water formed during the reaction waε continuouεly removed. After refluxing for 6 hr, the reaction mixture waε filtered and vacuum-distilled to give 354 g of a product, bp 141°C/0.05 mm Hg, with the following εtructure: (C1CH 2 ) 2 CHOCH 2 OCH( CH 2 Cl ) 2 The above acetal (354 g) was mixed with 70 g chloroform and 360 g 1 ,1 ,2-trichlorotrifluoroethane and fluorinated over a 24 hr period at 20°C using the procedure described in the previouε example. The reaction product was concentrated and the crude product was further treated with fluorine at 200°C to give 430 g of a clear fluid (69% yield) having a boiling point of 178°C and an F-nmr εpectra conεistent with the following structure: [ (C1CF. 2 CFO] 2 CF 2 Example 39 A mixture of 300 g 1-propanol (5.0 mol), 231 g epichlorohydrin and 10 g ion exchange resin was refluxed SUBSTITUTESHEET for 22 hr. The reaction mixture was then cooled, filtered and distilled to give 281 g of l-chloro-3-propoxy-2-propanol (74% yield). Reaction of thiε product with paraformaldehyde (2.8 mol) gave 202 g of product (69% yield), bp 132° C at 2 mm Hg having the following εtructure: CH 3 CH 2 CH 2 OCH 2 CH0CH 2 OCHCH.,OCH., CH., CH 3 CH 2 C1 CH 2 C1 Fluorination of the above acetal in a 23 hr reaction at 20°C gave 404 g of product (81% yield, bp 207°C), with a F-nmr spectra consiεtent with the following εtructure: CF 3 CF 2 CF 2 OCF 2 CFOCF.,OCFCF., OCF 2 CF., CF 3 CF 2 CL CF 2 C1 Example 40 A mixture of 600 ml ethoxyethanol, 200 g epichlorohydrin, and 10 g ion exchange reεin waε heated to 130°C for 20 hourε. The reaction mixture waε then cooled, filtered, and distilled to give 250 g of product which was then reacted with 116 g paraformaldehyde as in Example 38 to give 266 g of a product boiling above 150° C at 0.01 mm H 9- Fluorination of 261 g of the product in a reactor containing 5 liters of 1,1,2-trichlorotrifluoroethane and 1000 g sodium fluoride gave 446 g of perfluorinated fluid, bp 224, of which approximately 70% had a F-nmr spectra consiεtent with the following εtructure: CF 3 CF 2 OCF 2 CF 2 OCF 2 CFOCF.,OCFCF 2 OCF 2 CF 2 OCF 2 CF 3 CF 2 C1 CF 2 C1 Example 41 A mixture consisting of 100 g 2-chlo ' roethanol (12.4 mol), 573 g epichlorohydrin (6.2 mol) and 20 g of an acidic ion exchange resin were refluxed for 24 hr. The BSTITUTESHEET mixture waε then filtered to remove the ion exchange reεin and the excess alcohol and unreacted epichlorohydrin were removed by diεtillation. The reεidue waε diεtilled under vacuum and the product, l-chloro-3-(2-chloroethoxy)-2- propanol (804 g, 75% yield), diεtilled between 89 and 91°C at 0.05 mm Hg. Into a 1 liter εtirred flaεk waε placed 346 g l-chloro-3-( 2-chloroethoxy)-2-propanol (2 mol), 90 g paraformaldehyde (3 mol), 10 g ion exchange reεin and 300 ni benzene. The mixture aε refluxed for 4 hr aε the water formed during the reaction was removed. The reaction mixture was filtered and distilled to give 267 g of a product (75% yield) with the following εtructure: C : CH 2 CH 2 OCH 2 CHOCH 2 OCHCH 2 OCH 2 CH 2 Cl CH 2 C1 CH 2 C1 Fluorination of the product (660 g) in a typical reaction at 20°C gave 1086 g of a product (82% yield, bp 223°C), having a F-nmr εpectra consiεtent with the following εtructure: C1CF 2 CF 2 OCF 2 CFOCF., OCFCF., OCF 2 CF 2 Cl CF 2 C1 CF 2 C1 Example 42 Into a 1 liter flaεh waε charged 300 g trichloro- pentaerythritol, (1.58 mol), 150 ml of benzene, 10 g ion exchange reεin and 60 g paraformaldehyde (2 mol). The mixture waε refluxed aε water waε being removed continuouεly. A stripped portion of the above product, 192 g, waε diluted with 1 ,1 ,2-trichlorotrifluoroethane to give 210 ml of solution which was pumped into a 22° C reactor containing 4.3 liters of 1,1,2-trichlorotrifluoroethane . The reaction was complete in approximately 8 hr. The unreacted fluorine was flushed from the reactor with nitrogen gas and the product (307 g, 87.8% yield) waε SUBSTITUTESHEET recovered by distillation and its F-nmr spectra was consistent with the following structure: [(C1CF 2 ) 3 CCF 2 0] 2 CF 2 Example 43 Butoxyethoxyethanol (400 g, 2.47 mol) was reacted with 130 g polymeric chloroacetaldehyde in 150 ml benzene to give a fluid which distilled at 190° C at approximately 1 torr. The product (266 g) was mixed with 500 ml 1,1,2- trichlorotrifluoroethane and pumped into a 15 liter fluorination reactor containing 5.7 literε 1,1,2-tri¬ chlorotrifluoroethane and 1150 g εodium fluoride powder. Fluorine, diluted with approximately four volumeε of nitrogen, waε metered into the 0° C reactor at a rate approximately 10% greater than that required to react εtoichiometrically with the polyether. The organic feed rate waε set to allow complete addition in approximately 23 hours. Filtration of the product and removal of the 1,1 ,2-trichlorotrifluoroethane via a distillation gave a fluorocarbon product which was further purified by a 12 hour fluorination at 200° C with 40% fluorine. Approximately 520 g of fluid was recovered with approximately 50% being the target material. CF 3 CF 2 CF 2 CF 2 0CF 2 CF 2 OCF 2 CF 2 OCF ( CF 2 Cl ) OCF 2 CF 2 0CF 2 CF., OCF 2 CF 2 CF 2 CF 3 o b.p. 245.5"C 19 F NMR ( δ ppm vs CFC1 3 ) -73.3 :OCF( CF 2 Cl )0:-81.7 : CF 3 CF., CF 2 CF 2 0; -83.3 : CF 3 CF ~ CF 2 CF 2 0 ; -88.0 ~ and .88.7: 0CF 2 CF 2 0 ; -96.7:OCF(CF,Cl)0;-126.5:CF, CF, CF, CF, o Example 44 Chloroacetaldehyde dimethyl acetal (124 g, 1 mol) 1, 3-dichloro-2-propanol (258 g, 2 mol) and 5 g ion BSTITUTESHEET exchange reεin were mixed in a 1 liter stirred flask. The mixture was heated to allow the methanol formed in the reaction to εlowly diεtill from the flaεk. Approximately 70 ml of methanol waε recovered over a 6 hour period. The remaining εolution waε vacuum-diεtilled and the fraction (120 g, 38% yield) boiling between 100°C and 145°C at 2 mm Hg waε collected. The fluid waε εhown by 19 F NMR and elemental analyεiε to have the following structure: (C1CH, ), CHOCHOCH(CH, Cl) CH, Cl The above acetal (210 g) diluted with a small amount of chloroform and 1 , 1 , 2-trichlorotrifluoroethane waε metered over a 14 hour period into a 22°C fluorination reactor containing 5.7 literε of 1 ,1,2-trichlorotrifluoro¬ ethane. The crude product waε further treated with 30% fluorine at 200° C for εeveral hourε to give 197g (57% yield) of clear fluid: (CF 2 C1) 2 CF0CF0CF(CF 2 C1) 2 CF 2 C1 b.p. :202°C 19 F NMR (δ ppm vε CFCl 3 ):-64.5 and -65.0(a), -71.0(d), -86.7(c) and -133.7(b) [ (C1CF 2 ) 2 CF0] 2 CF(CF 2 C1) Variouε modificationε and variationε will become apparent to thoεe εkilled in the art without departing from the εpirit and εcope of thiε invention. SUBSTITUTESHEET

Claims: WHAT IS CLAIMED IS: 1. A perfluorinated gem-alkylenedioxy compoεition which is normally liquid and conεiεtε or conεiεtε eεεentially of one or a mixture of perfluorinated gem-alkylenedioxy compoundε having at leaεt 12 carbon atomε. 2. A perfluorinated compound represented by the 0 formula Y-O-C-O-Y' i R 2 5 wherein Y and Y' are the εame or different and are εelected from the group conεiεting of perfluoroalkyl, perfluoroalkyleneoxyalkyl, and perfluoropoly(alkyleneoxy)- alkyl wherein one or more of the fluorine atomε may be 0 halogen atomε other than fluorine; wherein 2 and R 2 are the εame or different and are εelected from the group conεiεting of -F, -Cl, -CF., Cl, -CFCl 2 , -CC1 3 , and perfluoroalkyl of 1 to 10 carbon atomε wherein one or more of the fluorine atoms may be halogen atoms other than ς fluorine and wherein the perfluoroalkyl group may contain one or more ether oxygen atoms. 3. A perfluorinated compound of Claim 2 wherein R χ and R 2 are fluorine. 4. A perfluorinated compound of Claim 2 wherein R χ , n is fluorine and R 2 is perfluoromethyl. 5. A normally liquid, perfluoroacetal compoεition which conεiεtε or consiεtε eεεentially of one or more εaturated perfluoro-1,l-bis-(alkoxy)alkane compounds each of which compounds can have two 35 perfluoro-1,1-alkylenedioxy moieties provided such moieties are separated from each other by at least two catenary carbon atomε of a perfluoroalkylene moiety. 6. The compoεition of Claim 1 conεiεting or SUBSTITUTESHEET conεiεting eεεentially of one of εaid compoundε. 7. The compoεition of Claim 1 conεiεting or consisting esεentially of a mixture of εaid compoundε. 8. The compoεition of Claim 1 wherein each εaid c compound iε repreεented by the formula 0 wherein R and R^ are independently εelected from the group conεiεting of C χ to C8 linear or branched perfluoroalkyl, C χ to C 8 linear or branched chloroperfluoroalkyl, and unεubεtituted or lower alkyl-εubεtituted perfluorocycloalkyl or chloroperfluorocycloalkyl wherein the number of ring carbon atomε iε 4 to 6; R f , R 3 f , and R f are independently εelected from the group conεiεting of C 2 to C 4 linear or branched perfluoroalkylene and C 2 to C 4 linear or branched chloroperfluoroalkylene; each R f iε independently a o fluorine atom or perfluoroalkyl with 1 to 4 carbon atomε; x and w are each independently an integer of 0 to 4; y iε an integer of 1 to 6; z iε an integer of 0 to 1; and where the total number of carbon atomε in εaid compound iε 6 to 30. 5 9. The compoεition of Claim 8, wherein each R^ iε independently F or CF 3 and the total number of carbon atomε in εaid compound iε 12 to 17. 10. The compoεition of Claim 5 wherein εaid compound iε repreεented by the formula 0 Cn F2, n+1. OCmF 2 ,m -OCF[ (CF, )p F]0-(Cn 2 in O bCn wherein each n and n' is independently an integer of 1 to 6, each m and m' iε independently an integer of 2 to 4, a 5 and b are each independently an integer of 0 to 4, and p iε 0 or 1, each εaid compound having 13 or 14 total carbon atomε, εaid compoεition having a viεcoεity at -70°C of less than about 300 centistokeε. SUBSTITUTESHEET -so¬ il. The compoεition of Claim 8 wherein εaid compound iε perfluoro-biε( 2-butoxyethoxy) ethane. 12. The composition of Claim 8 wherein said compound is perfluoro-3 ,6,9,11-tetraoxaheptadecane. i- 13. The compoεition of Claim 8 wherein said compound is perfluoro-5,7,10,13-tet aoxaheptadecane. 14. The composition of Claim 8 wherein εaid compound iε perfluoro-2,14-dimethyl-4,7,9,12-tetraoxapentadecane. 15. The compoεition of Claim 8 wherein εaid compound o iε perfluoro-3,6,9,11,14,17-hexaoxanonadecane. 16. The compoεition of Claim 8 wherein εaid compound is perfluoro-2, 5,7,10,13,16,18,21-octaoxadocoεane. 17. The compoεition of Claim 8 wherein εaid compound iε perfluoro-3,6,8,11,14,16 ,19-heptaoxaheneicoεane. 18. The compoεition of Claim 8 wherein εaid compound iε perfluoro-3, 5,8,11,14-pentaoxaoctadecane. 19. The compoεition of Claim 7 conεiεting or conεiεting eεεentially of a mixture of perfluoro-biε(2-butoxyethoxy)methane, perfluoro 0 3,6,9 , 11,14,17-hexaoxanonadecane, and, optionally, perfluoro-3,6,9,11,14-pentaoxaoctadecane. 20. The compoεition of Claim 1 wherein εaid compound iε repreεented by the formula 5 CF 3 CF 2 CF 2 CF 2 OCF 2 CF 2 0CF 2 CF., OCF 2 0CF 2 CF., OCF 2 CF 2 OCF 2 CF 2 - CF 2 CF 3 21. The compoεition of Claim 1 wherein εaid compound iε repreεented by the formula 30 CF 3 CF 2 OCF 2 CF 2 OCF 2 CF.,OCF 2 CF 2 OCF.,OCF., CF.,OCF., CF 2 OCF., - CF 2 OCF 2 CF 3 22. The compoεition of Claim 1 wherein εaid compound ,r iε represented by the formula CF 3 CF 2 CF 2 CF 2 OCF 2 CF.,OCF., CF 2 OCF 2 CF.,OCF 2 OCF 2 CF.,OCF 2 CF 2 - OCF 2 CF 2 OCF 2 CF 2 CF 2 CF 3 SUBSTITUTESHEET 23. The compoεition of Claim 1 wherein εaid compound iε represented by the formula CF 3 CF 2 CF 2 CF 2 OCF 2 CF 2 OCF., CF., 0CF 2 CF 2 0CF 2 CF., OCF 2 OCF 2 CF 2 - OCF 2 CF 2 0CF 2 CF 2 OCF 2 CF., OCF 2 CF., CF 2 CF 3 24. The composition of Claim 1 wherein εaid compound iε repreεented by the formula CF 3 0(iεo-C 3 F 6 0) 3 CF 2 (0-iεo-C 3 F 6 ) 3 OCF 3 25. The compoεition of Claim 1 wherein εaid compound iε repreεented by the formula CF 3 CF 2 0(CF 2 CF 2 0) 3 CF(CF 3 ) 0( CF 2 CF 2 O ) 2 CF ( CF 3 ) 0- (CF 2 CF 2 0) 3 CF 2 CF 3 26. The compoεition of Claim 1 wherein εaid compound is repreεented by the formula CF 3 CF 2 OCF 2 CF 2 OCF 2 CF., OCF 2 CF 2 OCF ( CF 3 ) OCF., CF., - CF 2 CF 2 OCF 2 CF 2 OCF 2 CF 3 27. The compoεition of Claim 1 wherein εaid compound iε repreεented by the formula CF, 3 P-iεo-C, 3 F6,0-iεo-C, 3 F6,0-OCF(CF, )0-iso-C, 3 F6 c O-iso- C 3 F 6 OCF 3 28. The compoεition of Claim 1 wherein εaid compound iε repreεented by the formula CF 3 CF 2 CF 2 CF 2 OCF 2 CF 2 OCF 2 CF 2 OCF(CF 2 Cl)OCF 2 CF., OCF 2 CF 2 O- CF.CF 2 CF 2 CF 3 29. The compoεition of Claim 1 wherein said compound is represented by the formula SUBSTITUTE SHEET (C1CH 2 ) 2 CHOCHOCH(CH 2 Cl) 2 CH 2 C1 30. The composition of Claim 1 wherein said compound iε repreεented by the formula (C1CH 2 ) 2 CH0CH 2 0CH(CH 2 C1) 2 31. The compoεition of Claim 1 wherein εaid compound iε repreεented by the formula CF 3 CF 2 CF 2 OCF 2 C CFFOOCCFF. 2 ,OOCCFICF., OCF., CF., CF 3 CF 2 C1 CF 2 C1 32. The compoεition of Claim 1 wherein εaid compound iε repreεented by the formula CF 3 CF 2 OCF 2 CF 2 OCF 2 CFOCF.,OCFCF 2 OCF 2 CF.,OCF 2 CF 3 CF 2 C1 CF 2 C1 33. The compoεition of Claim 1 wherein εaid compound iε repreεented by the formula C1CF 2 CF 2 OCF 2 CFOCF 2 OCFCF.,OCF 2 CF 2 Cl CF,C1 CF,C1 34. A proceεε for making the compoεition of Claim 1, which compriεeε contacting with fluorine the corresponding perfluorinateable, fluorine-free or partially fluorinated precurεor to perfluorinate the εame. 35. The proceεε of Claim 34 wherein εaid contacting iε carried out in the preεence of a hydrogen fluoride εcavenger. 36. A method of tranεferring heat from an article to a cooling liquid compriεing directly contacting the article with a cooling liquid compriεing the composition of Claim 5. SUBSTITUTESHEET 37. A method of inducing thermal εhock of an article compriεing: a) heating a firεt bath of a heating liquid to a temperature above ambient temperature; b) cooling a εecond bath of a cooling liquid to a temperature below ambient temperature; and c) εequentially: i) immersing the article in an initial bath which is one of said firεt and εecond bathε and allowing εaid article to come to the temperature of said initial bath before removing εaid article from εaid initial bath, and ii) then immerεing said article in the other of εaid firεt and εecond bathε and allowing said article to come to the temperature of said other bath before removing εaid article from εaid other bath; wherein εaid liquidε are inert, thermally εtable, perfluoroinated liquidε, at leaεt one of which iε the compoεition of Claim 5. 38. A method in accordance with Claim 23, wherein εaid heating and cooling liquidε are identical and are the compoεition of Claim 6. 39. A perfluorinated polyether having an average formula: Y-0-CF 2 -0-Y' wherein Y and Y' are the εame or different and are εelected from the group conεiεting of perfluoroalkyl, perfluoroalkoxyalkyl , and perfluoroalkyleneoxyalkyl ; and wherein the polyether compriεeε fewer than 8 or 12 or more carbon atomε provided that Y and Y' cannot both be -CF or 40. The perfluorinated polyether of Claim 39, wherein the polyether compriεeε from 12 to 20 carbon atomε. SUBSTITUTESHEET 41. A perhalogenated polyether having an average formula: wherein Y and Y' are the εame or different and are εelected from the group conεiεting of perfluoroalkyl, perfluoroalkoxyalkyl, and perfluoroalkyleneoxyalkyl; wherein R χ and R 2 are the εame or different and are εelected from the group conεiεting of -Cl, CF 2 C1, -CFC1 2 , -CC1 3 , perfluoroalkyl having 1 to 20 carbon atomε and perfluoroalkyleneoxyalkyl; and wherein the polyether compriεeε 12 or more carbon atomε. 42. The polyether of Claim 41, wherein the polyether compriεeε 12 to 25 carbon atomε. 43. A perhalogenated polyether having an average formula: Y-O-CF-O-Y" wherein Y and Y' are the εame or different and are εelected from the group conεiεting of perfluoroalkyl, perfluoroalkoxyalkyl , and perfluoroalkyleneoxyalkyl; wherein R iε selected from the group conεiεting of -Cl, CF 2 C1, -CFC1 2 , -CC1 3 , perfluoroalkyl having 1 to 20 carbon atomε and perfluoroalkyleneoxyalkyl; and wherein the polyether compriεeε 12 or more carbon atomε. 44. The polyether of Claim 43, wherein the polyether compriseε from 12 to 25 carbon atomε. 45. A perhalogenated polyether having an average formula: ' SUBSTITUTESHEET wherein Y and Y' are the same or different and are selected from the group consiεting of perfluoroalkyl, perfluoroalkoxyalkyl , and perfluoroalkyleneoxyalkyl; wherein R^ ^ and R 2 are the εame or different and are εelected from the group conεiεting of -F, -Cl, CF 2 C1, -CFC1 2 , -CC1 3 , perfluoroalkyl having 1 to 20 carbon atoms and perfluoroalkyleneoxyalkyl; and wherein the polyether contains at leaεt one halogen atom other than fluorine. SUBSTITUTESHEET

Inventors: BIERSCHENK THOMAS R, COSTELLO MICHAEL G, JUHLKE TIMOTHY, KAWA HAJIMU, LAGOW RICHARD J, MOORE GEORGE G I, BIERSCHENK, THOMAS, R., COSTELLO, MICHAEL, G., JUHLKE, TIMOTHY, KAWA, HAJIMU, LAGOW, RICHARD, J., MOORE, GEORGE, G., I.
Applicants: EXFLUOR RES CORP, MINNESOTA MINING & MFG, EXFLUOR RESEARCH CORPORATION, MINNESOTA MINING AND MANUFACTURING COMPANY
Application year: 1989
Main classification: C07C43
IPC codes: C07C41, C07C43, C08G2, C08G4, C08G65, C09K5