MANUFACTURE OF FLUORINATED COMPOUNDS

Abstract: Pentafluorophenoxy substituted perfluoro ether containing acyl fluorides are produced by the reaction of a pentafluorophenoxide with hexafluoropropylene oxide under specified reaction conditions. The process may produce better yields of the desired products and/or use ingredients less deleterious to the environment. The products are intermediates for the production of perfluorinated vinyl ethers which are useful as curesite monomers in perfluoroelastomers.

Description: TITLE MANUFACTURE OF FLUORINATED COMPOUNDS FIELD OF THE INVENTION Described herein is an improved process for making pentafluorophenoxy substituted perfluoroethers by reacting a pentafluorophenoxide salt with hexafluoropropylene oxide under specified process conditions. The resulting product, which is useful as an intermediate for the preparation of a monomer, is often obtained in improved yield, and/or the use of ozone depleting solvents is greatly reduced or avoided. TECHNICAL BACKGROUND Perfluorinated pentafluorophenoxy substituted vinyl ethers are useful as curesite monomers for perfluoroelastomers. These compounds can be made by the reaction of a pentafluorophenoxide salt (PFPS) with hexafluoropropylene oxide (HFPO) to yield a corresponding pentafluorophenyl substituted ether containing an acyl fluoride group. The acyl fluoride may then be converted to a vinyl ether, thereby forming the desired monomer. In the reaction of the PFPS with HFPO, highly fluorinated (which are sometimes also chlorinated, so-called CFC compounds) solvents which can act to decrease atmospheric ozone levels have typically been used. Also a typical problem in these processes has been obtaining a high yield of any particular oligomer desired, represented by "n" in the formula C 6 F 5 O[CF(CF 3 )CF 2 O] n CF(CF 3 )COF, wherein n is 0 or a lower integer. It would therefore be desirable to have a process for producing such compounds which eliminates the use of ozone depleting compounds, and/or more selectively produces the desired oligomer. SUMMARY OF THE INVENTION This invention concerns, a first process for the production of a pentafluorophenoxy substituted perfluoroether, comprising, contacting, in a solvent mixture consisting essentially of tetraglyme and 1 ,2-dimethoxyethane or methylene chloride or a mixture thereof, and at a temperature of about -60°C to about 0°C, an alkali metal salt of pentafluorophenol and hexafluoropropylene oxide to produce a compound ofthe formula C6F5OCF(CF3)CF 2 OM (I), wherein M is said alkali metal; provided that the total molar amount of said hexafluoropropylene oxide added to the process is no greater than 1.25 times the molar amount of said alkali metal salt of pentafluorophenol present in said process. This also concerns a second process for the production of a pentafluorophenoxy substituted perfluoroether, comprising, contacting, at a temperature of about +10°C to about +80°C, in a solvent mixture consisting essentially of adiponitrile and tetraglyme, a compound ofthe formula C6F 5 OCF(CF3)COF (III), with a catalytic amount of potassium fluoride and hexafluoropropylene oxide to produce a compound ofthe formula C 6 F 5 OCF(CF3)CF 2 OCF(CF3)COF (II). Also disclosed herein is a third process for the production of a pentafluorophenoxy substituted perfluoroether, comprising, (a) contacting, in a solvent mixture consisting essentially of tetraglyme and 1 ,2-dimethoxyethane or methylene chloride or a mixture thereof, and at a temperature of about -60°C to about 0°C, an alkali metal salt of pentafluorophenol and hexafluoropropylene oxide to produce a compound ofthe formula C 6 F 5 OCF(CF 3 )CF 2 OM (I), wherein M is said alkali metal; provided that the total molar amount of said hexafluoropropylene oxide added to the process is no greater than 1.25 time the molar amount of said alkali metal salt of pentafluorophenol present in said process to produce (I); and (b) heating (I) to produce a compound ofthe formula C 6 F 5 OCF(CF 3 )COF (III); (c) contacting, at a temperature of about +10°C to about +80°C, in a solvent mixture consisting essentially of adiponitrile and tetraglyme, (III) with a catalytically effective amount of potassium fluoride and hexafluoropropylene oxide to produce a compound ofthe formula C 6 F 5 OCF(CF3)CF 2 OCF(CF3)COF (IV). Also described herein is a fourth process for the production of a pentafluorophenoxy substituted perfluoroether, comprising: (a) contacting, in a solvent mixture consisting essentially of tetraglyme and 1,2-dimethoxyethane or methylene chloride or a mixture thereof, and at a temperature of about -60°C to about 0°C, an alkali metal salt of pentafluorophenol and hexafluoropropylene oxide to produce a compound ofthe formula C 6 F 5 OCF(CF 3 )CF 2 OM (I), wherein M is said alkali metal; provided that the total molar amount of said hexafluoropropylene oxide added to the process is no greater than 1.25 time the molar amount of said alkali metal salt of pentafluorophenol present in said process to produce (I); (b) adding a perfluorinated compound which is a liquid under the process conditions; and (c) then heating to about 25°C to about 50°C while adding approximately at least about one equivalent of HFPO to produce a compound of the formula C 6 F 5 O[CF(CF3)CF 2 O] n CF(CF3)COF (V), wherein n is an integer of 1 to 5. DETAILS OF THE INVENTION In the first process described herein one ofthe ingredients is a PFPS, which is also sometimes referred to an alkali metal pentafluorophenoxide. In a preferred PFPS the alkali metal is sodium or potassium, more preferably potassium. Since different alkali metal ions which may be present may promote the desired reaction or other side reactions at different rates, it may be necessary to adjust the first process conditions particularly in regards to temperature and the exact solvent mixture used (see below) to obtain the desired product. Some of these conditions are illustrated in the Examples, and others may be readily determined by simple experimentation. In the first process a solvent mixture is employed. This mixture must be a liquid at the process temperatures, must dissolve at least some ofthe PFPS (preferably at least about 25 g/L at the process temperature, more preferably at least about 50 g/L, and especially preferably 100 g/L), and should not significantly react with HFPO or the PFPS (i.e. should be chemically inert). The ratio ofthe two (or more) compounds in the solvent mixture may be adjusted by simple experimentation to maximize the yield ofthe desired product. Useful solvents for the mixture include tetraglyme combined with one or more of a second compound such as 1 ,2-dimethoxyethane, methylene chloride, 1 ,2-dichloroethane, tetrahydro¬ furan, and the like. Preferred second compounds are 1 ,2-dimethoxyethane and methylene chloride. It is also preferred that the solvent mixture contain at least 5 volume percent of tetraglyme and at least 5 volume percent ofthe second compound(s) (total). When tetraglyme and 1 ,2-dimethoxyethane and/or methylene chloride is used as the solvent mixture it is preferred that the tetraglyme is about 80 to about 95 volume percent ofthe solvent mixture. In the first process it is preferred that the temperature is about -30°C to about -15°C. It is also preferred that the molar ratio of HFPO to PFPS is about 1.0 to about 1.15. A preferred method of running the process is to add the PFPS to the solvent mixture, cool to the desired temperature and then add the HFPO at such at rate so the temperature can be controlled. Other methods may also be used to run the reaction, but care should be taken to be able to control the temperature during the exothermic reaction. The initial product of the first process is a potassium fluoride salt of an acyl substituted pentafluorophenoxy substituted perfluoroether (I). The potassium salt may be converted to the acyl fluoride (which is a starting material for the second process herein) by heating, typically under reduced pressure, at a temperature of about 20°C to about 150°C, preferably about 25°C to about 100°C, for a period of time sufficient to effect the transformation. This time period is typically 1 hr. to 1 day, depending mostly on the scale ofthe reaction (including time needed to remove the second compound ofthe solvent mixture). The acyl fluoride (III) may be isolated by distillation. Distillation is easier if the compounds employed in the solvent mixture have boiling points substantially different from the desired product. In the second process herein a starting material is the acyl fluoride (III) which is produced by heating the (intermediate) product ofthe first process. A catalytically effective amount of a fluoride ion source is also present, and preferably the fluoride ion source is potassium fluoride. A useful amount of potassium fluoride is about 2 to 10 mole percent ofthe amount of acyl fluoride charged. A solvent mixture is also present in the second process. This mixture may consist essentially of adiponitrile [NC(CH 2 ) 4 CN] and tetraglyme [CH 3 O(CH2CH 2 O)4CH3]. It is preferred that each of these ingredients in the solvent mixture is at least 5 volume percent ofthe mixture, and it is more preferred that that the adiponitrile is about 75 to about 95 volume percent ofthe solvent mixture. Instead of adiponitrile, benzonitrile or other similar nitriles may be used. Instead of tetraglyme, 1 ,2-dimethoxyethane, tetrahydrofuran, or other similar ethers may be used. In the second process it is preferred that the temperature is about 30°C to about 50°C. It is also preferred that the molar ratio of HFPO to the initial acyl fluoride is about 1.0 to about 1.2. A preferred method of running the process is to add the initial acyl fluoride and catalyst to the solvent mixture (in which it is at least partially soluble), adjusting to the desired temperature and then add the HFPO at such at rate as to control the temperature. Other methods may also be used to run the reaction, but care should be taken to be able to control the temperature during the exothermic reaction. As will be recognized, the third process herein is a combination the first and second processes, and all of the discussions and preferred items for the first and second processes, and the heating of (I) to produce (III), apply as well to their respective parts ofthe third process. Alternatively, a fourth process may be run to produce the desired final product (the above mentioned product of the second process). After the first process has been carried out, a completely perfluorinated compound which is a liquid under the process conditions is added, typically about one-half to an equal volume of the perfluorinated liquid to the volume ofthe initial solvent mixture, and then the process ingredients are heated to about 25°C to about 50°C while adding approximately at least one equivalent of HFPO. The larger the amount of HFPO added, the higher "n" in (V) will be, on average. Useful perfluorinated liquids include perfluoro(n-butyltetrahydrofuran), hexafluoropropylene cyclic dimer, and other relatively low boiling perfluorinated (poly)ethers. The desired product may then be isolated by distillation. In all ofthe processes herein it is preferred to exclude moisture and oxygen, especially moisture, since they may lead to undesired side reactions and reduce the yield ofthe desired product. Therefore reaction ingredients should preferably be dry. The processes should be agitated to ensure reasonably good mixing ofthe ingredients. In the Examples, the following abbreviations are used: FC-75 - perfluoro(n-butyltetrahydrofuran), available from the 3M Company, Minneapolis, MN, U.S.A. GC - gas chromatography glyme - 1 ,2-dimethoxyethane (HFPO) 2 - ester - CF 3 CF 2 CF 2 OCF(CF 3 )C(O)OC 6 F 5 In the Examples the products are sometimes referred to as x/y adducts, wherein x and y are integers. X refers to the number of "moles" of pentafluorophenoxy groups in the molecule, and y refers to the number of HFPO units in the molecule. "Ester" refers to the pentafluorophenyl ester of the corresponding acyl fluoride. EXAMPLE 1 A ca. 1000 mL resin kettle was fitted with overhead stirrer, thermocouple, combination HFPO addition port and dry ice condenser attached to a nitrogen line, and solid addition port (jointed glass tube which extended into the reaction vessel) was dried and then charged with dry tetraglyme (200 mL), glyme (1 ,2-dimethoxy- ethane) (22 mL), and C6F5OK (40.09 g, 180 mmol). The temperature increased to ca. 30°C upon addition ofthe solid. The mixture was then cooled to -35°C. HFPO (13.9 g, 83.7 mmol) was added using a mass flow controller and the temperature ofthe reaction mixture was maintained at -35° to -40°C. The mixture was warmed to -10°C in stages (ca. 0.5 h), and was sampled for GC analysis which showed functional equivalents of (area%): 1/1 COF = 86%, 1/2 COF = 5%, 1/1 C 6 F 5 ester = 8%, 1/2 C 6 F 5 ester = 1%. Another 33 g HFPO (199 mmol) was added to the stirred mixture while the temperature was maintained at ca. -15°C. When addition was complete, the mixture was warmed to 0°C and analyzed by GC: this showed functional equivalents of (area%): 1/1 COF = 13%, 1/2 COF - 58%, 1/3 COF = 19%, 1/4 COF - 5%, 1/1 C 6 F 5 ester - <1%, 1/2 C 6 F 5 ester = 5%. To verify above distribution, and to examine processing characteristics of the above mixture, it was transferred by cannula and vacuum transferred @7 Pa, overhead temperature up to 76°C. The fluorocarbon and tetraglyme were largely (but not completely) in separate layers, so this portion was redistilled to provide 48.3 g of 1/2 adduct, equivalent to 97.4 mmol. Based on C 6 F 5 OK charged, this is 97.4/180 = 54% yield, quite close to the expected value projected by GC analysis ofthe crude reaction mixture. EXAMPLE 2 A ca. 1000 mL resin kettle was fitted with overhead stirrer, thermocouple, combination HFPO addition port and dry ice condenser attached to a nitrogen line, and solid addition port (jointed glass tube which extended into the reaction vessel) was dried and then charged with dry tetraglyme (200 mL), glyme (22 mL), and C 6 F 5 OK (40.04 g, 180 mmol). The mixture was then cooled to -35°C. HFPO (33.0 g, 199 mmol) was added using a mass flow controller and the temperature of the reaction mixture was maintained at -31 °C to -35°C. After 20 min at -35°C, the mixture was warmed to -10°C in stages (ca. 0.5 h), and was sampled for GC analysis which showed functional equivalents of (area%): 1/1 COF = 89.5%, 1/2 COF = 7.6 %, 1/1 C 6 F 5 ester = 2.9%, 1/2 C 6 F 5 ester = not detected. FC-75 (108 g) was added to the reactor, and the mixture was warmed to 10°C. Another 33 g HFPO (199 mmol) was added to the stirred mixture while the temperature was maintained at ca. 10°C. When addition was complete, the mixture was warmed to room temperature. GC analysis ofthe top layer and bottom layer were carried out separately. Top layer showed functional equivalents of (relative area%): 1/1 COF = 15%, 1/2 COF = 66%, 1/3 COF = 18%, 1/4 COF = 1%, 1/1 CgF 5 ester = <1%. Using tetraglyme signal as a standard, it appeared that ca. 78% of fluorocarbon material was still present in the hydrocarbon phase. The bottom layer showed functional equivalents of (relative area%): 1/1 COF = 1%, 1/2 COF = 39%, 1/3 COF = 43%, 1/4 COF = 15%, 1/5 COF = 2%. To determine the overall composition, the lower-boiling materials were collected at 13 Pa, and the distillation was continued for a short time after the head temperature had reached that of tetraglyme. GC analysis ofthe resulting bottom layer showed (relative area %): 1/1 COF = 12%, 1/2 COF = 61%, 1/3 COF - 23%, 1/4 COF = 4%. Only a small amount of 1/1 and 1/2 adducts were present in the top layer, and this was discarded along with the top layer before proceeding with final distillation. This provided 44.5 g of 1/2 adduct. The selectivity values obtained from the crude reaction mixture were about the same as the control reaction, meaning that FC-75 has little effect on distributions at this temperature. EXAMPLE 3 A ca. 1000 mL resin kettle was fitted with overhead stirrer, thermocouple, combination HFPO addition port and dry ice condenser attached to a nitrogen line, and solid addition port (jointed glass tube which extended into the reaction vessel) was dried and then charged with dry tetraglyme (225 mL), glyme (25 mL), and C 6 F 5 OK (40.04 g, 180 mmol). The mixture was then cooled to -35°C. HFPO (33.0 g, 199 mmol) was added using a mass flow controller and the temperature of the reaction mixture was maintained at -31°C to -35°C. After 20 min at -35°C, the mixture was warmed to -10°C in stages (ca. 0.6 h), and was sampled for GC analysis which showed functional equivalents of (area %): 1/1 COF - 89.7%, 1/2 COF = 7.5%, 1/1 C 6 F 5 ester = 2.8%, 1/2 C 6 F 5 ester = not detected. FC-75 (100 mL) was added to the reactor, and the mixture was warmed to 35°C. Another 33 g HFPO (199 mmol) was added to the stirred mixture while the temperature was maintained at ca. 35°C. When addition was complete, the mixture was stirred for 40 min., then allowed to cool to room temperature. GC analysis ofthe top layer and bottom layer were carried out separately. The entire volatile portion was then collected up to the bp of tetraglyme. Cooling the resulting transferred material at 0°C gave two layers, and the small top layer contained only a very small amount of product. The bottom layer showed (relative area %): 1/1 COF = 6%, 1/2 COF = 69%, 1/3 COF - 24%, 1/4 COF = 2%. Only a small amount of 1/1 and 1/2 adducts were present in the top layer, and these were discarded along with the top layer before proceeding with final distillation. This gave a distilled yield of 1/1 adduct of 4.6 g and 1/2 adduct of 56.0 g, equivalent to an overall yield of 126.8 mmol/180 mmol = 70.4%. EXAMPLE 4 A 250 mL Fisher/Porter vessel was charged with C 6 F 5 OCF(CF 3 )COF (24.7 g, 74.8 mmol), 11 mL of 9/1 adiponitrile/tetraglyme and spray-dried potassium fluoride (0.35 g, 6 mmol). The pressure head was attached, and the contents were stirred for 0.5 h as a significant portion ofthe solid went into solution. The apparatus was attached to the HFPO line and was placed in a bath controlled at 25°C. HFPO (11.9 g, 71.7 mmol) was added over 30 min. Internal temperature increased to 29°C during the addition. Pressure returned to ca. atmospheric after 0.5 h. GC analysis ofthe bottom layer showed the following composition: component area % HFPO dimer+trimer 4.3 1/1 adduct 12.0 1/2 adduct 78.2 1/3 adduct 5.5 Another 1.78 g (10.7 mmol) of HFPO was added and the reaction mixture was stirred until pressure returned to atmospheric. Bottom layer was analyzed by GC: component area % HFPO dimer+trimer 6.4 1/1 adduct 5.6 1/2 adduct 80.1 1/3 adduct 7.9 Another 0.89 g (5.4 mmol) of HFPO was added and the mixture was stirred until pressure returned to atmospheric. Bottom layer was analyzed by GC: component area % HFPO dimer+trimer 6.3 1/1 adduct 3.0 1/2 adduct 81.1 1/3 adduct 9.6 Contents ofthe reactor were transferred by cannula to a flask and the bottom layer was separated and distilled using a short spinning band column @ 1.9 kPa to give a total of 27.6 g 1/2 adduct (74% based upon 1/1 adduct). EXAMPLE 5 A ca. 1000 mL resin kettle was fitted with overhead stirrer, thermocouple, combination HFPO addition port and dry ice condenser attached to a nitrogen line, and solid addition port (jointed glass tube which extended into the reaction vessel) was dried and then charged with dry glyme (200 mL) and cooled to -50°C. The HFPO addition tube extended into the reactor close to the solvent level. The solid addition tube was aimed to discharge toward the center ofthe reactor. The stirrer was a glass disk with attached blades. HFPO (16.5 g, 99 mmol) was added using a mass flow controller and the temperature ofthe reaction mixture was then lowered to -78°C. Then another 16.5 g of HFPO was added at ca. 0.5 g/min while the C6F5OK (40.15 g, 180 mmol) was simultaneously added over a period of ca. 45 min using a section of Gooch tubing. After stirring @ -78°C for 1 h, the mixture was warmed to -60°C. The solution was sampled for GC analysis which showed functional equivalents of (area%): 1/1 COF = 76%, 1/2 COF = 1 1%, 1/1 C 6 F 5 ester = 10%, 1/2 C 6 F 5 ester = 3%. Reactor contents were transferred to a single neck flask for distillation using a cannula, and the volatiles were then removed under vacuum. The solid remaining in the pot was coated with product liquid, so the flask was heated in order to drive over as much product as possible. Distillation under reduced pressure afforded 41.52 g of 1/1 adduct and 4.61 g of 1/2 adduct, equivalent to a combined molar yield of 75%. EXAMPLE 6 A ca. 1000 mL resin kettle was fitted with overhead stirrer, thermocouple, combination HFPO addition port and dry ice condenser attached to a nitrogen line, and solid addition port (jointed glass tube which extended into the reaction vessel) was dried and then charged with dry glyme (50 mL) and cooled to -50°C. The HFPO addition tube extended into the reactor nearly to the solvent level. Also, the solid addition tube was aimed to discharge toward the center ofthe reactor. The stirrer was a glass shaft with a Teflon® ring attached at the bottom. HFPO (6.00 g, 36 mmol) was added using a mass flow controller, and simultaneously the C^OK (8.03 g, 36 mmol) was added over a period of ca. 8 min using a section of Gooch tubing. After stirring @ -50°C for 5-10 min, the solution was sampled for GC analysis. This showed functional equivalents of (area %): 1/1 COF = 81%, 1/2 COF = 3%, 1/1 C 6 F 5 ester = 15%. The mixture was treated with FC-75 (25 mL), warmed to 10°C and treated with HFPO (7.2 g, 20% excess for the second stage addition) and stirred for 20 min. GC analysis ofthe bottom layer showed: 1/1 COF = 12.6%, 1/2 COF = 67.1%, 1/3 COF = 11%, 1/1 C 6 F 5 ester = 1.2%, 1/2 C 6 F 5 ester = 7.3%. (Ester values appear low because esters are predominantly in the glyme layer.) Contents ofthe reactor were transferred to a flask using a polyethylene cannula (receiver under controlled, partial vacuum). Some ofthe solvent was distilled from this pot (atmospheric pressure). The remainder ofthe volatiles were then transferred under vacuum with modest application of heat to drive volatiles away from solid KF. GC analysis showed 1/1 COF = 18%, 1/2 COF = 73%, 1/3 COF = 9%. To confirm identity ofthe above components and to verify lack of (HFPO) 2 -ester, the vacuum-transferred liquid was distilled again under reduced pressure to provide 1.55 g of 1/1 adduct and 6.34 g of 1/2 adduct. 19 F NMR of the 1/2 adduct (CDCI3): -77.61 and -84.59 (AB pattern, J=142 Hz, OCF 2 for one diastereomer) and -78.41 and -85.09 (AB pattern, J=142 Hz, OCF 2 for one diastereomer, combined area for 2F), -79.55 (overlapping m, CF 3 , 3F), -82.30 (s, CF 3 , 3F), -130.9 ( CF, IF), -139.24 ( t, J=18.3 Hz) and -139.53 (t, J=18.1 Hz, CF adjacent to OC 6 F 5 , IF), -150.8 (m, 2F), -155.4 (m, IF), -161.8 (m, 2F), 26.7 (m, COF, IF). EXAMPLE 7 A 250 mL 3 -neck rbf fitted with overhead stirrer, thermocouple, and combination HFPO addition port and dry ice condenser attached to a nitrogen line was charged with potassium pentafluorophenoxide (8.03 g, 36 mmol), dry glyme (50 mL) and FC-75 (35 mL). The mixture was cooled to ca -78°C, and a substantial amount ofthe solid precipitated and clung to the flask walls, although stirring was still functional. HFPO (6.0 g, 36 mmol) was added (3-4 min), and solid disappeared. After stirring @ -78°C for 20 min, the mixture was warmed in stages to 0°C. The top layer was sampled for GC analysis which showed (area%): 1/1 COF = 90%, 1/2 COF = 2%, 1/1 C 6 F 5 ester = 8%. The mixture was then warmed to 25°C and treated with another 6.00 g HFPO (addition over ca. 15-20 min on account of slower uptake). The mixture was stirred overnight. GC analysis ofthe lower layer showed the following composition: Distribution of acid fluorides 1/1 COF = 27% 1/2 COF = 67% 1/3 COF = 6 % Total area fraction of esters was about 5%. Since conversion ofthe 1/1 adduct was judged to be lower than desired, another 3.0 g HFPO was added, again at ca. 24°C. GC then showed distribution of adducts as 15/73/12. To obtain final, overall distribution of adducts, the volatiles were vacuum transferred and solvent was then distilled to afford a single layer which was GC analyzed and showed a 24%/69%/6% distribution of adducts. EXAMPLE S A 500 mL 4-neck rbf fitted with overhead stirrer, thermocouple, dropping funnel, and combination HFPO addition port and dry ice condenser attached to a nitrogen line was charged with dry glyme (25 mL) and cooled to -50°C. HFPO (6.00 g, 36 mmol) was added, and the solution was cooled to ca -78°C. A solution of C6F5OK (8.03 g, 36 mmol) in glyme (50 mL) was added over a period of ca. 15-20 min. After stirring @ -78°C for 5-10 min, the homogeneous solution was sampled for GC analysis which showed functional equivalents of (area %): 1/1 COF = 88%, 1/2 COF = 7%, 1/1 C 6 F 5 ester = 5%, 1/2 C 6 F 5 ester =<1%. The mixture was then warmed to 0°C and treated with 30 mL FC-75, warmed to 25°C and stirred for 0.5 h. GC analysis ofthe top layer showed only marginally diminished concentrations of adduct acid fluorides or their functional equivalents. The reaction mixture was treated with another 8.00 g HFPO over ca. 15-20 min. The mixture was stirred overnight. Volatiles were removed by vacuum transfer, then solvent was distilled until a homogeneous product solution remained. GC analysis showed the following composition: Distribution of acid fluorides 1/1 COF = 6% 1/2 COF = 76% 1/3 COF = 17% 1/4 COF = 1% EXAMPLE ? A 500 mL 3-neck rbf fitted with overhead stirrer, thermocouple, and combination HFPO addition port and dry ice condenser attached to a nitrogen line was charged with dry glyme (50 mL) and cooled to -50°C. HFPO (6.00 g, 36 mmol) was added using a mass flow controller, and simultaneously the solution of C^OK (8.03 g, 36 mmol) in glyme (50 mL) was added over a period of ca. 10 min. After stirring @ -50°C for 5-10 min, the residual portions of solid disappeared. The solution was warmed to 20°C and the mixture was sampled for GC analysis which showed functional equivalents of (area %): 1/1 COF = 86%, 1/2 COF = 5%, 1/1 C 6 F 5 ester = 8%, 1/2 C 6 F 5 ester = 1%. The mixture was then treated with another 6.00 g HFPO (addition over ca. 10 min ). Temperature increased to 26.3°C during the course of addition, and dropped to 24°C within ca. 15 min. The mixture was stirred 1.5 h. GC analysis showed the following composition: Distribution of acid fluorides 1/1 COF = 36% 1/2 COF = 55% 1/3 COF = 9% Since conversion of 1/1 to desired adduct was much lower than desired, another 4.0 g of HFPO was added, again @ 21-25°C. The mixture was stirred overnight before further GC analysis: Distribution of acid fluorides 1/1 COF = 19% 1/2 COF = 60% 1/3 COF = 17% 1/4 COF = 4% To determine the proportion of HFPO converted to HFPO dimer/trimer, the lower layer sample was treated with MeOH, water, and reanalyzed. Total (HFPO) n ester quantity was ca. 14%. EXAMPLE 10 A 3-liter multiport round-bottomed flask set up in a cooling bath was equipped with an air-driven overhead stirrer, a thermal well, a dry ice condenser and a gas inlet tube [reaching the lower half of the flask] connected by a Y-tube to nitrogen line and a HFPO cylinder. The flask was charged with 222 grams [1 mole] of potassium pentafluorophenoxide, 1200 ml of tetraglyme and 120 ml of dichloromethane. It was stirred vigorously and a nitrogen atmosphere was established. The condenser was filled with acetone and dry ice. The bath was filled with acetone and dry ice added in portions until the bath temperature read -40°C where it was maintained during the HFPO addition. The contents ofthe flask were cooled to -32°C and HFPO was fed in at a steady rate of about 6 grams per minute and the internal temperature was maintained in the range of -27°C to -32°C. If the temperature rose above -27°C rate of addition of HFPO was reduced. A gentle reflux of HFPO was seen at the dry ice condenser. When 183 grams [1.10 moles; 10% excess] of HFPO had been added, the HFPO cylinder was closed and conditions of reaction maintained for an additional 30 minutes. The cooling bath was drained and the reaction mixture was allowed to warm up to +10°C during 3 hours while maintaining stirring. A sample ofthe reaction was analyzed by GC and found to be a mixture of 82% of 1 : 1 -adduct, 8% of 2: 1 -adduct and 6% of ester ofthe acid fluoride and the phenoxide. Other impurities amounted to 4%. The reaction was transferred to an evaporating flask and the low boiling dichloromethane was stripped in a rotary evaporator at 100 mm Hg and a bath temperature of 40-45°C. The contents were then transferred to a 2-liter distilling still equipped with a 30" x 1 " column packed with Pro-pak® 316 stainless steel (0.24 x 0.24") packing [Aldrich Chemical Co.]. Distillation was carried at 35 mm Hg. After an initial collection of low boilers in the temperature range of 25° to 55°C the main bulk ofthe product steadily distilled in the temperature range of 55° to 68°C. It was collected and weighed. The weight was 238 grams [72% yield based on C6F5-OK] and found to be >97% 1 : 1 -adduct. Further distillation yielded 15 grams of a mixture of 1 :1 [42%] and 2:1 -adduct [57%]. EXAMPLE U Conditions were identical to Example 10. The only variation was the ratio of solvents. In this experiment the solvent was a mixture of 1000 ml of tetraglyme and 300 ml of dichloromethane. The GC-analysis ofthe product before distillation showed 85% of 1 : 1 -adduct, 7% of 2 : 1 -adduct and the rest ester and other unidentified impurities. Distilled yield was 248 grams [75% yield based on C6F5-OK] and a purity of 96%. EXAMPLE 12 Quantities were identical to those in Example 10. The reaction was carried out in a temperature range of -27°C to -21 °C. Yield was 232 grams [70% yield] and purity was 96%. EXAMPLE 13 Identical to Example 12, but the reaction temperature was in the range of -20°C to -14°C. The yield was 188 grams [57%]. The major impurity was the ester amounting to 38%. EXAMPLE 14 This experiment was carried out in a 20-gallon kettle under conditions described in Example 10. The following quantities of chemicals and solvents were used. C6F5-OK 33.31 moles = 7405 grams HFPO [15% excess] 38.3 moles = 6357 grams Tetraglyme = 40 liters Dichloromethane = 4 liters After the reaction with HFPO the crude product was worked up as follows. Dichloromethane from the crude product was distilled in a large [22 liter] rotary evaporator at a bath temperature of 45 °C and a vacuum of 200 mm Hg with continuous feed ofthe crude product into the evaporation flask at the same rate of distillation. When the pot could no longer hold additional quantities [about 12 liters], the vacuum was reduced to 100 mm Hg and maintained until no more solvent was collecting in the receiver. The flask was emptied to a storage vessel and a second batch was subjected to the same routine. When all the crude product had been subjected to the above operation, it was transferred in batches to a 12-liter distillation still and the 1 :1 -adduct was distilled at a vacuum of 30 mm Hg. The bulk of product distilled weighed 7145 grams [65%]. It had a purity of 95% with 3% of 2: 1 -adduct. EXAMPLE 15 This was carried out in a 20-gallon [76 liter] kettle. Adiponitrile [17 liters] and KF [580 grams; 10 moles] were transferred to the kettle under a nitrogen atmosphere and stirred for 20 minutes. Tetraglyme [1.6 liters] and the distilled 1 : 1 -adduct [100 moles; 33 kilograms] were then transferred to the kettle and the contents were heated by circulating warm water [40°C] through the jacket ofthe kettle while maintaining stirring. When the internal temperature reached 35°C HFPO was fed in at such a rate to maintain the internal temperature in the range of 35°C to 41 °C. The reaction was rapid as very little reflux was seen in the dry-ice condenser. When the addition of HFPO was completed, it was stirred for an additional 30 minutes. Stirring was stopped and after 15 minutes, the lower [mostly 2:1 -adduct with small quantities of 1 : 1 -adduct] layer was removed. GC analysis of a sample of this showed no solvent. It weighted 42.67 kg. It was transferred to a still and distilled in vacuum. Initially, the vacuum was set at 30 mm Hg and the unreacted 1 : 1 -adduct was distilled until the temperature reached 85°C. When no more distillation was seen as indicated by a drop in the head temperature below 40°C the vacuum was increased to a range of 6- 10 mm Hg and the 2: 1 -adduct free of the 1:1 -adduct was collected at a boiling range of 68°C to 78°C. The distilled 2:l-adduct weighed 39.6 kg [yield is 80% based on the charged 1 : 1 -adduct].

Claims: What is claimed is: 1. A process for the production of a pentafluorophenoxy substituted perfluoroether, comprising, contacting, in a solvent mixture consisting essentially of tetraglyme and 1 ,2-dimethoxyethane or methylene chloride or a mixture thereof, and at a temperature of about -60°C to about 0°C, an alkali metal salt of pentafluorophenol and hexafluoropropylene oxide to produce a compound ofthe formula C 6 F 5 OCF(CF 3 )CF 2 OM (I), wherein M is said alkali metal; provided that the total molar amount of said hexafluoropropylene oxide added to the process is about 1.0 to about 1.25 times the molar amount of said alkali metal salt of pentafluorophenol present in said process. 2. The process as recited in Claim 1 wherein said alkali metal is sodium or potassium. 3. The process as recited in Claim 1 wherein said alkali metal is potassium. 4. The process as recited in Claim 3 wherein said tetraglyme is about 80 to about 95 volume percent of said solvent mixture. 5. The process as recited in Claim 3 wherein said temperature is about -30°C to about -15°C. 6. The process as recited in Claim 3 wherein the total molar amount of said hexafluoropropylene oxide added to the process is about 1.0 to about 1.15 times the molar amount of said alkali metal salt of pentafluorophenol present in said process. 7. The process as recited in Claim 6 wherein said tetraglyme is about 80 to about 95 volume percent of said solvent mixture, and said temperature is about -30°C to about -15°C. 8. A process for the production of a pentafluorophenoxy substituted perfluoroether, comprising, contacting, at a temperature of about +10°C to about +80°C, in a solvent mixture consisting essentially of adiponitrile and tetraglyme, a compound ofthe formula CgF5OCF(CF3)COF (III), with a catalytically effective amount of potassium fluoride and hexafluoropropylene oxide to produce a compound ofthe formula C 6 F 5 OCF(CF 3 )CF 2 OCF(CF 3 )COF (II). 9. The process as recited in Claim 8 wherein said solvent mixture is about 75 to about 95 volume percent adiponitrile. 10. The process as recited in Claim 8 wherein a molar ratio of total HFPO to (II) is about 1.0 to about 1.2. 11. The process as recited in Claim 8 wherein said potassium fluoride is present in an amount of 2 to 10 mole percent of (III). 12. The process as recited in Claim 8 wherein said temperature is about +30°C to about +50°C. 13. The process as recited in Claim 12 wherein said solvent mixture is about 75 to about 95 volume percent adiponitrile, a molar ratio of total HFPO to (II) is about 1.1 to about 1.2, and said potassium fluoride is present in an amount of 2 to 10 mole percent of (II). 14. A process for the production of a pentafluorophenoxy substituted perfluoroether, comprising, (a) contacting, in a solvent mixture consisting essentially of tetraglyme and 1 ,2-dimethoxyethane or methylene chloride or a mixture thereof, and at a temperature of about -60°C to about -10°C, an alkali metal salt of pentafluorophenol and hexafluoropropylene oxide to produce a compound ofthe formula CgF 5 OCF(CF3)CF 2 OM (I), wherein M is said alkali metal; provided that the total molar amount of said hexafluoropropylene oxide added to the process is no greater than 1.25 time the molar amount of said alkali metal salt of pentafluorophenol present in said process to produce (I); and (b) heating (I) to produce a compound ofthe formula C 6 F 5 OCF(CF 3 )COF (III); (c) contacting, at a temperature of about +10°C to about +80°C, in a solvent mixture consisting essentially of adiponitrile and tetraglyme, (IV) with a catalytic amount of potassium fluoride and hexafluoropropylene oxide to produce a compound ofthe formula C 6 F 5 OCF(CF 3 )CF 2 OCF(CF3)COF (II). 15. The process as recited in Claim 14 wherein (b) is carried out at about +20°C to about +150°C. 16. The process as recited in Claim 14 wherein (b) is carried out at about +25°C to about +100°C. 17. A fourth process for the production of a pentafluorophenoxy substituted perfluoroether, comprising: (a) contacting, in a solvent mixture consisting essentially of tetraglyme and 1,2-dimethoxyethane or methylene chloride or a mixture thereof, and at a temperature of about -60°C to about 0°C, an alkali metal salt of pentafluorophenol and hexafluoropropylene oxide to produce a compound ofthe formula C 6 F 5 OCF(CF 3 )CF 2 OM (I), wherein M is said alkali metal; provided that the total molar amount of said hexafluoropropylene oxide added to the process is no greater than 1.25 time the molar amount of said alkali metal salt of pentafluorophenol present in said process to produce (I); (b) adding a completely perfluorinated compound which is a liquid under the process conditions; and (c) then heating to about 25°C to about 50°C while adding approximately at least one equivalent of HFPO to produce a compound ofthe formula C 6 F 5 O[CF(CF 3 )CF 2 O] n CF(CF 3 )COF (V), wherein n is an integer of 1 to 5. 18. The process as recited in Claim 17 wherein about one-half to about an equal volume compared to said solvent mixture of said perfluorinated compound is added. 19. The process as recited in Claim 17 wherein in (c) about one equivalent of said hexafluoropropylene oxide is added.

Inventors: FARNHAM WILLIAM BROWN, RESNICK PAUL RAPHAEL, SUBRAMANYAM VINAYAKAM, FARNHAM, WILLIAM, BROWN, RESNICK, PAUL, RAPHAEL, SUBRAMANYAM, VINAYAKAM
Applicants: DU PONT, FARNHAM WILLIAM BROWN, RESNICK PAUL RAPHAEL, SUBRAMANYAM VINAYAKAM, E.I. DU PONT DE NEMOURS AND COMPANY, FARNHAM, WILLIAM, BROWN, RESNICK, PAUL, RAPHAEL, SUBRAMANYAM, VINAYAKAM
Application year: 1996
Main classification: C07C51
IPC codes: C07C41, C07C43, C07C51, C07C59