CS53291A2 - Method of fluorination by halogen exchange - Google Patents

Description

- 1

Fluorocarbon exchange of halogen

Technical field

The present invention relates in particular to the conversion of a saturated halogenated hydrocarbon which is at least once substituted by chlorine or bromine into the corresponding halogenated hydrocarbon. wherein at least one fluoro substitution has been carried out in place of "at least one substitution with chlorine or bromine." The process of the invention is of the utmost importance for improving the conversion of 2-chloro- or 2-bromo-1,1,1-trifluoroethane, CF 2 Cl 2. Cl or CF 3 CH 3 Br (the latter two hydrocarbons are hereinafter described individually as "HCFC-133a" and "HBFC-133aBl") for 1,1,1,2-tetrafluoroethane and CF 4 CH 2 F 4 (hereinafter referred to as "HCFC-133a" and "HBFC-133aBl") "HFC-134a"), whereby the resulting chloride or bromide is recovered as metal fluoride to recycle conversion progression.

HFC-134a and its isomer, 1,1,2,2-tetrafluoroethane CHF2-CHF2 (hereinafter referred to as "HFC-134") are widely used as propellants in aerosols and as refrigerants. ® 12, which is a commercial refrigerant commonly used in virtually all automotive air conditioning systems, but hitherto, the production of HF'C-134 and HFC-134a has not been commercially attractive, as there is a need for the conversion of HCFC-133a to HFC-134a by a process that is easy adapt to a continuous process that minimizes the need for hydrogen fluoride as a fluorine source to provide the desired tetrafluoro compound at a high degree of conversion and selectivity and high purity.

U.S. Pat. No. 4,311,863 (Col. 1, line 26 et seq.), it is known in the art that the chlorine atom in the -CHOCl group (as well as in CFC-133a) is considerably resistant / halogen-exchanged using fluoro-hydrogen . The prior art discloses the following references: U.S. Pat. U.S. Patent 2,885,427, U.S. Patent 3,664,545; U.S. Pat. No. 4,129,603 and Hudson Chemistry of Organic Fluorine Compounds, MacMillan Co.New York, N.Y. (1962), p. 93. No. 2,885,427 discloses the preparation of HFC-134 by reacting trichlorethylene with HF in vapor phase in the presence of a catalyst prepared by heating hydrated fluoride in the presence of oxygen. The resulting product is a mixture of fluorinated hydrocarbons reported to be HFC-134 /, and is present in an amount of 3 mol%.

Hudlicky describes in his book and in U.S. Pat. No. 3,644,545, the difficulty associated with fluorine exchange on the -C -CC ^ groups with HF in the liquid phase reaction and antimony catalysed as well as in the vapor phase reaction. U.S. Pat. U.S. Pat. No. 4,129,603 describes the reaction of CFC-133a with HF in vapor phase in the presence of chromium oxide as a catalyst to obtain a mixture of fluorocarbons containing HFC-134a in an amount of 18.2% by volume. U.S. Pat. U.S. Patent 1,914,135, Australian Patent No. 3,141, U.S. Patent 2,739,989 and U.S. Pat. U.S. Pat. No. 3,843,546 discloses halogen fluorination using alkali metal fluorides or alkaline earth fluorides. However, these metal fluorides have a relatively high degree of reactivity, and the methods of using them are usually best carried out in a vapor phase at an elevated temperature of 350 to 550 ° C by introducing a gaseous halogenated hydrocarbon over or through a bed of solid metal fluoride. As a by-product, the metal halide seeks to cover the metal fluoride during the progressing reaction, so that the reaction rate slows down, the fluoride often needs to be replaced, and the other devices mentioned in these patents need to be used to solve this problem. British Patent Specification 941,144 states that the relatively high temperatures required for gas-solid systems can be reduced and the yields improved if the gas-liquid process is used. The chlorinated gaseous hydrocarbon is permeable to the metal fluoride melt and the metal chloride at a temperature of about 300 to 375 ° C. The metal fluorides described herein include, but are not limited to, sodium, potassium and calcium fluorides. The molten metal chloride which acts as a solvent for the fluoride can be represented by ferric chloride or zinc chloride or mixtures thereof, or the mixture with sodium chloride. U.S. Pat. No. 4,311,863 discloses a process for the exchange of halogen in a gas-liquid system in an aqueous medium. In particular, the conversion of HCFC-133a to HFC-134a by reaction with potassium, cesium or rubidium fluoride in a 25-65% aqueous solution at about 200-300 ° C under appropriate pressure. Although HFC-134a is obtained in this process in reasonable yields, the process cannot be readily adapted to make it inexpensive, economical, continuously feasible, especially due to the higher pressures required to maintain the aqueous composition in the liquid state. And / or due to excessive corrosion of the reactor materials under the process conditions. It should be noted that in column 5, line 34, and others, HF, in the absence of a reagent, indicates that 2-chloro-1,1,1-trifluoroethane, CFC-133a, has been contacted with molten KF.HF in the absence of water.

SUMMARY OF THE INVENTION The present invention provides a process for fluorinating the exchange of halogenated saturated halogenated hydrocarbons, preferably in a continuous manner comprising the steps of: 1. Contacting a solid composition consisting essentially of alkali metal fluoride of formula MF in which M is known at least one alkali metal atomic number 19 to 55,

ie potassium K or cesium Cs or rubidium Hb, preferably Cs, with a gaseous halogenated hydrocarbon having at least a mono-exchangeable halogen which is other than fluorine, ie chlorine or bromine, in the molecule ^ preferably CX ^ CHgCl in which X is m 1 Cl or F, at a temperature at which both the original halogenated hydrocarbon and the fluorinated products are in the gas phase at a temperature below the lower decomposition temperature / original halogenated hydrocarbon or fluorinated product, preferably about 150 to about 450 ° C, at a pressure of less than or greater than atmospheric pressure, up to a pressure of 140 kg · cm (2000 psi), preferably at said pressure to increase productivity, typically at 1 to about 106 kg.cm (14.7 to 14.7 kg / cm2). about 1500 psi), for a few seconds to several hours, usually 0.5 minutes to two hours, i.e., pressures and times that are sufficient to obtain at least one reaction product having a at least one fluorine in addition to the original halogenated hydrocarbon, preferably CX ^ C, F, and until the remaining solid composition of MF is at least partially free of fluoride content and enriched with a halogen content other than fluoride, i.e. MCI; 2. The fluorinated reaction product is isolated from the remainder of the composition and obtained from the remaining composition and optionally, the remaining composition is contacted with gaseous anhydrous HF in the presence or absence of a halogenated hydrocarbon to form a halide other than fluoride. - changed to. HX, where X is chloro or bromo, and HX gas is separated from the solid composition enriched with MF.

The process of the invention can be expressed by the following equation 1 CX 3 CH 2 Cl + MF -> CX 3 CH 2 F + MCI (1) wherein X and M are as defined above. Surprisingly, it has been found that in the case where at least one of X is Cl, such as -CCl 3, -CCl 2 F and -CClF 2, the reaction can be easily controlled to obtain essentially exclusively the compound with the -CH 2 F group, i.e., essentially free of money

Cl in the -CX 3 group · In the case where the -CX 3 group is -CF 3, - 5 -, it is the product CF 3 C 4 F, ie HFC-134a.

It should be noted that X may be both halogen, for example in -CC1F2 and H or R, wherein R is an alkyl or aryl group optionally containing halogen. Thus, a -CX 4 group may be -CH 2, -CR 1, or any of the combinations between the two extremities.

According to another aspect of the present invention, the fluoride alkali metal, MF in equation (1), can be prepared by reacting alkali metal chloride MCI, which may be freshly prepared or by-product of MCI from equation (1), with HF gas using either alone or, in conjunction with the gaseous reactant CX-CH 2 Cl 2, resulting in the conversion of CX-C 1-4 Cl to CX-CH 2 F by HF as shown in equation (2): CX 3 CH 2 Cl + HF -> CX 3 CH 2 F + HCl (2)

According to another aspect of the invention, the CX ^C ^Cl Cl and HF gas can be brought together and continuously or intermittently with the alkali metal fluoride under controlled temperature conditions, wherein the alkali metal fluoride is regenerated continuously or intermittently in alkaline chloride. metal by-product of the reaction. In a preferred embodiment of the present invention, the alkali metal fluoride is contacted intermittently or continuously with the gaseous tetrahalogenethane, optionally in the presence of an HF gas at an effective temperature ranging from about 150 to about 450 ° C to obtain the appropriate 1,1,1- trihalo-2-fluoroethane, the fluorinated product is obtained from the resulting gas product stream. The starting 1,1,1-trihalo-2-chloroethane material may be CCl 3 CHCl 2, CCl 2 FCH 2 Cl, CCF 3 2 Cl 2, CF 3 CH 2 Cl or any of two or more of them. CF 4 CH 3 Cl is preferred as the starting material, and CF 3 CFLF is the preferred trihalo-2-fluoroethane, given that it is the most recent of economic importance.

The process of the invention is therefore preferably used for the preparation of HFC-I34a. As further explained in the following examples, HFC-134ave can be produced according to the invention in high yields (at high selectivities) at a high conversion rate of CF 2 CH 2 Cl 2. In addition, HFC-134 can be extracted by virtually unpolluted 1,1-difluoro-2-chloroethylene or other impurities that are not readily separable by conventional methods. HFC-134a (b.p. -26.5 ° C) can be obtained in high purity by simple means such as fractional distillation. The unreacted CF 3 CH 2 Cl 2 (bp 6.1 ° C) can also be recovered at a high degree of purity and recycled to the next tetrafluoroethane process of the invention. CF 3 CIL 4 Cl and other CX 3 CH 2 Cl 2 material can be converted to the corresponding -CH 2 F derivative under relatively mild conditions in the gas phase, which is surprising due to the difficulties encountered in the prior art conversion of -CH 2 Cl to -CH 2 F compound.

The alkali metal fluoride composition essentially consists of alkali metal fluoride, in which the alkali metal may be Na, Li, K, Rb and Cs, but is preferably an atomic number 19 to 55, i.e. K, Rb and Cs. It can also be used with mixtures of these alkali metals, including mixtures containing small amounts of alkali metal or alkaline earth metal fluorides with a lower atomic number.

The alkali metal fluoride may be free of support, i.e., in the form of granules, finely divided powder, or other particulate form, or may be applied to a suitable support, such as carbon, calcium fluoride, or other alkaline earth fluoride, or aluminum fluoride. The latter may be a highly fluorinated alumina which is obtained by reacting HF with alumina, the fluorine content being at least 9% by weight, preferably at least 95%, of the AIF3.

The reaction temperature can be varied within a wide range. It is usually in the range of from about 150 ° C to about 450 ° C, preferably from about 200 ° C to about 400 ° C, which depends on CX 4 Cl 2 Cl and alumina fluoride. In general, the higher the fluorine content of the starting material, the higher the minimum reaction temperature. Also, the higher the alkali metal atomic number of the alkali metal fluoride, the lower the run temperature may be. low for commercial production, whereas, at temperatures below these limits, the selectivity of the reaction to produce the desired -Cl 3 F compound is reduced by dilution with side reactions.

The reaction pressure is not critical provided that it is not so high as to result in the condensation of the gaseous reactant of CX-CH 2 Cl 2 during the reaction at the desired performance standards.

The reaction time can vary within wide limits, from several seconds to more hours, depending on the reagents, temperature and desired result. It is usually desirable that if the reaction is carried out according to equation (1), as mentioned above, the alkali metal fluoride is reacted completely as necessary, i.e. to convert the corresponding alkali metal chloride.

The reaction time can be increased and the production rate of the product maintained by converting the alkali metal chloride to a more superior product, carried out in situ on fluoride by HF (Equation 3): MCI + HF -> MF + HCl (3)

The temperature of this conversion should be above the melting point of the corresponding MHF2 bifluoride formed by the further reaction of MFs HF (equation 4): MF + HF = MHF2 Ό / (4) Preferably a temperature of at least 100 ° C is used, more preferably at least 150 ° C higher than the melting temperature of the fluoride, which is much less active for the purpose of comparison with MF. Thus, when M is K, the temperature will preferably be at least about 330 ° C, more preferably at least about 380 ° C; the rubidium Rb, the temperature will preferably be at least 310 ° C, more preferably at least about 360 ° C; when M represents Cs, the temperature will be at least 280 ° C, more preferably at least 330 ° C. The temperature for the conversion of MCI to MF is preferably kept below 8 about 400 ° C when using as the starting air the CX-Cí ^Cls HF in the stream of gaseous reactants in order to achieve the least heat-decomposition and as few other branches as possible. of the reaction with the starting CX 4 Cl 2 Cl and its fluorinated reaction product. In the absence of starting material, it may be

A normal mixture of the gaseous reaction product containing CX-CH 2 F as the product, unreacted CX-CK-C-1, and by-products, if any, can be further processed by any of a variety of techniques known in the art. known. For example, the mixture may be washed with water, an aqueous base solution or an aqueous acid solution to remove any acidic or water-soluble substances that may be present. One of the suitable washings was 20.7% aqueous HCl pre-cooled to -60 ° C. This washing allows the collection of low boiling organic flies as liquids and further purifying them by fractional distillation. The fluorinated reaction products which can be prepared according to the process of the present invention include CCl 3 CH 2 F, CCl 3 CF 4 F, CCF 2 CH 2 F and CF 3 Cl 2 F, depending on the starting material. The unreacted starting material can be recycled to the reactor. By-products, which may also be present, include those resulting from such branching reactions as dehydrohalogenation and carbon-carbon cleavage. 'niL - -

As mentioned above, the reaction products of CX-CH2F are suitable for use as refrigerants, solvents, blowing agents and as intermediates for the preparation of other useful products. Because they contain hydrogen, they have less harmful effects on the environment.

The reaction apparatus is not unambiguous, so that any of the devices normally used for gas-to-gas / gas-solid reaction can be used. Suitably, a flat container in which a solid fluoride alkali metal is placed so as to obtain a large surface by reacting with the CX 2 Cl 2 gas compound is preferred. The reactor is constructed from materials that resist the action of halogenated substances, -9 - including HF and HCl. Suitable construction materials include stainless steel, high nickel alloys such as Monel, Hastalloy and Inconel, and plastics such as polyethylene, polypropylene, chlorotrifluoroethylene, and poly-tetrafluoroethylene.

The following examples illustrate the various embodiments of the present invention, with Example 6 being the best mode for carrying out the invention. The examples were conducted in a 1.54 cm (1 inch) and 13 cm (13 inch) stainless steel reaction tube equipped with a gas inlet tube, a drain tube, and an electrically heated tubular controlled tube located at the center of the reactor. The outlet pipe was connected in series with the primary scrubber containing the aqueous soda solution, with an additional scrubber and gas chromatograph (C-C), which was treated with an automatic sample and an analysis of the reactor effluent gas. In some examples, the results of the gas chromatograph were verified by mass spectrometer (MS). As a Gas Chromatograph All reactants used were anhydrous. The gas chromatograph used was the Hewlett Packard 5880 model, which uses a flame ionization detector and a conventional four-component column. Analyzes of solutions coming out of the washing machine were carried out using fluoride and chloride specific ion electrodes. EXAMPLES Example 1

A 2.54 cm diameter and 33 cm length stainless steel reaction tube is charged with 87 grams of the potassium fluoride reaction stage containing about 7 grams of water. The reaction tube contains an electrically heated oven inside. The metal fluoride is dried in place by bringing dry nitrogen at 30 ° C for 25 hours. CF 2 CH 2 Cl 2 is then fed to the reactor at an initial rate of 18 ml / min for 4,222 minutes at about 300 ° C. The feed rate of CF-Cl was reduced to 6.8 ml / minute during the reaction period as the cylinder gradually evacuates. The reaction product stream is examined periodically by taking a sample, which is found to consist essentially of CF 2 CH 2 F 2 ΟΓ 2 = ΟΗ 2, CF 2 = CHCl 1 and unreacted CF 3 Cl 2 Cl 2. During the first 5 to 77 minutes of reaction, the conversion of CF 3 Cl 2 Cl to the products varies between about 10 to 24%, the selectivity (or conversion yield) of the CF 3 Cl 2 F in the low range, about 2%, to the high range, about 73% · Conversion of CF2 = CH2 occurs between 16 and 28% and for CF2 = CHC1 the conversion is between 9 and 77%. Thereafter, the conversion of ωF CCř ^Cl Cl stabilizes at about 15-17 with product yields as follows: CF-C ^F72-75%, CF2 =CH2 21-25% and CF2 = CHCl3 3-5%. Example 2

The procedure of Example 1 was repeated except that sodium fluoride (57.6 grams) was used in place of potassium fluoride and the reactor was heated in a sand bath to 250 ° C. this is increased by 50 ° C to 400 ° C in 1680 minutes. Conversion of CF 3 CE 3 Cl is less than 11% during the reaction. Example 3

The carbon pellets (80 grams) of 6 to 8 mesh, i.e. the maximum grain size of 3.322 to 2.322 mm, are allowed to soak in a 30% by weight aqueous solution of KF. The wet pellets were placed in a 2.54 x 33 cm stainless steel reaction tube according to Example 1 and dried by introducing dry nitrogen at 300 ° C for 20 hours. After cooling to room temperature, the tube is capped, weighed, and found to contain 68.3 grams of pellets of KF-treated soak, KF content is 8% by weight.

The reactor was then heated to 253-257 ° C with a stream of dry nitrogen passed through the reactor. The stream of nitrogen was charged with a stream of CF 3 CH 3 Cl 2 at a rate of 31 mL / min for 432 min. After the first 70 minutes, the conversion of CF 3 Cl 2 Cl is 63% and the yield (selectivity) of CF 3 CO 2 is 98%, in CF 2 = CH 2 0.9% and in CF 2 = CHCl 1.1%. After 100 minutes, the yield of CF 3 Cl 2 Cl decreased to 7%, the yield of CF 3 CH 2 F remained at 94%, the yield of CF 2 = CH 2 remained unchanged, while the yield of CF 2 = CHCl was increased to 6%. Thereafter, the conversion of CF3H2Cl2 is less than less than about 1%, the yield of CF3Cl2F remains at a range of 80-90%. less than 1% over the entire period and the selectivity of the conversion to CF 3 Cl 2 F is 99 to 100%. Example 4

The procedure of Example 3 is repeated except that KF pads consisting of PCB carbon shavings (61 grams) are used. Contains 24.3 weight percent KF (80.3 grams) after soaking in KF solution and dried. ° C in a stream of dry nitrogen gas. Reaction time at 261 ° C for 560 minutes. The maximum conversion of CF 3 CH 3 Cl is 51% at a selectivity to CF 3 CO 2 F in the range between 70 and 80%. The secondary products contain CHF ^ and CF3CH3 except for CF2 = CH2. Example 5

The process is repeated, except that (a) the carbon pad is impregnated with 38.5% by weight of cesium fluoride solution, (b) 129 grams of wet carbon coated with CsF is charged into the reactor and dried under heating at 250 ° C and (c) the rate of introduction of CF 2 CH 2 Cl 2 is 50 ml / minute at 250-252 ° C. 59 samples are taken from the flow product within 805 minutes. Conversion of CF 3 CH 2 Cl 2 to the desired products is 99% during the first 26 minutes, CF 3 CH 2 F yield is 75%, CF 2 = CH 2 O 2%, CF 2 = CHF 3% and CF 2 = CHCl 3 zero. After a further 36 minutes 12, the conversion of CF 3 Cl 2 Cl to 73% decreases, while the yield of CF 3 CH 2 F 2 increases to 94%.

Further, the conversion of CF 3 --CH 2 Cl 2 decreases over time and is about 15 to 20% after about 380 minutes, while the CF 3 Cl 2 F yield remains at 98 to 99%. All yields, pKFγ CF 2 = CH 2, CF 2 = CKF and CF 2 = CHCl, are less than 1%, the yield of CF 2 = CHCl being zero during the last 640 minutes of reaction time. Example 6

Example 5 is repeated except that (a) 69.3 grams of carbon substrate (dry weight) containing 38.5 wt% CsF is used, (b) the reaction temperature is maintained at 200 to 202 ° C and (c) ) the reaction time is 555 minutes. During the first 56 minutes, CF 4 Cl 2 F was produced in quantitative yield which dropped to 20% over the next 128 minutes and was substantially 10% over the last 371 minutes. Example 7

The procedure of Example 3 is followed except that (a) 72.1 grams of KF on carbon (20% by weight KF) are placed in the reactor tube, the weight of the base pre-dried with nitrogen at 200 ° C, (b) organic the feedstock is 1,1,1,2-tetrachloroethane, which is fed at a rate of about 0.8 gram / minute to the vaporizer to obtain a vapor stream of about 130 ml / minute, and (c) the temperature of the reactor is initially at 264 ° C and gradually increasing to a round of 300 ° C during the first 60 minutes, then gradually decreasing to 245 ° C over a further 120 minutes.

Sampling of the reaction product stream is started after 75 minutes by condensation at 0 ° C and continued for another 5 minutes for the remainder of the reaction time. The product mixture consists essentially of CCl 3 Cl 2 F and CCl 2 = CHCl 3. Example 8

The procedure of Example 7 was followed except that (a) CClFgCl 2 Cl 2 was used as the feedstock and (b) the reaction temperature was maintained between 235 and 241 ° C. Product stream sampling begins after the first 100 minutes of reaction, samples are taken every 5 minutes over the next 80 minutes. Conversion of CCIF2CH2Cl is approximately 30% at a selectivity to CCIF2CH2F of about 55% at 100 minutes of reaction duration. During the next 10 minutes, both the conversion and the selectivity decrease to about 10% and then move between 5 and 10% for the remaining reaction time.

Again, it is noted that chlorine substitution with fluorine occurs unexpectedly on the -C 1 -C 2 group and not on the -CCIF 2 group. Example 9 In this example, a process for preparing CF 3 Cl 2 F 2 CF 2 CEL 1 Cl by KF, regenerating the spent (exhausted) KF reaction with HF and continuing production, CF 3 CE 5 F is described.

The procedure of Example 3 is followed, except that 86 grams of carbon pellets are charged into the reactor and left in the feed for about 16 hours in 6 molar aqueous KF solution, then filtered and dried in a vacuum dryer for 16 hours at 200 ° C. C. The carbon saturated KF is flushed with dry nitrogen with heating to 250 ° C. Subsequently, the stream of nitrogen is replaced with CF 2 Cl 2 Cl, which is fed at 50 mL / min for 944 minutes. During this time, the conversion of CF 3 CH 3 Cl 2 from 16% at selectivity to CF 3 CE 3 F increased by 89% after an initial 3 minutes of approximately 60% conversion with conversion selectivity to CF 3 CO 2 F 99% 10 minutes. Thereafter, the conversion is gradually reduced to below 1%, which is attributable to the loss of available KF over time, but the conversion selectivity to CF 3 CH 3 F remains at 98-99%.

At the end of the 944 minute period, the feed CF 4 Cl 2 Cl was replaced by - 14 - dry nitrogen inlet and the reaction temperature was raised to 500 ° C for approximately 50 minutes. The nitrogen stream is then replaced by a HF stream at a rate of 90-100 mL / min for 134 min, with the HF stream replaced with dry nitrogen and allowed to fall to 250 ° C. The CF-CH 2 Cl 2 stream is then re-introduced at 250 ° C for 368 minutes. In the first 18 minutes, the conversion rate of CF 3 CH 3 Cl to 7% is increased at a selectivity of conversion to CF 3 CH 3 F 100%, then gradually decreases to less than 1% and is accompanied by a decrease in the selectivity of conversion to CF 3 C 4 F at about 26% during remaining reaction time. The results demonstrate that the conversion of KCl to KF takes place in situ, but that the duration of action of HF is too short to cause the co-product of KCl as a by-product to convert to KF. EXAMPLE 10 In this example, the preparation of CF3C2F5 by reaction of CF3 CH2Cl2 with HF and KCl is described. The procedure of Example 8 is followed, except that 70 grams (dry weight) of a carbon pad impregnated with 11.2% w / w (dry weight) is introduced into the reactor tube. The reactor was heated to 250 ° C while introducing dry nitrogen through the reactor. Thereafter, the nitrogen is replaced by a gas mixture consisting of 1 volume of HF and 5 volumes of CF 3 CH 3 F at a common flow rate of about 62 ml / minute and the temperature is raised to 300 ° C. After 50 minutes, the conversion of CF 2 C 2 Cl 2 is 2%, the selectivity of the conversion to CF 3 C 4 F 5 is 28%. The reaction is continued for a further 400 minutes at temperatures between 250 and 300 ° C and a molar ratio of HF / CF 2 CH 2 Cl 2/5 to 2.5 / 5, while the conversion or yield of CF 3 / CH 3 is varying. The temperature is raised to 360 ° C and maintained for 80 minutes, during which time the conversion of CF 3 Cl 2 Cl is increased to 4-5%, the yield of CF-, CH 2 F being about 26%. The increase in temperature results in a further decrease in conversion, to 13%, which is increased to 21% over the next 250 minutes at a yield of CF 4 C 2 F moving between 16 and 19%. Increasing the temperature to 400 dC of the amorphous ratio HF / CF 3 CH 2 Cl to 1/1 results in an increase of - 15 - conversion to 31% and an increase in the selectivity of the conversion to CF 3 CH 3 F 4 by 28%. Example 11

The procedure of Example 9 was followed. 74.7 grams of carbon pad containing 20.5 wt% KF was charged into the reactor and the reactor contents were heated to 300 UC under dry nitrogen. The nitrogen flow was replaced with CF 2 Cl 2 Cl at a flow rate of 50 mL /. minute. After 55 minutes, the conversion of CF 3 CH 2 Cl 2 5% and the selectivity for CF 3 CH 2 F 5 were 75%. After 64 minutes, HF gas was fed at a rate of 50 ml / min at a 1/1 molar ratio of HF / CF 3 CH 2 Cl 2. After a total reaction time of 83 minutes, the conversion of CF 3 CH 2 Cl 2 is about 15% and the selectivity to CF- CH 3 F is about 84%. Both the conversion and the selectivity decreased over time and eventually settled individually to 2% and 80%, respectively. Example 12

The procedure of Example 11 is repeated except that (a) the reaction temperature is increased to 400 ° C, (b) used and dried metal halide-carbon (from Example 11) are used and dried at 300 ° C for 16 hours, with co-formation The HF is started at 75 minutes and (d) the reaction time is extended to 830 minutes.

After the first 63 minutes, the conversion of CF 3 Cl 2 Cl is 65% selectivity to CF 3 C 5 F about 70%. After 90 minutes, the conversion to about 20% and the selectivity to about 41%. Then, during the remainder of the reaction, the conversion of CF3C1Cl4 gradually increases from a lower value of 17% at 120 minutes to about 30%, with the conversion selectivity to CF3. Referring to Example 11, it should be noted that better results, in terms of CF 3 CH 2 Cl 2 conversion and selectivity for CF 2 CH 2 F, are obtained at 400 ° C than at 300 ° C. In this context, it should be pointed out that the vapor pressure of HF over-16 by the KHF2 system - the reaction product of KF and HF, which is much less effective than KF for a given purpose, is about 0.564 atmospheres at 400 ° C and only 0.052 atmospheres at 300 ° C. In other words, the higher the degree of dissociation of the bifluoride of the alkaline MHF2, the greater the conversion of the organic halide and the better the desired result.

Claims (13)

A process for fluorination by exchange of a halogen-saturated halogenated hydrocarbon having at least one substitutable halogen other than fluorine to a fluorinated product having at least one fluorine in the molecule in comparison to a saturated halogenated hydrocarbon characterized in that it comprises the following steps (1) a saturated halogenated hydrocarbon is contacted with a solid composition comprising an alkali metal fluoride RIF at a temperature at which both the original halogenated hydrocarbon and the fluorinated product are in the gaseous state at a temperature below the decomposition temperature of said halogenated hydrocarbon or said fluorinated product at both lower and lower temperatures at a pressure and time sufficient to provide at least one reaction product having at least one molecule in the molecule. one fluorine in addition to said saturated halogenated hydrocarbon and to remain solid the composition is at least partially freed of its fluoride content and enriched with a halide content other than fluoride; (2) whereupon the fluorinated reaction product is isolated and recovered. 2. A process for the preparation of a fluorinated ethane of the formula EMI2.0 wherein X is Cl or F, (i) a solid composition consisting essentially of fluoride-alkali metal R1F, wherein R1 is at least one of the atomic atoms. from 19 to 55, continuously in contact with (ii) a halogenogenetic gas stream CX-C18-C1, where X is Cl or F, at an effective temperature in the range of about 150 to about 450 ° C and a sufficient time to obtaining (a) a stream gas product containing CX 2 CH 2 F, wherein X is Cl or F, and that the alkali metal fluoride composition containing the alkali metal chloride is at least partially depleted, and (iii) the gaseous stream is separated from the alkali metal composition product. 18 3. The process of claim 2 wherein the alkali metal fluoride is supported on a rigid support. 4. The method of claim 3 wherein the support is carbon in particles. 5. The process according to claim 2, wherein the alkali metal fluoride is potassium fluoride and the temperature is in the range of about 250 to about 400 ° C. 6. The process of claim 2 wherein the alkali metal fluoride is fluoride and the temperature is in the range of about 200 ° C to about 350 ° C. 7. The process of claim 2 wherein the alkali metal fluoride is produced by reacting the hydrogen fluoride with the corresponding alkali metal chloride. 8. The process of claim 2 wherein the at least partially depleted fluoride-alkali metal composition is regenerated by treatment with gaseous hydrofluoride at a temperature in the range of an effective temperature that is at least about 100 ° C above the alkali metal fluoride corresponding to the alkali metal fluoride bifluoride. 9. The process of claim 8 wherein the hydrogen fluoride is contacted with said solid composition concurrently with the compound CX2CH3Cl. 10. A process according to claim 2, wherein CF3CH2Cl2 is used as halogenethane and said product gas stream comprises CF3C1F3F. 11. A process according to claim 2, characterized in that CCl2CH2Cl2 is used in the process of the invention and said gaseous product stream comprises CCF2CH2F. 12. The process of claim 2 wherein the haloethane is CCl2FCH2Cl and said gaseous product stream comprises CCl2FCH2F. 13. The process of claim 2 wherein said haloethane is Cl.sub.2CH.sub.3. Represents: