RU2200729C2 - Method of synthesis of perhalogenated cyclopentene - Google Patents

Abstract

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to method of synthesis of chlorofluoro-cyclopentenes and octafluorocyclopentene used as intermediate compounds for synthesis of 1,2,3,3,4,4,5,5-octafluorocyclopentane. Method of synthesis of 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentane is carried out by fluorination of octachlorocyclopentene with hydrogen fluoride in gaseous phase in the presence of the fluorination catalyst. Catalyst comprises compound taken among group consisting of

. The fluorination catalyst is placed on a carrier. Activated carbon, aluminium oxide, partially fluorinated aluminium oxide, fluorinated aluminium are used as a carrier. Reaction temperature is from 150 to 800 C, contact time of hydrogen fluoride and octachlorocyclopentane is from 0.1 to 300 s, reaction pressure is from 1 to 10 kg/cm². The reaction product synthesized at stage of fluorination of octafluorocyclopentene with hydrogen fluoride is fluorinated with metal fluoride replacing chlorine atom in product for fluorine atom and octafluorocyclopentene is prepared. Metal fluoride is taken among the group involving: lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride and rubidium fluoride. EFFECT: improved technological parameters of process. 11 cl, 5 tbl, 28 ex

Description

 The present invention relates to methods for producing chlorofluorocyclopentenes and octafluorocyclopentene, which can be used as intermediates for the preparation of 1,2,3,3,4,4,5,5-octafluorocyclopentane, used as a fluorine-containing detergent, a fluorine-containing drying solvent or the like, and also as intermediates in the preparation of various fluorine-containing compounds.

 It is known that fluorinated cyclopentanes are obtained, firstly, by fluorination of chlorinated cycloalkenes corresponding to fluorinated cyclopentanes to obtain derivatives of vicinally chlorinated fluorocyclopentene, and then by fluorination and hydrogenation of these derivatives. Derivatives of vicinally chlorinated fluorocyclopentene are known to be produced in the first method in which perchlorocycloolefins are used, or in the second method in which perchlorinated cyclic conjugated dienes are used. As an example of the first method in J. Am. Chem. Soc., 67, 1235 (1945) describes a method for producing 1,2-dichlorohexafluorocyclopentene by reacting octachlorocyclopentene with a mixture of antimony trifluoride and antimony trifluorodichloride. Further, German patent 3935493 discloses a method for producing 1,2-dichlorohexafluorocyclopentene by reacting octachlorocyclopentene with chlorine and hydrogen fluoride in the presence of antimony pentachloride. As an example of the second method, the first publication of Japanese patent JP-A-8333285 describes a method for the production of 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene by the initial reaction of hexachlorocyclopentadiene with chlorine in the presence of antimony trichloride for the corresponding conversion thus hexachlorocyclopentadiene and antimony trichloride in octachlorocyclopentene and antimony pentachloride, followed by the addition of hydrogen fluoride. US Pat. No. 2,459,783, on the other hand, discloses a method for producing 1,2-dichlorohexafluorocyclopentene by reacting hexachlorocyclopentene with antimony pentafluoride. US Pat. No. 2,449,233 discloses a process for producing 1,2-dichlorohexafluorocyclopentene by reacting hexachlorocyclopentadiene with hydrogen fluoride in the presence of antimony pentachloride.

In each of the aforementioned known methods, a liquid phase reaction is used in the presence of an antimony halide catalyst. Therefore, the corrosion activity of antimony halide can cause problems. Moreover, in the case of using hydrogen fluoride as a fluorination agent in industrial production, the reaction pressure may be 10-30 kg / cm ² . This may cause some restrictions in the selection of equipment.

 The objective of the invention is to provide a method for producing perhalogenated cyclopentene, in particular octafluorocyclopentene, which would be suitable for the production of this substance on an industrial scale.

The present invention provides a method for producing a first perhalogenated cyclopentene represented by the general formula C ₅ Cl _B F ₈ -B, in which B is an integer from 0 to 7. The method comprises the step of (a) fluorinating the second perhalogenated cyclopentene with hydrogen fluoride in the gas phase in the presence of fluorination catalyst. The second perhalogenated cyclopentene is represented by the general formula C ₅ Cl _A F _8-A , in which A is an integer from 1 to 8, and A is not less than B. Using this method, the first perhalogenated cyclopentene (for example, 1,2-dichloro-3, 3,4,4,5,5-hexafluorocyclopentene, another chlorofluorinated cyclopentene or octafluorocyclopentene) can easily be obtained continuously, for example, from octachlorocyclopentene obtained by chlorination of hexachlorocyclopentadiene, which is readily available. Therefore, the above method is very useful as a method of industrial production.

According to the present invention, in the case where the first perhalogenated cyclopentene is octafluorocyclopentene, the aforementioned method may further include a step (b) of fluorinating the reaction product of step (a) in a manner different from that of step (a) so as to convert the reaction product of step (a) in octafluoropentene. The reaction product of step (a) is a perhalogenated cyclopentene represented by the general formula C ₅ Cl _B F _8-B , in which B is an integer from 0 to 7, or the general formula C ₅ Cl _A F _8-A , in which A is a whole number from 1 to 8 and A is not less than B.

 According to the present invention, the above step (a) can be carried out by a multi-stage reaction in which there are “m” reaction zones, where m is an integer from 2 to 10. The reaction zones are arranged in series and so that the reaction temperature in each reaction zone can be controlled whatever. In such a multi-stage reaction, it becomes possible to reduce the production of resinous substances and thus achieve a long service life of the fluorination catalyst. Therefore, it becomes possible to produce the first perhalogenated cyclopentene continuously for a long time without interrupting the process.

 In the present invention, 1,2-dichloro-3,3,4,4,5,5, -hexafluoro-cyclopentene-1 is 1,2-dichlorohexafluorocyclopentene or 1,2-dichloro-3,3,4,4,5, 5-hexafluorocyclopentene. Below, unless otherwise specified, the octachlorocyclopentene used as a raw material in the method of the present invention can be replaced by chlorofluorocyclopentene obtained by partial fluorination of octachlorocyclopentene. Further, 1,2-dichlorohexafluorocyclopentene as a reaction product may include other chlorofluorocyclopentenes, chlorheptafluorocyclopentene and octafluorocyclopentene.

As defined above, the first perhalogenated cyclopentene, the target product of the present invention, is represented by the general formula C ₅ Cl _B F ₈ -B, in which B is an integer from 0 to 7. In other words, the number of chlorine atoms in this cyclopentene is an integer from 0 to 7, and the number of fluorine atoms, therefore, is an integer from 1 to 8, and the total number of chlorine atoms and fluorine atoms is 8. In this cyclopentene, a halogen atom can be bonded to any carbon atom. The first perhalogenated cyclopentene is not particularly limited, and non-limiting examples are octafluorocyclopentene, 1-chlorheptafluorocyclopentene, 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene, 1,2,4-trichloro-3, 3,4,5,5-pentafluorocyclopentene, 1,2,3,4-tetrachloro-3,4,5,5-tetrafluorocyclopentene, 1,2,3,4,4-pentachloro-3,5,5-trifluorocyclopentene hexachloro-3,3-difluorocyclopentene, hexachloro-4,4-difluorocyclopentene and heptachlor-5-fluorocyclopentene.

As defined above, the second perhalogenated cyclopentene is the feed of the present invention and is represented by the general formula C ₅ Cl _A F _8-A , where A is an integer from 1 to 8. In other words, the number of chlorine atoms in this cyclopentene is an integer from 1 to 8, and the number of fluorine atoms, therefore, is an integer from 0 to 7, and the total number of chlorine atoms and fluorine atoms is 8. In this cyclopentene, a halogen atom can be bonded to any carbon atom. The second perhalogenated cyclopentene is not particularly limited, and non-limiting examples are 1-chloro-heptafluorocyclopentene, 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene, 1,2,4-trichloro-3, 3,4,5,5-pentafluorocyclopentene, 1,2,3,4-tetrachloro-3,4,5,5-tetrafluorocyclopentene, 1,2,3,4,4-pentachloro-3,5,5-trifluorocyclopentene hexachloro-3,3-difluorocyclopentene, hexachlor-4,4-difluorocyclopentene, heptachlor-5-fluorocyclopentene and octachlorocyclopentene.

 The first or second perhalogenated cyclopentene in accordance with the present invention can be synthesized in a known manner. For example, Newcomer; McBee, J. Amer. Chem. Soc., 71 (1949) 946, 950 describes a process for producing octachlorocyclopentene by chlorinating hexachlorocyclopentadiene with chlorine in the presence of a catalyst (e.g., metal chloride). In addition, Henne et al. , J. Am. Chem. Soc., 67, 1235 (1945) describes the reaction of octachlorocyclopentene with a mixture of antimony trifluoride and antimony trifluorodichloride to thereby obtain 1,2-dichlorohexafluorocyclopentene, 1,2,4-trichloro-3,3,4,5,5-pentafluorocyclopentene, 1 2,3,4-tetrachloro-3,4,5,5-tetrafluorocyclopentene.

 According to the present invention, it is preferable that the fluorination catalyst includes at least one metal selected from metals of 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15 groups of the periodic system. These metals are preferably chromium, manganese, cobalt, nickel, iron, molybdenum, niobium, aluminum, zinc, copper, antimony, titanium, tin and tantalum. Of these, chromium and antimony are most preferred. In the event that at least two metals are used for the fluorination catalyst, one of these at least two metals is preferably chromium or antimony. Further, the fluorination catalyst may be at least one selected from the group consisting of metal oxides, metal fluorides (fluorinated metals), metal chlorides (chlorinated metals), metal fluorides (fluorinated and chlorinated metals), metal oxyfluorides (partially fluorinated metal oxides ), metal oxychlorides (partially chlorinated metal oxides) and metal oxyfluorochlorides (partially fluorinated and chlorinated metal oxides). At least one metal used in the fluorination catalyst may be supported on a conventional support. The carrier of the fluorination catalyst is not particularly limited in any way, provided that it is stable in the fluorination of the present invention. Examples of carriers are activated carbon, metallic aluminum, zirconia, magnesium oxide, titanium dioxide, modified clays obtained by removing silicon dioxide from them, for example hydrogen fluoride, aluminum oxide (alumina), aluminum fluoride, aluminum chloride, aluminum fluoride, aluminum oxyfluoride ( partially fluorinated alumina), aluminum oxychloride and aluminum oxyfluorochloride. The most preferred examples of the fluorination catalyst are chromium on an activated carbon carrier, chromium on an aluminum oxide carrier, chromium oxide on activated carbon, partially fluorinated chromium oxide on activated carbon, and antimony on an activated carbon carrier.

In accordance with the present invention, activated carbon used as a carrier for a fluorination catalyst is not limited to any particular type. Activated charcoal can be prepared from plant materials such as wood, sawdust, charcoal, coconut shell charcoal, palm kernel charcoal or untreated ash; from coal, such as peat, lignite, brown coal, bituminous coal or anthracite; petroleum feedstocks, such as fuel oil, tar sulphate or petroleum coal; or raw materials in the form of synthetic resins. Activated carbon can be selected from various activated carbons produced in industry. Examples of industrial activated carbons useful in the present invention are activated carbon under the trademark CALGON GRANULAR ACTIVATED CARBON CAL, obtained from bitumen coal by TOYO CALGON CO. and coconut shell coal manufactured by Takeda Chemical Industries, Ltd. The activated carbon used in the present invention is generally in the form of granules. The shape and dimensions are not particularly limited in any way and can be adopted depending on the size of the reactor. Preferably, the activated carbon used in the invention has a large specific surface area. Commercially available activated carbon will satisfy the invention in terms of specific surface area and micropore volume. In the present invention, the specific surface area of activated carbon is preferably greater than 400 m ² / g, more preferably from 800 to 3000 m ² / g. In addition, it is preferable if the volume of micropores in the activated carbon exceeds 0.1 cm ³ / g, more preferably it is from 0.2 to 1.0 cm ³ / g. If activated carbon is used as a carrier in the present invention, it is preferable to activate the surface of the carrier and remove ash from it by immersing the activated carbon in an alkaline aqueous solution of ammonium hydroxide, sodium hydroxide, potassium hydroxide or the like at room temperature for about 10 hours or more or by pretreating the activated carbon with an acid, such as nitric acid, hydrochloric acid or hydrofluoric acid at room temperature or when heated. Such pretreatment is traditionally used using activated carbon as a catalyst carrier.

 In accordance with the present invention, before using a high valency metal halide, it is preferable to remove water from the support as possible by heating, evacuating or the like, in order to prevent decomposition of the halide caused by hydrolysis or the like. The metal for such a halide is selected from antimony, titanium, tin, tantalum, or the like.

 In accordance with the present invention, alumina used as a fluorination catalyst support is not limited to any particular type. You can use alumina obtained by precipitation from an aqueous solution of an aluminum salt by using an alkaline substance such as ammonia, and then molding and drying the precipitate. In fact, it is preferable to use industrially produced γ-alumina as a catalyst or desiccant carrier.

 In accordance with the present invention, the amount of at least one metal that is supported on the carrier is preferably from 0.1 to 50 parts by mass, more preferably from 0.5 to 50 parts by mass, even more preferably from 2 to 50 parts by mass, and most preferably from 5 to 50 parts by mass with respect to 100 parts by mass of the carrier. As the amount of at least one metal increases, the catalyst becomes more active. However, if its amount is too large, the catalyst may become powdery and thus require great care in handling it.

In accordance with the present invention, a method for preparing a fluorination catalyst is not particularly limited in any way. The fluorination catalyst carrier may be, for example, alumina, such as γ-alumina, or partially fluorinated alumina that has been treated with hydrogen fluoride, hydrogen chloride, a chlorofluorinated hydrocarbon or the like, or activated carbon. In preparing the fluorination catalyst, the carrier can be immersed in a solution of at least one compound or in at least one compound if it is in liquid form, or alternatively, the solution or at least one compound in itself can be sprayed on a carrier. The carrier is then dried and then brought into contact with a fluorination agent in gaseous form (for example, hydrogen fluoride or a chlorofluoro-substituted hydrocarbon) under heating conditions, thereby partially or fully fluorinating the carrier or at least one compound deposited thereon. This completes the preparation of the fluorination catalyst. In the case of using fluorinated alumina as a support, it is preferable, when preparing the fluorination catalyst, to bring the support into contact with hydrogen fluoride at a temperature (preferably about 150-800 ^{° C.} ) not lower than the fluorination temperature of the second perhalogenated cyclopentene. Thus, the fluorine content in the fluorination catalyst will be stable during the reaction. In another case, when at least one compound is not applied to the carrier, this substance can be prepared as follows. First, metal hydroxide is precipitated from a solution of the compound of at least one metal using a basic substance, such as ammonia. This metal hydroxide is then converted to metal oxide, for example, by sintering, and then this metal oxide is partially or completely modified with halogen using hydrogen fluoride, hydrogen chloride, chlorofluorinated hydrocarbon or the like. For example, a metal oxide can be prepared by sintering a chromoxide gel precipitated from an aqueous solution of chromium nitrate using aqueous ammonia. Metal oxide can also be obtained by mixing a chromoxide gel with an alumina gel obtained in the same manner as a chromoxide gel, and then sintering the mixed mixture. In addition, metal oxide can be obtained by sintering a mixed gel obtained by coprecipitation from an aqueous solution of chromium nitrate in which at least one metal (e.g. manganese) used in the fluorination catalyst is dissolved. It is not necessary to mention that metal oxide can be obtained in a similar manner using another metal.

 In accordance with the present invention, an addition of at least one element from the group of alkaline earth metals, such as Mg and Ca, or an element from the group of lanthanides, such as La and Ce, can be added to the fluorination catalyst if desired. This additive prevents the recrystallization of the oxyhalide used as a compound of at least one metal or as a carrier, and thus supports the activity of the first fluorination catalyst. The mass ratio of at least one metal to the additive is preferably from 50:50 to 99.9: 0.1, and more preferably from 70:30 to 99: 1.

 In accordance with the present invention, at least one metal compound used in the preparation of the fluorination catalyst may be at least nitrate, chloride, an organic acid salt, an organic complex or the like of at least one metal compound, soluble in a solvent such as water, ethanol or acetone. In addition, to prepare the fluorination catalyst, at least one metal compound, such as an oxide or hydroxide, or elemental metal, can be dissolved in an inorganic acid, such as hydrochloric acid or nitric acid. Non-limiting examples of at least one metal compound are chromium nitrate, chromium trichloride, chromium trioxide, potassium dichromate, manganese nitrate, manganese chloride, manganese dioxide, manganese acetate, nickel nitrate, nickel chloride, nickel acetate, cobalt nitrate, cobalt chloride, nitrate iron, iron chloride, molybdenum chloride, niobium chloride, aluminum nitrate, aluminum chloride, zinc chloride, copper nitrate, copper chloride, antimony trichloride, antimony pentachloride, antimony pentafluoride, titanium tetrachloride, titanium trichloride, tin tetrachloride and foam tantalum tachloride.

 In accordance with the present invention, a fluorination catalyst with a support (for example, activated carbon) coated with a high valence metal halide such as antimony, titanium, tin and tantalum can be prepared as follows. For example, such a halide per se, if it is in liquid form at room temperature, is gradually added to the activated carbon, which has been pretreated, if necessary, such as drying, acid treatment, and the like. Alternatively, activated carbon is immersed in a solution in which such a halide is dissolved in an inert solvent, followed by heating and / or evacuation. Examples of such an inert solvent are chlorinated solvents such as carbon tetrachloride, chloroform, methylene chloride, tetrachlorethylene, trichlorethylene and tetrachloroethane; fluorochlorinated solvents such as 2,2-dichloro-1,1,1-trifluoroethane, 1,1-dichloro-1-fluoroethane, 3,3-dichloro-1,1,1,2,2-pentafluoropropane and 1,3 -dichloro-1,1,2,2,3-pentafluoropropane, and alcohols such as methanol, ethanol and isopropanol. Antimony compounds are relatively easily oxidized. Thus, it is possible to immerse the carrier in a solution containing a low valence metal halide such as antimony trichloride dissolved in the above inert solvent, and then convert this halide to a pentavalent halide, for example, with chlorine. In this case, it is assumed that such a halide works as a catalyst, while its high valency is maintained. As noted below, such a halide may have catalytic activity at a relatively low temperature. In accordance with the present invention, the high valence metal halide may be antimony pentachloride, antimony pentafluoride, tin tetrachloride, titanium tetrachloride or tantalum pentachloride. Activated carbon can serve as a carrier for such a halide. This halide may be a mixture of at least two halides. In fact, it is preferable to add to the antimony pentachloride a small amount of tin pentachloride, titanium tetrachloride, tantalum pentachloride or a metal chloride selected from chromium, manganese, cobalt, nickel, iron, molybdenum, niobium, aluminum, zinc and copper. Mixed halide, in which chlorine is partially substituted by fluorine, can be used as active types of catalyst, although it is not necessary.

 According to the present invention, a change in the composition of the fluorination catalyst during fluorination (i.e., during the above step (a)) can be effectively prevented by performing fluorination of the catalyst prior to fluorination by a fluorinating agent such as hydrogen fluoride, a fluorinated hydrocarbon or a fluorinated hydrocarbon at a temperature not lower than the temperature of the fluorination reaction. If, however, the activity of the fluorination catalyst is deactivated by the reaction, then the catalyst can be reactivated by bringing the deactivated catalyst into contact with an oxidizing agent such as oxygen, air, ozone and chlorine. In some cases, it is preferable to continuously or periodically supply an active substance, such as oxygen, ozone, chlorine, chlorine fluoride, chlorine trifluoride, nitric oxide or nitrous oxide to the reaction system to maintain catalyst life.

In accordance with the present invention, the temperature of the fluorination reaction of the second perhalogenated cyclopentene is preferably from 40 to 800 ^{° C.} and varies depending on the type and method of preparation of the metal of the fluorination catalyst. For example, even if the catalyst metal is chromium, manganese, cobalt, nickel, iron, molybdenum, niobium, aluminum, zinc, copper or the like, or antimony, titanium, tin, tantalum or the like, the reaction temperature is preferably from from about 150 to about 800 ^{° C.} , more preferably from 200 to 750 ^{° C.} , even more preferably from 250 to 700 ^{° C.} , especially in the case where the fluorination catalyst contains a metal that is in a low valence state as active sites. On the other hand, in the case where the fluorination catalyst contains high valence metal halides such as antimony, titanium, tin, tantalum or the like metal as active centers, the reaction temperature is preferably from about 40 to about 300 ^{° C.} , more preferably from 50 to 250 ^{° C.,} and even more preferably from 60 to 200 ^° C. If the reaction temperature is lower than the lower limit (150 or 40 ^{° C.} ), the reaction rate may become too low and thus impractical. If the reaction temperature is too high, the reaction rate becomes high. However, in this case, the fluorination catalyst can be destroyed and, in addition, it is uneconomical, since it requires a large amount of thermal energy.

 According to the present invention, the molar ratio of the second perhalogenated cyclopentene fed to the reaction zone to hydrogen fluoride varies depending on the particular types of the first and second perhalogenated cyclopentenes and the reaction temperature. For example, if it is intended to produce 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene from octachlorocyclopentene, the molar ratio (second perhalogenated cyclopentene / hydrogen fluoride) is preferably from 1/60 to 1/6, more preferably from 1/50 to 1/8 and even more preferably from 1/40 to 1/10. It is preferable to appropriately reduce the amount of hydrogen fluoride relative to the amount of the second perhalogenated cyclopentene in the case when the second perhalogenated cyclopentene is in partially fluorinated form, or when it is intended to produce the first perhalogenated cyclopentene with a lower degree of fluorination. If the amount of hydrogen fluoride is excessive, then the productivity per unit time may become too low. On the other hand, if it is too small, the conversion and yield may become too low.

In accordance with the present invention, the pressure of the fluorination reaction is not particularly limited. Preferably, it is from 1 to 10 kg / cm ² depending on the choice of equipment. It is preferable to select suitable reaction conditions under which the intermediates and hydrogen fluoride present in the reaction system do not substantially liquefy, that is, they are not in the form of liquid droplets. The contact time during fluorination is preferably from 0.1 to 300 s, more preferably from 1 to 100 s, and even more preferably from 5 to 50 s.

 In accordance with the present invention, the reactor used in fluorination is preferably made of a heat-resistant material that is resistant to the corrosive effects of hydrogen fluoride, hydrogen chloride and the like, such as stainless steel, hastelloy, monel metal or platinum, or a material lined with one of these metals. In the present invention, the reaction products (first perhalogenated cyclopentene) can be purified by a conventional purification process without any particular limitation. In this method, for example, the reaction products together with hydrogen chloride and unreacted hydrogen fluoride are removed from the reactor in the form of a gas or liquid. They are then washed with water and / or a base solution or subjected to a type of distillation or liquid phase separation treatment to remove hydrogen chloride and excess hydrogen fluoride. Then the remaining acidic substances are removed with a basic substance or the like, followed by distillation, thereby obtaining the first perhalogenated cyclopentene.

As determined above, after step (a), it is possible to carry out step (b) of fluorinating the reaction product of step (a) in a manner different from the method of step (a). If step (b) is carried out after step (a), then the aforementioned rectification is optional and depends on the fluorination method in step (a). In fact, in some cases, it may be necessary only to remove between steps (a) and (b) the acidic substances from the reaction products. In other cases, even the removal of acidic substances from them may not be necessary, and only a decrease in the acid content in the reaction products may be sufficient. For example, step (b) may be fluorination, in which the chlorine atom in the products of the reaction of step (a) is replaced by a fluorine atom from a metal fluoride. This metal fluoride is commonly used in the fluorination of chlorinated alkanes and chlorinated alkenes. In step (b), a mixture of the first perhalogenated cyclopentenes can be fluorinated. The metal fluoride used in step (b) is not particularly limited and may be alkali metal fluoride such as lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride and rubidium fluoride. Of these, potassium fluoride and cesium fluoride are most preferred. The number of moles of this metal fluoride is preferably at least B, more preferably from B to 10V and even more preferably from B to 5V per 1 mol of raw material in step (b), i.e., the first perhalogenated cyclopentene represented by the general formula C ₅ Cl _in F _8-c , where B is an integer from 0 to 7. According to need, it is possible to use a solvent in step (b). Examples of such a solvent are acid amides, such as formamide, acetamide, N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone, and sulfoxides, such as dimethyl sulfoxide and diethyl sulfoxide. If necessary, such a solvent can be mixed with a hydrocarbon (for example, xylene) compatible with this solvent. The reaction temperature in step (b) is preferably not higher than 200 ^{° C.} , more preferably from 60 to 180 ^{° C.} and even more preferably from 80 to 150 ^° C. The reaction time in step (b) is determined depending on the type of metal fluoride in step (b) ), and it can be up to 24 hours.

 In the case where chlorohydrocarbon is fluorinated in the gas phase with hydrogen fluoride in the presence of a catalyst, usually these chlorohydrocarbons and hydrogen fluoride are preliminarily converted to the vapor phase by heating, and then introduced into the reaction zone of such fluorination. This heating is usually carried out at a temperature close to the decomposition temperature of the raw material for such fluorination. In particular, a chlorohydrocarbon having a larger number of chlorine atoms has a higher boiling point. Moreover, it is known that hydrogen fluoride itself can act as a catalyst for polymerization or isomerization. Therefore, the above heating for vaporization can cause the polymerization of chlorohydrocarbon. Over time, the resulting compounds with a high boiling point can turn into resinous substances or solid carbon. These undesirable substances can clog the reactor and cover the surface of the catalyst, reducing the activity of the catalyst. If the reaction temperature in step (a) is lowered in order to prevent these problems, the conversion may occur too slowly.

 In view of the foregoing, in accordance with the invention, it is preferable to provide a plurality of reaction zones arranged in series during fluorination in step (a) and make the reaction temperature of each reaction zone independently controlled. Each reaction zone may be an independent reactor. In other words, it is possible to provide multiple reactors for carrying out stage (a). Alternatively, it is possible to provide only one reactor having a heating device for independently controlling the temperature of each reaction zone of the reactor. In other words, this reactor incorporates many reaction zones. The method for carrying out step (a) is not particularly limited and may be a fixed bed method, a fluidized bed method and a moving bed method. Of these, the fixed-bed method is most preferred. The type of reactor is not particularly limited in any way; it is preferable to use a single-tube or multi-tube type reactor having an external heating system.

In accordance with the present invention, the number of successive reaction zones is preferably at least two, and preferably not more than 10, from the point of view of economics and complexity of operation. More preferably two to four. Here, the first reaction zone, or reactor, is defined as the zone into which the feed of step (a) is introduced. Subsequent reaction zones, or reactors, to the last reaction zone, or reactor, are arranged in series. The corresponding temperature of the reaction zones can be regulated independently from each other, depending on the feedstock, catalyst in each reaction zone, reaction conditions, target reaction products. In fact, it is preferable to adjust the temperature of the last reaction zone, which is the main reaction zone for carrying out stage (a), so as to achieve the desired conversion and selectivity. Moreover, it is preferable that the temperature of the reaction zones from the first to the last reaction zone are adjusted incrementally. In other words, the temperature of the reaction zones increase stepwise from the first to the last reaction zone. The sizes of each reaction zone can be set arbitrarily. In fact, the main reaction zone is preferably larger than the first reaction zone to more easily control the reaction in step (a). The same or different catalysts can be introduced into the reaction zones, but it is preferable to use the same catalyst in all reaction zones. According to the invention, the temperature of the main reaction zone is associated with the desired conversion, selectivity and service life of the catalyst and is preferably from 80 to 800 ^o C. As previously established, the reaction temperature depends mainly on the type of catalyst. If the target reaction product can be obtained at a reaction temperature below 80 ^o C, then there is no need to create many reaction zones. If the reaction temperature is above 800 ^{° C.} , the reaction rate may be high. However, the catalyst life may become too short and require a large amount of thermal energy.

 In accordance with the present invention, it is preferable to adjust the reaction temperature in the first reaction zone so that it is lower than the boiling point of the second perhalogenated cyclopentene. In other words, the expected reaction to take place in the first reaction zone does not necessarily require that the reaction temperature be at least the boiling point of the second perhalogenated cyclopentene under pressure in the reaction system. At a reaction temperature lower than this boiling point, the chlorine atoms of the second perhalogenated cyclopentene can be partially replaced by fluorine atoms in the first reaction zone. In this case, the second perhalogenated cyclopentene can turn into a low-boiling intermediate product. It is believed that such a partially fluorinated, low boiling point intermediate is difficult to polymerize, but is effectively converted to the desired reaction product in a subsequent reaction zone having a temperature higher than the temperature of the first reaction zone. As a result, it may be possible to reduce the production of undesirable perforated compounds and resinous substances, increase the yield of the target reaction product, and extend the life of the fluorination catalyst.

 In the case where the fluorination of step (a) is carried out providing a plurality of reaction zones, the molar ratio of the second perhalogenated cyclopentene (e.g., octachlorocyclopentene) that is fed to the reaction zone and hydrogen fluoride are changed depending on the temperature of the main or last reaction zone. The molar ratio of the second perhalogenated cyclopentene to hydrogen fluoride is preferably from 1/60 to 1/6, more preferably from 1/50 to 1/8, and even more preferably from 1/40 to 1/10. It is preferable to sufficiently reduce the amount of hydrogen fluoride relative to the amount of the second perhalogenated cyclopentene if this second perhalogenated cyclopentene is in partially fluorinated form, or if it is intended to produce the first perhalogenated cyclopentene with a lower degree of fluorination. If the amount of hydrogen fluoride is too small, the conversion and yield may become too low. Even if the amount of hydrogen fluoride is excessive, it will be regenerated and separated after the reaction and then used again as a raw material in the reaction. Thus, it does not cause any problems.

 In accordance with the present invention, it is preferable to introduce in the first reaction zone hydrogen fluoride in an amount greater than for carrying out the reaction in the first reaction zone. In fact, the temperature of the first reaction zone can be adjusted to a relatively low value by introducing a sufficient amount of hydrogen fluoride into it. This hydrogen fluoride can be partially replaced with an inert gas. However, it is preferable to avoid the introduction of such an inert gas, unless the use of an inert gas has no other beneficial effects. With the exclusion of inert gas, separation and purification of the reaction product is facilitated. Thus, it is particularly preferred that the inert gas is substantially not present in each reaction zone. It is preferable to introduce the total amount of hydrogen fluoride required in step (a) into the first reaction zone in order to lower the reaction temperature, although this is not necessary.

In accordance with the present invention, it is preferable to heat the second perhalogenated cyclopentene at a temperature that is about 1-50 ^{° C.} lower than the boiling point of the second perhalogenated cyclopentene, and to heat hydrogen fluoride at a temperature close to the temperature of the first reaction zone. Although these compounds can be heated simultaneously in the same vessel, it is preferable to heat these compounds in different vessels.

 In accordance with the present invention, it is preferable from the point of view of carrying out the reaction to remove hydrogen chloride that is formed in one reaction zone before it enters the next reaction zone, since this hydrogen chloride is an undesirable substance in the next reaction in the subsequent reaction zone from the point of view of chemical equilibrium . However, the removal of hydrogen chloride often causes the simultaneous removal of unreacted hydrogen fluoride. Therefore, the removal of this hydrogen chloride is optional. On the other hand, if small amounts of high boiling organic substances are formed in each reaction zone, it may be preferable to remove these organic substances from there in order to extend the life of the catalyst. The method of such removal is not particularly limited. For example, they can be removed by adsorption by activated carbon, absorption by sulfuric acid or solvent, separation by means of cooling liquefaction.

 According to the present invention, when octachlorocyclopentene is fluorinated in step (a) by providing a plurality of reaction zones, intermediate products or reaction products such as octafluorocyclopentene, 1-chloro-2,3,3,4,4,5, are obtained in the reaction zones, 5-heptafluorocyclopentene, 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene, trichloropentafluorocyclopentene, tetrachlorotetrafluorocyclopentene, pentachlorotrifluorocyclopentene, hexachlorodifluorocyclopentene and heptachlorormonofluorocyclopentene. In the present invention, the intermediates are not particularly limited since they are chlorofluorocyclopentenes.

 The following options for the preparation of catalysts are not restrictive and are given as an illustration of the present invention. Fluorination catalysts C2-C21 were prepared in accordance with options 2-21 for the preparation of catalysts.

1 CATALYST PREPARATION OPTION
First, 800 g of activated alumina, KHS-46 (trade name) SUMITOMO CHEMICAL CO., LTD with a particle diameter of 4-6 mm was washed with water to remove dust from its surface. Separately, 306 g of hydrogen fluoride (anhydrous hydrofluoric acid) was dissolved in 2.760 g of water to prepare a 10% aqueous solution of hydrogen fluoride. Then this solution was gradually poured onto activated alumina, followed by stirring. After that, it was left for 3 hours, then the activated alumina was removed from the solution, washed with water, then filtered, and then dried for 2 hours in an electric oven at 200 ^o C. Dried activated alumina in an amount of 800 ml was introduced into a cylindrical reaction a stainless steel tube (SUS 304) having an inner diameter of 4.2 cm and a longitudinal length of 60 cm. The temperature of the reaction tube was raised in the furnace to 200 ^{° C.} , while nitrogen was passed through the reaction tube. Then, hydrogen fluoride was passed through it together with nitrogen in order to fluorinate activated alumina. During this fluorination, the temperature increased. However, the flow rates of nitrogen and hydrogen fluoride were adjusted so that the temperature was not higher than 400 ^° C. After the heating ceased, the temperature in the furnace was maintained at 400 ^{° C.} for 2 hours, so that fluorinated alumina was prepared.

2 OPTION OF PREPARATION OF THE CATALYST
First, a 1.3 liter solution of CrCl _{3 was} prepared by dissolving 435 g of CrCl ₃ • 6H ₂ O in pure water, as shown in Table 1. 200 g of fluorinated alumina obtained in the 1 preparation of the catalyst were immersed in this solution, as shown in Table 1, and the resulting solution was left for one day and one night. Then, the alumina was separated from the solution by filtration, and then dried for one day and one night at 100 ^{° C.} in an oven with hot air circulation. Thus obtained alumina on chromium support in an amount of 200 ml was placed in a cylindrical reaction tube equipped with an electric furnace made of stainless steel (SUS 304) and having a diameter of 2.5 cm and a longitudinal length of 40 cm. The temperature of the reaction tube was raised to 300 ^o C, while nitrogen gas was passed through it. Then, at the moment when it was established that the flow from it had stopped, they began to pass through it a stream of hydrogen fluoride together with gaseous nitrogen. Then, the concentration of hydrogen fluoride in the mixture of hydrogen fluoride and nitrogen was gradually increased. When the superheat obtained by fluorinating alumina on a chromium support reached the end of the exit from the reaction tube, the temperature of the reaction tube was further raised to 400 ^° C. Then these conditions were maintained for 1 h, thereby obtaining a fluorination catalyst C2.

3 CATALYST PREPARATION OPTION
First, a 1.3 liter solution of CrCl _{3 was} prepared by dissolving 448 g of CrCl ₃ • 6H ₂ O in pure water, as shown in Table 1. 200 g of activated carbon from a granulated coconut shell prepared by Takeda Chemical Industries, Ltd. under the trade name GRANULAR SHIRO SAGI GX and consisting of 4-6 mesh columnar grains was immersed in this solution for one day and one night. Then, activated carbon was separated from the solution by filtration and then placed in an eggplant-like flask for drying under vacuum at 70 ^° C using an evaporator. The thus obtained activated alumina on chromium support in an amount of 200 ml was placed in a cylindrical reaction tube equipped with an electric furnace made of stainless steel (SUS 304) and having a diameter of 2.5 cm and a longitudinal length of 40 cm. The temperature of the reaction tube was increased to 300 ^o C, while gaseous nitrogen flowed through it. Then, at the moment when it was determined that the flow from it had stopped, hydrogen fluoride began to pass through it together with gaseous nitrogen. Then, the concentration of hydrogen fluoride in the mixture of hydrogen fluoride and nitrogen was gradually increased. Subsequently, the temperature of the reaction tube was increased to 350 ^° C. Then these conditions were maintained for 1 h, thereby obtaining a fluorination catalyst C3.

4 CATALYST PREPARATION OPTION
First, 495 g of Cr (NO ₃ ) ₃ • 9H ₂ O was dissolved in 1000 g of pure water. In the resulting solution was immersed for one day and one night 200 g of granular activated carbon, the same as in embodiment 3 of the preparation of the catalyst. Then, activated carbon was separated from the solution by filtration, and then it was placed in an eggplant-shaped flask for drying under vacuum at 70 ^° C using an evaporator. After drying, the temperature was increased to 150 ^o C at atmospheric pressure for pyrolysis of nitrate. This heating was stopped at the moment when the formation of NO ₂ ceased. The obtained activated carbon coated with chromium in an amount of 200 ml was placed in a cylindrical reaction tube, the same as in example 2 of the preparation of the catalyst. The temperature of the reaction tube was raised to 350 ^{° C.} while nitrogen gas flowed through it. After that, the temperature was reduced to 150 ^o C, and then began to pass through it hydrogen fluoride together with gaseous nitrogen. Under these conditions, the temperature of the reaction tube was again raised to 350 ^° C. Then these conditions were maintained for 1 h, thereby obtaining a fluorination catalyst C4.

5 CATALYST PREPARATION OPTION
First, 495 g of Cr (NO ₃ ) ₃ • 9H ₂ O was dissolved in 1000 g of pure water. In the resulting solution was immersed for one day and one night 200 g of fluorinated alumina, the same as in embodiment 1 of the preparation of the catalyst. Next, the alumina was separated from the solution by filtration and then placed in an eggplant-like flask for drying under vacuum at 70 ^{° C.} using an evaporator. After drying, the temperature was increased to 150 ^o C at atmospheric pressure for pyrolysis of nitrate. This heating was stopped at the moment when the formation of NO ₂ ceased. The resulting chromium-coated alumina in an amount of 200 ml was placed in a cylindrical reaction tube, the same as in Example 2 of the preparation of the catalyst. The temperature of the reaction tube was raised to 400 ^{° C.} while nitrogen gas flowed through it. Then, at the time when it was determined that the flow from it had stopped, the temperature of the reaction tube was lowered to 150 ^° C and hydrogen fluoride was started to pass through it together with gaseous nitrogen. Under these conditions, the temperature of the reaction tube rose again to 400 ^° C. Then these conditions were maintained for 1 h, thereby obtaining a fluorination catalyst C5.

6 CATALYST PREPARATION OPTION
First, 3960 g of Cr (NO ₃ ) ₃ • 9H ₂ O was dissolved in 8000 g of pure water. In the resulting solution, 4200 g of granular activated carbon, the same as in embodiment 3 of the preparation of the catalyst, were immersed for one day and one night. Then, activated carbon was separated from the solution by filtration, and then it was placed in an eggplant-shaped flask for drying under vacuum at 70 ^° C using an evaporator. After drying, the temperature was increased to 150 ^o C at atmospheric pressure for pyrolysis of nitrate. This heating was stopped at the moment when the formation of NO ₂ ceased. The obtained activated carbon with deposited chromium in an amount of 4200 ml was placed in a cylindrical reaction tube equipped with an electric furnace made of stainless steel (SUS 304) and having a diameter of 5.4 cm and a longitudinal length of 200 cm. The temperature of the reaction tube was raised to 350 ^{° C.} while nitrogen gas was passed through it. After that, the temperature was reduced to 150 ^o C, and then began to pass through it hydrogen fluoride together with gaseous nitrogen. Under these conditions, the temperature of the reaction tube was again raised to 350 ^o C. Then these conditions were maintained for 1 h, thereby obtaining a fluorination catalyst C6.

7 CATALYST PREPARATION OPTION
First granulated Cr ₂ O ₃ in an amount of 200 ml from Kojundo Kagaku Kenkyusho Co. obtained by sintering and having a particle size of not more than 4 mesh, was placed in a cylindrical reaction tube, the same as in option 2 to obtain a catalyst. The temperature of the reaction tube was raised to 350 ^{° C.} , while nitrogen gas was passed through it. After that, the temperature was lowered to 150 ^o C and then began to pass through it hydrogen fluoride together with gaseous hydrogen. Under these conditions, the temperature of the reaction tube was again raised to 350 ^o C. Then these conditions were maintained for 1 h, thereby obtaining a fluorination catalyst C7.

8 CATALYST PREPARATION OPTION
First, 6.72 kg of Cr (NO ₃ ) ₃ • 9H ₂ O was dissolved in 3.28 kg of pure water. 2.00 kg of granular activated carbon, the same as in Example 3 of preparation of the catalyst, was immersed in the resulting solution for one day and night. Then, activated carbon was separated from the solution by filtration and then placed in an eggplant-like flask for drying under vacuum at 70 ^° C using an evaporator. After drying, the temperature was increased to 150 ^o C at atmospheric pressure for pyrolysis of nitrate. This heating was stopped at the moment when the formation of NO ₂ ceased, thereby obtaining a fluorination catalyst C8.

9 CATALYST PREPARATION OPTION
First, granular activated carbon, the same as in catalyst preparation 3, was dried under vacuum at 100-120 ^° C. Then 200 ml of this activated carbon was placed in an eggplant-shaped flask with a capacity of 300 ml. Then, 100 g of antimony pentachloride was added dropwise to the flask at a temperature not exceeding 50 ^{° C.} , while the contents of the flask were mixed well. Then 200 ml of the obtained catalyst was placed in a cylindrical reaction tube, the same as in example 2 of the preparation of the catalyst. Then, the temperature of the reaction tube was raised from room temperature to 150 ^° C and then maintained at 150 ^° C for 1 h, at which time nitrogen was introduced into the reaction tube at a rate of 1.2 L per hour and at the same time into the reaction tube 36 g / h of hydrogen fluoride introduced into the gaseous state were introduced at a gas generator located in the upper part of the reaction tube. Then, the supply of hydrogen fluoride was stopped and the reaction tube was cooled to room temperature. After that, when chlorine was introduced into the reaction tube at a flow rate of 300 ml / h, the temperature of the reaction tube was raised from room temperature to 150 ^° C. Then these conditions were maintained for an hour, thereby obtaining a fluorination catalyst C9.

10, 11, 12, 15, 17, 19 AND 21 CATALYST PREPARATIONS
In these examples of preparation of the catalysts, the preparation of catalyst 4 was repeated, except that the type and amount of the metal compound, the amount of water for dissolving the metal compound, and the amount of activated carbon in embodiment 3 of the preparation of the catalyst were changed, as shown in Table 1. Based on this, fluorination catalysts C10, C11, C12, C15, C17, C19 and C21 were prepared.

13 AND 18 OPTIONS FOR PREPARING CATALYSTS
In these catalyst preparation examples, the catalyst preparation option 5 was repeated, except that the type and amount of the metal compound, the amount of water to dissolve the metal compound, and the amount of fluorinated alumina according to embodiment 1 of the catalyst preparation were changed, as shown in Table 1. Based on this, catalysts C13 and C18 were prepared.

14, 16 AND 20 CATALYST PREPARATIONS
In these catalyst preparation examples, the catalyst preparation option 3 was repeated, except that the type and amount of the metal compound, the amount of water for dissolving the metal compound, and the amount of fluorinated alumina according to embodiment 1 of the catalyst preparation were changed, as shown in Table 1. Based on this, catalysts C14, C16 and C20 were prepared.

 The following non-limiting examples are provided to illustrate the present invention.

EXAMPLE 1
First, 190 ml of the gas-phase fluorination catalyst prepared according to option 2 of preparation of the catalyst was placed in a cylindrical reaction tube equipped with an electric furnace made of stainless steel (SUS 304), having a diameter of 2.5 cm and a longitudinal length of 40 cm. Then, until through the tube Nitrogen gas was passed at a flow rate of about 1.2 l / h, the temperature of the reaction tube was raised to 300 ^° C. Then, together with gaseous nitrogen, hydrogen fluoride was passed through the tube at a rate of 12 g / h. Then the temperature of the reaction tube was increased further. When it reached 330 ^{° C.} , the flow of nitrogen gas was stopped. Then, as shown in Table 2, the transmission of hydrogen fluoride and octachlorocyclopentene began at a rate of 12 g / h and 18 g / h, respectively. Thus, a total of 90 g of octachlorocyclopentene was introduced into the reaction tube, and the gaseous component formed in the reaction tube was collected in an ice water trap. Thus, 62 g of organic matter was collected. Using analysis using gas chromatography, as shown in table 3, it was found that this organic substance contains 27.3% of 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene, 40.7 % trichloropentafluorocyclopentene, 22.7% tetrachlorotetrafluorocyclopentene and 3.9% pentachlorotrifluorocyclopentene. These percentages were determined from area chromatograms, and PID was used as a detector in gas chromatography.

EXAMPLES 2-7
In these examples, Example 1 was repeated, except that the type of fluorination catalyst, the reaction time and flow rates of octachlorocyclopentene and hydrogen fluoride were modified as shown in Table 2. The results are shown in table.3.

EXAMPLE 8
First, 200 ml of activated carbon according to embodiment 9 of the preparation of the catalyst was placed in a cylindrical reaction tube, the same as in example 1. Then, while the flow of nitrogen and hydrogen fluoride passed through the reaction tube at a temperature of 50 ^o With the corresponding flow rate of 1.2 l / h and 41.2 g / h, 93.3 g of octachlorocyclopentene and 144.3 g of hydrogen fluoride were introduced into the reaction tube for 3.5 hours. The gas component formed in the reaction tube was collected in an ice water trap. The resulting organic matter was analyzed in the same manner as in example 1. The results are shown in table.3.

EXAMPLE 9
First, 100 ml of activated carbon according to embodiment 9 of the preparation of the catalyst was placed in a cylindrical reaction tube, the same as in example 1. Then, while the flow of nitrogen, chlorine and hydrogen fluoride passed through the reaction tube at a temperature of 50 ^o With the corresponding flow rate of 1.2 l / h, about 150 ml / h and 44 g / h, the temperature of the reaction tube was raised to 175 ^o C. At this point, the nitrogen flow was stopped, and then 99.1 g of octachlorocyclopentene and 153.9 g of hydrogen fluoride were introduced into the reaction tube for 3.5 hours. Gas component formed in the reaction. second tube, and collected in a trap with ice water. The resulting organic matter was analyzed in the same manner as in example 1. The results are shown in table.3.

EXAMPLE 10
In this example, Example 9 was repeated except that the reaction conditions were changed as shown in Table 2. The results are shown in table.3.

EXAMPLE 11
First, 190 ml of fluorinated alumina according to embodiment 5 of the preparation of the catalyst was placed in a cylindrical reaction tube, the same as in example 1. Then, while a stream of nitrogen gas was passed through the tube at a flow rate of about 1.2 l / h, the temperature of the reaction tube was raised to 300 ^o C. Then, together with gaseous nitrogen, hydrogen fluoride with a flow rate of 12 g / h was started to pass through the tube. Then, the temperature of the reaction tube was increased further to 450 ^{° C.} , and at that moment the flow of nitrogen gas was stopped. Then, hydrogen fluoride and 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene (2X6F-CPE) were started into the reaction tube with the corresponding flow rates of 12 g / h and 15 g / h, as shown in Table .4. A total of 75 g of 2X6F-CPE was introduced, and the gaseous component formed in the reaction tube was collected in an ice water trap. The resulting organic matter was analyzed in the same manner as in example 1. The results are shown in table 5.

EXAMPLES 12-25
In these examples, example 11 was repeated except that the reaction conditions were modified as shown in table. 4. The results are shown in table.5.

EXAMPLE 26
First, 59.5 g of dry potassium fluoride and 114 g of N, N-dimethylformamide were loaded into a 300 ml reactor, followed by heating to 130 ^° C. Then, 100 g of well-dried reaction products from Example 4, which are a mixture of perhalogenated cyclopentenes, whose composition is given in table 3, was added dropwise to the reactor over 4.9 hours, and at the same time, the organic substance obtained in the reactor was distilled off at a temperature of 27-28 ^o C, thus obtaining 76.3 g of octafluorocyclopentene (90% yield )

EXAMPLE 27
In this example, a fluorination reactor was used, consisting of the first and second reactors, connected to each other in series by pipelines. Activated carbon (a fluorination catalyst in the gas phase) was loaded into the first and second reactors from option 8 of preparing the catalyst in quantities of 400 ml and 2.0 l, respectively. The first reactor was a cylindrical reaction tube made of stainless steel (SUS304) with an electric heater for heating it, having a diameter of 4.2 cm and a longitudinal length of 40 cm.The second reactor was a cylindrical reaction tube of a jacket type, heated with a coolant, made of stainless steel ( SUS304) and having a diameter of 5.4 cm and a longitudinal length of 100 cm.

The preliminary device of the first reactor to stabilize the catalyst in it was carried out as follows. While nitrogen gas was passed through the first reactor at a flow rate of about 12 l / h, the temperature of the first reactor was raised to 350 ^° C. Then, the temperature of the first reactor was reduced to 150 ^° C. After that, hydrogen fluoride with nitrogen gas began to pass through it. . During a gradual increase in the concentration of hydrogen fluoride, the temperature of the first reactor was raised to 330 ^o C. At this point, the flow of gaseous nitrogen was stopped. Then the temperature of the first reactor was lowered to 250 ^o C. After that, hydrogen fluoride, which was heated to 250 ^o With passing through the heating device, was fed into the first reactor with a flow rate of 330 g / h.

The preliminary device of the second reactor to stabilize the catalyst in it was carried out as follows. While nitrogen gas was passed through the second reactor at a flow rate of about 12 l / h, the temperature of the second reactor was raised to 350 ^° C. Then the temperature of the second reactor was reduced to 150 ^° C. After that, hydrogen fluoride with nitrogen gas began to pass through it. . During a gradual increase in the concentration of hydrogen fluoride, the temperature of the second reactor was raised to 330 ^o C. At this point, the flow of gaseous nitrogen was stopped. Then, hydrogen fluoride exiting the first reactor was passed through a second reactor.

Then, octachlorocyclopentene, which was heated to 250 ^{° C.} , was fed as a liquid to the first reactor at a rate of 210 g / h. After the start of the reaction, samples of the resulting gas component were taken at the outlet of the first reactor. Then, acid gases (hydrogen fluoride and hydrogen chloride) were removed from the gas component, and the resulting gas component was analyzed by gas chromatography. It was found that the gas component has the composition:
2.3% 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene,
14.3% trichloropentafluorocyclopentene,
39.9% tetrachlorotetrafluorocyclopentene,
32.7% pentachlorotrifluorocyclopentene,
8.0% hexachlorodifluorocyclopentene
and 0.8% heptachlorormonofluorocyclopentene.

The reaction was continued in the same manner as described above. Thus, a total of 42 kg of octachlorocyclopentene was fed into the first reactor at a flow rate of 210 g / h in 200 hours, and the resulting gas leaving the second reactor was collected in an ice water trap. In this case, 26.4 kg of organic matter were obtained. This organic substance was analyzed by gas chromatography, and it was found that it has the composition:
2.0% 1-chloro-2,3,3,4,4,5,5-heptafluorocyclopentene,
77.0% 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene,
16.3% trichloropentafluorocyclopentene,
3.7% tetrachlorotetrafluorocyclopentene
and 0.3% pentachlorotrifluorocyclopentene.

 After the reaction, the condition of the heating devices for octacyclopentene and hydrogen fluoride was visually checked, as well as the state of the catalyst in the immediate vicinity of the entrance to the first reactor. In this case, organic matter, resinous substances and carbon residues were not detected.

EXAMPLE 28
First, a cylindrical reaction tube equipped with an electric furnace made of stainless steel (SUS 304) and having a diameter of 2.5 cm and a longitudinal length of 40 cm was filled with 4.2 liters of activated carbon from embodiment 6 of the preparation of the catalyst. Then, while nitrogen gas was passed through the reaction tube at a flow rate of about 30 l / h, the temperature of the reaction tube was raised to 300 ^° C. Then, together with gaseous nitrogen, hydrogen fluoride was passed through the reaction tube at a flow rate of 501 g / h. The temperature of the reaction tube was further raised to 330 ^{° C.} , at which time the flow of nitrogen gas was stopped. Then, octachlorocyclopentene was started to flow at a flow rate of 305 g / h, while hydrogen fluoride was passed at a flow rate of 501 g / h. In the same way, 82.35 kg of octachlorocyclopentene was fed into the reaction tube over 270 hours, and the resulting gas leaving the reaction tube was collected in a stainless steel receiver (SUS16) pre-cooled to -15 ^{° C.} The collected reaction products (hydrogen fluoride and organic matter) were separated into organic and aqueous layers. The separated organic layer was washed with a 10% aqueous sodium hydrogen carbonate solution and then dried with anhydrous calcium chloride. In this case, 51.53 kg of organic matter was obtained. Analysis by gas chromatography, it was determined that the organic substance has the composition:
1.37% 1-chloro-2,3,3,4,4,5,5-heptafluorocyclopentene,
77.6% 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene,
16.5% trichloropentafluorocyclopentene,
3.6% tetrachlorotetrafluorocyclopentene
and 0.3% pentachlorotrifluorocyclopentene.

 After the reaction, the conditions of the heating devices for octacyclopentene and hydrogen fluoride, as well as the state of the catalyst in the immediate vicinity of the entrance to the reaction tube, were visually checked. At the same time, significant amounts of carbon residues were found in the device for heating octacyclopentene. Thus, it is believed that the decomposition of octachlorocyclopentene has occurred. Moreover, carbon residues were also found on the catalyst in close proximity to the entrance to the reaction tube.

 The contents of Japanese patents 9-252222, filed September 17, 1997, and 10-194140, filed July 9, 1998, including descriptions, claims and abstracts, are fully incorporated into this description by reference to them.

Claims (10)

1. A method of producing 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene, said method comprising the step of (a) fluorinating octachlorocyclopentene with hydrogen fluoride in the gas phase in the presence of a fluorination catalyst, said fluorination catalyst comprising a compound selected from the group consisting of CrCl ₃ • 6H ₂ O, Cr (NO ₃ ) ₃ • 9H ₂ O, Cr ₂ O ₃ , SbCl ₅ , Fe (NO ₃ ) ₃ • 9H ₂ O, Zn (NO ₃ ) ₂ • 6H ₂ O, CoCl ₂ • 6H ₂ O, Co (NO ₃ ) ₂ • 9H ₂ O, NiCl ₂ • 6H ₂ O, Ni (NO ₃ ) ₃ • 9H ₂ O Cu (NO ₃ ) ₂ • 3H ₂ O , MnCl ₂ • 4H ₂ O, Al (NO ₃ ) ₃ • 9H ₂ O. 2. The method according to claim 1, wherein said fluorination catalyst is carried Le selected from the group consisting of activated carbon, alumina, partially fluorinated alumina, fluorinated alumina and fluorinated aluminum. 3. The method according to p. 1, in which stage (a) is carried out under conditions in which said hydrogen fluoride is in an amount of 6-60 moles per mole of said octachlorocyclopentene, the reaction temperature is 150-800 ^{° C.} , the contact time is 0.1 -300 s and the reaction pressure is 1-10 kg / cm ² .  4. The method according to p. 1, in which stage (a) is carried out by a multi-stage reaction, in which m reaction zones are provided, where m is an integer from 2 to 10, said reaction zones being arranged sequentially and so as to independently control the reaction temperature in each reaction zone.  5. The method according to p. 1, in which stage (a) is carried out in a multi-stage reaction, in which at least the first and second reaction zones are arranged in series, said first reaction zone preceding said second reaction zone in position and the reaction temperature said first reaction zone is set lower than the boiling point of said octachlorocyclopentene at the operating pressure of the reaction system in said first reaction zone.  6. The method according to p. 5, in which the reaction product formed in the specified first reaction zone, together with hydrogen chloride formed in the specified first reaction zone, and / or the specified hydrogen fluoride remaining unreacted in the specified first reaction zone after the reaction of the specified octachlorocyclopentene with said hydrogen fluoride in said first reaction zone is passed to said second reaction zone.  7. The method of claim 5, wherein prior to introducing said octachlorocyclopentene into said first reaction zone, said octachlorocyclopentene is heated at a temperature lower than said boiling point of said octachlorocyclopentene at an operating pressure of the reaction system. 8. A method for producing octafluorocyclopentene, the method comprising the steps of (a) fluorinating octachlorocyclopentene with hydrogen fluoride in the gas phase in the presence of a fluorination catalyst, said fluorination catalyst comprising a compound selected from the group consisting of CrCl ₃ • 6H ₂ O, Cr (NO ₃ ) ₃ • 9H ₂ O, Cr ₂ O ₃ , SbCl ₅ , Fe (NO ₃ ) ₃ • 9H ₂ O, Zn (NO ₃ ) ₂ • 6H ₂ O, CoCl ₂ • 6H ₂ O, Co (NO ₃ ) ₂ • 9H ₂ O, NiCl ₂ • 6H ₂ O, Ni (NO ₃ ) ₃ • 9H ₂ O Cu (NO ₃ ) ₂ • 3H ₂ O,
MnCl ₂ • 4H ₂ O, Al (NO ₃ ) ₃ • 9H ₂ O, and (b) fluorinating the reaction product of step (a) into said octafluorocyclopentene with metal fluoride to thereby replace the chlorine atom in said reaction product of step (a) with a fluorine atom of said metal fluoride.  9. The method of claim 8, wherein the reaction product of step (a) comprises 1,2-dichloro-3,3,4,4,5,5-hexafluorocyclopentene.  10. The method of claim 8, wherein said fluorination catalyst is on a carrier selected from the group consisting of activated carbon, alumina, partially fluorinated alumina, fluorinated alumina, and fluorinated aluminum.  11. The method of claim 8, wherein said metal fluoride is selected from the group consisting of lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride and rubidium fluoride.

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