Process for producing tetrakisfluorophenylborate

Abstract: A process for preparing a tetrakisfluorophenylborate which is useful as a catalyst component for the polymerization of olefins or as a raw material for synthesizing the same, efficiently at a high productivity per unit amount of a solvent and at a high yield. A mixed solvent of ether and an aliphatic hydrocarbon is used as a reaction solvent for preparing tetrakisphenylborate according to the following reaction formula, 4M 4 -C 6 Y 3 5 + BCl 3 → M 4 B(C 6 Y 3 5 ) 4 wherein M 4 is an alkali or alkaline earth metal, or represents R 6 2 Al, wherein R 6 is an alkyl group, and Y 3 is a hydrogen atom or a halogen atom.

Description: FIELD OF THE INVENTION The present invention relates to an improvement in a process for preparing a tetrakisfluorophenylborate, which is highly pure, has a superior olefin polymerization activity, and is useful as a catalyst component for the polymerization of olefins, such as α-olefins and styrene monomers, or as a raw material for synthesizing the same, efficiently at a high productivity per unit amount of a solvent and at a high yield. BACKGROUND ART Catalysts consisting of a zirconium compound and 'aluminoxane are known to exhibit a high polymerization activity in the polymerization of olefins, such as α-olefins (Japanese Patent Application Laid-open (kokai) No. 19309/1983). This method has a drawback in that a sufficient activity cannot be obtained unless expensive aluminoxane is used at a high ratio for a transition metal compound. In addition, not only preparing aluminoxane involves danger because of use of highly reactive trimethylaluminum to be reacted with water, but also its isolation from the reaction product as a single substance is difficult. Thus, controlling the catalyst for preparing a product with a stable quality has been difficult. A method of using a homogeneous polymerization catalyst containing a reaction product of a transition metal compound, a coordination complex compound, and an organo-aluminum compound, as a major component, has been disclosed (Japanese Patent Application Laid-open (kokai) No. 207704/1991). As the coordination complex compound, a compound which can form an ionic complex by the reaction with a transition metal compound is used. Tetrakisphenylborate compounds are known as typical compounds among such coordination complex compounds. This homogeneous catalyst containing the reaction product of such a tetrakisphenylborate complex compound and a transition metal compound as a major component is economical, because it requires no use of or only a small amount of expensive components such as aluminoxane. In addition, this catalyst can efficiently produce polymers having various characteristics. Because of these reasons, its active use as a catalyst for the polymerization of olefins, such as α-olefins and styrene monomers, is recently ongoing. As raw materials for the synthesis of said tetrakisphenylborate complex compounds, tetrakisphenylborates, for example, lithium(pentafluorophenyl)borate [Li[B(C 6 F 5 ) 4 ]], can be used. A process according to the following reaction formulas is known as a process for preparing these tetrakisphenylborates [J. Organometallic Chem., 2 , 245-250 (1964)]. BrC 6 F 5 + n-BuLi → LiC 6 F 5 (in pentane, -78°C) 3LiC 6 F 5 + BCl 3 → B(C 6 F 5 ) 3 (in pentane, -78°C) B(C 6 F 5 ) 3 + LiC 6 F 5 → Li[B(C 6 F 5 ) 4 ] (in pentane, -78°C) This process has drawbacks in that a complicated procedure is required for the synthesis of the final product, Li[B(C 6 F 5 ) 4 ], after isolation of the intermediate product, B(C 6 F 5 ) 3 , and further that the reaction is delayed and the yield is reduced due to the reaction which takes place between solid LiC 6 F 5 , which is produced by the use of pentane as a solvent, and liquid BCl 3 . Another process, in which the reaction proceeds according to the following formulas, has been reported [Report from Asahi Glass Co., Ltd., Industrial Technology Motivation Institution, 42 , 137 (1983)]. BrC 6 F 5 + n-BuLi → LiC 6 F 5 (in ether, -78°C) 4LiC 6 F 5 + BCl 3 → Li[B(C 6 F 5 ) 4 ] (in ether, -78°C) However, this process has a drawback of a low yield because of the use of ether as a solvent with which BCl 3 produces a complex, which is insoluble in ether. DISCLOSURE OF THE INVENTION According to the present invention, a process for preparing a tetrakisfluorophenylborate is provided, which comprises the following reaction (7), 4M 4 -C 6 Y 3 5 + BCl 3 → M 4 B(C 6 Y 3 5 ) 4 + 3M 4 Cl wherein M 4 is an alkali or alkaline earth metal, or represents R 6 2 Al, provided that R 6 is an alkyl group, and Y 3 represents a hydrogen atom or a halogen atom, in a mixed solvent of ether and an aliphatic hydrocarbon. Furthermore, a process for preparing a tetrakisfluorophenylborate is provided, which comprises adding a hydrocarbon solvent to said tetrakisfluorophenylborate to which a Lewis base is coordinated and removing the Lewis base by concentrating or drying it under reduced pressure. Further provided is a process for the preparation of said tetrakisfluorophenylborate, which comprises the purification of the tetrakisfluorophenylborate by dissolving it in a solvent having an SP value of 15 or larger and 30 or smaller and depositing it from water or an aliphatic hydrocarbon solvent. Tetrakisphenylborates obtained by the process of the present invention are suitable for use as a coordination complex compound, which is a catalyst component for the synthesis of olefin polymerization, or as a raw material for the synthesis of this coordination complex compound. Given as examples of such coordination complex compounds are, triethylammonium tetrakis(pentafluorophenyl)borate, tri-n-butylammonium tetrakis(pentafluorophenyl)borate, triphenylammonium tetrakis(pentafluorophenyl)borate, tetrabutylammonium tetrakis(pentafluorophenyl)borate, (tetraethylammonium)tetrakis(pentafluorophenyl)borate, [methyltri(n-butyl)ammonium]tetrakis(pentafluorophenyl)borate, [benzyltri(n-butyl)ammonium]tetrakis(pentafluorophenyl)borate, methyldiphenylammonium tetrakis(pentafluorophenyl)borate, methyltriphenylammonium tetrakis(pentafluorophenyl)borate, dimethyldiphenylammonium tetrakis(pentafluorophenyl)borate, anilinium tetrakis(pentafluorophenyl)borate, (N-methylanilinium)tetrakis(pentafluorophenyl)borate, (N,N-dimethylanilinium)tetrakis(pentafluorophenyl)borate, (N,N,N-trimethylanilinium)tetrakis(pentafluorophenyl)borate, (m-nitroanilinium)tetrakis(pentafluorophenyl)borate, (p-bromoanilinium)tetrakis(pentafluorophenyl)borate, pyridinium tetrakis(pentafluorophenyl)borate, (p-cyanopyridinium)tetrakis(pentafluorophenyl)borate, (N-methylpyridinium)tetrakis(pentafluorophenyl)borate, (N-benzylpyridinium)tetrakis(pentafluorophenyl)borate, (o-cyano-N-methylpyridinium)tetrakis(pentafluorophenyl)borate, (p-cyano-N-methylpyridinium)tetrakis(pentafluorophenyl)borate, (p-cyano-N-benzylpyridinium)tetrakis(pentafluorophenyl)borate, trimethylsulfonium tetrakis(pentafluorophenyl)borate, benzyldimethylsulfonium tetrakis(pentafluorophenyl)borate, tetraphenylphosphonium tetrakis(pentafluorophenyl)borate., triphenylphosphonium tetrakis(pentafluorophenyl)borate, ferrocenium tetrakis(pentafluorophenyl)borate, (1,1'-dimethylferrocenium)tetrakis(pentafluorophenyl)borate, decamethylferrocenium tetrakis(pentafluorophenyl)borate, acetylferrocenium tetrakis(pentafluorophenyl)borate, formylferrocenium tetrakis(pentafluorophenyl)borate, cyanoferrocenium tetrakis(pentafluorophenyl)borate, silver tetrakis(pentafluorophenyl)borate, trytyl tetrakis(pentafluorophenyl)borate, lithium tetrakis(pentafluorophenyl)borate, sodium tetrakis(pentafluorophenyl)borate, (tetraphenylporphyrine manganese)tetrakis(pentafluorophenyl)-borate, (tetraphenylporphyrine iron chloride)tetrakis(pentafluorophenyl)borate, (tetraphenylporphyrine zinc)tetrakis(pentafluorophenyl)-borate, diisobutylaluminum tetrakis(pentafluorophenyl)borate, and diethylaluminum tetrakis(pentafluorophenyl)borate. The specific embodiments of the present invention will be illustrated in detail hereinafter. The invention is characterized by using a mixed solvent of ether and an aliphatic hydrocarbon as a reaction solvent when carrying out the reaction of formula (7). In the invention, M 4 -C 6 Y 3 5 and boron trichloride (BCl 3 ) are reacted in the solvent to produce a tetrakisphenylborate, which consists of M 4 B(C 6 Y 3 5 ) 4 . M 4 in M 4 -C 6 Y 3 5 , which is a part of the raw materials, is an alkali metal such as lithium, sodium, or potassium; an alkaline earth metal such as calcium, magnesium, and strontium; or a group R 6 2 Al (R 6 is an alkyl group, especially a C 1 -C 8 alkyl group), with a preferred group being an alkali metal, in particular, lithium. Although Y 3 represents a hydrogen atom or a halogen atom, at least one of Y 3 s is preferably a halogen atom, in particular a fluorine atom. Given as preferred examples of M 4 -C 6 Y 3 5 are M 4 -C 6 F 5 , M 4 -C 6 HF 4 , M 4 -C 6 H 2 F 3 , M 4 -C 6 H 3 F 2 , and M 4 -C 6 H 4 F. The method of preparing M 4 -C 6 Y 3 5 is not particularly limited and conventionally known methods can be used. For example, when LiC 6 F 5 is produced as M 4 -C 6 Y 3 5 , BrC 6 F 5 and n-butyl lithium may be reacted in a suitable solvent. As a suitable solvent used here, the same a mixed solvent of ether and an aliphatic hydrocarbon, the same solvent which is described below, is advantageous from the aspect of the reaction. It is essential to use a mixed solvent of ether and an aliphatic hydrocarbon as a reaction solvent for the reaction of M 4 -C 6 Y 3 5 and boron trichloride in the present invention. If either ether or an aliphatic hydrocarbon is used singly as a reaction solvent, the object of the present invention cannot be achieved because the yield of the target tetrakisphenylborate is low. Given as examples of ethers are aliphatic ethers such as diethyl ether, dipropyl ether, propyl methyl ether, propyl ethyl ether, dibutyl ether, butyl methyl ether, butyl ethyl ether, and butyl propyl ether. Either one of them may be used singly or two or more of them may be used in combination. On the other hand, given as examples of aliphatic hydrocarbons are C 5 -C 12 paraffins, such as pentane and hexane; and C 5 -C 8 cycloparaffins, such as cyclohexane and cycloheptane. They may be used either singly or two or more of them may be used in combination. Although there are no particular limitations to the proportion of said ethers and aliphatic hydrocarbons, it is desirable that the ratio by weight be in the range of 100:1 to 1:100. The amount of ethers mixed is advantageously equimolar to or greater than boron trichloride. A reaction temperature below -20°C may be used without specific limitation, with a temperature -50°C or below being preferred. Although there are no particular restrictions to the reaction pressure, the reaction in an inert gas atmosphere, such as a nitrogen gas atmosphere, is preferred. Tetrakisphenylborate consisting of M 4 B(C 6 Y 3 5 ), wherein M 4 and Y 3 are the same as defined above, can be obtained at a high yield in this manner. Ionic complexes between an isomer, such as B(C 6 F 5 ) 4 -, B(C 6 HF 4 ) 4 -, B(C 6 H 2 F 3 ) 4 -, B(C 6 H 3 F 2 ) 4 -, and B(C 6 H 4 F) 4 -, or the like, and an alkali metal, an alkaline earth metal, or R 6 2 Al (wherein R 6 is an alkyl group) are given as specific examples of said tetrakisphenylborate. It is a preferred embodiment of The invention to add a hydrocarbon solvent to the tetrakisfluorophenylborate prepared according to the invention to which a Lewis base is coordinated and to remove the Lewis base by concentrating or drying it under reduced pressure. Here, the Lewis base (L) which is coordinated to the tetrakisfluorophenylborate and which is to be removed by this embodiment means a compound containing an element which comprises a lone pair, such as oxygen, sulfur, nitrogen, and phosphorus. Given as specific examples of such Lewis bases are, as those containing oxygen, methanol, ethanol, diethyl ether, tetrahydrofuran, acetone, ethyl acetate, and methyl ethyl ketone; as those containing sulfur, diethyl thioether, tetrahydrothiophene, and dimethylsulfoxide; as those containing nitrogen, triethylamine, dimethylaniline, pyridine, piperidine, and acetonitrile; and as those containing phosphorus, triethylphosphine and trimethylphosphine. Although there are no specific limitations as to the hydrocarbon solvents used when the Lewis base is removed by concentration or drying under reduced pressure, those having a boiling point of 80°C or higher and 180°C or lower are preferred. Specifically, aromatic compounds, such as benzene, toluene, xylenes, trimethylbenzenes, and ethylbenzenes; and aliphatic hydrocarbons, such as hexane and heptane, are given, with preferred solvents being toluene and xylenes. The solvent can be suitably selected depending on the types of Lewis bases which are coordinated. Regarding the conditions under which the concentration or the drying under reduced pressure is carried out are pressure of 1 mmHg or below, preferably 0.5 mmHg or below, and a temperature of -20°C to 100°C, preferably 0°C to 80°C. This concentration or drying under reduced pressure may be carried-out only once or may be repeated two or more times. The quantity of the solvent is preferably reduced to 1/2 by the concentration or the drying. The proportion in molar ratio of the tetrakisfluorophenylborate and the hydrocarbon solvent used in this invention (hydrocarbon solvent/tetrakisfluorophenylborate) is 10 to 1,000, and preferably 50 to 200. Further, it is desirable that the purity of the tetrakisfluorophenylborate obtained by this invention satisfy the inequality 0 ≤ Lewis acid/tetrakisfluorophenylborate ≤ 0.5, and preferably 0 ≤ Lewis acid/tetrakisfluorophenylborate < 0.1. According to a further preferred embodiment of the invention the tetrakisfluorophenylborate prepared according to the invention is purified by dissolving tetrakisfluorophenylborate in a solvent having an SP value of 15 or larger and 30 or smaller and depositing it from water or an aliphatic hydrocarbon solvent. Tetrakisfluorophenylborates immediately after the synthesis are colored and contain residual salts. Because of this, they cause problems, such as coloration of the polymer, corrosion of molds when the polymer is molded, and the like, if they are used as are. This embodiment of the invention relates to a purification process for the tetrakisfluorophenylborates by removing impurities therefrom. Illustrating the embodiment in detail, a tetrakisfluorophenylborate after the synthesis contains by-products, including salts such as lithium chloride, and decomposed substances such as n-butyl lithium, LiC 6 F 5 , B(C 6 F 5 ) 3 , and MgBrC 6 F 5 . In this invention, in order to remove these impurities the tetrakisfluorophenylborate as produced is first dissolved in a solvent having an SP value of 15 or larger and 30 or smaller. Used as this solvent are ethers, such as diethyl ether, dibutyl ether, ethyl butyl ether, methyl butyl ether, and tetrahydrofuran; alcohols, such as methanol, ethanol, propanol, and buthanol; ketones, such as acetone, methyl ethyl ketone, or diethyl ketone; and halogenated hydrocarbons, such as dichloromethane, chloroform, chloroethane, dichloroethane, and trichloroethane. Two or more of these solvents may be used together. Then, the tetrakisfluorophenylborate is deposited from water or an aliphatic hydrocarbon solvent. As illustrated above, the processes for the preparation and purification of a tetrakisfluorophenylborate of the present invention can produce a high purity tetrakisphenylborate, especially a high purity tetrakisfluorophenylborate, having a superior olefin polymerization activity and useful as a catalyst component for the polymerization of olefins or as a raw material for synthesizing the same, efficiently at a high productivity per unit amount of a solvent and at a high yield. BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be illustrated in detail by way of examples. Example 1 Production of lithium tetra(pentafluorophenyl)borate 180 ml of dry hexane, 180 ml of diethyl ether, and 24.7 g (0.1 mol) of bromopentafluorobenzene were charged into a reaction vessel, which had been displaced by nitrogen, and the mixture was cooled to -70°C, followed by the addition of 0.1 mol of n-butyl lithium dropwise while stirring. Then, 0.025 mol of boron trichloride was added dropwise at -70°C. The temperature was slowly raised to the room temperature. The precipitate was collected by filtration, washed with hexane, and dried to obtain 0.023 mol of Li[B(C 6 F 5 ) 4 ]·O(C 2 H 5 ) 2 containing LiCl. The yield based on bromopentafluorobenzene was 92%. Comparative Example 1 The same procedure as in Example 1 was carried out, except that 360 ml of dry diethyl ether was used instead of 180 ml of dry hexane and 180 ml of diethyl ether. 0.016 mol of Li[B(C 6 F 5 ) 4 ]·O(C 2 H 5 ) 2 was thus obtained. The yield based on bromopentafluorobenzene was 64%. Example 2 Production of lithium tetra(pentafluorophenyl)borate 40 ml of dry hexane, 320 ml of diethyl ether, and 24.7 g (0.1 mol) of bromopentafluorobenzene were charged into a reaction vessel, which had been displaced by nitrogen, and the mixture was cooled to -70°C, followed by the addition of 0.1 mol of n-butyl lithium dropwise while stirring. Then, 0.025 mol of boron trichloride was added dropwise at -70°C. The temperature was slowly raised to the room temperature. The precipitate was collected by filtration, washed with hexane, and dried to obtain 0.022 mol of Li[B(C 6 F 5 ) 4 ]·O(C 2 H 5 ) 2 containing LiCl. The yield based on bromopentafluorobenzene was 88%. Example 3 Production of lithium tetra(pentafluorophenyl)borate 340 ml of dry hexane, 20 ml of diethyl ether, and 24.7 g (0.1 mol) of bromopentafluorobenzene were charged into a reaction vessel, which had been displaced by nitrogen, and the mixture was cooled to -70°C, followed by the addition of 0.1 mol of n-butyl lithium dropwise while stirring. Then, 0.025 mol of boron trichloride was added dropwise at -70°C. The temperature was slowly raised to the room temperature. The precipitate was collected by filtration, washed with hexane, and dried to obtain 0.020 mol of Li[B(C 6 F 5 ) 4 ]·O(C 2 H 5 ) 2 containing LiCl. The yield based on bromopentafluorobenzene was 80%. Example 4 The same procedure as in Example 3 was carried out, except that 340 ml of dry pentane, instead of dry hexane, and 20 ml of diisopropyl ether, instead of diethyl ether, were used, obtain 0.021 mol of Li[B(C 6 F 5 ) 4 ]·O(C 3 H 7 ) 2 . The yield based on bromopentafluorobenzene was 84%. Example 5 Synthesis and purification of dimethylanilinium tetra(pentafluorophenyl)borate 1000 ml of diethyl ether and 49.4 g (0.4 mol) of bromopentafluorobenzene were charged into a reaction vessel which was displaced by nitrogen, and the mixture was cooled to -70°C, followed by the addition of 0.4 mol of n-butyl lithium dropwise while stirring. Then, 0.10 mol of boron trichloride was added dropwise at -70°C. The temperature was slowly raised to the room temperature. The precipitate was collected by filtration, washed with hexane, and dissolved into 200 ml of water. To this solution was added dropwise a solution of 0.10 mol of dimethylanilinium chloride dissolved in 50 ml of water to obtain 79 g of crude dimethylanilinium tetra(pentafluorophenyl)borate. 50 g of the crude dimethylanilinium tetra(pentafluorophenyl)borate was dissolved in 20 ml of methanol and the solution was added dropwise to 500 ml of water. 46 g of purified white dimethylanilinium tetra(pentafluorophenyl)borate was obtained by drying the product under vacuum. Example 6 Polymerization of styrene 6 l of styrene was charged into a 10 l container which was dried and displaced with nitrogen, and heated to 70°C. To this was added a solution of 9 mmol of triisobutyl aluminum, 150 µmol of purified dimethylanilinium tetra(pentafluorophenyl )borate, and 150 µmol of pentamethylcyclopentadienyltitaniumtrimethoxide dissolved in 75 ml of toluene, and the polymerization was carried out for 2 hours. The reaction was terminated by the addition of 1 l of methanol. Methanol was removed by filtration, and the produced polymer was dried under vacuum at 150°C for 5 hours to obtain 4.1 kg of a polymer product. This polymer was melted at 290°C and injection molded 100 times using a mold made of iron at 140°C. The mold was allowed to leave for one day at RH 50% to confirm that no corrosion was produced. The molded product has an Y.I. value of 19. Comparative Example 2 Styrene was polymerized in the same manner as in Example 6, except that crude dimethylanilinium tetra(pentafluorophenyl)borate was used, to obtain 4.0 kg of a polymer product. This polymer was injection molded. Corrosion was found in the mold. The Y.I value of the molded product was 25. INDUSTRIAL APPLICABILITY As illustrated above, tetrakisphenylborate obtained by the preparation processes of the present invention is useful as a catalyst component for the polymerization of olefins, such as α-olefins and styrene monomers, or as a raw material for synthesizing the same. In particular, the tetrakisfluorophenylborate obtained by the present invention is excellent in its olefin polymerization activity, and owing to its high purity, is especially useful as a catalyst component for the polymerization of olefins or as a raw material for synthesizing the same.

Claims: A process for preparing a tetrakisfluorophenylborate which comprises carrying out the following reaction (7), 4 M 4 C 6 Y 3 5 + BCl 3 → M 4 B(C 6 Y 3 5 ) 4 + 3 M 4 Cl wherein M 4 is an alkali or alkaline earth metal, or represents R 6 2 Al, wherein R 6 is an alkyl group; and Y 3 represents a hydrogen atom or a halogen atom, in a mixed solvent of ether and an aliphatic hydrocarbon. The process for preparing a tetrakisfluorophenyl borate comprising, adding a hydrocarbon solvent to the tetrakisfluorophenylborate prepared according to Claim 1 to which a Lewis base is coordinated, and removing the Lewis base by concentrating or drying under reduced pressure. The process for preparing a tetrakisfluorophenylborate further comprising the purification of the tetrakisfluorophenylborate prepared according to Claim 1 which comprises dissolving the tetrakisfluorophenylborate solvent having an SP value of 15 ≤ SP ≤ 30 and depositing it from water or an aliphatic hydrocarbon solvent.

Inventors: NAGANUMA SHOJI, TOMOTSU NORIO, WATANABE MASAMI, NAGANUMA, SHOJI, TOMOTSU, NORIO, WATANABE, MASAMI, Tomotsu, Norio c/o Idemitsu Petrochem. CO.,LTD.
Applicants: DOW CHEMICAL CO, IDEMITSU PETROCHEMICAL CO, IDEMITSU PETROCHEMICAL CO., LTD., THE DOW CHEMICAL COMPANY
Application year: 1993
Main classification: C07F5
IPC codes: C08F4, C08F12, C07F5, C08F10