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. The tetrakisfluorophenylborate is dissolved in a solvent with a SP value of 15 ≤ SP ≤ 30 and deposited from water or an aliphatic hydrocarbon solvent.

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. 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. Halogenoorganometalllc lithium salt complexes are described in DE -A- 29 01 367. DISCLOSURE OF THE INVENTION According to the invention a process for the purification of a tetrakisfluorophenylborate is provided, which comprises dissolving the 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. 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(pentafluprophenyl)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 process of the invention (a purification process), as mentioned above, is characterized by dissolving a 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. The invention relates to a purification process for the tetrakisfluorophenylborates by removing impurities therefrom. Illustrating the invention 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 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 Lithium tetrakis(pentafluorophenyl)borate was synthesized by the following first and second.steps. All the following steps were carried out under a nitrogen gas stream. (I) Synthesis of tris(pentafluorophenyl)boron (the first step) 24.7 g of bromopentafluorobenzene (BrC 6 F 5 ) (F.W. 246.97, 0.1 mol) and 500 ml of dry hexane were mixed and cooled to -70°C. To the mixture was added slowly and dropwise a solution of 0.1 mol of n-butyl lithium in hexane (1.5 mol/l) while stirring. The stirring was continued at -70°C for two hours to react the mixture. Then, a solution of 0.04 mol of boron trichloride dissolved in hexane (1.35 mol/l) was rapidly added dropwise to the reaction solution. The stirring was continued at -70°C for two hours to react the mixture. The reaction solution was filtered at -70°C to remove the hexane layer (in which impurities were dissolved). 500 ml of hexane was added to the solid thus obtained and the mixture was allowed to come to the room temperature. 12.1 g of tris(pentafluorophenyl)boron (B(C 6 F 5 ) 3 ) was contained in the hexane layer (containing no impurities dissolved) obtained by the further removal of a solid (yield based on BrC 6 F 5 : 71%). (II) Synthesis of lithium tetrakis(pentafluorophenyl)borate (the second step) 5.85 g (0.0237 mol) of bromopentafluorobenzene and 100 ml of dry diethyl ether were mixed and cooled to - 70°C. To the mixture was added slowly and dropwise a solution of 0.0237 mol of n-butyl lithium in hexane (1.5 mol/l) while stirring. The stirring was continued at -70°C for 30 minutes to react the mixture. Then, the reaction solution (-70°C) was slowly added dropwise to a solution of 12.1 g of tris(pentafluorophenyl)boron , obtained in (1) above, dissolved in hexane (500 ml, room temperature) and the mixture was stirred for 30 minutes at room temperature. 17.1 g of a white solid of lithium tetrakis(pentafluorophenyl)boratediethyl ether complex (LiB(C 6 F 5 ) 4 •OEt 2 ) was obtained by removing the solvent and drying the residue under reduced pressure (yield: 95%). The lithium tetrakis(pentafluorophenyl)boratediethyl ether complex was obtained by steps (I) and (II) at an overall yield of 67.5% based on the raw material BrC 6 F 5 . (III) Synthesis of dimethylanilinium tetrakis(pentafluorophenyl)borate 2 g (2.92 x 10 -3 mol) of the lithium tetrakis(pentafluorophenyl)borate-diethyl ether complex was dissolved in 70 ml of water and 0.44 g (2.78 x 10 -3 mol) of dimethylanilinium chloride was added to the solution, followed by stirring at room temperature for one hour. The solid thus obtained was thoroughly washed with water and hexane. The above solid was dissolved in 20 ml of acetone, and this acetone solution was poured into a large quantity of water to re-precipitate the solid. The solid component was collected by filtration. 10 ml of dry toluene was added to the solid component and the mixture was dried under reduced pressure, to obtain 2.01 g of dimethylanilinium tetrakis(pentafluorophenyl)borate ([PhNMe 2 H][B(C 6 F 5 ) 4 ]) (yield: 86%). No Lewis base was coordinated to this complex. (IV) Polymerization using dimethylanilinium tetrakis(pentafluorophenyl)borate 400 ml of toluene and 4 x 10 -4 mol of triisobutyl aluminum (2 mol/l toluene solution) was thoroughly stirred in an autoclave. To the autoclave were charged 1 x 10 -5 mol of isopropylidene(cyclopentadienyl-9-fluorenyl)zirconium dichloride (0.01 mol/l toluene solution) and 1 x 10 -5 mol of dimethylanilinium tetrakis(pentafluorophenyl)borate obtained in (III) above (0.01 mol/l toluene solution) in sequence, and the mixture was thoroughly stirred. Next, propylene was continuously fed to the autoclave at 25°C at a constant propylene pressure of 3 kg/cm 2 , and reacted for one hour. After the completion of the reaction, the catalyst was deactivated by the addition of methanol. The resulting reaction mixture was filtered and dried under reduced pressure to obtain 54.5 g of syndiotactic polypropylene. The polymerization activity was 59.7 kg/g•Zr and 5.05 kg/g•Al. The melting point of the polymer measured by the differential scanning calorimeter was 132°C, and the weight average molecular weight and the number average molecular weight as determined by the gel permeation chromatography based on polystyrene were 6.0 x 10 4 and 2.7 x 10 4 , respectively. Tacticity determined by 13 C-NMR at rrrr (racemi pentad) was 88%. Comparative Example 1 (I) 2 g of lithium tetrakis(pentafluorophenyl)borate-diethyl ether complex (2.92 x 10 -3 mol) obtained in Example 1, (II), was dissolved in 70 ml of water. 0.44 g (2.78 x 10 -3 mol) of dimethylanilinium chloride was added to the solution and the mixture was stirred at room temperature for one hour. The solid thus obtained was thoroughly washed with water and hexane, and dried under reduced pressure. 1 H-NMR was measured on the solid thus obtained to confirm that this solid was an about 1:1 complex of dimethylanilinium tetrakis(pentafluorophenyl)borate and diethyl ether. The yield was 2.3 g (2.66 x 10 -3 mol). (II) 400 ml of toluene and 4 x 10 -4 mol of triisobutyl aluminum (2 mol/l toluene solution) were thoroughly stirred in an autoclave. To the autoclave were charged 1 x 10 -5 mol of isopropylidene(cyclopentadienyl-9-fluorenyl)zirconium dichloride (0.01 mol/l toluene solution) and 1 x 10 -5 mol of dimethylanilinium tetrakis(pentafluorophenyl)borate-ethyl ether complex obtained in (I) above (0.01 mol/l toluene solution) in sequence, and the mixture was thoroughly stirred. Next, propylene was continuously fed to the autoclave at a temperature of 25°C or below at a constant propylene pressure of 3 kg/cm 2 , and reacted for one hour. After the completion of the reaction, the catalyst was deactivated by the addition of methanol. The resulting reaction mixture was filtered and dried under reduced pressure to obtain 22.2 g of syndiotactic polypropylene. The polymerization activity was 24.3 kg/g•Zr and 2.06 kg/g•Al. Example 2 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 3 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 3, 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 purification 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 the purification of a tetrakisfluorophenylborate, which comprises dissolving the tetrakisfluorophenylborate in a 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, C07F5, C08F12, C08F10