Method of Producing Tetrakis\Pentafluorophenyl\Borate

Europaisches Patentamt J European Patent Office © Publication number: 0 608 563 A2 Office europeen des brevets

EUROPEAN PATENT APPLICATION

@ Date of filing: 27.12.93

® Priority: 28.12.92 JP 361478/92 © Applicant: TOSOH AKZO CORPORATION 28.12.92 JP 361479/92 No. 11-37, Akasaka 8-chome, Minato-ku @ Date of publication of application: Tokyo(JP) 03.08.94 Bulletin 94/31 @ Inventor: Ikeda, Yoshihiko © Designated Contracting States: No. 4-6, Mandokoro DE FR GB IT NL Shinnanyo-shi, Yamaguchi-ken(JP) Inventor: Yamane, Takeo No. 773-1, Shimogo, Ogori-machi Yoshiki-gun, Yamaguchi-ken(JP) Inventor: Kaji, Eiichi No. 1-1-31, Miyanomae Shinnanyo-shi, Yamaguchi-ken(JP) Inventor: Ishimaru, Kenji No. 1-1-31, Miyanomae Shinnanyo-shi, Yamaguchi-ken(JP)

© The invention relates to a production method, ganometallic compound represented by the formula wherein, with 1 equivalent of pentafluorobenzene re- [II] are reacted at -120 °C to 80 °C in an ether type presented by a formula [I], 0.5 to 1 .5 equivalents of solvent, a hydrocarbon type solvent or a mixed sol- formula of the ether solvent with the CM organometallic compound represented by a vent type hydrocarbon < [II] are reacted at -120 °C to 80 °C in an ether type type solvent to generate pentafluorophenyl alkali solvent, a hydrocarbon type solvent or a mixed sol- metal salt represented by the formula [III], and then, 00 vent of the ether solvent with the with 1 of CO type hydrocarbon equivalent tris(pentafluorophenyl)borane re- m type solvent to generate pentafluorophenyl alkali presented by a formula [VIII], not less than 0.8 metal salt represented by a formula [III], and then, equivalents of pentafluorophenyl metal compound oo o with 1 equivalent of boron compound represented by represented by the formula [III] are reacted to pro- CO a formula [IV], not less than 3.7 equivalents of pen- duce tetrakis(pentafluorophenyl)borate derivatives re- tafluorophenyl metal compound represented by the presented by the formula [VII]. formula [III] are reacted to produce tetrakis- (pentafluorophenyl)borate derivatives represented by a formula [VII], or a production method, wherein, with 1 equivalent of pentafluorobenzene represented by the formula [I], 0.5 to 1.5 equivalents or or-

Rank Xerox (UK) Business Services (3. 10/3.09/3.3.4) 1 EP 0 608 563 A2 2

The present invention relates to a novel pro- that of pentafluorobenzene as a starting substance duction of tetrakis(pentafluorophenyl)borate deriva- for the production of tetrakis(pentafluorophenyl)- tives using pentafluorobenzene. borate derivatives and eliminating the brominating The boron derivatives obtainable according to process of pentafluorobenzene, leading to the in- the invention is a very useful substance as an 5 vention. intermediate of a cocatalyst for the cationic com- The gist of the invention lies in a production plex polymerization. method, wherein, with 1 equivalent of pen- In recent years, scientific literatures or patents tafluorobenzene represented by a formula [I], 0.5 to on the studies, in which a cationic complex is 1 .5 equivalents of organometallic compound repre- generated using tetrakis(pentafluorophenyl)borate io sented by a general formula [II] are reacted at -120 derivatives and cyclopentadienyl transition metal ° C to 80 ° C in an ether type solvent, a hydrocar- complex, so-called metallocene derivatives, and bon type solvent or a mixed solvent of the ether this is used as a catalyst for the polymerization type solvent with the hydrocarbon type solvent to reaction, have increased remarkably. For example, generate pentafluorophenyl alkali metal salt repre- Macromol. Chem. Rapid Commun., 2, p.p. 663-667 75 sented by a formula [III], and then, with 1 equiv- (1991) etc. are available. However, for the produc- alent of boron compound represented by a formula tion of tetrakis(pentafluorophenyl)borate derivatives, [IV], not less than 3.7 equivalents of pen- relatively expensive bromopentafluorobenzene has tafluorophenyl metal compound represented by the been used conventionally as a starting substance formula [III] are reacted to produce tetrakis- for the source of pentafluorophenyl group. 20 (pentafluorophenyl)borate derivatives represented The method was that bromopentafluoroben- by a formula [VII], or a production method, wherein, zene was submitted to the bromine-metal ex- with 1 equivalent of pentafluorobenzene represent- change reaction using organometallic compounds ed by the formula [I], 0.5 to 1.5 equivalents of such as butyllithium to generate pentafluorophenyl- organometallic compound represented by the gen- lithium, which was then reacted with boron trichlo- 25 eral formula [II] are reacted at -120 °C to 80 °C in ride, boron trifluoride, or the like as a starting raw an ether type solvent, hydrocarbon type solvent or material for the source of boron to synthesize di- a mixed solvent of the ether type solvent with the rectly, or that bromopentafluorobenzene was reac- hydrocarbon type solvent to generate pen- ted with magnesium to generate a Grignard tafluorophenyl alkali metal salt represented by the reagent such as pentafluorophenylmagnesium bro- 30 formula [III], and then, with 1 equivalent of tris- mide, which was then reacted with boron trichlo- (pentafluorophenyl)borane represented by a formu- ride, boron trifluoride, or the like similarly as a la [VIII], not less than 0.8 equivalents of pen- starting raw material for the source of boron to tafluorophenyl metal compound represented by the synthesize tris(pentafluorophenyl)borane, and this formula [III] are reacted to produce tetrakis- was further reacted with pentafluorophenyllithium to 35 (pentafluorophenyl)borate derivatives represented produce tetrakis(pentafluorophenyl)borate deriva- by the formula [VII]. tives (J. Organometallic Chem., 2, 245-250 (1964)). In following, the invention will be illustrated Bromopentafluorobenzene is obtained by concretely. brominating pentafluorobensene. If it is possible to The ether type solvents referred to so in the directly produce tetrakis(pentafluorophenyl)borate 40 specification indicate diethyl ether, dipropyl ether, derivatives from pentafluorobenzene, then the pro- diisopropyl ether, dibutyl ether, diisoamyl ether, duction processes can be reduced by one process, 1 ,2-dimethoxyethane, 1 ,2-diethoxyethane, di-2- leading to easy availability and also decreased methoxyethyl ether, tetrahydrofuran, price of a starting raw material. Moreover, litera- tetrahydropyran, 1,4-dioxane, etc. tures, in which pentafluorophenyllithium or pen- 45 Next, the hydrocarbon type solvents referred to tafluorophenylmagnesium bromide is generated us- so in the invention indicate saturated hydrocarbons ing pentafluorobenzene as a starting raw material such as pentane, isopentane, hexane, cyclohexane, and this is used for reaction, have already been heptane, octane, nonane, decane, undecane, presented (J. Chem. Soc, 166 (1959), Synthesis of dodecane, tridecane, tetradecane, pentadecane, Fluoroorganic Compounds, p141, J. Org. Chem., 50 hexadecane, n-paraffin and petroleum ether, ar- 29, 2385 (1964) and ibid, 3^, 4229 (1966)), but omatic hydrocarbons such as benzene, toluene, o- application to the production of tetrakis- xylene, m-xylene, p-xylene, 1 ,2,3-trimethylbenzene, (pentafluorophenyl)borate derivatives is not made. 1 .2.4- trimethylbenzene, 1 ,2,5-trimethylbenzene, In view of the said situation, the inventors in- 1 .3.5- trimethylbenzene, ethylbenzene, propylben- vestigated extensively on a synthetic method with- 55 zene and butylbenzene, and mixtures thereof. out using relatively expensive bromopen- Next, the functional groups having no influence tafluorobenzene as a starting raw material by on the reaction in the formula [II] referred to so in changing the use of bromopentafluorobenzene to the specification indicate methyl group, ethyl

2 3 EP 0 608 563 A2 4 group, propyl group, isopropyl group, propenyl then a lot of unreacted pentafluorobenzene comes group, 2-isopropenyl group, allyl group, butyl to remain, and, if excess amount of organometallic group, sec-butyl group, tert-butyl group, isobutyl compound is used, then there is a fear of the group, pentyl group, sec-pentyl group, tert-pentyl halogen-metal exchange reaction with also fluorine group, neo-pentyl group, isopentyl group, sec- 5 of pentafluorophenyl metal salt produced and re- isopentyl group, hexyl group, sec-hexyl group, presented by the formula [III]. Hence, it is prefer- isohexyl group, sec-isohexyl group, cyclohexyl able to use 0.8 to 1.20 equivalents of the or- group, phenyl group, benzyl group, o-tolyl group, ganometallic compound represented by the formula m-tolyl group, p-tolyl group, methoxymethyl group, [II]. If the reaction temperature is too lower than -80 methylthiomethyl group, 2-dimethylaminoethyl io °C, the reaction proceeds extremely slowly, while group, o-anisyl group, m-anisyl group, p-anisyl if it is too higher than 0 ° C, side reactions proceed group, trimethylsilylmethyl group, etc., and exam- extremely rapidly, thus coming to very low yield in ples of organometallic compounds represented by both cases. Hence, it is desirable to conduct the the formula [II] include methyllithium, ethyllithium, reaction in a range of -80 to 0 °C. The reaction propyllithium, isopropyllithium, butyllithium, is mixture is allowed to react for 5 to 120 minutes at isobutyllithium, sec-butyllithium, tert-butyllithium, the same temperature, thereby pentafluorophenyl pentyllithium, isopentyllithium, sec-pentyllithium, alkali metal salt represented by the formula [III] is tert-pentyllithium, sec-isopentyllithium, hexyllithium, prepared. isohexyllithium, sec-hexyllithium, cyclohexyllithium, Pentafluorophenyl alkali metal salt produced phenyllithium, o-tolyllithium, m-tolyllithium, p-tolyl- 20 herein and represented by the formula [III] is lithium, trimethylsilyllithium, phenylsodium, o-tolyl- CgH5IJ, CGH5Na or CGH5K. sodium, m-tolylsodium, p-tolylsodium, butyl- Although the use level of pentafluorophenyl lithium/potassium-tert-butiode, butyllithium/sodium- alkali metal salt is 4 equivalents as a theoretical tert-butoxide etc., and isopropyllithium, sec-butyl- amount when using the boron compound repre- lithium, tert-butyllithium, sec-pentyllithium, tert-pen- 25 sented by the formula [IV] for the reaction, the tyllithium, sec-isopentyllithium, sec-hexyllithium, decrease in the yield of tetrakis(pentafluorophenyl)- cyclohexyllithium, etc. which are strong in basicity borate derivatives becomes remarkable in the case and hard to influence on the reaction, are prefer- of under 3.7 equivalents shown here, hence a use able. of not less than 3.7 equivalents is desirable. As the examples of boron compounds repre- 30 Moreover, when using tris(pentafluorophenyl)- sented by the formula [IV] referred to so in the borane for the reaction as a boron compound, the specification, boron trifluoride, boron trichloride, bo- theoretical amount is 1 equivalent, but the de- ron tribromide, boron triiodide, trimethyl borate, tri- crease in the yield of tetrakis(pentafluorophenyl)- ethyl borate, trioropyl borate, triisopropyl borate, borate derivatives is remarkable in the case of tributyl borate, trimethyleneborate, tris- 35 under 0.7 equivalents shown here, hence use of (dimethylamino)borate, tris(diethylamino)borate, not less than 0.7 equivalents is desirable. tripyrrolidinoborate, tripiperidinoborate, trimor- As for the mixing temperature of pen- pholinoborate, et. are mentioned. In addition, the tafluorophenyl alkali metal salt with boron com- complexes such as boron trifluoride-diethyl ether pound, the reaction proceeds extremely slowly at a complex, boron trifluoride-dibutyl ether complex, 40 temperature lower than -100 °C, hence a tempera- boron trifluoride-dimethyl sulfide complex, boron ture higher than this is desirable, and, if it is too trichloride-diethyl ether complex and boron trichlo- higher than 0 ° C, side reactions proceed extremely ride-dibutyl ether complex are also included in this rapidly, thus coming to very low yield in both scategory. cases. Hence a temperature lower than this is The concrete production method will be illus- 45 desirable. trated below in sequence. Also, if the reaction temperature is lower than Pentafluorobenzene represented by the formula -100 °C, then the reaction proceeds extremely [I] is dissolved into an ether type solvent, a hy- slowly, and, if it is higher than 0 °C, then the drocarbon type solvent or a mixed solvent thereof. unreacted pentafluorophenyl alkali metal salt de- With this solution, 0.5 to 1.5 equivalents of the 50 composes, hence, reacting at -100 to 0 °C is orgnometallic compound represented by the for- desirable. mula [II] per 1 equivalent of pentafluorobenzene The invention provides a method of producing are reacted within a range from -120 to 80 °C. tetrakis(pentafluorophenyl)borate derivatives, being In this reaction, when generating pen- an important intermediate of a cocatalyst on pre- tafluorophenyl alkali metal salt represented by the ss paring the catalyst for cationic complex polymeriza- formula [III], if the organometallic compound repre- tion, in high yield via pentafluorophenyl alkali metal sented by the formula [II] is too less than pen- salt not from bromopentafluorobenzene but from tafluorobenzene represented by the formula [I], more inexpensive pentafluorobenzene. In this point,

3 5 EP 0 608 563 A2 6 the effect of the invention is tremendous. dropwise a 20 wt. % tert-butyllithium/pentane solu- In following, the invention will be illustrated in tion (7.98 g, 25.0 mmol) while keeping the tem- more detail using the examples, but the invention perature of the reaction mixture at -55 to -65 °C, undergoes no restriction by the examples below, and, after the completion of dropwise addition, the so long as it does not exceed the gist. 5 mixture was stirred for about 0.5 hours while keep- The yield of a reaction is a value obtained by ing the temperature at -25 to -50 ° C. Thereafter, a quantitatively determining the amount of tetrakis- 20.0 wt. % tris(pentafluorophenyl)borane/toluene (pentafluorophenyl)borate derivatives produced by solution (63.8 g, 25.0 mmol) was mixed while keep- means of 19 F NMR using pentafluorotoluene as an ing the temperature of reaction mixture at -25 to internal standard material, or by calculating on the io -40 °C, which was stirred for 30 minutes at the basis of dried weight of crystals after derived to same temperature and then temperature was N,N-dimethylanilinium or tributylammonium raised to room temperature. From the solution of tetrakis(pentafluorophenyl)borate by cation ex- lithium tetrakis(pentafluorophenyl)borate thus ob- changing with N,N-dimethylanilinium chloride or tained, diethyl ether was removed by distillation tributylammonium chloride. The purity was deter- is and the organic layer was washed thrice with 20 mined by means of 19 F NMR using pen- mL of water. After combined the aqueous layers, tafluorotoluene as an internal standard material. 1.1 equivalent to the boron source of aqueous solution of N,N-dimethylanilinium chloride was Example 1 reacted with aqueous layer to deposit white cry- 20 stals. The crystals obtained were filtered, washed A 100 ml volume glass three-neck flask was with water and then dried under vacuum to obtain equipped with a 50 ml volume glass dropping N,N-dimethylanilinium tetrakis(pentafluorophenyl)- funnel, temperature resistor and septum rubber and borate in 97.3 % yield. When determining the the inside of system was sufficiently replaced with purity by means of 1H and 19 F NMR using pen- nitrogen. Into the flask, 5 g (29.8 mmol) of pen- 25 tafluorotoluene as an internal standard material, it tafluorobenzene and 30 ml of diethyl ether were showed 98 % or higher. charged, and the solution was cooled to -65 °C. Thereafter, a 16.1 wt. % pentane solution (12.3 Example 3 g, 29.8 mmol) of tert-butyllithium charged into the dropping funnel was added dropwise while making 30 To a solution of pentafluorobenzene (4.40 g, the inner temperature not to exceed -55 ° C. After 26.2 mmol) and diethyl ether (50 ml) was added the completion of dropwise addition, the reaction dropwise a 20 wt. % secbutyllithium/hexane solu- mixture was stirred at -65 to -55 °C to prepare tion (7.98 g, 25.0 mmol) while keeping the tem- pentafluorophenyllithium. perature of the reaction mixture at -55 to -65 °C, To the solution of pentafluorophenyllithium thus 35 and, after the completion of dropwise addition, the prepared was added 1 mol/L hexane solution (7.45 mixture was stirred for about 0.5 hours while keep- mL, 7.45 mmol) of boron trichloride at -65 to -55 ing the temperature at -25 o -50 ° C. Thereafter, a °C, and the mixture was stirred for 30 minutes at 20.0 wt. % tris(pentafluorophenyl)borane/toluene the same temperature. Then, the temperature was solution (63.8 g, 25.0 mmol was mixed while keep- raised to room temperature, diethyl ether was re- 40 ing the temperature of the reaction mixture at -25 moved by distillation from the reaction mixture, and to -40 ° C, which was stirred for 30 minutes at the the organic layer was washed thrice with 20 mL of same temperature and then temperature was water. After combined the aqueous layers, 1.1 raised to room temperature. From the solution of equivalent to the boron source of aqueous solution lithium tetrakis(pentafluorophenyl)borate thus ob- of N,N-dimethylanilinium chloride was reacted with 45 tained, diethyl ether was removed by distillation aqueous layer to deposit white crystals. The cry- and the organic layer was washed thrice with 20 stals obtained were filtered, washed with water and mL of water. After combined the aqueous layers, then dried under vacuum to obtain N,N- 1.1 equivalent to the boron source of aqueous dimethylanilinium tetrakis(pentafluorophenyl)borate solution of N,N-dimethylanilinium chloride was in 92.3 % yield. When determining the purity by 50 reacted with aqueous layer to deposit white cry- means of 1H and 19 F NMR using pen- stals. The crystals obtained were filtered, washed tafluorotoluene as an internal standard material, it with water and then dried under vacuum to obtain showed 98 wt. % or higher. N,N-dimethuylanilinium tetrakis(pentafluorophenyl)- borate in 96.1 % yield. When determining the Example 2 55 purity by means of 1H and 19 F NMR using pentafluorotoluene as an internal standard material, it To a solution of pentafluorobenzene (4.40 g, showed 98 % or higher. 26.2 mmol) and diethyl ether (50 ml) was added

4 7 EP 0 608 563 A2 8

Example 4 (28.1 g, 87.7 mmol) was added and the mixture was stirred for 10 hours at -30 to -40 °C. There- A 100 ml volume glass three-neck flask was after, boron trifluoride-diethyl ether complex (2.84 equipped with a 50 mol volume glass dropping g, 20.0 mmol) was added at -40 °C and the funnel, temperature resistor and septum rubber and 5 temperature was raised to room temperature over 2 the inside of system was sufficiently replaced with hours. After stirring overnight at room temperature, nitrogen. Into the flask, 5 g (29.8 mmol) of pen- toluene (200 ml) was added and, after distilled off tafluorobenzene and 30 ml of diethyl ether were diethyl ether and hexane under heat, toluene was charged, and the solution was cooled to -65 °C. also distilled off further under heat to an extent of Thereafter, a 16.1 wt. % pentane solution (12.3 io recovering about 30 % of the added amount. After g, 29.8 mmol) of tert-butyllithium charged into the filtered off precipitated lithium fluoride, toluene was dropping funnel was added dropwise while making removed to bone-dry to obtain lithium tetrakis- the inner temperature not to exceed -55 ° C. After (pentafluorophenyl)borate in 51 % yield. the completion of dropwise addition, the reaction mixture was stirred at -65 to -55 °C to prepare is Example 7 pentafluorophenyllithium. To the solution of pentafluorophenyllithium thus After a solution of pentafluorobenzene (14.8 g, prepared was added 1 mol/L hexane solution (7.45 88.0 mmol) and diethyl ether (100 ml) was cooled mL, 7.45 mmol) of boron trichloride at -65 to -55 to -40 °C, a 24 wt. % tert-butyllithium/pentane °C, and the mixture was stirred for 30 minutes at 20 solution (23.4 g, 87.7mmol) was added and the the same temperature. Then, the temperature was mixture was stirred for 10 hours at -30 to -40 °C. raised to room temperature and lithium chloride Thereafter, boron trifluoride-diethyl ether complex produced as a by-product was filtered off. When (2.84 g, 20.0 mmol) was added at -40 °C and the determining the solution of lithium tetrakis- temperature was raised to room temperature over 2 (pentafluorophenyl)borate obtained by means of 25 hours. After stirring overnight at room temperature, 19 F NMR using pentafluorotoluene as an internal toluene (200 ml) was added, and after distilled off standard material, the yield was 94.3 %. diethyl ether and pentane under heat, toluene was also distilled off further under heat to an extent of Example 5 recovering about 30 % of the added amount. After 30 filtered off precipitated lithium fluoride, toluene was After a solution of pentafluorobenzene (15.8 g, removed to bone-dry to obtain lithiuma tetrakis- 100.0 mmol) and diethyl ether (100 ml) was cooled (pentafluorophenyl)borate in 68 % yield. to -40 °C, a 25 wt. % tert-butyllithium/pentane solution (22.5 g, 88.0 mmol) was added and the Example 8 mixture was stirred for 22 hours at -30 to -40 °C. 35 Thereafter, 1 .0 mol/L boron trichloride/hexane solu- After a solution of pentaluorobenzene (15.1 g, tion (21.0 ml, 21.0 mmol) was added at -40 °C and 90.0 mmol)and diethyl ether (100 ml) was cooled to the temperature was raised to room temperature -40 °C, a 20 wt. % sec-butyllithium/hexane solu- over 2 hours. From the solution of lithium tetrakis- tion (28.2 g, 88.0 mmol) was added and the mix- (pentafluorophenyl)borate thus obtained, diethyl 40 ture was stirred for 10 hours at -30 to -40 °C. ether was removed by distillation and the organic Thereafter, boron trifluoride-diethyl ether complex layer was washed thrice with 30 mL of water. After (2.84 g, 20.0 mmol) was added at -40 °C and the combined the aqueous layers, 1.1 equivalent to the temperature was raised to room temperature over 2 boron source of aqueous solution of tributylam- hours. After stirring overnight at room temperature, monium chloride was reacted with aqueous layer to 45 toluene (200 ml) was added and, after distilled off deposit white crystals. The crystals obtained were diethyl ether and hexane under heat, toluene was filtered, washed with water and then dried under also distilled off further under heat to an extent of vacuum to obtain tributylammonium tetrakis- recovering about 30 % of the added amount. After (pentafluorophenyl)borate in 95.2 % yield. When filtered off precipitated lithium fluoride, toluene was determining the purity by means of 1H and 19 F 50 removed to bone-dry to obtain lighium tetrakis- NMR using pentafluorotoluene as an internal stan- (pentafluorophenyl)borate in 65 % yield. dard material, it showed 98 wt. % or higher. Example 9 Example 6 55 After a solution of pentafluorobenzene (14.8 g. After a solution of pentafluorobenzene (14.8 g, 88.0 mmol) and diethyl ether (100 ml) was cooled 88.0 mmol) and diethyl ether (100 ml) was cooled to -40 °C, a 15 wt. % butylsodium/hexane solution to -40 ° C, a 20 wt. % butyllithium/hexane solution (47.0 g, 88.0 mmol) was added and the mixture

5 9 EP 0 608 563 A2 10 was stirred for 1 hour at -30 to -40 ° C. Thereafter, N,N-dimethylanilinlum tetrakis(pentafluorophenyl)- boron trifluoride-diethyl ether complex (2.84 g, 20.0 borate in 95.1 % yield. When determining the mmol) was added at -40 °C and the temperature purity by means of 1H and 19 F NMR using pen- was raised to room temperature over 2 hours. From tafluorotoluene as an internal standard material, it the solution of sodium tetrakis(pentafluorophenyl)- 5 shsowed 98 wt. % or higher. borate thus obtained, diethyl ether was removed by distillation and the organic layer was washed thrice Example 12 with 20 mL of water. After combined the aqueous slayers, 1.1 equivalent to the boron source of aque- After a solution of pentafluorobenzene (14.8 g, ous solution of N,N-dimethylanilinium chloride was io 88.0 mmol) and diethyl ether (100 ml) was cooled reacted with aqueous layer to deposit white cry- to -40 °C, a 15 wt. % tert-butyllithium/pentane stals. The crystals obtained were filtered, washed solution was added and the mixture was stirred for with water and then dried under vacuum to obtain 30 hours at -30 to -40 °C. Thereafter, trimethyl N,N-dimethylanilinium tetrakis(pentafluorophenyl)- borate (2.08 g, 20.0 mmol) was added at -40 °C borate in 86.1 % yield. When determining the is and the temperature was raised to room tempera- purity by means of 1H and 19 F NMR using pen- ture over 2 hours. After stirring overnight at room tafluorotoluene as an internal standard material, it temperature, octane (200 ml) was added. Then, showed 98 wt. % or higher. diethyl ether was removed by distillation and the organic layer was washed thrice with 20 mL of Examle 10 20 water. After combined the aqueous layers, 1.1 equivalent to the boron source of aqueous solution After a solution of pentafluorobenzene (16.8 g, of N,N-dimethylanilinium chloride was reacted with 100.0 mmol) and dibutyl ether (100 ml) was cooled the aqueous layer to deposit white crystals. The to -40 °C, a 20 wt. % sec-butyllithium/hexane crystals obtained were filtered, washed with water solution (28.2 g, 88.0 mmol) was added and the 25 and then dried under vacuum to obtain N,N- mixture was stirred for 2 hours at -30 to -40 °C. dimethylanilinium tetrakis(pentafluorophenyl)borate Thereafter, boron trifluoride-diethyl ether complex in 83.2 % yield. When determining the purity by (2.84 g, 20.0 mmol) was added at -40 °C and the means of 1H and 19 F NMR using pen- temperature was raised to room temperature over 2 tafluorotoluene as an internal standard material, it hours. After stirring overnight at room temperature, 30 showed 98 wt. % or higher. octane (200 ml) was added and, after distilled off diethyl ether and hexane under heat, octane was Claims also distilled off further under heat to an extent of recovering about 30 % of the added amount. After 1. A production method of tetrakis- filtered off precipitated lithium fluoride, octane was 35 (pentafluorophenyl)borate derivatives repre- removed to bone-dry to obtain lithium tetrakis- sented by a following general formula [VII] (pentafluorophenyl)borate in 67.3 % yield. (CGF5)+BM [VII] Example 1 1 40 (wherein M denotes an alkali metal ion), After a solution of pentafluorobenzene (14.8 g, wherein, with 1 equivalent of pentafluoroben- 88.0 mmol) and diisopropyl ether (100 ml) was zene represented by a following formula [I], cooled to -40 °C, a 18 wt. % sec-butyllithium/hexane solution (31.3 g, 88.0 mmol) was CgHF5 [I] added and the mixture was stirred for 0.5 hours at 45 -30 to -40 °C. Thereafter, 1 mol/L boron trichlo- 0.5 to 1.5 equivalents of organometallic com- ride/hexane solution (20 mL, 20.0 mmol) was ad- pound represented by a general formula [II] ded at -40 °C and the temperature was raised to room temperature over 2 hours. From the solution RM [II] of lithium tetrakis(pentafluorophenyl)borate thus ob- 50 tained, diisopropyl ether was removed by distilla- (wherein M denotes an alkali metal ion, R tion and the organic layer was washed thrice with denotes a hydrocarbon group with carbon 20 mL of water. After combined the aqueous lay- atoms of 1 to 10 and the said hydrocarbon ers, 1.1 equivalent to the boron source of aqueous group may contain functional groups having no solution of N,N-dimethylanilinium chloride was 55 influence on the reaction), are reacted at a reacted with aqueous layer to deposit white cry- temperature range from -120 to 80 °C in an stals. The crystals obtained were filtered, washed ether type solvent, a hydrocarbon type solvent with water and then dried under vacuum to obtain or a mixed solvent of the ether type solvent

6 11 EP 0 608 563 A2 12 with the hydrocarbon type solvent to generate pentafluorophenyl alkali metal salt represented by a following general formula [III]

CgF5M [III]

(wherein M denotes an alkali metal ion), and, with 1 equivalent of boron compound represented by a general formula [IV] 10 BX3 [IV] wherein X denotes a halogen atom, substituent represented by a following general formula [V] 15 OR [V]

(wherein R denotes a hydrocarbon group with carbon atoms of 1 to 10 and the said hydrocarbon may contain functional groups having no 20 influence on the reaction) or substituent represented by a following general formula [VI]

NRR' [VI] 25 (wherein R and R' denote identically or dif- ferently hydrogen atoms or hydrocarbon groups with carbon atoms of 1 to 20, said hydrocarbon group may contain functional groups having no influence on the reaction and 30 R and R' may link one another to form a ring), and may form 1:1 complex with the ether type solvent, not less than 3.7 equivalents of pentafluorophenyl metal compound represented by the formula [III] are reacted. 35

A production method of tetrakis- (pentafluorophenyl)borate derivatives represented by the formula [VII], 40 (CgF5)+BM [VII] wherei pentafluorophenyl alkali metal salt represented by the formula [III] is generated similarly to the method of Claim 1 and, with 1 45 equivalent of tris(pentafluorophenyl)borane represented by a following formula [VIII],

(CGF5)3B [VIII] 50 not less than 0.8 equivalents of pentafluorophenyl metal compound represented by the formula [III] are reacted.