Method for the Preparation of Cyclopentyl Trichlorosilane

Europaisches Patentamt (19) European Patent Office Office europeenpeen des brevets EP 0 460 589 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.e: C07F 7/14 of the grant of the patent: 04.11.1998 Bulletin 1998/45

(21) Application number: 91109082.7

(22) Date of filing: 04.06.1991

(54) Method for the preparation of cyclopentyl Trichlorosilane Verfahren zur Herstellung von Cyclopentyl-trichlorosilan Procede de preparation de cyclopentyl trichlorosilane

(84) Designated Contracting States: (74) Representative: DE FR GB IT Luderschmidt, Schiiler & Partner GbR Patentanwalte, (30) Priority: 07.06.1990 JP 149338/90 Postfach 3929 65029 Wiesbaden (DE) (43) Date of publication of application: 11.12.1991 Bulletin 1991/50 (56) References cited: EP-A- 0 278 863 DE-A- 1 941 411 (73) Proprietor: SHIN-ETSU CHEMICAL CO., LTD. GB-A-2 013 207 Chiyoda-ku Tokyo (JP) • CHEMICAL ABSTRACTS vol. 89, no. 17, 23 (72) Inventors: October 1 978, page 61 9, abstract no. 1 46975f , • Shinohara, Toshio Columbus, Ohio, US; R.A. BENKESER: Takasaki-shi, Gunma-ken (JP) "Chloroplatinic acid catalyzed additions of • Iwabuchi, Motoaki silanes to isoprene" Annaka-shi, Gunma-ken (JP)

DO O) 00

CO ^- Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice the Patent Office of the Notice of shall be filed in o to European opposition to European patent granted. opposition a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. a. 99(1) European Patent Convention). LU

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Description such as chloroplatinic acid as a catalyst according to a procedure well known in the hydrosilation between a sil- BACKGROUND OF THE INVENTION icon compound having a silicon-bonded hydrogen atom and a linear alkenyl compound. Different from other cy- The present invention relates to a method for the 5 cloalkene compounds such as cyclohexene of a 6-mem- synthetic preparation of cyclopentyl trichlorosilane or, bered ring, nevertheless, no report is found in the liter- more particularly, to a method for the preparation of cy- atures for the hydrosilation reaction of cyclopentene clopentyl trichlorosilane from trichlorosilane and cy- with trichlorosilane. This is presumably due to the low clopentene by the hydrosilation reaction. reactivity of cyclopentene even by the catalytic promo- Cyclopentyl trichlorosilane is a compound having 10 tion of the reaction by conventional platinum catalysts. usefulness as an intermediate in the synthetic prepara- EP-A-0 278 863 discloses the reaction of cyclopen- tion of various kinds of organosilicon compounds having tene with trichlorosilane in the presence of a platinum two or three cycloalkyl groups in a molecule. Since cy- catalyst prepared from chloroplatinic acid and an alco- clopentyl-containing organosilicon compounds have a hol. Acceptable yields of cyclopentyl trichlorosilane are refractive index intermediate between those of methyl- is only obtained under UV-irradiation. and phenyl-containing organosilicon compounds, an advantage is expected in matching of the refractive in- SUMMARY OF THE INVENTION dices when a transparent silicone composition is desired. Further, the bulkiness of the cyclopentyl group The present invention accordingly has an object to promisingly indicates the usefulness of cyclopentyl-con- 20 provide a novel and efficient method for the synthetic taining silane compounds as a silylating agent in various preparation of cyclopentyl trichlorosilane by the hydrosi- organic syntheses for which tert-butyl dimethyl chlorosi- lation reaction between trichlorosilane and cyclopen- lane is the most conventional. Several methods are tene without the problems and disadvantages in the known in the prior art for the preparation of this com- above described prior art methods such as the "direct pound. For example, the so-called "direct method" pro- 25 method" and the Grignard method. posed by E.G. Rochow is also applicable to the prepa- Thus, the method of the present invention for the ration of this silane compound in which metallic silicon preparation of cyclopentyl trichlorosilane comprises the and cyclopentyl chloride are reacted in the presence of steps of: a copper catalyst. Alternatively, it can be synthesized by the reaction of cyclopentyl magnesium halide as a Grig- 30 (a) mixing trichlorosilane, cyclopentene and a plat- nard reagent with tetrachlorosilane. inum catalyst, which is a reaction product of chloro- The above mentioned "direct method" is not advan- platinic acid with a basic compound so as to de- tageous when the organosilane compound to be pre- crease the atomic ratio of chlorine to platinum in the pared is cyclopentyl trichlorosilane because by-prod- range from 0.001 to 0. 1 , to form a reaction mixture; ucts are formed in large amounts so that great difficulties 35 and are encountered in the isolation and purification of cy- (b) heating the reaction mixture at a temperature clopentyl trichlorosilane. The Grignard method has an higher by at least 1°C than the boiling point of the economical disadvantage as an industrial method due reaction mixture under normal pressure or, prefer- to the expensiveness of the Grignard reagent in addition ably, in the range from 50 to 80°C. to the problem of troublesomeness and danger of fire or 40 explosion accompanying the use of a very inflammable DETAILED DESCRIPTION OF THE PREFERRED organic solvent such as ether. Moreover, the productiv- EMBODIMENTS ity of the Grignard method cannot be high enough due to the formation of a large amount of a magnesium hal- As is understood from the above description, the ide as the by-product which must be removed from the 45 most characteristic feature of the inventive method for reaction mixture. Further, the Grignard reagent, i.e. cy- the hydrosilation reac-tion consists in the use of a very clopentyl magnesium halide, is highly susceptible to ox- specific platinum catalyst and in the specific reaction idation by oxygen in the atmospheric air to be converted conditions relative to the temperature. into cyclopentyloxy magnesium halide from which cy- While the amounts of trichlorosilane and cyclopen- clopentyloxy trichlorosilane is formed as the product of 50so tene pertaining to the hydrosilation reaction are equimo- the Grignard reaction while this compound can hardly lar, the molar ratio of cyclopentene to trichlorosilane in be separated from cyclopentyl trichlorosilane, for exam- the reaction mixture should be in the range from 0.6 to ple, by distillation because these two compounds have 1 .5 or, preferably, from 0.9 to 1 .1 from the standpoint of physical properties very close to each other. productivity of the process. When one of the reactants It would be a speculatively possible way that cy- 55 is used in an excessive amount over equimolar, a por- clopentyl trichlorosilane could be prepared by the hy- tion of the reactant remains unreacted in the reaction drosilation reaction between trichlorosilane and cy- mixture after completion of the reaction as a matter of clopentene in the presence of a platinum compound course and must be removed from the mixture to isolate

2 3 EP 0 460 589 B1 4 the cyclopentyl trichlorosilane as the product. When the sure-resistance of the reac-tion vessel.. reaction is performed under appropriately selected con- In the following, the method of the present invention ditions according to the inventive method, the reac-tion is described in more detail by way of examples. proceeds almost quantitatively with formation of very small amounts of by-products. 5 Example 1 . Different from the platinum catalysts conventionally used in the hydrosilation reaction, the platinum catalyst The atomic ratio of chlorine to platinum was 0.05 in used in the inventive method is a chlorine-deficient chlo- the chlorine-deficient chloroplatinic acid catalyst, re- roplatinic acid catalyst, of which the atomic ratio of chlo- ferred to as the catalyst I hereinbelow, used in this ex- rine to platinum is in the range from 0.001 to 0. 1 . When 10 ample, which was prepared by treating chloroplatinic ac- conventional chloroplatinic acid or chloroplatinous acid, id hexahydrate with sodium hydrogen-carbonate and in which the atomic ratio of chlorine to platinum is 6 or was in the form of a solution in toluene in a concentration 4, respectively, is used as such as the catalyst for the of 0.5% by weight as platinum. hydrosilation reaction between trichlorosilane and cy- Into an autoclave of 2-liter capacity were introduced clopentene, the extent of the reaction can rarely exceed is 1 41 g (1 .04 moles) of trichlorosilane, 71 g (1 .04 moles) 20%. It was discovered quite unexpectedly that the hy- of cyclopentene and 4.1 g of the catalyst I mentioned drosilation reaction could proceed almost to complete- above corresponding to 97 ppm by weight as platinum ness when the catalyst was a chlorine-deficient chloro- based on the total amount of trichlorosilane and cy- platinic acid catalyst of which the atomic ratio of chlorine clopentene to form a reaction mixture, which was heated to platinum was in the above specific range. Such a chlo- 20 at 65 to 75 °C for 24 hours under a spontaneously pro- rine-deficient chloroplatinic acid catalyst can be pre- duced pressure of about 4 kg/cm2G. Small portions of pared by the treatment of chloroplatinic acid with sodium the reaction mixture were periodically taken out of the hydrogencarbonate and an organosiloxane compound autoclave and analyzed by the gas chromatography to having a silicon-bonded vinyl group in a molecule ac- monitor progress of the reaction. More than 99% of the cording to the disclosure in Japanese Patent Publication 25 starting reactants had been reacted at the end of the 47-23679. The chlorine-deficient chloroplatinic acid cat- reaction time of 24 hours. The reaction mixture after alyst is prepared usually in the form of a solution in a cooling to room temperature was taken out of the auto- solvent such as lower aliphatic alcohols, e.g., ethyl, n- clave and distilled under normal pressure to remove the butyl and 2-ethylhexyl alcohols, aromatic hydrocarbon unreacted starting materials and other volatile constitu- solvents, e.g., toluene, and silicone fluids in a concen- 30 ents. The residue after this stripping treatment was sub- tration of 0.01 to 10% by weight as platinum. The jected to distillation under reduced pressure to give 1 99 amount of the platinum catalyst added to the reaction g of a fraction boiling at 70 °C under a pressure of 18 mixture is usually in the range from 1 to 1000 ppm by mmHg, which could be identified to be the desired cy- weight or, preferably, in the range from 10 to 500 ppm clopentyl trichlorosilane. The molar yield of the product by weight as platinum based on the total amount of 35 was 0.94 mole corresponding to 90% of the theoretical trichlorosilane and cyclopentene. value after isolation. The reaction mixture prepared by mixing trichlorosilane, cyclopentene and the platinum catalyst is then Example 2. heated under an atmosphere of an inert gas at a temperature higher by at least 1 °C than the boiling point of 40 The experiment was conducted in substantially the the mixture under normal pressure. In view of the boiling same manner as in Example 1 by preparing a reaction point 31 .5 °C of trichlorosilane, the reaction temperature mixture from 19.5 g (0.144 mole) of trichlorosilane, 9.9 is preferably in the range from 50 to 80 °C. Needless to g (0. 1 46 mole) of cyclopentene and 0. 1 4 g of the catalyst say, the reaction must be performed in a closed pres- I corresponding to 238 ppm by weight as platinum based surizable vessel which should withstand the pressure 45 on the total amount of trichlorosilane and cyclopentene spontaneously produced by heating the reaction mix- and heating the mixture in a polytetrafluoroethylene- ture in the above mentioned reac-tion temperature. The made pressure-resistant vessel at 60 °C for 26 hours pressure is usually in the range from 2 to 10 kg/cm2G. under a spontaneously produced pressure of 3 kg/ The reaction is complete under the above mentioned cm2G. About 97% of the starting reactants had been re- conditions usually within 50 hours or, in most cases, 50 acted at the end of the reaction time as determined by within 30 hours. When the reaction temperature is too the gas chromatographic analysis. Treatment of the re- low, the velocity of the reac-tion cannot be high enough. action mixture after the reaction was performed in the On the other hand, no further advantages can be ob- same manner as in Example 1 to give cyclopentyl tained by further increasing the reaction temperature to trichlorosilane in a yield of 91 % as isolated based on the exceed the above mentioned upper limit due to the in- 55 theoretical value. stability of the catalyst at such a high temperature rather with a disadvantage due to an increase in the amounts of by-products if not to mention the problem in the pres-

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Example 3. of the catalyst III corresponding to 93 ppm by weight as platinum based on the total amount of trichlorosilane The atomic ratio of chlorine to platinum was 0.05 in and cyclopentene to form a reaction mixture which was the chlorine-deficient chloroplatinic acid catalyst, re- heated at 80 °C for 22 hours in the closed vessel to effect ferred to as the catalyst II hereinbelow, used in this ex- 5 the reac-tion. The pressure inside the vessel was about ample, which was prepared by treating chloroplatinic ac- 5 kg/cm2G throughout the reaction time. The reaction id hexahydrate with sodium hydrogencarbonate accord- mixture after the reaction time was analyzed by the gas ing to the disclosure in Japanese Patent Publication chromatography for the content of cyclopentyl trichlo- 47-23679 and was in the form of a solution in ethyl al- rosilane to find that the reaction had proceeded only to cohol in a concentration of 3.0% by weight as platinum. 10 22% of the theoretical yield. The experiment was conducted in substantially the same manner as in Example 1 by preparing a reaction mixture from 20.5 g (0.151 mole) of trichlorosilane, 9.7 Claims g (0. 1 43 mole) of cyclopentene and 0.09 g of the catalyst II corresponding to 88 ppm by weight as platinum based is 1 . A method for the preparation of cyclopentyl trichlo- on the total amount of trichlorosilane and cyclopentene rosilane which comprises the steps of: and heating the mixture in a polytetrafluoroethylene- made pressure-resistant vessel at 80 °C for 18 hours (a) mixing trichlorosilane, cyclopentene and a under a spontaneously produced pressure of 5 kg/ chlorine-deficient chloroplatinic acid catalyst, cm2G. About 97% of the starting reactants had been re- 20 of which the atomic ratio of chlorine to platinum acted at the end of the reaction time as determined by is in the range from 0.001 to 0.1 , to form a re- the gas chromatographic analysis. Treatment of the reaction mixture; and action mixture after the reaction was performed in the (b) heating the reaction mixture at a tempera- same manner as in Example 1 to give cyclopentyl ture higher by at least 1 °C than the boiling point trichlorosilane in a yield of 90% as isolated based on the 25 of the reaction mixture under normal pressure. theoretical value. 2. The method for the preparation of cyclopentyl Comparative Example 1. trichlorosilane as claimed in claim 1 in which the temperature in step (b) is in the range from 50 to 80 The reaction was performed by agitating the reac- 30 °c. tion mixture, which was prepared from 19.1 g (0.141 mole) of trichlorosilane, 9.2 g (0. 1 35 mole) of cyclopen- 3. The method for the preparation of cyclopentyl tene and 0.13 g of the catalyst I corresponding to 23 trichlorosilane as claimed in claim 1 in which the ppm by weight as platinum based on the total amount molar ratio of the amount of cyclopentene to the of trichlorosilane and cyclopentene, in a glass flask at 35 amount of trichlorosilane is in the range from 0.6 to 30 °C for 22 hours under normal pressure. Only about 1.5. 22% of the starting reactants had been reacted after the end of this reaction time as determined by the gas chro- 4. The method for the preparation of cyclopentyl matographic analysis. Treatment of the reaction mixture trichlorosilane as claimed in claim 1 in which the after the reaction was performed in the same manner 40 amount of the catalyst is in the range from 1 to 1 000 as in Example 1 to give 5.2 g (0.0256 mole) of cy- ppm by weight as platinum based on the total clopentyl trichlorosilane in a yield of 19% as isolated amount of trichlorosilane and cyclopentene. based on the theoretical value.

Comparative Example 2. 45 Patentanspriiche

The atomic ratio of chlorine to platinum was 3.5 in 1. Verfahren zur Herstellung von Cyclopentyl-trichlor- the chlorine-deficient chloroplatinic acid catalyst, re- silan, umfassend folgende Stufen: ferred to as the catalyst 1 1 1 hereinbelow, used in this comparative example, which was prepared by treating chlo- 50 (a) Vermischen von Trichlorsilan-Cyclopenten roplatinic acid hexahydrate with sodium hydrogencar- und einem Katalysator aus Chloroplatinsaure bonate according to the disclosure in Japanese Patent mit Chlormangel, deren Atomverhaltnis von Publication 47-23679 and was in the form of a solution Chlor zu Platin im Bereich von 0,001 bis 0,1 in 2-ethylhexyl alcohol in a concentration of 2% by liegt, unter Bildung eines Reaktionsgemischs; weight as platinum. 55 und Into a pressure-resistant polytetrafluoroethylene vessel were introduced 20.5 g (0.151 mole) of trichlo- (b) Erwarmen des Reaktionsgemischs auf eine rosilane, 9.7 g (0.143 mole) of cyclopentene and 0.14 g Temperatur, die zumindest 1°C hoher als der

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Siedepunkt des Reaktionsgemischs unter Nor- maldruck ist.

2. Verfahren zur Herstellung von Cyclopentyl-trichlorsilan gema(3 Anspruch 1, bei dem die Temperatur s in der Stufe (b) im Bereich von 50-80°C liegt.

3. Verfahren zur Herstellung von Cyclopentyl-trichlorsilan gemaB Anspruch 1 , bei dem das Molverhaltnis der Cyclopentenmenge zur Trichlorsilanmenge im 10 Bereich von 0,6 bis 1 liegt.

4. Verfahren zur Herstellung von Cyclopentyl-trichlorsilan gemaB Anspruch 1, bei dem die Katalysator- menge im Bereich von 1 bis 1.000 ppm, bezogen 15 auf das Gewicht, als Platin, bezogen auf die Ge- samtmenge von Trichlorsilan und Cyclopenten, liegt.

Revendications

1 . Methode de preparation du cyclopentyltrichlorosila- ne, laquelle comprend les etapes de : 25 (a) melange de trichlorosilane, de cyclopentene et d'un catalyseur a base d'acide chloropla- tinique deficient en chlore, dont le rapport ato- mique de chlore au platine se situe dans le domaine de 0,001 a 0,1 , pour former un melange 30 reactionnel ; et (b) chauffage du melange reactionnel a une temperature superieure d'au moins 1°C au point d'ebullition du melange reactionnel sous une pression normale. 35

2. Methode de preparation du cyclopentyltrichlorosila- ne selon la revendication 1 , dans laquelle la temperature de I'etape (b) est comprise entre 50 et 80 °C. 40 3. Methode de preparation du cyclopentyltrichlorosila- ne selon la revendication 1 , dans laquelle le rapport molaire de la quantite de cyclopentene a la quantite de trichlorosilane est compris entre 0,6 et 1 ,5. 45 4. Methode de preparation de cyclopentyltrichlorosila- ne selon la revendication 1 , dans laquelle la quantite du catalyseur se situe dans le domaine de 1 a 1 000 ppm en poids de platine par rapport a la quantite totale de trichlorosilane et de cyclopentene. so