PROCESS FOR CONVERTING ORGANOSILANES

Abstract

A method for converting organosilanes by reacting at least one silane (1) of the general formula

R.sub.aSiCl.sub.4-a  (I)

with at least one further silane (2) of the general formula

R.sub.bSiCl.sub.4-b  (II)

wherein silane (2) is identical or different from silane (1), optionally with additional use of silanes (3) which contain Si-bonded hydrogen and have the formula

R.sub.dH.sub.eSiCl.sub.4-d-e  (III)

in the presence of aluminum salts, preferably aluminum halides, as catalysts and in the presence of cocatalysts, to obtain at least one silane (4) which differs from silanes (1) and (2) and has the general formula

R.sub.cSiCl.sub.4-c  (IV).

Claims

1-14. (canceled)

15. A method for converting organosilanes by reacting at least one silane (1) of the general formula
R.sub.aSiCl.sub.4-a  (I) with at least one further silane (2) of the general formula
R.sub.bSiCl.sub.4-b  (II) wherein silane (2) is identical or different from silane (1), preferably different from silane (1), optionally with additional use of silanes (3) which contain Si-bonded hydrogen and have the formula
R.sub.dH.sub.eSiCl.sub.4-d-e  (III) in the presence of aluminum salts, preferably aluminum halides, as catalysts and in the presence of cocatalysts, to obtain at least one silane (4) which differs from silanes (1) and (2) and has the general formula
R.sub.cSiCl.sub.4-c  (IV), wherein R denotes in each case identical or different alkyl radicals having 1 to 4 carbon atoms or a phenyl radical, a is 2, 3 or 4, b is 0, 1, 2 or 3, c is 1, 2 or 3, d is 0, 1, 2 or 3 and e is 1, 2 or 3, with the proviso that the sum total of d+e is at most 4, characterized in that the cocatalysts used are those selected from the group of trifluoromethanesulfonic acid, trifluoromethanesulfonic esters, aluminum tris(trifluoromethanesulfonate), metal salts of yttrium and hafnium, metal salts of the lanthanides and actinides, and mixtures of these cocatalysts.

16. The method as claimed in claim 1, characterized in that the catalyst used is aluminum trichloride.

17. The method as claimed in claim 16, characterized in that aluminum trichloride is either used as such or is produced in situ.

18. The method as claimed in claim 16, characterized in that aluminum trichloride is produced in situ from ethylaluminum sesquichloride and hydrogen chloride.

19. The method as claimed in claim 15, characterized in that, as the metal salts of yttrium or hafnium or of the lanthanides and actinides, use is made of halides, preferably fluorides, chlorides or bromides; sulfonates; oxides or carboxylates.

20. The method as claimed in claim 15, characterized in that the metals of the lanthanides and actinides that are used are lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium, preferably cerium, gadolinium or terbium.

21. The method as claimed in claim 15, characterized in that the metal salts used are yttrium trichloride, cerium trichloride, neodymium trichloride, gadolinium trifluoride, gadolinium trichloride, gadolinium tribromide, gadolinium(III) acetate, terbium trichloride, holmium trichloride or lutetium trichloride, preferably cerium trichloride, gadolinium trichloride or terbium trichloride.

22. The method as claimed in claim 15, characterized in that aluminum salts, by preference aluminum halides, preferably aluminum trichloride, are/is used in amounts of from 0.2% to 10% by weight, preferably 0.8% to 3.0% by weight, based in each case on the total weight of silanes (1) and (2) used.

23. The method as claimed in claim 15, characterized in that cocatalysts are used in amounts of by preference 0.002% to 2.5% by weight, preferably 0.008% to 0.3% by weight, based in each case on the total weight of silanes (1) and (2) used.

24. The method as claimed in claim 15, characterized in that the silane (1) used is tetramethylsilane, trimethylchlorosilane, dimethyldichlorosilane and phenyltrichlorosilane, preferably tetramethylsilane.

25. The method as claimed in claim 15, characterized in that the silane (2) used is dimethyldichlorosilane, methyltrichlorosilane and tetrachlorosilane.

26. The method as claimed in claim 15, characterized in that the silane (1) used is tetramethylsilane and the silane (2) used is dimethyldichlorosilane, with trimethylchlorosilane being obtained.

27. The method as claimed in claim 15, characterized in that the silane (1) used is tetramethylsilane and the silane (2) used is tetrachlorosilane, with trimethylchlorosilane being obtained.

Description

EXAMPLES 1 TO 14 AND COMPARATIVE EXPERIMENTS 1 TO 5

[0036] Reaction of tetramethylsilane with dimethyldichlorosilane

[0037] Examples 1 to 14 and comparative experiments 1 to 5 were carried out under inert conditions in a three-neck flask with stirrer, reflux condenser (operated with a cryostat), dropping funnel and reaction temperature measurement. Dimethyldichlorosilane was initially charged and to this was added the catalyst and cocatalyst (examples 1-14). For comparative experiments 1 and 5 only the catalyst was added, and for comparative experiments 2 to 4 only the cocatalysts were added.

[0038] Technical-grade tetramethylsilane (approx. 85% by weight, determined by gas chromatography (GC), containing approx. 3-5% by weight of dimethylchlorosilane) was subsequently metered in.

[0039] The mixture was heated to reflux and samples were taken at regular intervals. The samples were distilled to remove the solids contents and the distillate was analyzed by means of gas chromatography (GC, column: Agilent DB 210, length: 60 m, diameter: 0.32 mm).

Example 1

[0040] 150 g of dimethyldichlorosilane

[0041] 115 g of technical-grade tetramethylsilane

[0042] 8 g of AlCl.sub.3

[0043] 1.5 g of trifluoromethanesulfonic acid

[0044] After a reaction time of 105 min, the remaining tetramethylsilane content was less than 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Example 2

[0045] 150 g of dimethyldichlorosilane

[0046] 115 g of technical-grade tetramethylsilane

[0047] 8 g of AlCl.sub.3

[0048] 1.5 g of trimethylsilyl trifluoromethanesulfonate

[0049] After a reaction time of 120 min, the remaining tetramethylsilane content was approx. 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Example 3

[0050] 150 g of dimethyldichlorosilane

[0051] 115 g of technical-grade tetramethylsilane

[0052] 8 g of AlCl.sub.3

[0053] 1.5 g of aluminum tris(trifluoromethanesulfonate)

[0054] After a reaction time of 120 min, the remaining tetramethylsilane content was approx. 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Example 4

[0055] 150 g of dimethyldichlorosilane

[0056] 115 g of technical-grade tetramethylsilane

[0057] 8 g of AlCl.sub.3

[0058] 1.5 g of cerium trichloride

[0059] After a reaction time of 95 min, the remaining tetramethylsilane content was approx. 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Example 5

[0060] 150 g of dimethyldichlorosilane

[0061] 115 g of technical-grade tetramethylsilane

[0062] 8 g of AlCl.sub.3

[0063] 1.5 g of gadolinium trichloride

[0064] After a reaction time of 60 min, the remaining tetramethylsilane content was approx. 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Example 6

[0065] 1.45 t of dimethyldichlorosilane

[0066] 1 t of technical-grade tetramethylsilane

[0067] 18 kg of AlCl.sub.3 (produced in situ from 16.7 kg of ethylaluminum sesquichloride and hydrogen chloride)

[0068] 2.5 kg of trifluoromethanesulfonic acid

[0069] After a reaction time of 4 h under reflux conditions, the remaining tetramethylsilane content was approx. 2% by weight and the content of trimethylchlorosilane was 85% by weight.

Example 7

[0070] The final reaction mixture from example 6 was worked up by distillation and to the remaining distillation bottoms of approx. 0.15 t were added 1.45 t of dimethyldichlorosilane and 1 t of technical-grade tetramethylsilane, and the mixture was reacted analogously to example 6. After a reaction time of 4 h, the remaining tetramethylsilane content was approx. 2% by weight and the content of trimethylchlorosilane was 85% by weight.

Example 8

[0071] 1.45 t of dimethyldichlorosilane

[0072] 1 t of technical-grade tetramethylsilane

[0073] 18 kg of AlCl.sub.3 (produced in situ from 16.7 kg of ethylaluminum sesquichloride and hydrogen chloride)

[0074] 1.0 kg of cerium trichloride

[0075] After a reaction time of 1 h, the remaining tetramethylsilane content was approx. 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Example 9

[0076] The final reaction mixture from example 8 was worked up by distillation and to the remaining distillation bottoms of approx. 0.15 t were added 1.45 t of dimethyldichlorosilane and 1 t of technical-grade tetramethylsilane, and the mixture was reacted analogously to example 8. After a reaction time of 1 h, the remaining tetramethylsilane content was approx. 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Example 10

[0077] 150 g of dimethyldichlorosilane

[0078] 115 g of technical-grade tetramethylsilane

[0079] 6 g of AlCl.sub.3

[0080] 1 g of terbium trichloride

[0081] After a reaction time of 60 min at 40° C., the remaining tetramethylsilane content was approx. 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Example 11

[0082] 150 g of dimethyldichlorosilane

[0083] 115 g of technical-grade tetramethylsilane

[0084] 6 g of AlCl.sub.3

[0085] 1 g of gadolinium trifluoride

[0086] After a reaction time of 60 min at 40° C., the remaining tetramethylsilane content was approx. 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Example 12

[0087] 150 g of dimethyldichlorosilane

[0088] 115 g of technical-grade tetramethylsilane

[0089] 6 g of AlCl.sub.3

[0090] 1 g of gadolinium tribromide

[0091] After a reaction time of 60 min at 40° C., the remaining tetramethylsilane content was approx. 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Example 13

[0092] 150 g of dimethyldichlorosilane

[0093] 115 g of technical-grade tetramethylsilane

[0094] 6 g of AlCl.sub.3

[0095] 0.1 g of gadolinium trichloride

[0096] After a reaction time of 60 min at 40° C., the remaining tetramethylsilane content was approx. 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Example 14

[0097] 150 g of dimethyldichlorosilane

[0098] 115 g of technical-grade tetramethylsilane

[0099] 6 g of AlBr.sub.3

[0100] 0.3 g of gadolinium trichloride

[0101] After a reaction time of 60 min at 40° C., the remaining tetramethylsilane content was approx. 1% by weight and the content of trimethylchlorosilane was 86% by weight.

Comparative Experiment 1

[0102] 150 g of dimethyldichlorosilane

[0103] 115 g of technical-grade tetramethylsilane

[0104] 8 g of AlCl.sub.3

[0105] After a reaction time of 120 min, the remaining tetramethylsilane content was approx. 23% by weight; the content of trimethylchlorosilane was 34% by weight. Only after a reaction time of 360 min under reflux conditions was the remaining tetramethylsilane content approx. 1% by weight and the content of trimethylchlorosilane 86% by weight.

Comparative Experiment 2

[0106] 150 g of dimethyldichlorosilane

[0107] 115 g of technical-grade tetramethylsilane

[0108] 8 g of trifluoromethanesulfonic acid

[0109] After a reaction time of 120 min it was not possible to detect any conversion, that is to say any change in the composition of the silane mixture.

Comparative Experiment 3

[0110] 150 g of dimethyldichlorosilane

[0111] 115 g of technical-grade tetramethylsilane

[0112] 8 g of aluminum tris(trifluoromethanesulfonate)

[0113] After a reaction time of 120 min it was not possible to detect any conversion, that is to say any change in the composition of the silane mixture.

Comparative Experiment 4

[0114] 150 g of dimethyldichlorosilane

[0115] 115 g of technical-grade tetramethylsilane

[0116] 9.5 g of reaction product of aluminum trichloride and trifluoromethanesulfonic acid

[0117] After a reaction time of 120 min it was not possible to detect any conversion, that is to say any change in the composition of the silane mixture.

Comparative Experiment 5

[0118] Example 6 was repeated with the modification that no trifluoromethanesulfonic acid was added. After a reaction time of 12 h under reflux conditions, the remaining tetramethylsilane content was approx. 2% by weight and the content of trimethylchlorosilane was 85% by weight.

[0119] Examples 15 to 30 and comparative experiments 6 to 8:

[0120] Reaction of tetramethylsilane with tetrachlorosilane

[0121] A mixture of tetrachlorosilane and technical-grade tetramethylsilane (TMS, approx. 85% by weight determined by gas chromatography (GC)) with a content of tetramethylsilane of 46 mol % and tetrachlorosilane of 47 mol % (the remainder consists inter alia of methylchlorohydrogensilanes and chlorohydrogensilanes) is heated to 100° C. under inert conditions with 2 mol %

[0122] (mol % based on the silanes) of aluminum trichloride and 0.5 mol % (mol % based on the silanes) of cocatalyst as per table 1 in an autoclave for 4 h with stirring. After cooling, the sedimented catalyst is removed and the reaction product is analyzed using .sup.29Si NMR. The results are summarized in table 1.

TABLE-US-00001 TABLE 1 Starting materials remaining Target products in the Comp. in the reaction mixture reaction mixture experiments/ Co- % TMS Si(CH.sub.3).sub.4 SiCl.sub.4 CH.sub.3SiCl.sub.3 (CH.sub.3).sub.2SiCl.sub.2 (CH.sub.3).sub.3SiCl Examples catalyst converted mol % mol % mol % mol % mol % C 6 — 14.6 39.6 43.6 14.6 C 7* — 19.0 37.7 43 16 C 8** GdCl.sub.3 3 48.5 50.7 — — 0.7 E 15 HfCl.sub.4 36 29.7 42.2 — — 24.1 E 16 LaCl.sub.3 32.2 31.4 43.3 — — 21.9 E 17 SmCl.sub.3 57.9 19.5 40.1 — — 36.7 E 18 YCl.sub.3 78.4 10.0 37.8 — — 48.9 E 19 Dy(CF.sub.3SO.sub.3).sub.3 26.7 34.0 44.3 — — 18.6 E 20 TbCl.sub.3 97.0 1.4 34.6 — 1.6 58.8 E 21 Gd(CH.sub.3COO).sub.3 73.1 12.5 39.1 — — 46 E 22 NdCl.sub.3 75.5 11.4 38.1 — 0.1 47 E 23 GdCl.sub.3 98.5 0.5 44.6 — 3.8 58 E 24 CeCl.sub.3 50.4 18.2 39.6 — — 38.1 E 25 PrCl.sub.3 64.6 16.3 39 — 0.1 41 E 26 TmCl.sub.3 40.8 27.3 43.5 — — 25.8 E 27 Gd.sub.2O.sub.3*** 49.2 23.4 41.5 — — 32.0 E 28 LuCl.sub.3 77.2 10.5 37.3 — 0.2 48.8 E 29 ErCl.sub.3 59.7 18.5 40.2 — — 37 E 30 HoCl.sub.3 84.7 7.0 36.2 — — 53.9 *2.5 mol % aluminum trichloride **mixture of 50 mol % pure tetramethylsilane and 50 mol % silicon tetrachloride (the mixture does not contain any H-Si compound). No catalyst (AlCl.sub.3) is used. ***0.5 mol % of cocatalyst, based on gadolinium

Examples 31 and 32

[0123] Reaction of Tetramethylsilane with Methyltrichlorosilane

[0124] A mixture of tetrachlorosilane and technical-grade tetramethylsilane (TMS, approx. 85% by weight determined by gas chromatography (GC)) with a content of tetramethylsilane of 48 mol % and methyltrichlorosilane of 48 mol % (the remainder consists inter alia of methylchlorohydrogensilanes and chlorohydrogensilanes) is heated to 80° C. under inert conditions with 2 mol % (mol % based on the silanes) of aluminum trichloride and 0.5 mol % (mol % based on the silanes) of cocatalyst as per table 2 in an autoclave for 4 h with stirring. After cooling, the sedimented catalyst is removed and the reaction product is analyzed using .sup.29Si NMR. The results are summarized in table 2.

TABLE-US-00002 TABLE 2 Starting materials Target products remaining in the in the reaction mixture reaction mixture Co- % TMS Si(CH.sub.3).sub.4 CH.sub.3SiCl.sub.3 (CH.sub.3).sub.2SiCl.sub.2 (CH.sub.3).sub.3SiCl Examples catalyst converted mol % mol % mol % mol % E 31 GdCl.sub.3 100 0 2.1 54.3 42.6 E 32 CeCl.sub.3 99.8 0.1 12.1 35.1 51.1

Example 33

[0125] Reaction of Trimethylchlorosilane with Methyltrichlorosilane

[0126] A mixture of 47.5 mol % trimethylchlorosilane and 47.5 mol % methyltrichlorosilane, containing 2.5 mol % of dimethylchlorosilane and 2.5 mol % methyldichlorosilane, is heated to 80° C. under inert conditions with 2 mol % (mol % based on the silanes) of aluminum trichloride and 0.5 mol % (mol % based on the silanes) of cocatalyst as per table 3 in an autoclave for 4 h with stirring. After cooling, the sedimented catalyst is removed and the reaction product is analyzed using .sup.29Si NMR. The results are summarized in table 3.

TABLE-US-00003 TABLE 3 Starting Target product materials remaining in the reaction in the reaction mixture mixture Co- (CH.sub.3).sub.3SiCl CH.sub.3SiCl.sub.3 (CH.sub.3).sub.2SiCl.sub.2 Examples catalyst mol % mol % mol % E 33 GdCl.sub.3 17.3 15.6 63

Example 34

Disproportionation of Dimethyldichlorosilane

[0127] A mixture of 95 mol % dimethyldichlorosilane, 2.5 mol % dimethylchlorosilane and 2.5 mol % methyldichlorosilane is heated to 100° C. under inert conditions with 2 mol % (mol % based on the silanes) of aluminum trichloride and 0.5 mol % (mol % based on the silanes) of cocatalyst as per table 4 in an autoclave for 4 h with stirring. After cooling, the sedimented catalyst is removed and the reaction product is analyzed using .sup.29Si NMR. The results are summarized in table 4.

TABLE-US-00004 TABLE 4 Starting material remaining in the reaction Target products in mixture the reaction mixture (CH.sub.3).sub.2SiCl.sub.2 (CH.sub.3).sub.3SiCl CH.sub.3SiCl.sub.3 Example Cocatalyst mol % mol % mol % E 34 GdCl.sub.3 88 4.4 4.1

Example 35

Disproportionation of Phenyltrichlorosilane

[0128] A mixture of 95 mol % phenyltrichlorosilane, 2.5 mol % dimethylchlorosilane and 2.5 mol % methyldichlorosilane is heated to 100° C. under inert conditions with 2 mol % (mol % based on the silanes) of aluminum trichloride and 0.5 mol % (mol % based on the silanes) of cocatalyst as per table 5 in an autoclave for 2 h with stirring. After cooling, the sedimented catalyst is removed and the reaction product is analyzed using .sup.29Si NMR. The results are summarized in table 5.

TABLE-US-00005 TABLE 5 Starting material Target products remaining in the in the reaction reaction mixture mixture PhSiCl.sub.3 Ph.sub.2SiCl.sub.2 Example Cocatalyst mol % mol % E 35 GdCl.sub.3 90 10