Partially hydrogenated chlorosilanes and methods for preparing same by selective hydrogenation

Abstract

A method is useful for preparing partially hydrogenated chlorosilanes by selective hydrogenation with a compound of the formula R.sub.2AlH, wherein R is a branched or cyclic hydrocarbon. Partially hydrogenated chlorosilanes can be prepared with said method, in particular partially hydrogenated chlorosilanes represented by the formula Cl.sub.3SiSi(SiH.sub.3).sub.3, (Cl.sub.3Si).sub.2Si(SiH.sub.3).sub.2 or HSi(SiH.sub.3).sub.2SiCl.sub.3.

Claims

1: A method for preparing a partially hydrogenated chlorosilane by selective hydrogenation, the method comprising: reacting an educt chlorosilane of formula Si.sub.nX.sub.2n+2, wherein n is an integer of at least 2, and X is independently selected from the group consisting of H, Cl, alkyl, and aryl, with the proviso that at least two chloro substituents are present, with a hydrogenation agent to form a reaction product comprising a partially hydrogenated chlorosilane, wherein compared to the educt chlorosilane at least one of the at least twee chloro substituents hut not all of the at least two chloro substituents is/are transferred to a hydrido substituent; and (ii) separating said partially hydrogenated chlorosilane from the reaction product, wherein the hydrogenation agent is a compound of formula R.sub.2AlH, wherein R is a branched hydrocarbon or a cyclic hydrocarbon and the hydrogenation agent is present in a sub-stoichiometric amount relative to the at least two chloro substituents present in the educt chlorosilane.

2: The method of claim 1, wherein n is 2 to 10.

3: The method of claim 1, wherein X is independently selected from H or Cl.

4: The method of claim 1, wherein the educt chlorosilane comprises at least two SiCl.sub.3-groups.

5: The method of claim 4, wherein the partially hydrogenated chlorosilane comprises at least one SiCl.sub.3-group and at least one SiH.sub.3-group.

6: The method of claim 1, wherein the educt chlorosilane is selected from the group consisting of Si(SiCl.sub.3).sub.4, HSi(SiCl.sub.3).sub.3, Cl.sub.3SiSiCl.sub.2SiCl.sub.3, and Cl.sub.3SiSiCl.sub.3.

7: The method of claim 1, wherein R is selected from the group consisting of iso-propyl, iso-butyl, sec-butyl, tert-butyl, iso-pentyl, 2,6-dimethylphenyl, mesityl (Mes), 2,6-bis-iso-propylphenyl, 2,4,6-tris-iso-propylphenyl, 2,4, tris-tert-butylphenyl (Mes*), 2,4,6-Triphenylphenyl (Trip), 2,6-Mes(C.sub.6H.sub.3) and 2,6-Trip(C.sub.6H.sub.3).

8: The method of claim 1, wherein the hydrogenation agent is diisobutylaluminium hydride.

9: The method of claim 1, wherein the reaction (i) is carried out at a temperature in the range of −70° C. to 100° C..

10: The method of claim 1, wherein the hydrogenation agent is used in an amount of about m-k cools per mol of the educt chlorosilane, wherein m is the number of the at least two chloro substituents in the educt chlorosilane and k is the number of the at least two chloro substituents in the partially hydrogenated chlorosilane.

11: The method of claim 1, wherein the separation (ii) is carried out by distillation.

12: The method of claim 1, wherein the reaction (i) is solvent-free.

13: The method of claim 1, wherein reaction times of (i) are between 0.1 and 12 h.

14: A chlorosilane represented by the formula Cl.sub.3SiSi(SiH.sub.3).sub.3, (Cl.sub.3Si).sub.2Si(SiH.sub.3).sub.2 or HSi(SiH.sub.3).sub.2SiCl.sub.3.

15: The method of claim 2, wherein n is 2 to 6.

16: The method of claim 3, wherein X is Cl.

17: The method of claim 9, wherein the reaction (i) is carried out at a temperature of 0° C.

18: The method of claim 11, wherein the separation (ii) is carried out by distillation at a temperature in the range of −30° C. to 100° C. and at a pressure in the range of 0.01 mbar to 1100 mbar.

19: The method of claim 13, wherein reaction times of (i) are between 2 and 6 h.

Description

LIST OF FIGURES

[0033] FIG. 1: .sup.1H-NMR spectrum of the compound Cl.sub.3SiSi(SiH.sub.3).sub.3 dissolved in C.sub.6D.sub.6 measured at 25° C.

[0034] FIG. 2: Proton decoupled .sup.29Si{.sup.1H}-NMR spectrum of the compound Cl.sub.3SiSi(SiH.sub.3).sub.3 dissolved in C.sub.6D.sub.6 measured at 25° C.

[0035] FIG. 3: Proton coupled .sup.29Si-NMR spectrum of the compound Cl.sub.3SiSi(SiH.sub.3).sub.3 dissolved in C.sub.6D.sub.6 measured at 25° C.

[0036] FIG. 4: .sup.1H-NMR spectrum of the compound (Cl.sub.3Si).sub.2Si(SiH.sub.3).sub.2 dissolved in C.sub.6D.sub.6 measured at 25° C.

[0037] FIG. 5: Proton decoupled .sup.29Si{.sup.1H}-NMR spectrum of the compound (Cl.sub.3Si).sub.2Si(SiH.sub.3).sub.2 dissolved in C.sub.6D.sub.6 measured at 25° C.

[0038] FIG. 6: Proton coupled .sup.29Si-NMR spectrum of the compound (Cl.sub.3Si).sub.2Si(SiH.sub.3).sub.2 dissolved in C.sub.6D.sub.6 measured at 25° C.

[0039] FIG. 7: Proton decoupled .sup.29Si{.sup.1H}-NMR spectrum of the raw product mixture of example 4 dissolved in C.sub.6D.sub.6 measured at 25° C.

[0040] FIG. 8: .sup.1H-NMR spectrum of the raw product mixture of example 5 dissolved in C.sub.6D.sub.6 measured at 25° C.

[0041] FIG. 9: .sup.29Si{.sup.1H}-spectrum of the raw product mixture of example 5 dissolved in C.sub.6D.sub.6 measured at 25° C.

EXAMPLES

[0042] All experiments were carried out in a glovebox (manufactured by M. Braun Inert Gas Systemes GmbH) or by using methods of the standard Schlenk technique (according to the methods of D. F. Shriver, M. A. Drezdzon, The manipulation of air sensitive compounds, 1986, Wiley VCH, New York, USA) under an inert atmosphere of dry nitrogen (N.sub.2, purity 5.0; O.sub.2 content <0.1 ppm; H.sub.2O content <10 ppm). Dry and oxygen-free solvents (diethyl ether, pentane) were prepared using a solvent drying system of the type MB-SPS-800-Auto (manufactured by M. Braun Inert Gas Systemes GmbH). Deuterated benzene (C.sub.6D.sub.6) was obtained from Sigma-Aldrich Coorp. and stored on molecular sieve for drying for at least 2 days before use.

[0043] Compounds Si(SiCl.sub.3).sub.4 and HSi(SiCl.sub.3).sub.3 were produced according to known methods (DE102009053804B3 and U.S. Pat. No. 8,575,381B2).

[0044] NMR spectra were measured in solution using C.sub.6D.sub.6 as the solvent. Varian 25 INOVA 300 (1H: 300.0 MHz, 29Si: 59.6 MHz) spectrometer from Varian, Inc. at 25° C. was used. Chemical shifts are given in comparison to an external reference (.sup.1H and .sup.29Si: TMS, corresponding to tetramethylsilane, for δ=0 ppm). NMR spectra were interpreted using the software MestReNova from MestreLab Research, Chemistry Software Solutions.

[0045] Infrared spectra were measured of solid samples using a Bruker Alpha-P Diamond ATR spectrometer.

[0046] Elemental analyses were performed on a Hanau Vario Elementar EL.

[0047] Mass spectroscopic and gas chromatographic analyses were performed by coupling HP 5971 and 5890-II instruments. A capillary column type HP 1 with a length of 25 m, a diameter of 0.2 mm and a filling with 0.33 mm polydimethylsiloxane particles was used.

Example 1

[0048] ##STR00001##

[0049] 204 mL (1145 mmol) i-Bu.sub.2AlH was added over a period of several hours at a temperature of 0° C. to 72 g (127 mmol) Si(SiCl.sub.3).sub.4 (dodecachloroneopentasilane). The suspension formed at the beginning of the addition changed into a clear solution during the reaction. After addition was completed, the reaction mixture was stirred overnight at room temperature (23° C.). The reaction progress was monitored by .sup.1H und .sup.29Si-NMR spectroscopy. The product Cl.sub.3SiSi(SiH.sub.3).sub.3 was isolated from the reaction mixture by distillation at room temperature and a pressure of 0.01 mBar (yield: 7.2 g, 38%).

[0050] Elemental analysis: found: H, 3.60%. calculated: H, 3.55%. .sup.29Si-NMR (C.sub.6D.sub.6, TMS, ppm): −127.9 ppm (m, Si(SiH.sub.3).sub.3, .sup.2JSi-H=5.7 Hz,); −93.1 ppm (q, .sup.1JSi-H=208.6 Hz, .sup.3JSi-H=2.9 Hz, SiH.sub.3); 20.2 (s, SiCl.sub.3). .sup.1H-NMR (C.sub.6D.sub.6, TMS, ppm): 3.32 (s, 9H, SiH.sub.3). IR (pur): v(Si—H)=2145 (s) cm.sup.−1. GC/MS (70 eV): m/z (%) 254.8 (3) [M+], 223.9 (47) [M+-SiH.sub.3], 191.8 (100) [M+-2SiH.sub.3].

Example 2

[0051] ##STR00002##

[0052] 136 mL (762 mmol) i-Bu.sub.2AlH was added over a period of several hours at a temperature of 0° C. to 72 g (127 mmol) Si(SiCl.sub.3).sub.4 (dodecachloroneopentasilane). The suspension formed at the beginning of the addition changed into a clear solution during the reaction. After addition was completed, the reaction mixture was stirred overnight at room temperature. The reaction progress was monitored by means of .sup.1H und .sup.29Si-NMR spectroscopy. The by-product Cl.sub.3SiSi(SiH.sub.3).sub.3 was separated from the reaction mixture by distillation at room temperature and a pressure of 0.01 mBar. The main product (Cl.sub.3Si).sub.2Si(SiH.sub.3).sub.2 was isolated from the reaction mixture by subsequent distillation at 90° C. and a pressure of 0.01 mBar. (yield: 8.2 g, 25%).

[0053] To clearly prove that the main product is indeed (Cl.sub.3Si).sub.2Si(SiH.sub.3).sub.2, said compound was also produced in a second way by using protective groups:

[0054] A solution of 1 g (1.64 mmol) (Ph.sub.3Si).sub.2Si(SiH.sub.3).sub.2 (1,1,1,3,3,3-hexaphenyl neopentasilane) in 15 mL benzene was mixed with a catalytic amount of AlCl.sub.3 (2 mg, 1 mol %). The reaction solution was cooled to 0° C. Subsequently, gaseous HCl was passed through the reaction mixture via a gas introduction tube until complete conversion of (Ph.sub.3Si).sub.2Si(SiH.sub.3).sub.2 was achieved. The reaction start was indicated by a yellowing of the reaction solution. The reaction progress was monitored by .sup.1H and .sup.29Si-NMR spectroscopy measurements. After completion of the reaction, the solvent was removed in vacuo. The residue was mixed with 15 mL pentane. The obtained suspension was filtered to remove AlCl.sub.3from the reaction mixture. After evaporation of pentane at room temperature, the product (Cl.sub.3Si).sub.2Si(SiH.sub.3).sub.2 was obtained as a colorless, wax-like solid (yield: 0.23 g, 39%).

[0055] Elemental analysis: found: H, 1.71%. calculated: H, 1.68%. .sup.29Si-NMR (C.sub.6D.sub.6, TMS, ppm): −101.3 ppm (m, Si(SiH.sub.3).sub.3); −95.9 ppm (q, .sup.1JSi-H=215.8 Hz, .sup.3JSi-H=3.6 Hz, SiH.sub.3); 13.9 (s, SiCl.sub.3). .sup.1H-NMR (C.sub.6D.sub.6, TMS, ppm): 3.34 (s, 6H, SiH.sub.3). IR (pur): v(Si—H)=2139 (s) cm.sup.−1. GC/MS measurements were not possible due to the high chlorine content of the compound.

Example 3

[0056] ##STR00003##

[0057] 42 mL (222 mmol) i-Bu.sub.2AlH was added over a period of several hours at a temperature of 0° C. to 16 g (37 mmol) HSi(SiCl.sub.3).sub.3 (1,1,1,3,3,3-hexachloro-2-(trichlorosilyl)trisilane). After addition was completed, the reaction mixture was stirred overnight at room temperature. The reaction progress was monitored by means of .sup.1H and .sup.29Si-NMR spectroscopy. The volatile by-product HSi(SiH.sub.3).sub.3 was isolated from the reaction mixture by distillation at room temperature and a pressure of 0.01 mBar. The product HSi(SiH.sub.3).sub.2SiCl.sub.3 was isolated by subsequent distillation at a temperature of 50° C. and a pressure of 0.01 mBar. (yield: 3.2 g, 38%)

[0058] Elemental analysis: found: H, 3.25%. calculated: H, 3.13%. .sup.29Si-NMR (C.sub.6D.sub.6, TMS, ppm): −106.0 ppm (dm, Si(SiH.sub.3).sub.2, .sup.2JSi-H=5.7 Hz,); −97.7 ppm (q, .sup.1JSi-H=209 Hz, .sup.3JSi-H=2.1 Hz, SiH.sub.3). .sup.1H-NMR (C.sub.6D.sub.6, TMS, ppm): 3.24 (d, 6H, SiH.sub.3), 3.05 (m, 1H, SiH).

Example 4

[0059] ##STR00004##

[0060] 33.9 mL (185 mmol) i-Bu.sub.2AlH was added over a period of several hours at a temperature of 0° C. to 10 g (37 mmol) Cl.sub.3SiSiCl.sub.2SiCl.sub.3 (Octachlorotrisilane). Subsequently, partially hydrogenated chlorotrisilanes were separated in vacuo (0.01 mBar) at room temperature. GC-MS measurements of the reaction mixture confirmed that H.sub.3SiSiH.sub.2SiCl.sub.3 was synthesized with a proportion of 75% of the reaction mixture. .sup.29Si{.sup.1F1}-NMR (C.sub.6D.sub.6, TMS, ppm): −115.3 ppm (s, Si.sub.3H.sub.8); −101.2 ppm (s, Si.sub.3H.sub.8); −99.8 (s, H.sub.3SiSiH.sub.2SiCl.sub.3); −97.2 (s, H.sub.3SiSiCl.sub.2SiH.sub.3); 15.9 (s, H.sub.3SiSiH.sub.2SiCl.sub.3).

Example 5

[0061] ##STR00005##

[0062] 20.7 mL (111 mmol) i-Bu.sub.2AlH was added over a period of several hours at a temperature of 0° C. to 10 g (37 mmol) Cl.sub.3SiSiCl.sub.3 (hexachlorodisilane). Subsequently, partially hydrogenated chlorodisilanes were separated in vacuo (0.01 mBar) at room temperature. The yield of the partially hydrogenated chlorodisilane H.sub.3SiSiCl.sub.3 was 60%. .sup.29Si{.sup.1H}-NMR (C.sub.6D.sub.6, TMS, ppm): −101.5 (s, Si.sub.3H.sub.8), −84.8 (s, H.sub.3SiSiCl.sub.3), −89.2 ppm (s, Cl.sub.2HSiSiH.sub.3); −6.5 (s, Cl.sub.3SiSiCl.sub.3), 4.0 (s, Cl.sub.3SiSiH.sub.2C.sub.1), 12.9 ppm (s, H.sub.3SiSiCl.sub.3). .sup.1H-NMR (C.sub.6D.sub.6, TMS, ppm): 3.10 (Si.sub.3H.sub.8), 3.20 (s, H.sub.3SiSiCl.sub.3), 4.28 (Cl.sub.3SiSiH.sub.2Cl).