Title of Invention	PROCESS FOR PLASMA-ASSISTED ORGANOFUNCTIONALIZATION OF SILICON TETRAHALIDES OR ORGANOHALOSILANES
Abstract	A method for the plasma-assisted synthesis of organohalosilanes is described according to which organohalosilanes of the general empirical formula R1mR2oSiX4-P (X=F, CI, Br or I; p=l-4; p=m+o; m=l-4; o=0-3; R1, R2 = alkyl alkenyl, alkinyl, aryl) and/or carbosilanes of the general empirical formula R3qSiX3-qCH2SiR4rX3-r(X=F/ CI, Br or I; q=0-3; r=0-3; R3, R4= alkyl, alkenyl, alkinyl, aryl) are formed by activating a plasma in a mixture of one or more volatile organic compounds from the group of alkanes, alkenes, alkines and aromates with SiX4 and/or organohalosilanes RnSiX4-n(X=F/ CI, Br or I; n=l-4; R = alkyl, alkenyl, alkinyl, aryl).

Title of Invention

PROCESS FOR PLASMA-ASSISTED ORGANOFUNCTIONALIZATION OF SILICON TETRAHALIDES OR ORGANOHALOSILANES

Abstract

A method for the plasma-assisted synthesis of organohalosilanes is described according to which organohalosilanes of the general empirical formula R1mR2oSiX4-P (X=F, CI, Br or I; p=l-4; p=m+o; m=l-4; o=0-3; R1, R2 = alkyl alkenyl, alkinyl, aryl) and/or carbosilanes of the general empirical formula R3qSiX3-qCH2SiR4rX3-r(X=F/ CI, Br or I; q=0-3; r=0-3; R3, R4= alkyl, alkenyl, alkinyl, aryl) are formed by activating a plasma in a mixture of one or more volatile organic compounds from the group of alkanes, alkenes, alkines and aromates with SiX4 and/or organohalosilanes RnSiX4-n(X=F/ CI, Br or I; n=l-4; R = alkyl, alkenyl, alkinyl, aryl).

Full Text	FORM 2 THE PATENT ACT 1970 (39 of 1970) The Patents Rules, 2003 COMPLETE SPECIFICATION See Section 10, and rule 13 TITLE OF INVENTION PLASMA-ASSISTBD ORGANOFUNCTIONALIZATION OR ORGANOHALOSILANES OF SILICON TETRAHALIDES APPLICANT(S) a) Name b) Nationality c) Address REV RENEWABLE ENERGY VENTURES, SWISS Company GARTENSTR. 4 , CH-6304 ZUG, SWITZERLAND INC 3. PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed : - The present invention is directed to a method for the plasma-assisted synthesis of organohalosilanes. The prior art is characterized by the fact that dimethyldichlorosilane is produced according to the so-called Miiller-Rochow-Process from silicon and methylchlo-ride (gas) at 270-350cC For this qualitatively high-grade metallurgical silicon is required to which catalysts (Cu) and exact amounts of promoters (several metals in small amounts) have to be still added. It is disadvantageous that it has to be operated with relatively expensive metallurgical silicon and expensive and toxic (cancerigenous) methylchloride. In addition to the desired Me2SiCl2 other silanes, as MeSiCl3, Me3SiCl, Me4Si and SiCl4, and higher-boiling oligosilanes are still generated in varying amounts. Solar cells of monocrystalline silicon have a high efficiency but are expensive in their production. Layers of amorphous silicon (a-Si) are cheaper, however, for its use it is advantageous to incorporate carbon (a-SiCx:H) into a hydrogenated amorphous silicon layer (a-Si:H) since thereby the effective wavelength range of sunlight is substantially enlarged. a-SiCx:H is generally obtained by chemical deposition from the gaseous phase (for instance plasma-CVD) of gas mixtures consisting of silane, hydrocarbons and hydrogen. However, the elements Si, C and H are deposited according to such a method in a not sufficiently exactly controllable manner so that undesired chemical linkages can be formed which reduce the efficiency. Instead of gas mixtures alkylsilanes for the production of a-SiCx:H-layers are used in order to avoid this effect. Since methylsilane results not only in the thermal deposition but also in the plasma deposition in layers with a relatively low Si content or a high C content and thus in a high electrical resistance, according to the prior art silyl-richer compounds are used, so for instance bis(silyl)methane, H3SiCH2SiH3 (compare US 4690830, EP-A-0233613). The production of this compound is carried out ac- 3 0 OCT 2009 cording to the prior art by the conversion of chloroform with trichlorosilane (HSiCl3) in the presence of an amine to H2C(SiCl3)2 which is reduced with lithiu-maluminumhydride (LiAlH4) to bis(silyl)methane. Another production path emanates from a conversion of dibromomethane with KSiH3 [compare Z. Natur-forsch. 41b, pages 1527-1534 (1986)]. It is reported about a three-step synthesis in DE 3941997 CI. CH2X2 + 2 PhSiH2X + 2 Mg -> CH2(SiH2Ph)2 + 2 MgX2 CH2(SiH2Ph)2 + 2 HBr — CH2(SiH2Br)2 + PhH 2CH2(SiH2Br)2 + LiAIH4 - 2 CH2(SiH3)2 + AlBr3 + LiBr Suitable starting compounds for the production of disilylmethane are furthermore perhalogenated bis(silyl)methanes of the type (X3Si)2CH2 wherein X is chlorine in the most favourable case. However, until today no synthesis is known to produce (Cl3Si)2CH2 from the simply accessible and thus cheap compounds sili-contetrachloride and methane. It is the object of the invention to provide an especially simple and cheap method for the plasma-assisted synthesis of organohalosilanes. According to the invention this object is achieved by a method which is characterized in that organohalosilanes of the general empirical formula R1mR20SiX4-p (X=F, CI, Br or I; p=l-4; p=m+o; m=l-4; o=0-3; R1, R2= alkyl, alkenyl, alkinyl, aryl) and/or carbosilanes of the general empirical formula R3qSiX3-qCH2SiR4rX3-r(X=F; CI, Br or I; q=0-3; r=0-3; R3, R4 = alkyl, alkenyl, alkinyl, aryl) are formed by activating a plasma in a mixture of one or more volatile organic compounds from the group of alkanes, alkenes, alkines and aromates with SiX4 and/or organohalosilanes RnSiX4-n (X=F, CI, Br or I; n=l-4; R = alkyl, alkenyl, alkinyl, aryl). 3 3 0 OCT 2009 Further embodiments of the inventive method are described in the subclaims. So, one embodiment is characterized by reacting the mixture of reactants by the use of a non-isothermal plasma. Furthermore, the mixture of reactants is preferably reacted at reduced pressure. Practically, the mixture of reactants is passed through at least one plasma reaction zone. Furthermore, it is preferably passed through several reaction zones and rest zones which alternately follow one upon the other. Preferably, the mixture of reactants is converted in a plasma reactor at a pressure of 0,1 to 100 hPa, preferably of 1,0 to 10,0 hPa. Practically, it is converted at reaction temperatures of -80°C to +400°C, preferably of 0°C to 250°C For carrying out the plasma reactions specially electro-magnetic alternating fields, preferably in the range of 1,0 MHz to 2,45 GHz, are coupled in. According to another embodiment the reaction products are gained in an intercepting vessel behind the plasma reactor by low cooling condensation at about -80°C. Preferably, the organohalosilanes are obtained from a distillation vessel in a distillation column by distillation and are trapped in an intercepting vessel. The reactor and the intercepting vessel can be washed with SiX4. Preferably, methane alone or in addition to methane other volatile compounds of the group of the aliphatic and/or aromatic compounds are used. Especially, ethane, ethene and/or ethine are used in addition to methane. Arylated halosilanes can be obtained instead of or in addition to alkylated halosi-lanes by using aromatic compounds instead of or in addition to alkanes. Al-kenylated halosilanes can be obtained instead of or in addition to alkylated halosilanes by using alkenes instead of or in addition to alkanes. Alkinylated halosi- 4 3 0 OCT 2009 lanes can be obtained instead of or in addition to alkylated halosilanes if alkines are used instead of or in addition to alkanes. Preferably, organohalosilanes with different organyl substituents are produced. Si2X6 can be supplied to the plasma reactor instead of SiX4 too. Preferably, one or several volatile compounds of the group of the halosilanes, especially SiF4, SiCl4 and/or SiBr4, are used. Furthermore, one or several volatile compounds of the group of the organohalosilanes, especially methyltrichlorosi-lane, can be converted. The volatile compounds, preferably of the form MeSiX3, can be gained by a distillation of the organohalosilanes trapped in the intercepting vessel. According to another embodiment hydrogen is additionally converted. According to another embodiment twofold silylated methane (carbosilane), especially a bis(silyl)methane X3Si-CH2SiX3, is produced. According to another embodiment additionally bis(silyl)methane H3Si-CH2-SiH3 and/or a silylorganylated and/or a silylhalogenated derivative of the bis(silyl)methane can be produced. Furthermore, one or several organohalosilanes, especially RnSiX4-n, wherein R is especially selected from group vinyl and ethinyl, can be additionally contained in the starting mixture as educt. According to still another embodiment one or several organosubstituted bis(silyl)methanes, especially RX2Si-CH2SiX3 and/or (RX2Si)2CH2, wherein R is 3 0 OCT 2009 especially selected from the group containing vinyl and ethinyl, can be additionally produced. The inventive method deals with the above-cited problems by emanating from cheap SiX4 or corresponding organohalosilanes and methane (not toxic) or other volatile compounds of the group of the alkanes, alkenes, alkines and aromatic compounds. These substances are stimulated by a plasma and are reacted wherein, among others, the desired silanes Me2SiX2, MeSiX3 and (X3Si)2CH2 are generated. Another advantage consists in the fact that also other groups can be attached to the silicon by replacing methane by other volatile hydrocarbons. For instance, this is also successful by reacting ethene or ethine with the tetraha-losilane in the reactor in a plasma-assisted manner wherein vinyl- or ethinylha-losilanes and the bis(silyl)alkanes (X3Si)2CH2/ RX2SiCH2SiCH2SiX3 and (RSiX2)2CH2 (R = vinyl, ethinyl) can be obtained. If organosubstituted halosilanes RnSiX4-n (n=l-3) are reacted with hydrocarbons in the plasma reactor instead of the tetrahalosilane one succeeds in synthesizing products with higher organosubstitution at the silicon atom or in increasing their portions in the reaction mixture emanating from silicontetrahalide. The method for the plasma-assisted organofunctionalizing of SiX4 or organohalosilanes passes several method steps and is described in connection with the drawing with the example of SiCLi as follows: 1. CH4 and SiCl4 are introduced into the reactor (5) through the gas inlet (1) and 2. a plasma is activated at reduced pressure (0,1-l00hPa) by the application of electromagnetic alternating fields. 30 OCT 2009 3. The reactor can contain several plasma zones (2) and rest zones (3) as well as cool surfaces. The reaction gases flow through the reactor (5) to the vacuum pump wherein 4. the high volatile components (SiCl4, MeSiCl3, Me2SiCl2) are held back in an intercepting vessel by deep cooling (16) (for instance at -80°C with cry-ostat). 5. After a fixed time the reaction is terminated and the intercepted silane mixture is discharged into a distillation vessel (10) wherein 6. it can be separated through fractionated distillation into individual components. SiCU (educt), MeSiCl3 and Ne2SiCl2 are obtained as colourless liquids. 7. Furthermore, yellow to brownish coatings of methylated oligosilanes and polysilanes are obtained in the range of the reactor which 8. are transferred into the intercepting vessel for polysilanes (13) by resolving with SiCU. The method for the methylation of tetrachlorosilane is shown in the drawing with the following reference numbers: 30 OCT 2009 1. Supply pipe for silicontetrachloride and methane 2. Plasma reaction zone 3. Plasma rest zone 4. Plasma electrodes 5. Plasma reaction vessel 6. Pipe to the vacuum pump 7. Deep cooling intercepting vessel 8. Cooler 9. Distillation column 10. Distillation vessel 11. Bottom discharge pipe 12. Discharge valve 13. Intercepting vessel 1 14. Service valve for application with protective gas or vacuum 15. Intercepting vessel 2 16. Deep cooling device Examples 1. General proceeding SiCU is sprayed into the reactor (5) together with the reactant gas (about 10-15 1/min) and the plasma is ignited. The volume ratio SiCU / reactant gas can be arbitrarily varied. Further admixing of inert gas or hydrogen is possible. Gas mixtures (for instance methane/ethylene or methane/hydrogen) in different mixing ratios are also used as reactant gases. The SiCl4/product mixture is collected at the exit of the reactor and is worked up distillatively. The products are isolated according to their boiling points and are spectroscopically identified. In the examples described here the products are extensively re- 30 OCT 2009 leased from SiCU wherein the product formation is between 25 and 60% dependent on the conditions. The product mixture is gaschromatographically tested and the identity of individual compounds is secured by a comparison of the fragmentation patterns and the retention times with such authentic samples. The product formation can be formally understood with the predetermined plasma conditions as a combination of radical reactions (for instance SiCl4—» Cl+Cl3Si-; CH4— CH3+H-Cl3Si+H-Cl3SiH; Cl3Si + Me→ Cl3SiMe) and of car-bene introduction reactions into Si-C and Si-Si linkages (for instance CH4→ CH2+H2; R3SiCH3+ I CH2-> R3SiCH2CH3; 2 Cl3Si→ Cl3Si-SiCl3 \|CH2 →Cl3Si-CH2-SiCl3 etc. Explanations/definitions: > Me = methyl = -CH3 > Vi =vinyl = -CH=CH2 > Et = ethyl = -CH2-CH3 1. SiCU in the presence of methane, CH4: Me(H)SiCl2(3%), MeSiCl3 (8%), Me2SiCl2 (5%) Especially the portion of Me(H)SiCl2 is increased by admixing hydrogen (H2): Me(H)SiCl2(18%)/ MeSiCl3 (17%), Me2SiCl2 (12%) If the portion of methane is significantly reduced Cl3SiCH2SiCl3 is formed in a portion of more than 40%. The portions of Me(H)SiCl2»MeSiCI3>Me2SiCl2 are now significantly smaller. 9 30 OCT 2009 If ethane, C2H6, is used instead of methane the relative portion of methyl radicals and carbenes (CH3 or CH2) in the reaction mixture is increased whereby the portion of methylated products and carbosilanes is increased: Cl3SiCH2CH3(2.8%)/ ViSiCb (25.49%), MeViSiCl2 (1.6%), CbSiCH2CiCb (53%), ViCl2SiCH2SiCl2Me (17.6%), in addition small amounts of CbSiH, Me(H)SiCl2, Cl6Si2 are generated. SiCl4 in the presence of ethene, C2H4 HSiCb (3%), ViSiCb (29%), Cl3Si-C= CH (10.6%), Vi2SiCl2 (2.4%), ViEtSiCl2 (12.7%), Cl3SiCH2CH2CH3 (4.7%), CbSiCH2SiCl3 (38%), Cl3SiCH2SiCl2Vi (2.6%). If only a small amount of ethene is added preliminarily chlorinated hydrocarbons, benzene and of the silanes nearly exclusively CbSiCH2SiCl3 and a small amount of ViSiCb are generated. If more methane, CH4, is added to the ethane the following products are produced: HSiCb (2%), MeSiCb (1%), Me2SiCl2 ( The portion of MeSiCb is significantly increased in the presence of methane by the use of methyltrichlorosilane, MeSiCb, instead of SiCl4. If the combination MeSiCb/ethene is used the following products are isolated: SiCl4 (6.9%), Me2ViSiH (1.2%), ViSiCl3 (32.2%), EtSiCl3 (6.4%), MeViSiCl2 (31%), Cl3SiCH2SiCb (17.2%), MeCl2SiCH2SiCb (5.1%). The combination MeSiCb/CH=CH (4-5 1/min) results in the products SiCl4 (43.4%), ViSiCb (3.6%), MeViSiCl2 (6.8%), CbSiCH2SiCl3 (46.4%). 30 OCT 2009 4. Alternative proceedings with reduced gas flows (0,2 1/min respectively): A mixture of CH4 and SiCl4 (1:1) is introduced into the plasma reaction vessel 5 with the pipe 1 and a pressure of 1-2 hPa and a plasma is generated in the range of the plasma electrodes (4). Thereafter methylated chloropolysilanes are precipitated in the plasma reaction vessel 5 and in the intercepting vessel 13. The higher volatile chlorosilanes and methylchlorosilanes are condensed in the vessel 7 and are intercepted in the vessel 10 while the gaseous reaction products are drawn off with the pipe 6. During 2,5h 181 g product mixture are intercepted in the vessel 10 and the product mixture is separated into the individual products by the distillation column 9. From the product mixture 21,6 g MeSiCl3 and 1,8 g MeSiCl2 are obtained as colourless liquids. The methylated chloropolysilanes are transferred from the plasma reaction vessel 5 into the intercepting vessel 13 by resolving in SiCl4 and are withdrawn through the bottom discharge pipe (11). 30 OCT 2009 CLAIM: 1. A method for the plasma-assisted synthesis of organohalosilanes, characterized in that organohalosilanes of the general empirical formula R1mR20SiX4-p (X=F, CI, Br or I; p=l-4; p=m+o; m=l-4; o=0-3; R1,R2=alkyl, al-kenyl, alkinyl, aryl) and/or carbosilanes of the general empirical formula R3qSiX3-qCH2SiR4rX3-r (X=F, CI, Br or I; q=0-3; r=0-3; R3, R4 = alkyl, alkenyl, alkinyl, aryl) are formed by activating a plasma in a mixture of one or more volatile organic compounds from the group of alkanes, alkenes, alki-nes and aromates with SiX4 and/or organohalosilanes RnSiX4-n (X=F/ CI, Br or I; n=l-4; R = alkyl, alkenyl, alkinyl, aryl). 2. The method for the plasma-assisted synthesis of organohalosilanes according to claim 1, characterized in that the reactant mixture is reacted by the use of a non-isothermal plasma. 3. The method for the plasma-assisted synthesis of organohalosilanes according to claim 1 or 2, characterized in that the reactant mixture is reacted at reduced pressure. 4. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 3, characterized in that the reactant mixture is passed through at least one plasma reaction zone. 5. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 4, characterized in that the reactant mixture is passed through several reaction zones and rest zones which alternately follow one upon the other. 30 OCT 2009 6. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 5, characterized in that the reactant mixture is converted in a plasma reactor at a presstire of 0,1 - 100 hPa, preferably of 1,0 -10,0 hPa. 7. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 6, characterized in that the reactant mixture is converted in a plasma reactor at reaction temperatures of -80°C - +400°C/ preferably of 0°C - 250°C 8. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 7, characterized in that electromagnetic alternating fields, preferably in the range of 1,0 MHz - 2,45 GHz, are coupled in for carrying out the plasma reactions. 9. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 8, characterized in that the reaction products are gained in an intercepting vessel (7) behind the plasma reactor by deep cooling condensation at about -80°C. 10. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 9, characterized in that the organohalosilanes of a distillation vessel (10) are obtained in a distillation column (9) by distillation and are trapped in an intercepting vessel (15). 11. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 10, characterized in that the reactor and the intercepting vessel are washed with SiX4. 30 OCT 2009 12. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 11, characterized in that methane alone or in addition to methane other volatile compounds of the group of the aliphatic compounds and/or aromatic compounds are used. 13. The method for the plasma-assisted synthesis of organohalosilanes according to claim 12, characterized in that ethane, ethene and/or ethine are used in addition to methane. 14. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 13, characterized in that instead of or in addition to alkylated halosilanes arylated halosilanes are obtained by using aromatic compounds instead of or in addition to alkanes. 15. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 13, characterized in that instead of or in addition to alkylated halosilanes alkenylated halosilanes are obtained by using alkenes instead of or in addition to alkanes. 16. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 13, characterized in that instead of or in addition to alkylated halosilanes alkenylated halosilanes are obtained by using alkines instead of or in addition to alkanes. 17. The method for the plasma-assisted synthesis of organohalosilanes ac cording to one of the claims 1 - 16, characterized in that organohalosilanes with different organylsubstituents are produced. 3 0 OCT 2009 18. The method for the plasma-assisted synthesis of organohalosilanes according to one of tHe claims 1 -17, characterized in that Si2X6 is supplied to the plasma reactor instead of SiX4. 19. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 18, characterized in that one or more volatile compounds of the group of the halosilanes, especially SiF4, SiCl4 and/or Site, are used. 20. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 18, characterized in that one or more volatile compounds of the group of the organohalosilanes, especially methyltri-chlorosilane, are converted. 21. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 20, characterized in that the volatile compounds, preferably of the form MeSiX3, are gained by a distillation of the organohalosilanes trapped in the intercepting vessel (15). 22. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 21, characterized in that additionally hydrogen is converted. 23. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 22, characterized in that twofold silylated methane (carbosilane), especially a bis(silyl)methane X3Si-CH2-SiX3, is produced. 3 0 OCT 2009 15 24. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 23, characterized in that additionally bis(silyl)methane H3Si-CH2-SiH3 and/or a silylorganylated and/or a silyl-halogenated derivative of the bis(silyl)methane are produced. 25. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 24, characterized in that one or more different organohalosilanes, especially RnSiX4-n, wherein R is especially selected from the group vinyl and ethinyl, are additionally contained in the starting mixture as educt. 26. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 25, characterized in that additionally one or different organosubstituted bis(silyl)methaneS/ especially RX2Si-CH2-SiX3 and/or (RX2Si)2CH2, wherein R is especially Selected from the group vinyl and ethinyl, are produced. Dated this 29th day of October, 2009 HIRAL CHANDRAKANT JOSHI AGENT FOR REV RENEWABLE ENERGY VENTURES, INC. 30 OCT 2009 16

Full Text

FORM 2
THE PATENT ACT 1970 (39 of 1970)
The Patents Rules, 2003 COMPLETE SPECIFICATION See Section 10, and rule 13

TITLE OF INVENTION
PLASMA-ASSISTBD ORGANOFUNCTIONALIZATION
OR ORGANOHALOSILANES

OF SILICON TETRAHALIDES

APPLICANT(S)
a) Name
b) Nationality
c) Address

REV RENEWABLE ENERGY VENTURES,
SWISS Company
GARTENSTR. 4 ,
CH-6304 ZUG,
SWITZERLAND

INC

3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -

The present invention is directed to a method for the plasma-assisted synthesis of organohalosilanes.
The prior art is characterized by the fact that dimethyldichlorosilane is produced according to the so-called Miiller-Rochow-Process from silicon and methylchlo-ride (gas) at 270-350cC For this qualitatively high-grade metallurgical silicon is required to which catalysts (Cu) and exact amounts of promoters (several metals in small amounts) have to be still added. It is disadvantageous that it has to be operated with relatively expensive metallurgical silicon and expensive and toxic (cancerigenous) methylchloride. In addition to the desired Me2SiCl2 other silanes, as MeSiCl3, Me3SiCl, Me4Si and SiCl4, and higher-boiling oligosilanes are still generated in varying amounts.
Solar cells of monocrystalline silicon have a high efficiency but are expensive in their production. Layers of amorphous silicon (a-Si) are cheaper, however, for its use it is advantageous to incorporate carbon (a-SiCx:H) into a hydrogenated amorphous silicon layer (a-Si:H) since thereby the effective wavelength range of sunlight is substantially enlarged.
a-SiCx:H is generally obtained by chemical deposition from the gaseous phase (for instance plasma-CVD) of gas mixtures consisting of silane, hydrocarbons and hydrogen. However, the elements Si, C and H are deposited according to such a method in a not sufficiently exactly controllable manner so that undesired chemical linkages can be formed which reduce the efficiency. Instead of gas mixtures alkylsilanes for the production of a-SiCx:H-layers are used in order to avoid this effect. Since methylsilane results not only in the thermal deposition but also in the plasma deposition in layers with a relatively low Si content or a high C content and thus in a high electrical resistance, according to the prior art silyl-richer compounds are used, so for instance bis(silyl)methane, H3SiCH2SiH3 (compare US 4690830, EP-A-0233613). The production of this compound is carried out ac-
3 0 OCT 2009

cording to the prior art by the conversion of chloroform with trichlorosilane (HSiCl3) in the presence of an amine to H2C(SiCl3)2 which is reduced with lithiu-maluminumhydride (LiAlH4) to bis(silyl)methane. Another production path emanates from a conversion of dibromomethane with KSiH3 [compare Z. Natur-forsch. 41b, pages 1527-1534 (1986)]. It is reported about a three-step synthesis in DE 3941997 CI.
CH2X2 + 2 PhSiH2X + 2 Mg -> CH2(SiH2Ph)2 + 2 MgX2 CH2(SiH2Ph)2 + 2 HBr — CH2(SiH2Br)2 + PhH 2CH2(SiH2Br)2 + LiAIH4 - 2 CH2(SiH3)2 + AlBr3 + LiBr
Suitable starting compounds for the production of disilylmethane are furthermore perhalogenated bis(silyl)methanes of the type (X3Si)2CH2 wherein X is chlorine in the most favourable case. However, until today no synthesis is known to produce (Cl3Si)2CH2 from the simply accessible and thus cheap compounds sili-contetrachloride and methane.
It is the object of the invention to provide an especially simple and cheap method for the plasma-assisted synthesis of organohalosilanes.
According to the invention this object is achieved by a method which is characterized in that organohalosilanes of the general empirical formula R1mR20SiX4-p (X=F, CI, Br or I; p=l-4; p=m+o; m=l-4; o=0-3; R1, R2= alkyl, alkenyl, alkinyl, aryl) and/or carbosilanes of the general empirical formula R3qSiX3-qCH2SiR4rX3-r(X=F; CI, Br or I; q=0-3; r=0-3; R3, R4 = alkyl, alkenyl, alkinyl, aryl) are formed by activating a plasma in a mixture of one or more volatile organic compounds from the group of alkanes, alkenes, alkines and aromates with SiX4 and/or organohalosilanes RnSiX4-n (X=F, CI, Br or I; n=l-4; R = alkyl, alkenyl, alkinyl, aryl).
3
3 0 OCT 2009

Further embodiments of the inventive method are described in the subclaims. So, one embodiment is characterized by reacting the mixture of reactants by the use of a non-isothermal plasma. Furthermore, the mixture of reactants is preferably reacted at reduced pressure.
Practically, the mixture of reactants is passed through at least one plasma reaction zone. Furthermore, it is preferably passed through several reaction zones and rest zones which alternately follow one upon the other.
Preferably, the mixture of reactants is converted in a plasma reactor at a pressure of 0,1 to 100 hPa, preferably of 1,0 to 10,0 hPa. Practically, it is converted at reaction temperatures of -80°C to +400°C, preferably of 0°C to 250°C
For carrying out the plasma reactions specially electro-magnetic alternating fields, preferably in the range of 1,0 MHz to 2,45 GHz, are coupled in.
According to another embodiment the reaction products are gained in an intercepting vessel behind the plasma reactor by low cooling condensation at about -80°C. Preferably, the organohalosilanes are obtained from a distillation vessel in a distillation column by distillation and are trapped in an intercepting vessel. The reactor and the intercepting vessel can be washed with SiX4.
Preferably, methane alone or in addition to methane other volatile compounds of the group of the aliphatic and/or aromatic compounds are used. Especially, ethane, ethene and/or ethine are used in addition to methane.
Arylated halosilanes can be obtained instead of or in addition to alkylated halosi-lanes by using aromatic compounds instead of or in addition to alkanes. Al-kenylated halosilanes can be obtained instead of or in addition to alkylated halosilanes by using alkenes instead of or in addition to alkanes. Alkinylated halosi-
4
3 0 OCT 2009

lanes can be obtained instead of or in addition to alkylated halosilanes if alkines are used instead of or in addition to alkanes.
Preferably, organohalosilanes with different organyl substituents are produced.
Si2X6 can be supplied to the plasma reactor instead of SiX4 too.
Preferably, one or several volatile compounds of the group of the halosilanes, especially SiF4, SiCl4 and/or SiBr4, are used. Furthermore, one or several volatile compounds of the group of the organohalosilanes, especially methyltrichlorosi-lane, can be converted. The volatile compounds, preferably of the form MeSiX3, can be gained by a distillation of the organohalosilanes trapped in the intercepting vessel.
According to another embodiment hydrogen is additionally converted.
According to another embodiment twofold silylated methane (carbosilane), especially a bis(silyl)methane X3Si-CH2SiX3, is produced.
According to another embodiment additionally bis(silyl)methane H3Si-CH2-SiH3 and/or a silylorganylated and/or a silylhalogenated derivative of the bis(silyl)methane can be produced.
Furthermore, one or several organohalosilanes, especially RnSiX4-n, wherein R is especially selected from group vinyl and ethinyl, can be additionally contained in the starting mixture as educt.
According to still another embodiment one or several organosubstituted bis(silyl)methanes, especially RX2Si-CH2SiX3 and/or (RX2Si)2CH2, wherein R is
3 0 OCT 2009

especially selected from the group containing vinyl and ethinyl, can be additionally produced.
The inventive method deals with the above-cited problems by emanating from cheap SiX4 or corresponding organohalosilanes and methane (not toxic) or other volatile compounds of the group of the alkanes, alkenes, alkines and aromatic compounds. These substances are stimulated by a plasma and are reacted wherein, among others, the desired silanes Me2SiX2, MeSiX3 and (X3Si)2CH2 are generated. Another advantage consists in the fact that also other groups can be attached to the silicon by replacing methane by other volatile hydrocarbons.
For instance, this is also successful by reacting ethene or ethine with the tetraha-losilane in the reactor in a plasma-assisted manner wherein vinyl- or ethinylha-losilanes and the bis(silyl)alkanes (X3Si)2CH2/ RX2SiCH2SiCH2SiX3 and (RSiX2)2CH2 (R = vinyl, ethinyl) can be obtained.
If organosubstituted halosilanes RnSiX4-n (n=l-3) are reacted with hydrocarbons in the plasma reactor instead of the tetrahalosilane one succeeds in synthesizing products with higher organosubstitution at the silicon atom or in increasing their portions in the reaction mixture emanating from silicontetrahalide.
The method for the plasma-assisted organofunctionalizing of SiX4 or organohalosilanes passes several method steps and is described in connection with the drawing with the example of SiCLi as follows:
1. CH4 and SiCl4 are introduced into the reactor (5) through the gas inlet (1) and
2. a plasma is activated at reduced pressure (0,1-l00hPa) by the application of electromagnetic alternating fields.
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3. The reactor can contain several plasma zones (2) and rest zones (3) as well as cool surfaces. The reaction gases flow through the reactor (5) to the vacuum pump wherein
4. the high volatile components (SiCl4, MeSiCl3, Me2SiCl2) are held back in an intercepting vessel by deep cooling (16) (for instance at -80°C with cry-ostat).
5. After a fixed time the reaction is terminated and the intercepted silane mixture is discharged into a distillation vessel (10) wherein
6. it can be separated through fractionated distillation into individual components. SiCU (educt), MeSiCl3 and Ne2SiCl2 are obtained as colourless liquids.
7. Furthermore, yellow to brownish coatings of methylated oligosilanes and polysilanes are obtained in the range of the reactor which
8. are transferred into the intercepting vessel for polysilanes (13) by resolving with SiCU.
The method for the methylation of tetrachlorosilane is shown in the drawing with the following reference numbers:
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1. Supply pipe for silicontetrachloride and methane
2. Plasma reaction zone
3. Plasma rest zone
4. Plasma electrodes
5. Plasma reaction vessel
6. Pipe to the vacuum pump
7. Deep cooling intercepting vessel
8. Cooler
9. Distillation column
10. Distillation vessel
11. Bottom discharge pipe
12. Discharge valve
13. Intercepting vessel 1
14. Service valve for application with protective gas or vacuum
15. Intercepting vessel 2
16. Deep cooling device
Examples
1. General proceeding
SiCU is sprayed into the reactor (5) together with the reactant gas (about 10-15 1/min) and the plasma is ignited. The volume ratio SiCU / reactant gas can be arbitrarily varied. Further admixing of inert gas or hydrogen is possible. Gas mixtures (for instance methane/ethylene or methane/hydrogen) in different mixing ratios are also used as reactant gases. The SiCl4/product mixture is collected at the exit of the reactor and is worked up distillatively. The products are isolated according to their boiling points and are spectroscopically identified. In the examples described here the products are extensively re-
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leased from SiCU wherein the product formation is between 25 and 60% dependent on the conditions. The product mixture is gaschromatographically tested and the identity of individual compounds is secured by a comparison of the fragmentation patterns and the retention times with such authentic samples.
The product formation can be formally understood with the predetermined plasma conditions as a combination of radical reactions (for instance SiCl4—» Cl+Cl3Si-; CH4— CH3+H-Cl3Si+H-Cl3SiH; Cl3Si + Me→ Cl3SiMe) and of car-bene introduction reactions into Si-C and Si-Si linkages (for instance CH4→ CH2+H2; R3SiCH3+ I CH2-> R3SiCH2CH3; 2 Cl3Si→ Cl3Si-SiCl3
|CH2 →Cl3Si-CH2-SiCl3 etc.
Explanations/definitions:
> Me = methyl = -CH3
> Vi =vinyl = -CH=CH2
> Et = ethyl = -CH2-CH3
1. SiCU in the presence of methane, CH4:
Me(H)SiCl2(3%), MeSiCl3 (8%), Me2SiCl2 (5%)
Especially the portion of Me(H)SiCl2 is increased by admixing hydrogen
(H2):
Me(H)SiCl2(18%)/ MeSiCl3 (17%), Me2SiCl2 (12%)
If the portion of methane is significantly reduced Cl3SiCH2SiCl3 is formed in a portion of more than 40%. The portions of Me(H)SiCl2»MeSiCI3>Me2SiCl2 are now significantly smaller.
9
30 OCT 2009

If ethane, C2H6, is used instead of methane the relative portion of methyl radicals and carbenes (CH3 or
CH2) in the reaction mixture is increased whereby the portion of methylated products and carbosilanes is increased:
Cl3SiCH2CH3(2.8%)/ ViSiCb (25.49%), MeViSiCl2 (1.6%), CbSiCH2CiCb (53%), ViCl2SiCH2SiCl2Me (17.6%), in addition small amounts of CbSiH, Me(H)SiCl2, Cl6Si2 are generated.
SiCl4 in the presence of ethene, C2H4
HSiCb (3%), ViSiCb (29%), Cl3Si-C= CH (10.6%), Vi2SiCl2 (2.4%), ViEtSiCl2 (12.7%), Cl3SiCH2CH2CH3 (4.7%), CbSiCH2SiCl3 (38%), Cl3SiCH2SiCl2Vi (2.6%). If only a small amount of ethene is added preliminarily chlorinated hydrocarbons, benzene and of the silanes nearly exclusively CbSiCH2SiCl3 and a small amount of ViSiCb are generated. If more methane, CH4, is added to the ethane the following products are produced: HSiCb (2%), MeSiCb (1%), Me2SiCl2 ( The portion of MeSiCb is significantly increased in the presence of methane by the use of methyltrichlorosilane, MeSiCb, instead of SiCl4. If the combination MeSiCb/ethene is used the following products are isolated: SiCl4 (6.9%), Me2ViSiH (1.2%), ViSiCl3 (32.2%), EtSiCl3 (6.4%), MeViSiCl2 (31%), Cl3SiCH2SiCb (17.2%), MeCl2SiCH2SiCb (5.1%). The combination MeSiCb/CH=CH (4-5 1/min) results in the products SiCl4 (43.4%), ViSiCb (3.6%), MeViSiCl2 (6.8%), CbSiCH2SiCl3 (46.4%).
30 OCT 2009

4. Alternative proceedings with reduced gas flows (0,2 1/min respectively): A mixture of CH4 and SiCl4 (1:1) is introduced into the plasma reaction vessel 5 with the pipe 1 and a pressure of 1-2 hPa and a plasma is generated in the range of the plasma electrodes (4). Thereafter methylated chloropolysilanes are precipitated in the plasma reaction vessel 5 and in the intercepting vessel 13. The higher volatile chlorosilanes and methylchlorosilanes are condensed in the vessel 7 and are intercepted in the vessel 10 while the gaseous reaction products are drawn off with the pipe 6. During 2,5h 181 g product mixture are intercepted in the vessel 10 and the product mixture is separated into the individual products by the distillation column 9. From the product mixture 21,6 g MeSiCl3 and 1,8 g MeSiCl2 are obtained as colourless liquids. The methylated chloropolysilanes are transferred from the plasma reaction vessel 5 into the intercepting vessel 13 by resolving in SiCl4 and are withdrawn through the bottom discharge pipe (11).
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CLAIM:
1. A method for the plasma-assisted synthesis of organohalosilanes, characterized in that organohalosilanes of the general empirical formula R1mR20SiX4-p (X=F, CI, Br or I; p=l-4; p=m+o; m=l-4; o=0-3; R1,R2=alkyl, al-kenyl, alkinyl, aryl) and/or carbosilanes of the general empirical formula R3qSiX3-qCH2SiR4rX3-r (X=F, CI, Br or I; q=0-3; r=0-3; R3, R4 = alkyl, alkenyl, alkinyl, aryl) are formed by activating a plasma in a mixture of one or more volatile organic compounds from the group of alkanes, alkenes, alki-nes and aromates with SiX4 and/or organohalosilanes RnSiX4-n (X=F/ CI, Br or I; n=l-4; R = alkyl, alkenyl, alkinyl, aryl).
2. The method for the plasma-assisted synthesis of organohalosilanes according to claim 1, characterized in that the reactant mixture is reacted by the use of a non-isothermal plasma.
3. The method for the plasma-assisted synthesis of organohalosilanes according to claim 1 or 2, characterized in that the reactant mixture is reacted at reduced pressure.
4. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 3, characterized in that the reactant mixture is passed through at least one plasma reaction zone.
5. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 4, characterized in that the reactant mixture is passed through several reaction zones and rest zones which alternately follow one upon the other.
30 OCT 2009

6. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 5, characterized in that the reactant mixture is converted in a plasma reactor at a presstire of 0,1 - 100 hPa, preferably of 1,0 -10,0 hPa.
7. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 6, characterized in that the reactant mixture is converted in a plasma reactor at reaction temperatures of -80°C - +400°C/ preferably of 0°C - 250°C
8. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 7, characterized in that electromagnetic alternating fields, preferably in the range of 1,0 MHz - 2,45 GHz, are coupled in for carrying out the plasma reactions.
9. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 8, characterized in that the reaction products are gained in an intercepting vessel (7) behind the plasma reactor by deep cooling condensation at about -80°C.
10. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 9, characterized in that the organohalosilanes of a distillation vessel (10) are obtained in a distillation column (9) by distillation and are trapped in an intercepting vessel (15).
11. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 10, characterized in that the reactor and the intercepting vessel are washed with SiX4.
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12. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 to 11, characterized in that methane alone or in addition to methane other volatile compounds of the group of the aliphatic compounds and/or aromatic compounds are used.
13. The method for the plasma-assisted synthesis of organohalosilanes according to claim 12, characterized in that ethane, ethene and/or ethine are used in addition to methane.
14. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 13, characterized in that instead of or in addition to alkylated halosilanes arylated halosilanes are obtained by using aromatic compounds instead of or in addition to alkanes.
15. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 13, characterized in that instead of or in addition to alkylated halosilanes alkenylated halosilanes are obtained by using alkenes instead of or in addition to alkanes.
16. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 13, characterized in that instead of or in addition to alkylated halosilanes alkenylated halosilanes are obtained by using alkines instead of or in addition to alkanes.
17. The method for the plasma-assisted synthesis of organohalosilanes ac
cording to one of the claims 1 - 16, characterized in that organohalosilanes
with different organylsubstituents are produced.
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18. The method for the plasma-assisted synthesis of organohalosilanes according to one of tHe claims 1 -17, characterized in that Si2X6 is supplied to the plasma reactor instead of SiX4.
19. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 18, characterized in that one or more volatile compounds of the group of the halosilanes, especially SiF4, SiCl4 and/or Site, are used.
20. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 18, characterized in that one or more volatile compounds of the group of the organohalosilanes, especially methyltri-chlorosilane, are converted.
21. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 20, characterized in that the volatile compounds, preferably of the form MeSiX3, are gained by a distillation of the organohalosilanes trapped in the intercepting vessel (15).
22. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 21, characterized in that additionally hydrogen is converted.
23. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 22, characterized in that twofold silylated methane (carbosilane), especially a bis(silyl)methane X3Si-CH2-SiX3, is produced.
3 0 OCT 2009
15

24. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 23, characterized in that additionally bis(silyl)methane H3Si-CH2-SiH3 and/or a silylorganylated and/or a silyl-halogenated derivative of the bis(silyl)methane are produced.
25. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 24, characterized in that one or more different organohalosilanes, especially RnSiX4-n, wherein R is especially selected from the group vinyl and ethinyl, are additionally contained in the starting mixture as educt.
26. The method for the plasma-assisted synthesis of organohalosilanes according to one of the claims 1 - 25, characterized in that additionally one or different organosubstituted bis(silyl)methaneS/ especially RX2Si-CH2-SiX3 and/or (RX2Si)2CH2, wherein R is especially Selected from the group vinyl and ethinyl, are produced.
Dated this 29th day of October, 2009

HIRAL CHANDRAKANT JOSHI
AGENT FOR
REV RENEWABLE ENERGY VENTURES, INC.
30 OCT 2009
16

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Patent Number

278069

Indian Patent Application Number

2032/MUMNP/2009

PG Journal Number

52/2016

Publication Date

16-Dec-2016

Grant Date

09-Dec-2016

Date of Filing

30-Oct-2009

Name of Patentee

SPAWNT PRIVATE S.a.r.l.

Applicant Address

16, Rue Jean 1' Aveugle, L-1148, Luxembourg, Luxembourg

Inventors:

#	Inventor's Name	Inventor's Address
1	AUNER NORBERT	AUF DER PLATT 51, 61479 GLASHUETTEN.
2	BAUCH CHRISTIAN	AM FUCHSTANZ 10, 61250 USINGEN.
3	DELTSCHEW RUMEN	BAUMEISTER-GUENTHER-STRASSE 7, 04319 LEIPZIG.
4	LIPPOLD GERD	MITTELSTRASSE 12, 04416 MARKKLEEBERG.
5	SEYED-JAVAD MOHSSENI-ALA	FREIHERR-VOM-STEIN STRASSE 5, 06766 BITTERFELD-WOLFEN, GERMANY

PCT International Classification Number

C07F 7/08

PCT International Application Number

PCT/EP2008/002551

PCT International Filing date

2008-03-31

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	102007015749.7	2007-03-30	Germany