GB2234511A - Electrochemical synthesis of organosilicon compounds - Google Patents

Electrochemical synthesis of organosilicon compounds Download PDF

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GB2234511A
GB2234511A GB9016403A GB9016403A GB2234511A GB 2234511 A GB2234511 A GB 2234511A GB 9016403 A GB9016403 A GB 9016403A GB 9016403 A GB9016403 A GB 9016403A GB 2234511 A GB2234511 A GB 2234511A
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silicon
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Franck Andre Daniel Renauld
James S Tonge
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Dow Silicones UK Ltd
Dow Silicones Corp
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Dow Corning Ltd
Dow Corning Corp
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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07FACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00Compounds containing elements of Groups 4 or 14 of the Periodic Table
    • C07F7/02Silicon compounds
    • C07F7/08Compounds having one or more C—Si linkages
    • C07F7/12Organo silicon halides
    • C07F7/121Preparation or treatment not provided for in C07F7/14, C07F7/16 or C07F7/20
    • C07F7/122Preparation or treatment not provided for in C07F7/14, C07F7/16 or C07F7/20 by reactions involving the formation of Si-C linkages
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07FACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00Compounds containing elements of Groups 4 or 14 of the Periodic Table
    • C07F7/02Silicon compounds
    • C07F7/08Compounds having one or more C—Si linkages
    • C07F7/0801General processes
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07FACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00Compounds containing elements of Groups 4 or 14 of the Periodic Table
    • C07F7/02Silicon compounds
    • C07F7/08Compounds having one or more C—Si linkages
    • C07F7/0803Compounds with Si-C or Si-Si linkages
    • C07F7/0825Preparations of compounds not comprising Si-Si or Si-cyano linkages
    • C07F7/0827Syntheses with formation of a Si-C bond
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07FACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00Compounds containing elements of Groups 4 or 14 of the Periodic Table
    • C07F7/02Silicon compounds
    • C07F7/08Compounds having one or more C—Si linkages
    • C07F7/12Organo silicon halides
    • C07F7/121Preparation or treatment not provided for in C07F7/14, C07F7/16 or C07F7/20
    • C07F7/127Preparation or treatment not provided for in C07F7/14, C07F7/16 or C07F7/20 by reactions not affecting the linkages to the silicon atom
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25BELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00Electrolytic production of organic compounds
    • C25B3/20Processes
    • C25B3/25Reduction

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  • Organic Chemistry (AREA)
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Abstract

A method of making silanes, carbosilanes or polycarbosilanes having at least one silicon-bonded organic group, linked to the silicon atom via a Si-C bond by electroreduction of a compound (I), having a substituent -RX wherein R is a divalent carbon or hydrocarbon compound which may be substituted and X is halogen in the presence of (II), a silane of the general formula R'4-a-bSiXa(RX)b wherein R' is hydrogen, a hydrocarbon group, a group containing H, C and O atoms, S atoms and/or P atoms and groups consisting of C, H and N atoms, a has a value of 1 to 4, b has a value of 0 to 3 and a+b has a value of 2, 3 or 4. Examples of compound (I) include carbohalides, e.g. methyl-, benzyl-, phenyl- and vinyl-halides, silanes, e.g. trimethylchloromethylsilane and siloxanes. Examples of compound (II) include dimethyldichlorosilane, methyltrichlorosilane, methyldichlorosilane and dichlorosilane. Alternatively, the same reagent for compound (I) and compound (II) may be used, e.g. a silane having at least one silicon-bonded halogen atom and one or more groups -RX, e.g. chloromethylchlorosilanes. The products may be linear and/or cyclic compounds.

Description

ELECTROCHEMICAL SYNTHESIS OF ORGANOSILICON COMPOUNDS This invention relates to an electrochemical method of synthesising organosilicon compounds, in particular polycarbosilane compounds.
The term organosilicon compounds where used herein denotes those compounds in which at least one organic group is attached to a silicon atom via a Si-C bond. These compounds include silanes having one silicon atom and at least one organic substituent which is linked to the silicon atom via a silicon-carbon linkage and carbosilane compounds having at least two silicon atoms which are linked via a group R, which denotes a divalent carbon or hydrocarbon group which may be substituted, linked to each silicon atom via a Si-C bond. Said carbosilanes include silanes of the general formula -Si-R-Si- and polycarbosilanes having at least 2 units of the general structure -(R-Si)-, wherein R is as defined above.
The formation of Si-C and Si-CH2-Si bonds is usually obtained via Grignard or Wurtz reactions involving the use of metals such as magnesium, sodium and lithium. These methods are complicated and costly and require the protection of any additional functional groups which may be present on the reagents.
Electrochemical synthesis is known and has been practised in organic chemistry for some time. Recently it has been shown that silylation of certain compounds with trimethylchlorosilane is possible via electrochemical synthesis. Shono et al (Chem. Letters 1985, pages 463 466) have demonstrated the electrochemical reduction of benzyl and allyl halides in the presence of trimethylchlorosilane to give the corresponding benzylsilanes and allylsilanes. They also show electroreduction or 1,4 dichloro butene to give 1,4 bis(trimethylsilyl)butene.
P. Pons et al (J. Organometallic Chemistry 1988, pages 31 37) disclose the electroreduction of carbon tetrachloride, chloroform and methylene chloride with trimethylchlorosilane to give the corresponding trimethylsilyl substituted compounds in the presence of a sacrificial electrode. They also exemplify the electro-reduction of trimethylchloromethylsilane with trimethylchlorosilane to obtain hexamethylsilmethylene.
We have now found that it is possible to use electrochemical synthesis for the production of organosilicon compounds as defined above by using dihalosilanes, trihalosilanes, tetrahalosilanes or halocarbohalosilanes.
According to the invention there is provided a method of making organosilicon compounds having at least one silicon-bonded organic group linked to the silicon atom via a Si-C bond by electroreduction of a compound (I) having a substituent of the general formula -RX, wherein R denotes a divalent carbon or hydrocarbon compound which may be substituted, and X is a halogen atom in the presence of (II) a silane of the general formula R'4 a bSiXa(RX)b wherein R' is selected from hydrogen, hydrocarbon groups, groups containing H, C and 0 atoms, S atoms and/or P atoms and groups consisting of C, H and N atoms and optionally 0 atoms wherein N does not form part of an amino group, X and R are as defined above, a has a value of 1, 2, 3 or 4, b has a value of 0, 1, 2 or 3 and a+b has a value of 2, 3 or 4.
Compound (I) for use in the method of the invention may be any compound which has a halogen substituted carbon atom. The halogen atom is preferably chlorine, bromine or iodine, the latter being the most reactive. For reasons oz commercial availability and for cost purposes however, chlorine and bromine are preferred. The halogen atom is linked to a compound which may be purely organic or which may be a compound having both organic and inorganic parts, for example an organosilicon compound or an organogermanium compound. The group R, to which a halogen atom is linked, is a diva lent carbon or hydrocarbon group which may be substitued. Carbon groups include e.g. acetylene and 1,3 butadiynylene. Hydrocarbon R groups can vary from methylene groups to very large hydrocarbon groups.These may be saturated alkylene groups, e.g. ethylene, isopropylene, hexylene and octadecylene, unsaturated aliphatic groups for example alkenylene or alkynylene, e.g. vinylene, propenylene, butadienylene, hexynylene, propynylene and 1,4 octadecenylene, aromatic groups, e.g. phenylene, benzylene, tolylene and phenylethylene. Substituted hydrocarbon groups are those in which the carbon atoms have one or more substituents which may be any groups which are not reactive with the halogen groups of compound (II) under reaction conditions. Such substituents include fluorine, cyano groups, nitro groups, oxyethylene groups, silyl groups, siloxane groups, carbosilyl groups. Examples of such substituted hydrocarbon groups include hexafluoropropylene, oxyethyleneoxypropylene substituted groups, acetyl substituted groups, ether substituted groups and ester substituted groups.It is preferred that the group R is an aromatically unsaturated, aliphatically unsaturated or aliphatically saturated hydrocarbon, e.g. benzylene, propenylene, isopentylene, butylene, propylene, ethylene or phenylene. Most preferred are methylene and vinylene. The R group may be linked at the other side to any atom or group. These include e.g. hydrogen atoms, hydrocarbon groups, organosilicon groups, organofunctional groups, e.g. sulphur containing groups, phosphor containing groups and even halogen atoms. Preferably the R group is linked on the other side from the X group to a hydrogen atom or a halogen atom.Examples of compound (I) include carbohalides for example methylhalide, e.g. methylchloride, dichloromethane, benzylhalide, e.g. benzylchloride, phenyl- halide, vinylhalide, 1,4 dichloro 2-butene, dibromoethylene, 1,2,bis- chloromethylbenzene, silanes, e.g.
trimethylchloromethylsilane, dimethylchloromethylchlorosilane, siloxanes, e.g. those having at least one unit of the general formula 4 x (CH2X)y wherein R' is as 2 defined above but is preferably hydrogen, a hydrocarbon, e.g. alkyl, aryl, alkenyl or alkaryl or a group containing C, H and optionally N or 0 atoms, x has a value of 0, 1 or 2, y has a value of 1, 2 or 3 and x+y are not more than 3, any other units when present having the average formula O4zSiR' wherein R' is as defined above and z has a value 2 of 0, 1, 2 or 3, or those having at least one unit of the general formula O4ySiR x(RCH2X) y wherein R, R', x and 2 are as defined above. Preferably siloxanes are avoided as it is difficult to control the nature of the reaction product.
Compound (II) for use in the method of the invention is a silane which has at least two halogen containing substituents of which at least one is a silicon-bonded halogen atom. Iodine is the most reactive halogen but for reasons of commercial availability and for cost reasons chlorine and bromine atoms are preferred. Non siliconbonded halogen atoms are linked to the silicon atom via a group R as defined above for compound (I). Examples of these halogen containing substituents are haloalkyl, e.g.
chloromethyl, chloroisopropyl, bromoheptyl, haloalkenyl, e.g. chlorovinyl, bromopropenyl, haloaryl groups, e.g.
chlorophenyl and bromobenzyl. Non-halogen containing substituents R' when present, include hydrogen, hydrocarbon groups, for example alkyl, aryl, alkaryl, aralkyl, alkenyl, alkynyl, groups containing C, H and 0 atoms for example carboxyl group containing substituents, C=O containing groups, aldehyde containing groups and epoxy containing groups, ether containing groups, sulphur containing groups or groups containing C, H and N atoms wherein N does not form part of an amino group, for example cyano group containing substituents and NO2 containing substituents.
Examples of such groups are methyl, ethyl, propyl, phenyl, phenylethyl, tolyl, vinyl, allyl, hexenyl, ethynyl, buta diynyl, stearyl, lauryl, ethoxy, methoxy, polyoxyethyl and benzyl. Preferably R' is hydrogen, alkyl or aryl, most preferably methyl or phenyl. It is preferred that the value of a+b is equal to 2, there being two R' groups which independently denote a substituent as described above. The values for a and b are preferably either 1 and 1 respectively or 2 and 0. Examples of compound (11) include dimethyldichlorosilane, dimethylchloromethylchlorosilane, methyltrichlorosilane, carboxymethyltrichlorosilane, phenylmethyldichlorosilane, diphenyldichlorosilane, methylcyanopropyldichlorosilane, methyldichlorosilane, dichlorosilane, methylbis(chloromethyl)chlorosilane and methylglycidoxypropylchloromethylchlorosilane.
Depending on which organosilicon compound one desires to synthesise certain types of compounds (I) and (II) should be selected. Additional compounds may also be added. Organosilicon compounds which may be made by the method of the invention include silanes. Silanes would be produced if (I) is a purely organic compound not having a silicon atom in its structure, and if only one -RX group is present in (I) or if more than one -RX group is present in (I) only a sufficient amount of (II) is provided to allow reaction with one -RX group of (I). Resulting silanes include e.g. methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, tetramethylsilane, chloromethyltrimethylsilane, chloromethyldimethylbutylsilane, dibromovinyldimethylsilane and many others.Carbosilanes as defined above would be provided by the elctrochemical reaction of a compound (I) with more than one -RX groups or a compound I of the formula XRX and a sufficient amount of compound (II) to react with at least two of these -RX groups or X atoms linked to R, or provision of sufficient of compound (I) having only one -RX group with compound (II) having more than one silicon-bonded halogen atoms, or the provision of certain silicon containing compounds (I), for example those having one -RX group and one SiX group for reaction with a compound (II) which may be the same.
As a general rule the value of a+b in compound (II) will, in most cases, determine the general character of the carbosilane produced. Where a+b is 2 using such compound (II) will extend the chain length of the organosilicon compound produced, whereas if a+b has a value of 3 or 4 it will introduce a certain amount of branching in the organosilicon compound leading to a three dimensional structure in some cases. Mixture of compound (II) where a+b is two and compound (Il) where a+b is 3 or 4 can lead to basically linear carbosilanes with some branching, whereas an increase in the amount of compound (II) having a value of 3 or 4 will increase the amount of branching eventually leading to a resin type carbosilane reaction product.
Depending on the nature of the desired carbosilane compound, one type of each compounds (I) and (II) may be reacted together or a mixture of different types of compound (I) and/or compound (II) may be reacted together.
It is also possible to use the same reagent for compound (I) and compound (II), for example a silane having one or more silicon-bonded halogen atoms and one or more groups -RX. For example chloromethylchlorosilanes fall within the definition of both compounds (I) and (II) can react with each other . Such reaction results in the formation of a polycarbosilane having repeating units of the formula -[Si(R')2CH]-. These compounds may be linear or cyclic or a mixture of linear and cyclic organosilicon compounds.
When linear polycarbosilanes are desired it may be preferred to add other compounds, for example end-blocking compounds which may be silanes of the formula R'3SiX, wherein R' and X are as defined above. For example in order to obtain a linear polymer having the general formula R'[Si(R')2-R]mSiR'3 the reagents should include, as well as compounds (I) and (it), a silane of the general formula R' 3SiX in sufficient amount to act as end-blocker of a polymer of the desired chain length.
it is, however, preferred to make relatively small molecules, e.g. polycarbosilanes having 2 or 3 silicon atoms which may then be used as precursors for higher molecuiar weight materials using e.g. conventional polymerisation techniques.
The reaction may be carried out in any convenient way using a cell having a cathode and an anode. The cell may be a single chamber cell but it is preferred to have two chambers which are separated by a membrane, for example a sintered disc. The cell is provided with a potentiostat and/or a galvanostat to regulate the potential or intensity of the current. The electrodes which may be used as cathode or working electrode are preferably made of an inert metal such as gold, silver or platinum, most prefer- ably silver, or of another metal or alloy which is reasonably inert, e.g. stainless steel whilst the counter electrode (anode) is either inert or may be sacrificial to some extent. The choice of counter electrode sometimes depends on the desired reaction.In certain cases a relatively inert counter electrode is preferred whilst in other cases a sacrifical electrode will perform better. Useful metals for the manufacture of the counter electrode include e.g. C, Al, Pt, Ni, Zn and Mg, C being particularly preferred as inert electrode and Al being particularly preferred as sacrificial electrode.
It is preferred to use a complexing agent in conjunction with a sacrificial Al electrode. The use of complexing agents counteracts the catalytic activity of the Lewis acids formed. Lewis acids, e.g. All3, are known catalysts for ring opening of e.g. tetramethylsilacyclobutane and even tetrahydrofuran which is suitable as a solvent for the method according to the invention.
Suitable complexing agents are known to the persons skilled in the art and include tris(dioxa-3,6 heptyl)amine and hexamethylpho sphoramide.
The cell is filled with a solution of an electrolyte which may be any of those which are commercially available and soluble in the solvent used for the reagents. These electrolytes are salts of the general formula M+Y wherein M denotes for example Li, Na, NBu4, NMe4, NEt4 and Y denotes for example C104, C1, Br, I, NO3, BF4, AsF6, BPh4, PF6, All4, CF3SO3 and SCN wherein Bu, Me, Et and Ph respectively denote a butyl, methyl, ethyl and phenyl group. Examples of suitable electrolytes include tetraethyl ammonium p-toluene sulphonic acid, tetrabutyl ammonium hexafluoro phosphate, tetrabutyl ammonium bromide, tetraethyl ammonium tetrafluoro borate, lithium chloride and magnesium chloride.
Solvents which dissolve both reagents and electrolytes are usually employed. Suitable solvents are those in which the reagent is at least partially soluble under operating conditions of concentration and temperature.
They include tetrahydrofuran, acetonitrile, y butyrolactone, dimethoxyethane with nitromethane, 1,3 dioxolane, liquid SO2, trimethylurea and dimethylformamide. The electrochemical reaction may be carried out by keeping the intensity constant at predetermined levels or by retaining a constant potential which has been determined by cyclic voltametry. Standard electrochemical techniques are applied cable to the method of the invention.
There now follow a number of examples which illustrate the invention in which all parts and percentages are expressed by weight unless otherwise stated.
Example 1 A one compartment cell equipped with a nitrogen inlet, agitation and an air cooling system was charged with 50ml of a 0.2 molar solution of tetrabutylammonium. hexafluorophosphate In tetrahydrofuran and 8.5g of chloromethyldimethylchlorosilane. A constant current density of 125mA was applied via a galvanostat/potentiostat using aluminium foil as anode and a silver wire as cathode. The current was applied over a period of 22 hours in order to apply 1.9 Faraday per mole of C1CH2.A reaction product mixture was obtained which was analysed by gas chromotography/mass spectrometry and was found to consist of about 50% cyclic compounds of which about 65% had the formula [(CH3)2Si-CH2]2, about 35% had the formula [(CH3)2Si-CH2]3 and of about 50% linear compounds of the formula ClCH2SiCCH3)2[CH2SiCCH3)2]nCl where 84% had a value for n equal to 3, about 5 to 8% each of compounds where n had the value of 2, 4 and 5 and traces of the compound where n had the value of 1.
Example 2 A 250ml flask was equipped with a nitrogen purge, magnetic stirrer, condenser and air cooling device. 100ml of a 0.2 molar solution of tetrabutylammonium hexafluorophosphate in tetrahydrofuran and 15.4g of 3-chloropropyl dimethylchlorosilane were added. An electrochemical reaction was carried out using a model 362 potentiostat galvanostat. The cathode was a silver wire (5cm length and 0.25mm diameter) and the anode was 4 aluminium strips (3 x 5 x 0.01cm).A constant current was applied during 25 hours (giving 2.5 Faraday per mole of silane) at a temperature of 23"C. The resulting reaction mixture was analysed by gas chromatography/mass spectrometry. 83.71 was l,l-dimethyl-l-silacyclobutane, 8.1 unreacted 3-chloropropyl dimethylchlorosilane and 7.9 propyl dimethylchlorosilane.
Example 3 A 250ml flask was equipped with a nitrogen purge, magnetic stirrer, condenser and air cooling device. 150ml of a 0.2 molar solution of tetrabutylammonium hexafluorophosphate in tetrahydrofuran and 25.5g of chloromethyl dimethylchlorosilane were added. An electrochemical reaction was carried out as in the previous example except that 2.8 Faraday was applied per mole of silane at a temperature of 30"C. The resulting reaction mixture was analysed as above. 62.6% was 1,1,3,3-tetramethyl-1,3- disilacyclobutane and 31.4% 1,1,3,3,5,5-hexamethyl-1,3,5trisilacyclohexane.
Example 4 A 250ml flask was equipped with a nitrogen purge, magnetic stirrer, condenser and air cooling device. 100ml of a 0.2 molar solution of tetrabutylammonium hexafluorophosphate in tetrahydrofuran and 5.24g of a,a,o-dichloroxylene and 4g of dichlorodimethylsilane were added. AI1 electrochemical reaction was carried out as in the previous example except that 4.8 Faraday was applied per mole of o-dichloroxylene. The resulting reaction mixture was washed in water, extracted with diethylether, dried and analvsed as above. 65% had the formula
Example 5 A 250ml flask was equipped with a nitrogen purge, magnetic stirrer, condenser and air cooling device. 100ml of a 0.2 molar solution of tetrabutylammonium hexafluorophosphate in tetrahydrofuran, 3.70g of cis-dichlorobutene and 4g of dichlorodimethylsilane were added.An electrochemical reaction was carried out as in the previous example except that 2.13 Faraday was applied per mole of cis-dichlorobutene. The resulting reaction mixture was analysed and showed 15% dimethylsilacyclopentene.
Example 6 A 250ml flask was equipped with a nitrogen purge, magnetic stirrer, condenser and air cooling device. 100ml of a 0.2 molar solution of tetrabutylammonium hexafluorophosphate in tetrahydrofuran, 12.5g of chloromethyltrimethylsilane and 6.5g of dichloromethylsilane were added.
An electrochemical reaction was carried out as in the previous example except that 2.3 Faraday was applied per mole of chloromethyltrimethylsilane. The resulting reaction mixture was analysed and showed 25% bis(trimethylsilyl)methylsilane.
Example 7 A Schlenk tube was equipped with an aluminium rod as anode (99.5% pure, 6.35mm diameter) and a cylindrical stainless steel gauze as cathode (20 mesh, 30cm2). A solution of 14.3ml of tetrahydrofuran, 0.08g of tetraethylammonium tetrafluoroborate, 3.6ml of hexamethylphosphoramide and O.lml of trimethylchlorosilane was preelectrolysed at lOOmA for 2 hours. 2.28g of chloromethyl- dimethylchlorosilane were added. An electrochemical reaction was carried out by applying a constant current during 10 hours (giving 2.3 Faraday per mole of silane) at a temperature of 23"C. The resulting reaction mixture was filtered and stripped under reduced pressure to give 11.68g of distillate.Analysis by gas chromatography/mass spectrometry yielded 69% of 1,1,3,3-tetramethyl-1,3- disilacyclobutane.
Example 8 Using the set-up of Example 7, 4.24g of chloropropyltrichlorosilane was added to the reaction product of the previous example and the electrolysis continued at 200mA for almost 6 hours. After three and a half hours a maximum conversion to dichlorosilacyclobutane of 45% was observed.
Example 9 The set-up of Example 7 was used except that a condenser, cooled with solid carbon dioxide, was added to minimise loss of reagents. A solution of 8.45ml of tetrahydrofuran, 0.08g of tetraethylammonium tetrafluoroborate, 2.lml of hexamethylphosphoramide, 6.4ml of dichloromethane and O.lml of trimethylchlorosilane was pre-electrolysed at 50mA for 2 hours. 3.03ml of chloromethyldimethylchlorosilane were added. An electrochemical reaction was carried out by applying a constant current during 53 hours (giving 4 Faraday per mole of silane) at a temperature of 23"C.
The resulting reaction mixture was analysed by gas chromatography/mass spectrometry yielding 74% of dimethyldichloromethylsilane.
Example 10 The set-up of Example 9 was used. A solution of 9.16ml of tetrahydrofuran, 0.08g of tetraethylammonium tetrafluoroborate, 2.29my of hexamethylphosphoramide, 1.28ml of dichloromethane and O.lml of trimethylchlorosilane was pre-electrolysed at 50mA for 2 hours. 7.27ml of dimethyldichlorosilane was added and the electrolysis continued at 50mA for 24 hours giving 2.2 Faraday per mole of silane). The resulting reaction mixture was analysed by gas chromatography/mass spectrometry yielding 81% (based on reacted silane) of chlorodimethyl chloromethylsilane.
Example 11 The set-up of Example 9 was used. A solution of 12.67ml of tetrahydrofuran, 0.08g of tetraethylammonium tetrafluoroborate, 3.12ml of hexamethylphosphoramide, 0.85ml of dichloromethane and O.lml of trimethylchlorosilane was pre-electrolysed at 50mA for 2 hours. 4.48ml of methyltrichlorosilane was added and the electrolysis continued at 50mA for 12.5 hours giving 2.2 Faraday per mole of silane). The resulting reaction mixture was analysed by gas chromatography/mass spectrometry yielding 62% of methyldichloro chloromethylsilane and 13% of methylchlorodichloromethylsilane.
Example 12 The set-up of Example 9 was used. A solution of 11.8ml of tetrahydrofuran, 0.08g of tetraethylammonium tetrafluoroborate, 2.95my of hexamethylphosphoramide, 0.64ml of dichloromethane and O.lml of trimethylchlorosilane was pre-electrolysed at 50mA for 2 hours. 6.79g of tetrachlorosilane was added and the electrolysis continued at 50mA for 12.5 hours (giving 2.2 Faraday per mole of silane). The resulting reaction mixture was analysed by gas chromatography/mass spectrometry yielding 58% of trichlorochloromethylsilane, 15% of dichloro dichloromethylsilane and 3% of chloro trichloromethylsilane.
Example 13 The set-up of Example 9 was used. A solution of 12.37m1 of tetrahydrofuran, 0.08g of tetraethylammonium tetrafluoroborate, 3.09ml of hexamethylphosphoramide, 1.12ml of phenylchloride and O.lml of trimethylchlorosilane was pre-electrolysed at 50mA for 2 hours. 4.48g of methyltrichlorosilane was added and the electrolysis continued at 50mA for 12.5 hours (giving 2.2 Faraday per mole of silane). The resulting reaction mIxture was analysed by gas chromatography/mass spectrometry yielding 65% dichlorophenylmethylsilane, 10% of methylchlorodiphenylsilane and 6% of dichloromethyl silphenylene.
Example 14 The set-up of Example 9 was used. A solution of 11.52ml of tetrahydrofuran, 0.08g of tetraethylammonium tetrafluoroborate, 2.88my of hexamethylphosphoramide, 1.12ml of phenylchloride and O.lml of trimethylchlorosilane was pre-electrolysed at 50mA for 2 hours. 6.79g of methyltrichlorosilane was added and the electrolysis continued at 50mA for 12.5 hours (giving 2.2 Faraday per mole of silane). The resulting reaction mixture was analysed by gas chromatography/mass spectrometry yielding 68% trichlorophenylsilane, 10% of dichlorodiphenylsilane and 8% of trichloro silphenylene.

Claims (18)

  1. I. A method of making organosilicon compounds having at least one silicon-bonded organic group, linked to the silicon atom via a Si-C bond by electroreduction of a compound (I) having a substituent of the general formula -RX wherein R denotes a divalent carbon or hydrocarbon compound which may be substituted and X is a halogen atom in the presence of (II), a silane of the general formula R 4~a~bSiXa(RX)b wherein R' is selected from hydrogen, hydrocarbon groups, groups containing H, C and 0 atoms, S atoms and/or P atoms and groups consisting of C, H and N atoms and optionally 0 atoms wherein N does not form part of an amino group, X and R are as defined above, a has a value of 1, 2, 3 or 4, b has a value of 0, 1, 2 or 3 and a+b has a value of 2, 3 or 4.
  2. 2. A method according to Claim 1 wherein X is chlorine.
  3. 3. A method according to either Claim 1 or Claim 2 wherein the group R in compound (I) is an aromatically unsaturated, aliphatically unsaturated or aliphatically saturated hydrocarbon.
  4. 4. A method according to any one of the preceding claims wherein in compound (II) R' is hydrogen, alkyl or aryl.
  5. 5. A method according to Claim 4 wherein R' is methyl or phenyl.
  6. 6. A method according to any one of the preceding claims wherein in compound (II) the value of a+b is equal to 2.
  7. 7. A method according to any one of the preceding claims carried out in a cell having two chambers which are separated by a membrane.
  8. 8. A method according to any one of the preceding claims wherein the cathode is made of silver or stainless steel.
  9. 9. A method according to any one of the preceding claims wherein the anode is inert.
  10. 10. A method according to Claim 9 wherein the anode is made from C.
  11. 11. A method according to any one of Claims 1 to 8 wherein the anode is sacrifical to some extent.
  12. 12. A method according to Claim 11 in which the anode is made of aluminium.
  13. 13. A method according to any one of the preceding claims wherein a complexing agent is used.
  14. 14. An organosilicon compound in which at least one organic group is attached to a silicon atom via a Si-C bond, made by a method, according to any one of the preceding claims.
  15. 15. A silane having one silicon atom and at least one organic substituent which is linked to the silicon atom via a siliconcarbon linkage, made by a method, according to any one of Claims I to 13.
  16. 16. A carbosilane having at least two silicon atoms which are linked via a group R which denotes a divalent carbon or hydrocarbon group which may be substituted, linked to the silicon atoms via Si-C bonds, made by a method, according to any one of Claims 1 to 13.
  17. 17. A polycarbosilane having at least 2 units of the general structure -(R-Si)- wherein R is as defined above, made by a method, according to any one of Claims 1 to 13.
  18. 18. A method for making organosilicon compounds essentially as described herein with reference to any one of the examples.
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2681866A1 (en) * 1991-09-27 1993-04-02 Rhone Poulenc Chimie Process for the synthesis of organosilicon compounds and organosilicon compounds
EP0629718A1 (en) * 1993-06-17 1994-12-21 Wacker-Chemie GmbH Process for electrochemical synthesis of organic silicon compounds as well as an apparatus for carrying outsaid process and the use of said apparatus for preparing said organic silicon compounds
WO1996008519A2 (en) * 1994-09-12 1996-03-21 The Dow Chemical Company Silylium cationic polymerization activators for metallocene complexes
FR2791705A1 (en) * 1999-04-01 2000-10-06 Rhodia Chimie Sa Preparation of a silylated carbonylated and halogenated derivative by electrolysis of a polyhalogenated or fluorinated carbonylated substrate in the presence of a silylating agent
WO2014070270A1 (en) * 2012-11-02 2014-05-08 Dow Corning Corporation Electrochemical route to prepare hydrocarbyl-functional silicon compounds
CN107835815A (en) * 2015-05-27 2018-03-23 陶氏环球技术有限责任公司 The method for preparing double (chloromethyl) dichlorosilanes and double (chloromethyl) (aryl) chlorosilanes
WO2023222245A1 (en) 2022-05-20 2023-11-23 Wacker Chemie Ag Process for producing organosilicon compounds

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Benzylsilanes", pages 463-466 Journal of ORGANOMETALLIC CHEMISTRY *
CHEMISTRY LETTERS,1985, T.SHONO et al,"An Electroreductive systhesis of Allylsilanes and *

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2681866A1 (en) * 1991-09-27 1993-04-02 Rhone Poulenc Chimie Process for the synthesis of organosilicon compounds and organosilicon compounds
EP0629718A1 (en) * 1993-06-17 1994-12-21 Wacker-Chemie GmbH Process for electrochemical synthesis of organic silicon compounds as well as an apparatus for carrying outsaid process and the use of said apparatus for preparing said organic silicon compounds
US5538618A (en) * 1993-06-17 1996-07-23 Wacker-Chemie Gmbh Process for the electrochemical synthesis of organosilicon compounds, and an appliance for carrying out the process, and use thereof for preparing organosilicon compounds
WO1996008519A2 (en) * 1994-09-12 1996-03-21 The Dow Chemical Company Silylium cationic polymerization activators for metallocene complexes
WO1996008519A3 (en) * 1994-09-12 1996-06-13 Dow Chemical Co Silylium cationic polymerization activators for metallocene complexes
FR2791705A1 (en) * 1999-04-01 2000-10-06 Rhodia Chimie Sa Preparation of a silylated carbonylated and halogenated derivative by electrolysis of a polyhalogenated or fluorinated carbonylated substrate in the presence of a silylating agent
WO2000060139A1 (en) * 1999-04-01 2000-10-12 Rhodia Chimie Method for preparing silylated, carbonylated and halogenated derivatives by electrolysis
WO2014070270A1 (en) * 2012-11-02 2014-05-08 Dow Corning Corporation Electrochemical route to prepare hydrocarbyl-functional silicon compounds
CN107835815A (en) * 2015-05-27 2018-03-23 陶氏环球技术有限责任公司 The method for preparing double (chloromethyl) dichlorosilanes and double (chloromethyl) (aryl) chlorosilanes
CN107835815B (en) * 2015-05-27 2021-02-26 陶氏环球技术有限责任公司 Process for preparing bis (chloromethyl) dichlorosilane and bis (chloromethyl) (aryl) chlorosilane
WO2023222245A1 (en) 2022-05-20 2023-11-23 Wacker Chemie Ag Process for producing organosilicon compounds

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