Improved direct synthesis of alkenyl halosilanes

Abstract

Process for the direct synthesis of alkenyl halosilane monomers. In a thermally stable solvent, a slurry of a liquid and copper-activated silicon is formed from fresh silicon, cyclonic fines and / or fines from silicon milling, ultrafine particles and / or waste contact materials from direct synthesis of alkyl halosilanes and aryl halosilanes. In the presence of a Lewis base additive that inhibits polymerization, at a reaction time, temperature, and pressure effective to produce an alkenyl halosilane having the formulae R1SiHX2, R12aSiHX, R13SiX, R1SiX3, and R12SiX2, or mixtures thereof, the alkenyl halosilane is polymerized by stirring the slurry to produce an alkenyl halosilane having the formulae R1SiHX2, R12aSiHX, R13SiX, R1SiX3, and R12SiX2, or mixtures thereof. The silane is reacted with at least one unsaturated aliphatic or cycloaliphatic organohalide of formula R1X, and optionally an organohalosilane and / or hydrogen halide.

Description

TECHNICAL FIELD

[0001] The present invention relates to the synthesis of alkenyl halosilanes from reaction residues and by-products of silicon powders, in particular copper-activated silicon, in particular slurry-phase Direct Synthesis. Such silicon sources include silicon-containing solid residues generated during the direct synthesis of organohalosilanes from organic halides. BACKGROUND

[0002] Allyl halosilanes are useful intermediates for the synthesis of organic specialties and for the synthesis of sulfur-silanes for tire and rubber applications (see US 3,890,213; US 8,003,724; US 8,349,940; US 8,536,261). A particularly valuable intermediate is allyl trichlorosilane, which can be converted to allyl triethoxysilane for the synthesis of sulfur-containing silanes. US 2,563,288 and US 2,649,396 disclose the use of diallyldiethoxysilane for the preparation of polyester-glass fiber laminates. Polymerization of the products can occur during the direct synthesis of allyl chlorosilanes and other alkenyl halosilanes. Thus, the reactions are typically unstable and monomer yields are typically low.

[0003] Conventional methods for the synthesis of allyl silanes include Grignard reactions (see for example T. K. Sarkar, Science of Synthesis Vol. 4 (2002) 837-922) and dehydrohalogenation of halopropylsilanes (see for example Bailey, D. L.; Pines, A. N. Ind. Eng. Chem., 1954, 46, 2363).

[0004] Hurd (J. Amer. Chem. Soc, 67 (1945) 1813; US Patent 2,420,912) reported the direct reaction of allyl chloride with copper-silicon alloys in a fixed bed at 200-400 °C, optimally 230-300 °C. The product mixture contained allyldichlorosilane (ADCS, C3H5SiHCl2), diallyldichlorosilane (DADCS, (C3H5)2SiCl2) and allyltrichlorosilane (ATCS, C3H5SiCl3), the latter being the most abundant.

[0005] US 2,904,574 discloses the direct synthesis of allyl chlorosilanes via the fixed bed reaction of allyl chloride with silicon coated with Cu2S (copper (I) sulfide) at 150-220 °C. The examples illustrate that the product mixture contains 1-5 wt% allyldichlorosilane (ADCS, C3H5SiHCl2), 13-16 wt% allyltrichlorosilane (ATCS, C3H5SiCl3) and 11-24 wt% diallyldichlorosilane (DADCS, (C3H5)2SiCl2) in addition to unconverted allyl chloride and 30-50 wt% of a non-distillable, high-boiling residue.

[0006] US 5,338,876 discloses the direct synthesis of allyl chlorosilanes in stirred bed and fluidized bed reactors at 220-350 °C and 1-5 atmospheres, preferably at 300-330 °C and 1-3 atmospheres. The disclosure is specifically directed to the direct synthesis of allyldichlorosilane (ADCS) by reacting fresh silicon metal with a mixture of allyl chloride (AC) and hydrogen chloride, which is in molar excess. A journal publication accompanying this information is Yeon et al. (Organometallics, Vol. 12 (1993), pp. 4887-4891). Further references on the direct synthesis of allyl halosilanes and other alkenyl halosilanes with fresh silicon metal in fixed bed, stirred bed or fluidized bed reactors are as follows: R. J. H. Voorhoeve, Organohalosilanes: Precursors to Silicones, pp. 203-204; Petrov et al., Synthesis of Organosilicon Monomers, pp. 44-46 and Table 5 on p. 55.

[0007] Hurd (see above) points out the rapid polymerization of diallyldichlorosilane when heated above 150 °C in the absence of polymerization inhibitors. However, there is no teaching on how to control or avoid polymerization during the direct synthesis to achieve reaction stability. Polymerization of diallyl substrates including diallyldimethylsilane is reported in Forbes et al., J. Amer. Chem. Soc, Vol. 114 (1992) pp. 10978-10980; Marvel et al., J. Org. Chem., Vol. 25 (1960) pp. 1641-1642; Butler et al., J. Org. Chem., Vol. 25 (1960) pp. 1643-1644.

[0008] Alkyl and aryl halosilanes are valuable precursors to organosilanes and organofunctional silanes used in a wide range of industries. Methylchlorosilanes and phenylchlorosilanes are particularly valuable and are the most commonly manufactured products in these classes. Manufacture typically uses the Rochow-M ller Direct Process (also known as Direct Synthesis and Direct Reaction) in which copper-activated silicon is reacted with the corresponding organohalide in a gas-solid or slurry phase reactor at temperatures and pressures sufficient to achieve the desired reaction rate and stability as well as product selectivity and yield. Fluidized bed reactors are the most commonly used gas-solid reactors. ller Direct Process, copper-activated silicon is reacted with the corresponding organohalide in a gas-solid or slurry phase reactor at temperatures and pressures sufficient to achieve the desired reaction rate and stability as well as product selectivity and yield. Fluidized bed reactors are the most commonly used gas-solid reactors.

[0009] Organohalosilanes have the general formula R 1 a SiX b where R 1 is a saturated or unsaturated aromatic group, a saturated or unsaturated aliphatic group, an alkylaryl group, or an alicyclic hydrocarbyl group, such as methyl, ethyl, or phenyl, X is a halogen atom, such as chlorine or bromine, and a and b are positive integers, with the proviso that the sum (a+b)=4.

[0010] Organohalohydrosilanes have the general formula R 1 c SiH d X e where R 1 and X have the same meaning as above. The subscripts c, d, and e are positive integers that satisfy the sum (c+d+e=4).

[0011] In halosilanes (H f SiX g ), f≥0 and g is an integer such that (f+g=4). X is a halogen atom as defined above.

[0012] Organohalodisilanes contain one Si-Si bond, as shown in the general formula (R 1 h X j SiSiX k R 1 l ). R 1 and X have the same meaning as defined above. The subscripts h, j, k, and l are individually≥0, with the sum (h+j=3) and (k+l=3). By extension, trisilanes contain Si-Si-Si units, and polysilanes have more than three catenated Si atoms.

[0013] Typically, for the Direct Process (Rochow-M The silicon produced by the direct process (Iller process) is chemical grade with a pure silicon content of 98.5–99.5% by weight. (All percentages herein are by weight unless otherwise stated.) This silicon can be produced by any method currently in practice, such as casting, water granulation, atomization, and acid leaching. These methods are described in more detail in: Silicon for the Chemical Industry (edited by H. Oye et al.), Volume I (pp. 39–52), Volume II (pp. 55–80), Volume III (pp. 33–56, 87–94), Tapir Publishers, Norwegian Institute of Technology; and U.S. Patents 5,258,053, 5,015,751, 5,094,832, 5,128,116, and 4,539,194.

[0014] The hot effluent from a fluidized bed reactor (in which copper-activated silicon undergoes a reaction with organohalides) typically contains a mixture of copper, metal halides, silicon, silicides, carbon, gaseous organohalides, organohalosilanes, organohalodisilanes, carbosilanes, and hydrocarbons. This mixture typically undergoes gas-solid separation first in a cyclone separator and filter (see US4,328,353). The gaseous mixture and ultrafine solids condense in a setter or sludge tank, from which the organohalides, organohalosilanes, hydrocarbons, and a subset of organohalodisilanes and carbosilanes are evaporated and sent to fractional distillation. Ultrafine solids typically accumulate in settling tanks along with less volatile silicon-containing compounds, and this mixture (slurry) is typically periodically removed and sent to waste disposal or secondary treatment to recover monomers from the liquid fraction.

[0015] Three silicon-containing solid wastes are typically generated from a fluidized bed. (1) Elutriated solids captured by cyclone separators or filters are called cyclone fines or cyclone solids; (2) those particulates that escape the cyclone and are collected in a settler are called ultrafines, settler solids, or reboiler solids; and (3) the unreacted solids remaining in the fluidized bed at the end of a campaign. This is called spent mass or spent contact mass. Typically, the spent mass has a larger average particle size and a broader particle size distribution than the cyclone solids. The cyclone solids are typically larger than the ultrafines. The spent mass and cyclone fines are dry solids, which can be pyrophoric. The ultrafines are typically wet and agglomerate into a slurry. For this reason, the ultrafines are sometimes called slurry.

[0016] World-scale methyl chlorosilane plants typically generate and therefore need to dispose of thousands of tons of ultrafines, cyclone solids, and spent mass per year at considerable cost and loss of raw material value. In addition, there are environmental impacts of the waste disposal methods employed. Accordingly, it is desirable to recover valuable materials from these waste solids. Methods for reusing the solids for copper recovery, for producing chlorosilanes, alkoxysilanes, methyl chlorosilanes, and phenyl chlorosilanes have been disclosed in patent and journal literature. However, the reactions can be unstable and monomer yields are typically low.

[0017] US 5,342,430 discloses passivation of cyclone solids for safe landfill disposal or later copper recovery.

[0018] US 2,803,521 discloses a process for separating and recovering silicon and copper from spent reaction mass. Soucek et al. (Chem. Abstr. Vol. 64 (1966) 17638c) and Kopylov et al. (Chem. Abstr. Vol. 75 (1971) 14421g) disclose metallurgical processes for recovering copper from calcined spent mass.

[0019] Rathousky et al. (Chem. Abstr., Vol. 81 (1974) 78008) reported the direct synthesis of phenylchlorosilanes from waste material directly synthesized from methylchlorosilanes. Takami et al. (Chem. Abstr., Vol. 89 (1978) 509946) disclosed a similar direct synthesis of phenylchlorosilanes from methylchlorosilane waste material first heated to 500-900°C.

[0020] Ritzer et al. (US 4,390,510) and others have shown that cyclone fines react with HCl to produce trichlorosilane and silicon tetrachloride. Cyclone fines react with alcohols to produce alkoxysilanes. These uses of cyclone solids are mentioned in Catalyzed Direct Reactions of Silicon, K. M. Lewis and D. G. Rethwisch (eds.), Elsevier, NY 1993, pp. 28-29 and references cited therein.

[0021] US 5,712,405 discloses collecting cyclone fines and filtered fines and recycling them to the bottom of a fluidized bed reactor for further reaction with organic halides to produce organohalosilanes.

[0022] US 6,465,674 discloses introducing cyclone fines into liquid silane and re-injecting the suspension into a fluidized bed for direct synthesis of chloro- or organochloro-silanes.

[0023] US 4,224,297 discloses a method of reusing waste material having a maximum particle size of 50 microns by heating it in air or nitrogen at 100-350°C for at least 15 hours before reacting it with methyl chloride to produce methylchlorosilane monomers. This particle size distribution is too small for most conventional Rochow-M ller fluidized bed reactors.

[0024] The foregoing references describing the synthesis of organohalosilanes from cyclone fines and waste material involve gas-solid reactions in two-phase reactors. Those cited below are conducted in three-phase reactors such as mechanically agitated slurry reactors and bubble columns employing all three phases.

[0025] British Patent GB 1,131,477 describes a process for preparing alkylhalosilanes which involves suspending a contact mass composition in an inert liquid such as a halogenated aromatic hydrocarbon at a temperature above 175°C and reacting it with an alkyl halide to produce an alkylhalosilane.

[0026] US7,153,991 discloses the direct slurry phase synthesis of organohalosilanes, which includes preparing a slurry of nano-sized copper catalyst and silicon (90% of which is between about 1 and about 300 micrometers) in a thermally stable organic solvent, and subsequently reacting it with an organohalide at a temperature greater than 250°C.

[0027] US Patent 9,249,165 discloses a direct catalytic slurry phase synthesis of finely separated organohalosilanes from cyclone separation, wherein specific additives are used to pre-prevent solvent decomposition. The accompanying drawings depict the conversion used to produce dimethyldichlorosilane. The additives include terpenes, hexamethyldisiloxane, diphenylamine, and... - Solvent-protecting additives for dialkyl polyethers.

[0028] All references cited in this specification (above and below) are incorporated herein by reference in their entirety.

[0029] Numerous attempts have been made to recover valuable components, particularly methylchlorosilane monomers, from waste materials and cyclone-separated solids generated during the direct synthesis of organohalosilanes (e.g., methylchlorosilanes). However, none of these attempts have yielded a reliable process for producing sufficient quantities of high-value alkenylhalosilane compositions.

[0030] The aim is to develop an improved method for synthesizing alkenyl halosilanes that avoids the drawbacks of conventional methods. Summary of the Invention

[0031] This invention provides a stable and efficient direct synthesis of alkenyl halosilanes (particularly allyl halosilanes) from fresh copper-activated silicon, cyclone-separated fine particles, waste materials, ultrafine particles, silicon dust from grinding, and mixtures thereof, offering improved product yields and efficiency. This includes the direct synthesis of organohalosilanes (Rochow-M... The silicon-containing solid residues generated during the Lewis direct process and appropriate organohalides are used to synthesize alkenyl halosilanes. According to the invention, certain additives exhibiting Lewis base properties effectively prevent or inhibit undesirable side reactions, including the polymerization of allyl halosilanes, in advance.

[0032] One embodiment of the present invention provides a process for synthesizing alkenyl halosilanes. The process includes forming a slurry of copper-activated silicon in a heat-stable solvent, the copper-activated silicon being derived from fresh silicon, cyclone-separated fine particles, fine dust from silicon milling, ultrafine particles, and / or waste contact material from the direct synthesis of organohalosilanes. The slurry is stirred and then mixed with at least one of the formulas R... 1 X reacts with unsaturated aliphatic or unsaturated cycloaliphatic organohalides, and optionally with organohalosilanes and / or hydrogen halides.

[0033] According to the present application, selected additives are added to suppress or control undesired side reactions and polymerization of the desired monomers. These additives typically exhibit Lewis base properties which can coordinate or react with Lewis acids or adsorb on free copper surfaces, among other mechanisms.

[0034] Reaction time, temperature and pressure are controlled to produce a mixture of R 1 SiHX2, R 1 2SiHX, R 1 3SiX, R 1 SiX3and R 1 2SiX2or mixtures thereof. R 1 is an unsaturated aliphatic or cyclic alkenyl group and X is a halogen. The alkenyl halosilane or mixtures thereof can then be recovered from the solvent or more reactants can be added.

[0035] According to the present application, additives exhibiting Lewis base properties include selected sulfur-containing compounds. These preferably include aliphatic and / or aromatic mercaptans, aliphatic and aromatic sulfides, thioureas and aliphatic and aromatic thioureas, phenothiazines and thioesters.

[0036] In another aspect of the present application, the additives can be tetramethyl urea and mixtures of tetramethyl urea and hexamethyldisiloxane, and mixtures thereof with one or more sulfur-containing additives.

[0037] Yet another aspect of the present application is directed to the selective slurry phase direct synthesis of allyl trihalosilane, or mixtures of allyl trihalosilane and allyl dihalosilane, from copper-activated silicon (including fresh silicon, mill dust, cyclone fines, ultrafines and / or waste material) and allyl halide, in the presence of hydrogen halide and an additive capable of suppressing Lewis acid catalyzed polymerization of the allyl halosilane.

[0038] Thus, the present application enhances the stability of the slurry phase direct synthesis. The present application also enables the stable slurry phase direct synthesis of allyl chlorosilane from cyclone fines and / or fresh silicon at acceptable yields. DETAILED DESCRIPTION

[0039] The present application relates to the production of monomers such as alkenyl halosilanes. A catalytic process is provided for converting process by-products, including fresh copper-activated silicon, as well as ultrafines, waste material and / or cyclone fines from the direct synthesis of organohalosilanes, into more useful and potentially valuable products such as alkenyl halosilanes. Preferred products include monomers having the general formula: 1 SiHX2, R 1 2SiHX, R1 2SiX2, R 1 3SiX and R 1 SiX3 (and mixtures thereof). Particularly desirable monomers have the following general formula: R 1 SiHX2 and R 1 SiX3. R 1 Preferably, it is an unsaturated aliphatic or cycloalkenyl group, and X is a halogen atom.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Generally, the nomenclature used herein and the laboratory procedures described are well-known and customarily adopted in the art. When a term is given in the singular, the inventors also anticipate that the plural form of that term will also apply.

[0041] The phrase "fresh silicon and fresh copper-activated silicon" refers to silicon that has not previously reacted with organohalides or alcohols, but may have reacted with hydrogen halides, and copper-activated silicon.

[0042] "Direct process," "direct synthesis," and "direct reaction" refer to Eugene Rochow and Richard M. The Ller process (which is the most commonly used technique for the industrial-scale preparation of organosilicon compounds) involves a copper-catalyzed reaction of alkyl halides with silicon, and typically occurs in a chemical reactor, particularly in a fluidized bed reactor.

[0043] As used herein, "alkyl" refers to straight, branched, and cyclic alkyl groups. Specific and non-limiting examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, and isobutyl.

[0044] In this document, "substituted alkyl" means an alkyl group containing one or more substituents that are inert under the process conditions experienced by the compound containing these groups. The substituents will not materially or harmfully interfere with the process.

[0045] As used herein, “aryl” refers to a non-limiting group of any aromatic hydrocarbon from which one hydrogen atom has been removed. An aryl group may have one or more fused aromatic rings linked by single bonds or other groups. Specific and non-limiting examples of aryl groups include, but are not limited to, tolyl, xylyl, phenyl, and naphthyl.

[0046] "Substituted aryl" herein refers to substituted aromatic groups as set forth in the definition of "substituted alkyl" above. Like aryl groups, substituted aryl groups can have one or more aromatic rings that can be fused, connected by single bonds or other groups; however, when the substituted aryl group has a heteroaromatic ring, the free valence in the substituted aryl group can be to a heteroatom (e.g., nitrogen) rather than carbon of the heteroaromatic ring. Unless otherwise specified, it is preferred that substituted aryl groups herein contain from 1 to about 30 carbon atoms.

[0047] The present invention can involve a three-phase catalytic process. Copper-activated silicon, waste material, cyclone fines and / or ultrafines are suspended in a thermally stable liquid. This is then reacted with a gaseous alkenyl halide in the presence of an additive that exhibits Lewis base properties that suppress side reactions and polymerization. Hydrogen halide can optionally be included. The desired organohalosilane is then recovered. Temperature, pressure, solvent / solids ratio, catalyst concentration and reaction time can be adjusted to selected levels to achieve the desired conversion to alkenylhalosilane monomers. This type of three-phase catalytic process can also be referred to as a slurry phase process.

[0048] A preferred slurry phase process for the direct synthesis of alkenylhalosilane monomers from fresh copper-activated silicon, waste material, cyclone solids and ultrafines according to the present invention can provide a silicon conversion of at least 40 wt% or higher. The sum (ATCS + ADCS) can be 40 wt%, 60 wt% and even higher of the crude. Allyl chloride is the preferred reactant and gaseous HCl is preferably injected with it.

[0049] The process according to the present invention can be characterized by additives, such as selected sulfur-containing compounds that suppress side reactions. These can reduce or eliminate polymerization of the alkenylhalosilane and enable both lower solvent / solids ratios and increased silicon conversion to produce higher value alkenylhalosilane monomers.

[0050] When the organic halide is an alkenyl halide (R 1 X), the reaction product is typically R 1 2SiX2, R 1 2SiHX, R 1 SiHX2, R 1 3SiX and R 1 SiX3, where R 1 is an alkenyl group having 2 to 8 carbon atoms, such as vinyl, allyl, methallyl or cyclohexenyl, and X is a halogen. When the organic halide is an allyl halide, both the allyltrihalosilane and the allyldihalosilane are highly desirable.

[0051] Accordingly, the present application provides a process for the synthesis of organohalosilane monomers of the general formula R 1 X in a three-phase reactor. The process comprises the steps of: 1 SiHX2, R 1 2SiHX, R 1 3SiX, R 1 SiX3, and R 1 2SiX2, or mixtures thereof, wherein R 1 is an unsaturated aliphatic or cyclic alkenyl group, and X is a halogen. Preferably, R 1 Examples include allyl, vinyl, methallyl, and cyclohexenyl groups.

[0052] A preferred process according to the present application comprises the steps of:

[0053] (1) forming a slurry of copper-activated silicon in a thermally stable solvent, the copper-activated silicon being derived from fresh silicon, cyclone fines, cyclone fine dust, silicon ultrafines, and / or waste contact material from direct synthesis of organohalosilanes;

[0054] (2) agitating the slurry;

[0055] (3) reacting the agitated slurry with at least one unsaturated aliphatic or cyclic aliphatic organohalide of the formula R 1 X in the presence of an additive exhibiting Lewis base properties, the additive being effective to inhibit polymerization of the alkenylhalosilane, the reaction being conducted at a reaction time, reaction temperature, and reaction pressure effective to produce an alkenylhalosilane of the formula R 1 SiHX2, R 1 2SiHX, R 1 3SiX, R 1 SiX3, and R 1 2SiX2, or mixtures thereof, wherein R 1 is an unsaturated aliphatic or cyclic alkenyl group, and X is a halogen; and

[0056] (4) recovering the alkenylhalosilane from the slurry.

[0057] In another embodiment, the process of the present application can further comprise the additional steps of:

[0058] (5) separating the solid reaction residue from the liquid and recovering the liquid for reuse in step (1); and / or

[0059] (6) passivating the solids for disposal or copper recovery.

[0060] to the general formula R 1 SiX3and R 1 The preference for alkenyl halosilanes of the general formula SiHX2may be expressed in terms of the following weight ratios:

[0061] (R 1 SiX3 / R 1 2SiX2),

[0062] (R 1 SiHX2+ R 1 SiX3) / R 1 2SiX2,

[0063] R 1 SiX3 / (R 1 2SiX2+ R 1 3SiX + R 1 SiHX2+ R 1 2SiHX), and

[0064] (R 1 SiHX2+ R 1 SiX3) / (R 1 2SiX2+ R 1 3SiX + R 1 2SiHX).

[0065] Each of these ratios is desirably greater than 1 and more preferably greater than 5. For R 1 SiX3and R 1 One reason for the desirability of SiX3and SiHX2is that they can be readily converted to alkenylalkoxysilanes, such as allyltriethoxysilane, which has utility as an organofunctional silane coupling agent.

[0066] Reaction rates can be recorded as the temporal consumption of silicon or alkenyl halide, or as the temporal formation of alkenylhalosilane. Typical rate units include weight percent silicon conversion per hour, weight of crude alkenylhalosilane produced per hour, or kilogram of alkenylhalosilane per kilogram of silicon per hour. Stability can be considered as the maintenance of a desired rate and selectivity until all of the starting materials are consumed, or until a pre-set limit of silicon conversion is exceeded.

[0067] The alkenyl halide is introduced into the slurry as a gas, vapor, and / or liquid. Liquid feeds can be used provided that the flow rate is controlled to avoid a substantial decrease in reaction temperature and / or rapid expansion of bubbles formed during vaporization. Mixtures of alkenyl halides and mixtures of alkenyl halides and hydrogen halide can also be used. Mixtures of allyl halide and hydrogen halide provide increased R 1 Formation of SiHX2. According to a preferred embodiment of the present application, it is advantageous that the molar ratio of allyl halide to hydrogen halide in the feed is greater than or equal to 0.8 to 1 and desirably in the range of 1-100. This ratio is one of the variables that influences the relative amounts of R 1 SiHX2and R 1 SiX3. Values that provide the desired product composition can be established by experiment.

[0068] As noted above, allyl alkoxysilanes are important intermediates for the preparation of sulfur organofunctional silanes. The alkenyl halosilanes R 1 SiHX2and R 1 SiX3can be converted to alkenyl alkoxysilanes by reaction with the appropriate alcohol. For example, allyl dichlorosilane (ADCS) and allyl trichlorosilane (ATCS), alone or mixtures thereof, can be reacted with ethanol to form allyl triethoxysilane (Equations 1 and 2) as has been disclosed in US 6,878,839. Effective removal of hydrogen chloride or the presence of a hydrogen chloride acceptor is important for high yield production of allyl triethoxysilane. In the absence of a hydrogen chloride acceptor, hydrogen chloride readily adds to the double bond in allyl triethoxysilane (Equation 3) resulting in cleavage of the C-Si bond, formation of a by-product and low yield of allyl triethoxysilane.

[0069]

[0070] When sodium ethoxide is used as the HC1 acceptor, tetraethoxysilane is typically the major product. With 1-methylimidazole, the hydrochloride forms a dense ionic liquid (see US 7,351,339), which facilitates the isolation of allyltriethoxysilane. The yield is 87%. With poly(vinylpyridine) as the HC1 acceptor, allyldichlorosilane is quantitatively converted to allyldiethoxysilane, and allyltrichlorosilane similarly to allyltriethoxysilane. The insolubility of poly(vinylpyridine) enables easy recovery of the reaction products. Thus, the crude allyltrichlorosilane product containing ADCS, ATCS, and DADCS can be ethoxylated in the presence of 1-methylimidazole to produce allyltriethoxysilane (bpt 147°C) and diallyldiethoxysilane (bpt 189.5°C). When ethoxylated in the presence of poly(vinylpyridine) as the HC1 acceptor, the same crude product produces allyldiethoxysilane (bpt 108°C), allyltriethoxysilane (bpt 147°C), and diallyldiethoxysilane (bpt 189.5°C), which can be individually recovered by distillation.

[0071] Silicon, spent contact mass, cyclone fines and ultrafines

[0072] The silicon metal reactant used in the preferred embodiments of the process according to the present application can be any commercially available silicon grade in particulate form. It can be produced by any of the methods currently practiced, such as casting, water granulation, atomization, and acid leaching. These methods are more fully described in Silicon for the Chemical Industry (H. Oye, et al. eds.), Vol. I (pp. 39-52), Vol. II (pp. 55-80), Vol. III (pp. 33-56, 87-94), Tapir Publishers, Norwegian Institute of Technology; and, U.S. Patents 5,258,053, 5,015,751, 5,094,832, 5,128,116, and 4,539,194.

[0073] Special types of chemical grade silicon containing controlled levels of promoters and alloying elements are also suitable, provided that copper is not one of the alloying elements. Special silicon of this type is described in U.S. Patents 5,059,43, 5,714,131, 5,334,738, 5,605,583, 5,973,177, 6,057,467 and European Patents 0,494,837 and 0,893,448. A typical composition of commercial, chemical grade silicon metal useful according to the present application is expressed in weight percent as Si ~ 98.5%, Fe ~ 0.1 to 0.7%, Al ~ 0.05 to 0.7%, Ca ~ 0.001 to 0.3%; Pb < 0.001%, water < 0.1%. Generally, smaller particle size is preferred to facilitate dispersion in the slurry, faster reaction and minimization of reactor erosion. Preferably, there are no particles larger than 500 microns to minimize reactor erosion. Preferred is a particle size distribution wherein at least 90% by weight of the silicon is between 1-300 microns. Particularly preferred is a distribution wherein at least 90% by weight of the silicon particles are between 1-100 microns. This includes dust from silicon milling operations.

[0074] During direct synthesis of methylchlorosilanes and phenylchlorosilanes, particularly fluid bed direct synthesis, the silicon is typically depleted from the contact mass gradually (steadily) and converted to the volatile organic chlorosilane products. Even with the batchwise or continuous addition of additional silicon, copper catalyst and promoter, a point is reached where the yield and selectivity of the desired products can no longer be economically maintained. A solid residue will typically remain in the reactor at the end of the process. This residue is referred to as spent contact mass or spent material. It typically contains unreacted silicon, unreacted copper activated silicon, copper, chlorides of copper and of metals originally present in the silicon (e.g. AlCl3, TiCl4, FeCl3), chlorides of promoter elements (e.g. Zn, Sn, P, Bi) and carbon. Its particle size distribution is depleted in particles smaller than about 75 microns relative to the fresh contact mass.

[0075] The elutriated solids captured by the cyclone or filter are called cyclone fines or cyclone solids. Cyclone solids are typically less than about 50 microns in size, and 90% of the particles are between 1.0 and 20 microns. The silicon content should be about 40-80 wt% and the content of Cu, Al, Fe, Sn, Zn, P, C and other elements is enriched relative to fresh or spent contact mass. For example, the copper content is typically 2 wt% in spent mass and 10 wt% in cyclone solids. Aluminum is typically about 1 wt% in spent mass and about 2 wt% in cyclone solids. Iron is typically about 1.5 wt% in spent mass and about 3% in cyclone solids. Tin, zinc and phosphorus can be 5-50 times more enriched in cyclone solids than in spent mass.

[0076] The particulate matter that escapes the cyclone and is collected in the settler is called ultrafines, settler solids or reboiler solids. The particle size range is typically about 0.1 to 5 microns. The silicon content should be about 40-60 wt%, copper about 10-20 wt%, and Al, Fe, Sn, Zn, C and P are typically more enriched than in cyclone fines and spent mass. Although spent mass and cyclone fines are dry solids that can be self-igniting, ultrafines are wetted with organohalosilane and coalesce into a slurry. For this reason, ultrafines are sometimes called sludge.

[0077] The sludge can be filtered, centrifuged or dried to separate the solids from the liquid. The liquid typically comprises organohalosilane monomer, organohalodisilane, organosiloxane and hydrocarbons. Fractionation of the liquid allows the recovery of separate monomer and disilane fractions, which can be cleaved into monomers by conventional means and by the enhanced process disclosed in U.S. Patents 8,637,895 and 8,697,901. The solids content of the sludge is advantageously less than 65 wt% and preferably 20-60 wt% to facilitate agitation and flow. The sludge can be thermally dried with or without vacuum to produce a free-flowing powder for use in the present invention. Alternatively, the sludge is added to the reaction solvent in an amount that permits the resulting slurry to be easily agitated, and the organohalosilane monomer, organohalodisilane, organosiloxane and hydrocarbons are volatilized by heating and inert gas stripping prior to the introduction of the organohalide reactants.

[0078] The process according to embodiments of the present invention can use fresh silicon, mill dust, spent contact mass, cyclone fines, ultrafines and mixtures thereof to achieve the direct synthesis of alkenylhalosilane. It has been found that the product composition can be advantageously controlled by the choice of silicon source. Thus, the product composition can be controlled by combining fresh silicon and cyclone fines in the appropriate proportions.

[0079] Alkenylhalide - R 1 X

[0080] General Formula R1 X represents an alkenyl halide for reacting with the copper-activated silicon of the present invention. R 1 is an unsaturated aliphatic or cyclic alkenyl group and X is a halogen atom. R 1 Examples are groups such as ethenyl, allyl, methallyl and cyclohexenyl. Suitable examples of alkenyl halides are ethenyl chloride, allyl chloride, allyl bromide, methallyl chloride and cyclohexenyl chloride. Allyl chloride and cyclohexenyl chloride are preferred organic halides.

[0081] Allyl chloride preferably has a purity greater than 98%. It advantageously vaporizes at temperatures below those that initiate its thermal decomposition and polymerization. It can be mixed with hydrogen chloride, methyltrichlorosilane or dimethyldichlorosilane and vaporized at 80-100°C for injection into the reaction slurry.

[0082] Reaction solvent

[0083] Solvents used for direct synthesis according to embodiments of the present invention should maintain the particulate solids in a well dispersed state and promote the mass transfer of the alkenyl halide to the catalytic sites located on the copper-activated silicon. Ideal solvents useful in the process of the present invention are thermally stable compounds or mixtures that do not degrade under the activation and reaction conditions. Structurally, they are advantageously linear and branched paraffins, as well as naphthenes. One preferred class of paraffin-type solvents are high temperature stable organic solvents typically used as heat transfer media. Examples include aliphatic heat transfer fluids such as Calflo™ AF, Calflo™ LT and Calflo™ HTF available from Petro Canada.

[0084] Naphthenes are cyclic alkanes (cycloparaffins). They are components of white mineral oil, petroleum distillates and some fuels. White mineral oil and petroleum distillates also contain normal and branched paraffins (see A. Debska-Chwaja et al., Soap, Cosmetics and Chemical Specialties (November 1994), pp. 48-52; As aboveSuitable examples of commercial products containing cycloparaffins and paraffins and useful as the reaction solvent used in the present application are white mineral oil, CARNATION 70, KAYDOL, and petroleum distillates (sold by Sonneborn, Inc.). Other examples of paraffins useful as the reaction solvent are decalin, perhydroanthracene, perhydrophenanthrene, perhydrofluorene and alkylated derivatives thereof, perhydroterphenyl, perhydrobinaphthyl and alkylated derivatives thereof.

[0085] CALFLO™ heat transfer fluids sold by Petro-Canada are paraffin-type materials that are thermally stable up to about 250-330°C. Suitable examples are CALFLO™ LT, CALFLO™ AF, and CALFLO™ HTF. Squalane is another paraffin-type solvent suitable for use in the present slurry phase direct synthesis process. Its unsaturated derivative, squalene, is also an effective solvent. The direct synthesis with paraffins and olefinic solvents is desirably carried out at temperatures less than 330°C. Mixtures of cycloparaffins with normal and branched paraffins can also be used as the reaction solvent used in the present application.

[0086] It is desirable that all solvents be free of components having standard boiling points less than 200°C, and in particular compounds having standard boiling points that overlap with the standard boiling point of the alkenyl halosilane to be produced. In addition, it is advantageous to the practice of the present application that the solvent not degrade to lower molecular weight compounds when the solvent is heated alone or in contact with silicon, copper-activated silicon, cyclone fines, ultrafines, and slurry at temperatures up to about 350°C and pressures up to about 10 bar. Product analysis, distillation, and refining can be complicated by lower molecular weight hydrocarbons and other compounds having standard boiling points that overlap with the standard boiling point of the alkenyl halosilane. Formation of these impurities is desirably avoided or prevented.

[0087] Used solvents can be treated to remove solids, metal salts, polymer-type byproducts, and other accumulated impurities prior to recycling and reuse in the slurry reactor. Remediation includes filtration of solids and stripping of the filtrate at temperatures up to about 250°C (atmospheric pressure) to remove lower boiling hydrocarbons and distillable silicon-containing byproducts. Alternatively, the solvent can be recovered by vacuum distillation to separate it from copper- loaded solids intended for copper recovery.

[0088] Silicon, copper-activated silicon, cyclone fines, ultrafines, waste material, and mixtures thereof can be added to the reactor with the solvent in any order. The solvent should be present in an amount sufficient to uniformly disperse the solids and gaseous reactants. Typically, the reaction is initiated with a weight ratio of solvent to solids of about 1 :2 to about 6:1, preferably about 2:1 to about 5:1. However, as the silicon is consumed during the batchwise direct synthesis, the ratio of solvent to solids increases. For continuous reactions, the ratio can be maintained within narrow limits of the preferred range.

[0089] Additives

[0090] It has been determined that the presence of Lewis acids (e.g., A1C13, TiCl4, and FeCl3) and free copper in cyclone fines, ultrafines, and waste material can undesirably cause cleavage and / or polymerization of the alkenyl halide, solvent conversion, and other side reactions, either not producing the desired alkenyl halosilane, or promoting polymerization of the alkenyl halosilane once formed. These undesirable reactions can be inhibited or controlled by the use of selected additives. Among other mechanisms, these additives can coordinate or react with Lewis acids, or adsorb on the surface of free copper. These additives have been found to exhibit Lewis base properties.

[0091] Bases (e.g., amines) bonded to copper residues are generally not the most desirable polymerization inhibition additives. Generally, "hard" Lewis acids tend to include smaller molecules, such as various chlorides. Thus, in accordance with the present invention, "soft" Lewis bases tend to be the most effective as polymerization inhibitors. Those of ordinary skill in the art will be able to determine, without undue experimentation, which additives exhibiting Lewis base properties will effectively inhibit the undesirable polymerization, in addition to those identified below.

[0092] The Lewis acids and free copper referred to include both those present in the initial cyclone fines, ultrafines, and waste material feed materials, and those generated as a result of the direct synthesis of the alkenyl halide in the reaction slurry. The additives should be selected so as not to inhibit the direct synthesis, and / or not induce undesirable chemical reactions in the alkenyl halosilane being produced. However, as will be shown by examples below, not all additives are equally effective in inhibiting polymerization of the alkenyl halosilane. For example, dibutyl sulfide, thiourea, and tetramethyl urea are more effective in inhibiting polymerization of allyl trichlorosilane than in inhibiting polymerization of allyl dichlorosilane.

[0093] Sulfur-containing additives with -SH functionality (thiol or mercaptan), -CH2-S-CH2- (sulfide), -S-S- (disulfide), >C=S (thione), (>N)2C=S (thioamide and thioimidazole) are effective in inhibiting the polymerization of alkenyl halosilanes in experiments and during direct synthesis. Cyclic sulfur-containing compounds (e.g., thiophene, phenothiazine, thiomorpholine, 1,4-oxathiane) have also been found to be effective inhibitors of alkenyl halosilane polymerization and polymerization occurring during direct synthesis of alkenyl halosilanes. Advantageously, the additives are resistant to decomposition during direct synthesis and they have a boiling or sublimation point higher than the temperature at which the direct synthesis is performed.

[0094] The mercaptan additives of the present invention have the general formula RSH and HS(Q)SH, where R is a straight or branched aliphatic group, an aryl group, an alkylaryl group, or an alicyclic group. Q is a group that links between sulfur atoms in a thiol having more than one sulfur atom. Thus, Q can be a straight-chained or branched alkylene group having from two to twenty carbon atoms. Q can also be an oxyalkylene group, a phenylene group, or an alicyclic group. Examples of Q are: -(CH2) n -, (n = 1-8); and, -(CH2) n -O(CH2CH2O) x -CH2CH2-, n = 1-4, x = 1-8.

[0095] Aliphatic examples of R include C8-C20 alkyl groups, such as octyl, dodecyl, and octadecyl. Suitable mercaptan additives are C 10 H 21 SH, C6H 13 C(CH3)2SH (tert-nonyl mercaptan), p-heptylbenzyl mercaptan, furfuryl mercaptan, and grapefruit mercaptan (1-p-menthene-8-thiol). 1,5-pentanedithiol, HS(CH2)5SH, 1,9-nonanedithiol, HS(CH2)9SH, and 2,2'-(ethylenedioxy)diethylthiol, HSCH2CH2OCH2CH2OCH2CH2SH are examples of HS(Q)SH.

[0096] The effective amount of the mercaptan or mixture of mercaptans used should be at least stoichiometrically sufficient to bond to and deactivate Lewis acids initially present and / or generated during the direct synthesis. An amount can be added at the beginning of the reaction, with additional amounts introduced periodically or continuously. When cyclone fines and / or waste material is the source of silicon for the direct synthesis, the initial level of mercaptan use can be determined by the aluminum content of the cyclone fines and waste material. The stoichiometric ratio (SH / Al) at the beginning of the reaction or at any point during the reaction can be 0.05 to 15, preferably 2 to 5. With fresh, chemical grade silicon, a lower ratio value can be used initially, with increasing ratio values used in subsequent silicon charges. Higher ratios provide inhibition of polymerization induced by Lewis acids other than AlX3.

[0097] Thiophene, phenothiazine, thiomorpholine, and 1,4-oxathiane are examples of heterocyclic sulfur-containing additives that are effective inhibitors of alkenyl halosilane polymerization.

[0098] Dodecyl methyl sulfide CH3(CH2) 11 SCH3and ethyl xanthate CH3CSSCH2CH3are representative of sulfur ether and thioester additives, respectively, that are effective inhibitors of alkenyl halosilane polymerization.

[0099] Urea, tetraalkylurea, thiourea, and tetraalkylthiourea are another class of additives that are effective in inhibiting the polymerization of alkenyl halosilanes, including the polymerization of alkenyl halosilanes generated during the direct synthesis. These additives can be used alone or in combination with the sulfur-containing additives described above.

[0100] The effective level of use of all additives is advantageously greater than or equal to the molar concentration of Lewis acids in the reaction mixture. Nonetheless, their inhibitory effect on alkenyl halosilane polymerization is observable at lower concentrations. In all cases, the additives should be initially charged and preferably continuously or intermittently dosed during the course of the reaction. The initial charge and subsequent doses should be effective in providing stable selectivity to the desired silane (allyltrichlorosilane and allyldichlorosilane when the organic halide is allyl chloride) and precluding solvent decomposition.

[0101] Reaction conditions

[0102] Design, description, and operational considerations associated with three-phase reactors (e.g., stirred slurry reactors, bubble columns, trickle beds) are contained in the following treatises, articles, and patents, all of which are incorporated herein by reference:

[0103] • A. Ramachandran and R. V. Chaudhari, Three Phase Catalytic Reactors, Gordon and Breach Science Publishers, NY, 1983

[0104] • N. Gartsman et al., International Chemical Engineering, Vol. 17 (1977) pp. 697-702

[0105] • H. Ying et al., Industrial & Engineering Chemistry, Process Design & Development, Vol. 19 (1980) pp. 635-638

[0106] • N. Satterfield et al., Chemical Engineering Science, Vol. 35 (1980) pp. 195-202

[0107] • M. Boxall, et al., Journal of Metals (August 1984) pp. 58-61

[0108] • W. Roeckel, C. Scaccia and J. Conti, U.S. Patent 4,328,175 (May 4, 1982)

[0109] • L. M. Litz, U.S. Patent 4,454,077 (June 12, 1984)

[0110] The reactor can be operated in batchwise or continuous mode. In batchwise operation, a single addition of the silicon and copper catalyst precursors, optionally including the cyclone fines, ultrafines, or waste material, alone or blended with each other, is made to the reactor at the start, and the addition of the alkenyl halide vapor is made continuously or intermittently until the silicon is fully reacted or reacted to the desired conversion. In continuous operation, the cyclone fines, ultrafines, and / or waste material and optional additives are initially added to the reactor, and thereafter the solids content and composition of the slurry are maintained within desired limits.

[0111] In its preferred form according to the present application, the direct synthesis of alkenylhalosilane from copper-activated silicon is conducted in a continuously stirred slurry reactor containing: solvent, silicon and copper catalyst precursor; optionally cyclone fines, ultrafines or waste material, individually or admixed with each other; tetramethylurea and / or sulfur-containing additives and a foam control agent in contact with gaseous alkenylhalide. The reactor can have a single nozzle or multiple nozzles for the introduction of gas. Means for the continuous or intermittent addition of silicon, copper catalyst precursor, cyclone fines, ultrafines or waste material, and polymerization-inhibiting additives are also provided. Means for the continuous removal and recovery of volatile alkenylhalosilane reaction products and unreacted alkenylhalide are also desirably provided. Separation and purification of the alkenylhalosilane product is optimally conducted by continuous fractional distillation.

[0112] The reaction is typically conducted at a temperature above about 180°C, but below a temperature at which the reactants, solvent or desired product would degrade or decompose. Preferably, the reaction of allyl chloride with copper-activated silicon is conducted at a temperature below about 300°C, more preferably in the range of about 200°C to about 280°C. The pressure at which the reaction is conducted can vary from below atmospheric to above atmospheric pressure. Atmospheric pressure and pressures up to about 10 atmospheres are typically employed. The preferred range is 1 to 5 atmospheres. The reaction time ranges from 0.1 to 100 hours.

[0113] Preferably, the contents of the reaction mixture are stirred to maintain a well-mixed slurry of copper-activated silicon, polymerization-inhibiting additives, foam control agent and gaseous alkenylhalide in the solvent. The stirring speed and power input must be sufficient to effect mass transfer of the reactants to the surface of the copper-activated silicon, as well as to maintain maximum particle suspension in the solvent and not settling on the bottom of the reactor. Power input is typically calculated as the ratio of power to volume. Those skilled in the art are familiar with the relevant equations.

[0114] The outlet line from the reactor carrying the reaction mixture is preferably well insulated to ensure that the alkenylhalosilane remains gaseous. Solvent vapor and droplets present in the gas stream can be removed by cooling to a temperature at which they can condense and return to the reactor while maintaining the alkenylhalosilane in the gaseous state, and / or by passing the reaction mixture through a demister. Volatile metal salts (e.g., AICI3, FeCI2, SnCI2, TiCI4, ZnCI2and mixed metal salts (e.g., CuAlCI4)) that escape the slurry can also be removed in this manner.

[0115] The presence of gaseous alkene halide, alkene halosilane and other gases in the reactor can occasionally cause foaming. This is undesirable because it can cause loss of solvent and solids from the reactor. U.S. Patent 5,783,720 (1998) discloses the addition of a foam control agent, preferably a silicon-containing foam control agent (e.g. Momentive's product SAG ® 1000, SAG ® 100, SAG ® 47 and Dow Corning FS 1265) will counteract or control foaming in the direct synthesis of trialkoxysilane in the slurry phase. It is also an effective foam control agent in the process of the present invention. SAG ® 1000, SAG ® 100 and SAG ® 47 is a composition comprising polydimethylorganosiloxane and silica. FS 1265 and FF 170 comprise fluorinated organosilicon, e.g. poly(dimethylsiloxane-co-trifluoropropyl-methylsiloxane). The foam control agent is preferably persistent, such that a single addition at the start of the batch reaction is sufficient to avoid or mitigate foaming until all of the silicon has been consumed. The effective use level of the foam control agent is a span of 0.000001-5 wt% based on the total initial weight of the reaction slurry. Higher levels can occasionally cause a reduced reaction rate. Physical and mechanical methods of preventing or controlling foaming can also be employed. These include rakes, ultrasonic devices and foam arrestors.

[0116] Examples

[0117] The following examples are presented to illustrate preferred embodiments of the present invention. They are not intended to limit the scope of the present invention. Rather, they are presented to illustrate the scope and content of the present invention.

[0118] Abbreviations and units used

[0119]

[0120] When the allyl chloride is the alkene halide, the reaction product and unreacted alkene halide are passed through a foam arrestor and controlled at 140-160°C through a 40 cm long 2.5 cm diameter Vigreux column was placed downstream of the reactor. This served as an entrainment separator for solvent droplets and metal salt. The gaseous reaction mixture was then allowed to reach a condenser cooled to ~0°C with chilled silicone oil, after which it was collected in a sampling flask attached to a dry ice-isopropanol cold finger (-65°C). The gas exiting the collection flask was cooled through a second dry ice-isopropanol cold finger (-65°C) before being vented to a hood through a vapor lock bubbler. The liquid collected in this second or final trap was removed at the end of the experiment, weighed, and analyzed, and the data used to calculate the overall silicon conversion. The bubbler contained silicone oil and had an additional opening for release of overpressure.

[0121] The samples were collected in weighed flat bottom flasks and analyzed by gas chromatography. Gas chromatography analysis of the reaction products was performed on a HP 5890E chromatograph. The column was as follows: 10 feet <0.1 inch internal diameter packed with 30 wt% OV-210 on acid-washed Chrom P. The program, flow rate, and other conditions were appropriate for the sample being analyzed.

[0122] The gas chromatography thermal conductivity response factors for allyl chloride and allyl chlorosilane were determined using a mixture experiment in dodecane. The values agreed well with those calculated from stoichiometric parameters (see A. E. Smith (Editor), The Analytical Chemistry of Silicones, pp. 282-284). Quantitative analysis had an error of ±2%.

[0123] Gas chromatography / mass spectrometry (GC / MS) analysis was performed with an Agilent 6890 GC / 5973 MSD instrument equipped with a 30 meter long ZB5 (5% phenyl, 95% methyl polysiloxane) capillary column. The column internal diameter was 0.25 mm, and the film thickness was 2.5 μιη. The carrier gas was helium with a 200: 1 split injection ratio. The temperature of the injection port and GC / MS interface were 250 °C and 270 °C, respectively. The injection volume was 1 μΐ. The oven temperature was held at 50 °C for 2 minutes before ramping at a rate of 8 °C / minute to 340 °C, and then held for 16 minutes. The mass spectrometer was operated in EI (70 eV electron impact ionization) full scan (m / z 10-800) mode.

[0124] For NMR characterization, samples were analyzed with a Bruker AVANCE 600 spectrometer operating at a field strength of 14.1 T. 1 Protons of H resonate at 600 MHz at this field strength. The samples for 29 Si nmr were prepared as 25 to 30 volume percent solutions in Cr(AcAc)3 / CDCl3 to achieve a final Cr salt concentration of ~0.05 M Cr(AcAc)3. The solutions were placed in 10 mm NMR tubes. Chemical shifts were referenced externally to tetramethylsilane (TMS). For 29 Si, an inverse gated decoupling pulse sequence was used with a 45 degree pulse width. A delay of 10 seconds (1.4 second AQ) was used between scans. Data was processed using a LB of 2 Hz.

[0125] Materials used for exemplary embodiments

[0126] Fines and ultrafines (slimes) cyclone were obtained from commercial production of methylchlorosilanes. Cyclone fines had a size of 1-10 microns, with a mean of 5 microns. The composition is summarized in Table 1. In some experiments, fresh silicon having an average particle size of 30 pm and an elemental composition of Fe = 0.31%, Al = 0.27%, Ti = 0.033%, Ca = 0.021%, P = 0.0045% was used.

[0127] Solvents used included Calflo™ AF and Calflo™ LT.

[0128] Table 1: Composition of cyclone fines

[0129]

[0130] The allyl chloride used was a commercial product of 98.5-99.5% purity. Principal impurities included 2-chloropropene, 2-chloropropane, 1-chloro-1-propene, and 1,5-hexadiene. In some experiments, the allyl chloride was delivered to the top of the reaction slurry by syringe. In other experiments, it was vaporized at 80°C and introduced at the bottom of the reactor. Mixtures of allyl chloride with methylchlorosilanes or HCl were also used in some experiments.

[0131] Examples 1A-1C (comparative)

[0132] Desired monomers are volatile and will evaporate from the reaction slurry. Undesired polymers are heavy and will accumulate in the vessel. Thus, an increase in weight indicates that undesired polymerization is occurring. The three experiments of this example show the increase in weight and volume of the reaction mixture during the direct synthesis of allyl trichlorosilane and allyl dichlorosilane from a slurry phase of cyclone fines and allyl choride-HCl mixture in Calflo™ AF. This increase in weight is due to polymerization and side reactions, primarily the formation of diallyldichlorosilane (DADCS) as discussed below. The amounts of materials used and reaction conditions are summarized in Table 2.

[0133] In each experiment, Calflo™ AF and cyclone fines (~70 wt% Si) were charged to the reactor along with FF-170. The reaction mixture was sparged with 100 mL / min of nitrogen, stirred at 500 rpm, and heated to 235°C. HCl gas was then introduced into the reactor at 420 ml / min. Allyl choride was pumped from a reservoir to an evaporator heated at 80°C and then fed to the reactor as a vapor. Due to the exothermic nature of the reaction, the actual average reaction temperature (Table 3) was higher than the set value.

[0134] Table 2 Materials and reaction conditions for Examples 1A-1C

[0135]

[0136] The gaseous reaction products were condensed and liquid was collected every half hour for analysis by gas chromatography. The experiments were terminated after the reaction times shown in Table 2. Table 3 shows the total weight of the collected crude product and the percent silicon conversion calculated based on the weight and composition of the products collected and the weight of available silicon in the cyclone fines. Table 3 also summarizes the composition of the main silicon-containing products in the crude.

[0137] Table 3 Experimental data for Examples 1A-1C

[0138]

[0139]

[0140]

[0141] It was observed that the slurry had gained weight during the reaction. This indicates that reaction products were formed due to polymerization and other side reactions that did not exit the reactor at the reaction temperatures shown above. Polymer formation (300.4 g) was the most in Example 1A, which was run at the highest allyl chloride / HCl molar ratio and the shortest time. It also had the most DADCS and the highest ATCS / ADCS weight ratio (1.44). Based on the references cited above and the data and observations from Examples 2-5, it is hypothesized that the weight gain is due to polymerization of the allyl chlorosilane. The adjusted silicon conversion shown in Table 3 is calculated based on the assumption that diallyldichlorosilane (DADCS) with 15.50 wt% Si is the primary cause of polymer formation.

[0142] The rationale for this calculation is as follows. Typically, silicon is vaporized from the reactor as allyl chlorosilane, and the reactor shows a weight loss. When polymerization occurs, the mass produced must first be subtracted from the decrease due to the reacted silicon before an increase is apparent. Thus, the total polymer weight is the sum of the reacted silicon and the reactor weight gain.

[0143] Examples 2A-2C: Polymerization of allyl chloride under different conditions (comparative)

[0144] These examples show that it is the reaction product of allyl chloride with the cyclone fines that is polymerizing, not the allyl chloride itself.

[0145] The polymerization of allyl groups catalyzed by peroxides and metal complexes is well known in the literature (Forbes et al., Marvel et al., and Butler et al., see above). Therefore, a set of experiments was performed in the apparatus described in Example 1 under different conditions to determine if the mass gain observed in Examples 1A-1C was due to polymerization of allyl chloride. The different reaction conditions and the corresponding residue weight changes are listed in Table 4.

[0146] Table 4 Materials and reaction conditions for Examples 2A-2C

[0147]

[0148] At 235°C (Example 2A), 52 g (0.68 moles) of allyl chloride and 7.44 ml / min of HCl (3.32 10 -4feeding 52 g (0.68 mole) of allyl chloride (over 30 minutes) and 7.44 ml / min of HC1 (3.32 10 -4 feeding 52 g (0.68 mole) of allyl chloride (over 30 minutes) and 7.44 ml / min of HC1 (3.32 10 -4 When 52 g of allyl chloride (0.68 mole) and 7.44 ml / min of HC1 (3.32

[0149] Examples 3A-3C (comparative)

[0150] Examples 3A-3C show the Friedel-Crafts reaction of allylchlorosilane (Example 3A) with toluene and the undesired polymerization of allylchlorosilane when heated in the presence of A1C13in toluene or dodecane at 70°C (Examples 3B-3C). The experiments were performed in a 50 ml three necked round bottom flask equipped with a reflux condenser, magnetic stirrer and thermocouple. The amounts of materials used in the experiments are listed in Table 5.

[0151] In Example 3A, when the mixture of DADCS in toluene was added to the A1C13in the reaction flask, a vigorous exothermic reaction occurred. The product was a brown viscous solution. GC / MS of the reaction mixture showed a component with a mass of 272 which corresponds to the isomers of the Friedel-Crafts reaction of DADCS with toluene as shown in the following reaction.

[0152]

[0153] In Example 3B, no reaction was observed when DADCS and dodecane were refluxed at 70°C for two hours or stirred with 6.5 wt% A1C13at room temperature for one hour. However, heating DADCS with 6.5 wt% A1C13in dodecane at 70°C for 1.5 hours produced a brown, insoluble solid. GC analysis of the solution showed that 93% of the DADCS had been consumed.

[0154] Table 5: Materials, reaction conditions, and results for Examples 3A-3C

[0155]

[0156] In Example 3C, 0.213 g of AICI3was added to a mixture of 3.73 g of 65 wt% ATCS and 35 wt% ADCS dissolved in 6.0 g of dodecane. No observable reaction occurred after stirring at room temperature for one hour. Heating to 70°C for 1.5 hours produced insoluble polymer. GC analysis of the liquid showed that all of the ADCS and ATCS had been consumed.

[0157] The results of these experiments illustrate that Lewis acids, such as AICI3, can undesirably catalyze the polymerization of allyl chlorosilanes at temperatures even below those used in the direct synthesis reaction. Example 3A shows that aromatic solvents (heat transfer fluids) are not recommended for use in the practice of the present invention.

[0158] Examples 4A-4E: Control of allyl chlorosilane polymerization with thiol and disiloxane additives

[0159] Examples 4A-4E show the effective use of thiol and disiloxane additives to inhibit Lewis acid catalyzed polymerization of allyl chlorosilanes at temperatures below the direct synthesis temperature of the allyl chlorosilane. The additives used were octadecyl mercaptan (C 18 H 37 SH) and hexamethyldisiloxane. (See Table 6). The reactions were run at 70°C for 1.5 hours. The reaction mixtures were then cooled to room temperature and analyzed by gas chromatography.

[0160] Example 4A: The experiment of Example 4A was conducted in a similar manner to Example 3B. DADCS (2.27 g (1.25 10 -2 moles), C 18 H 37 SH (0.72 g (2.5 10 -3 moles), AICI3(0.227 g (1.70 10 -3 moles), and 5.07 g of dodecane were mixed and heated to 70°C and maintained there for 1.5 hours.

[0161] Example 4B: The experiment of Example 4B was conducted with a mixture of 5.17 g of 35 wt% ADCS and 65 wt% ATCS, AICI3(0.317 g (2.4 10 -3 moles), C 18 H 37SH (0.85 g (3.0 10 -3 mole) and 6.18 g dodecane at 70 °C for 1.5 hours.

[0162] Example 4C: In this experiment, a 5.18 g mixture of 35 wt% ADCS and 65 wt% ATCS, AICI3(0.317 g (2.4 10 -3 mole), hexamethyldisiloxane (3.1 g (1.91 10 -2 mole) and 2.7 g dodecane were heated at 70 °C for 1.5 hours.

[0163] Gas chromatography analysis of the reaction mixtures of Examples 4A-4C in terms of area ratios of the allyl substrates relative to dodecane are presented in Table 6. Thus, in Example 4A, the area ratio of diallyldichlorosilane (DADCS) to dodecane was 0.266 at the beginning of the experiment and 0.192 at the end of the experiment. This means that 72.2% of the original DADCS still existed in the final reaction mixture. In contrast, 93% of the DADCS was consumed in the experiment of Example 3B, only 27.8% was consumed in Example 4A. This demonstrates the inhibitory effect of octadecyl mercaptan on the AICI3-catalyzed polymerization of DADCS.

[0164] Table 6: Gas chromatography analysis of reaction mixtures of Examples 4A-4C 12 H 25 Reaction conditions and results for the inhibition of AICI3-induced polymerization of allyl chlorosilanes by SH and [(CH3)2Si]2O

[0165]

[0166]

[0167] Table 6 presents the individual area ratios of diallyldichlorosilane (ADCS) and allyltrichlorosilane (ATCS) obtained in Example 4B. Clearly, the polymerization of ATCS was completely inhibited by octadecyl mercaptan, and 85.6% of the original ADCS still existed. So, in contrast to Example 3C, where both allyl substrates were completely polymerized, only 14.4% was consumed and it was exclusively ADCS.

[0168] The area ratios in Example 4C were also within the ±2% error mentioned above for quantitative gas chromatography analysis. Thus, the polymerization of ATCS and ADCS catalyzed by AlCl3 was completely inhibited by hexamethyldisiloxane. Complete inhibition of DADCS polymerization was also observed in separate experiments using AlCl3 and hexamethyldisiloxane (Example 4D) and using a combination of ATCS + ADCS mixture with octadecyl mercaptan and hexamethyldisiloxane (Example 4E). The inhibition of polymerization is shown in the following equation.

[0169]

[0170] Inhibition of AlCl3-induced allyl chlorosilane polymerization in the presence of hexamethyldisiloxane (MM)

[0171] Examples 5A-5E: Control of allyl chlorosilane polymerization with urea and thio additives

[0172] These examples show effective inhibition of allyl chlorosilane polymerization by tetramethyl thiourea [(CH3)2NCSN(CH3)2], thiourea (H2NCSNH2), tetramethyl urea [(CH3)2NCON(CH3)2], and dibutyl sulfide [(CH3(CH2)3]2S.

[0173] All experiments were performed simultaneously in 75 ml reactors of the MRS-5000 combined reactor. The starting materials (stock solutions) for Examples 5A-5D were prepared from 18.54 g of dodecane, and 32.86 g of a mixture of 35 wt% ADCS and 65 wt% ATCS. An aliquot of this stock solution was charged to the 75 ml reactor along with AlCl3 and the appropriate additive shown in Table 7. The molar ratio of additive to AlCl3 was about 2. The starting materials for Example 5E were prepared in nonane because dibutyl sulfide and dodecane co-elute under the gas chromatography conditions used. After charging, the reactors were sealed under 1 bar of N2 pressure. The reaction mixtures were stirred at room temperature (23 °C) for 1 hour, and then heated to 70 °C for an additional hour. After the reactor had cooled to room temperature, it was opened and the liquid reaction mixture was recovered for analysis by gas chromatography.

[0174] In the control example 5A, complete polymerization of both ADCS and ATCS occurred, where no additives were used. The sulfur-containing additives used in examples 5B, 5C and 5E inhibited the polymerization of ATCS. At the molar ratio of additive to AlCl3 used (~2), the loss of ADCS due to polymerization was 14-16%. This means that 84-86% was recovered. When tetramethyl urea was used (example 5D), 79% of the ADCS and all of the ATCS was recovered.

[0175] Table 7: Use of tetramethyl thiourea, thiourea, tetramethyl urea and dibutyl sulfide to pre-inhibit polymerization of allyl chlorosilane

[0176]

[0177] Examples 6A, 6B

[0178] Examples 6A and 6B show the use of hexamethyldisiloxane to improve the reaction stability for the direct synthesis of allyl trichlorosilane and allyl dichlorosilane from a slurry phase of cyclone fines and allyl chloride-HCl mixture in Calflo™ AF. A 2 liter glass reactor was used.

[0179] Example 6A

[0180] The reactor was charged with 641.5 g of Calflo™ AF and 212.3 g of cyclone fines (70 wt% Si) along with 2.0 g of FS1265 and 25.7 g of hexamethyldisiloxane. Since the fines contain ~2 wt% Al, the amount of hexamethyldisiloxane was equimolar to the aluminum. The reaction mixture was sparged with 100 mL / min of nitrogen, stirred at 500 rpm and heated to 80°C and maintained there for one hour. 9.8 g of distillate was collected.

[0181] Thereafter, the reactor temperature was raised to 235°C and hydrogen chloride was introduced at a rate of 7.44 mL / min. Allyl chloride was pumped from a reservoir to an evaporator heated at 80°C and then fed to the reactor as a vapor. The experiment was discontinued after 4 hours, during which time a total of 355 mL of allyl chloride had been delivered to the reactor.

[0182] The reservoir was recharged with a mixture of 8.8 g of hexamethyldisiloxane and 350 g of allyl chloride. The flow of HCl and allyl chloride was then resumed and the reaction was continued at 235°C for 3 hours.

[0183] In total, 2.45 liters of HC1 (0.11 moles) and 582.8 g of allyl chloride (7.62 moles) were introduced to the reactor. The molar ratio [allyl chloride / HCl] was 69.3. The product was collected hourly and analyzed by GC. 603.3 g of crude product was collected and a silicon conversion of 59.98% was obtained from the available silicon in the cyclone fines. Based on the crude product collected, the average reaction rate was 8.57% silicon conversion per hour. The weight of the reactor increased by 120 g. Therefore, the adjusted silicon conversion was 82%.

[0184] Table 8 summarizes the composition of the main silicon-containing products in the crude. It is seen that the sum of ATCS and ADCS remains fairly stable until about 48% silicon conversion. The steady state average is 83.69 ± 2.46 wt%.

[0185] Table 8: Composition of samples collected in the experiment of Example 6A

[0186]

[0187] Table 9: Control reaction

[0188]

[0189] Example 6B was run without the addition of hexamethyldisiloxane and is therefore a control reaction, which is compared to Example 6A as well as other reactions using additives.

[0190] 638.6 g CALFLO AF, 212.70 g cyclone fines, and 2 g FS 1265 were used in the experiment. The reaction was run at 235 °C and 500 rpm using allyl chloride and HC1 as described in Example 6A above. In total, the reaction lasted 7 hours during which 545.2 g of allyl chloride and 2.54 liters of HC1 were fed and 566.6 g of crude allyl chlorosilane was collected. The AC / HCl molar ratio was 63.4. The silicon conversion was 55.2% and the average reaction rate was 7.88% silicon conversion per hour. The weight of the reactor increased by 110 g. The adjusted silicon conversion was 75.1%.

[0191] As shown, the use of hexamethyldisiloxane provides an increased silicon conversion to the desired allyl chlorosilane (82% vs 75.1%). Additional amounts are required to achieve higher reaction rates and stability.

[0192] In Example 6B (control), the sum of the concentrations of ADCS and ATCS remained approximately constant (81.95 ± 1.63) from the start of the reaction until about 43% silicon conversion. Thus, the use of hexamethyldisiloxane in Example 6A extended the steady state region by 5% and thus improved the reaction stability. A z-test (see R. Langley, Practical Statistics Explained. Dover Publications, Inc. NY. pp. 152-154) was performed to determine if the difference in the steady state values of (ADCS + ATCS) in Examples 6A and 6B was statistically significant. As shown in the following calculation, the z-value was 2.61, which is greater than the threshold value of 2.58 for chance variation at P = 1%. Thus, the sum in Example 6A was statistically different from the sum in Example 6B.

[0193]

[0194] n = number of samples (6), M = mean of control group (81.95), m = mean of test group (83.69), S = standard deviation of control group (1.63)

[0195] Examples 7A, 7B, and 7C

[0196] Examples 7A, 7B, and 7C show the use of phenathiazine to inhibit the polymerization of allyl chlorosilanes during the direct reaction of cyclone separated fines with allyl chloride. Example 6B is a comparative control for these experiments. The amounts of raw materials used and reaction conditions are set forth in Table 10 and the results are summarized in Table 11.

[0197] Table 10: Reaction Conditions for Showing the Beneficial Effect of Phenathiazine in Allyl Chlorosilane Direct Synthesis Using Cyclone Separated Solids

[0198]

[0199]

[0200] The data show that use of >0.37 wt% phenathiazine resulted in higher silicon conversion to the desired allyl chlorosilane than was achieved in the control experiment (Example 6B). The weight increase of the reactor decreased from 110 g in the control to 52 g and 32 g in Examples 7B and 7C, respectively. These reductions are due to the inhibition of allyl chlorosilane polymerization by the phenathiazine. In addition, the average reaction rate increased from 7.88 %Si / h in Example 6B to 8.82 %Si / h in Example 7B and 9.33 %Si / h in Example 7C. Thus, a trend of improved reactivity and stability with increasing phenathiazine usage has been established. In addition, the data of Example 7B show that intermittent (or continuous) addition of phenathiazine is more advantageous than a single shot addition at the start of the reaction.

[0201] Table 11: Data to show the beneficial effect of phenathiazine on the direct synthesis of allyl chlorosilane using cyclone separation of solids

[0202]

[0203] Example 8:

[0204] Direct synthesis of allyl chlorosilane with CuCl, Zn, Sn and ~30 micron fresh Si

[0205] Example 8 shows the direct synthesis of allyl chlorosilane slurry phase by reaction of allyl chloride with fresh silicon, catalyzed with CuCl and promoted with zinc and tin. 157.5 g of silicon (~30 micron average particle size) was added to 599 g of Calflo AF along with 7.63 g of CuCl, 0.96 g of anhydrous zinc formate, 0.02 g of anhydrous tin formate, 1.8 g of FS1265. This fine powdered silicon is similar to the waste silicon powder that can be generated during silicon processing. The reaction was run at 235 °C for 6 hours using 500 rpm agitation, HC1 (7.44 ml / min) and allyl chloride (1.44 ml / min). The total amount of allyl chloride used was 520 ml (488.8 g, 6.39 moles) and the total amount of HC1 was 2.68 liters (0.119 moles). The molar ratio of allyl chloride to HC1 was 53.67.

[0206] Table 12: Summary of experimental data for direct synthesis of allyl chlorosilane using fresh silicon

[0207]

[0208] A total of 617 g of crude allyl chlorosilane was collected. The reactor weight decreased by 73 g. Using the hourly product composition and sample weight, it was calculated that 74.68 g of silicon was converted to allyl chlorosilane. During the reaction, the average reaction rate was 7.90% Si conversion per hour and (ADCS + ATCS) was 84.19 ± 4.30%. Additional data is summarized in Table 12.

[0209] Examples 9A and 9B: Initial fresh Si with and without inhibitor (phenothiazine). Second charge with cyclone fines

[0210] These examples show the effect of phenothiazine on the direct synthesis of allyl chlorosilane from slurries of fresh silicon with and without added cyclone fines. Example 9A was run similarly to Example 8, but with the addition of 1 wt% phenothiazine. Example 9B is a continuation of Example 9A with the addition of cyclone fines and phenothiazine. No additional materials were added to the experiment of Example 9B, except for the reactants (allyl chloride and HC1).

[0211] The average reaction rates in Examples 8, 9A, and 9B were 7.90% Si conversion per hour, 8.17% Si conversion per hour, and 9.05% Si conversion per hour, respectively. Thus, there was an approximately 11% boost in reactivity when cyclone solids were added to the fresh silicon initiated reaction. The reactions using only fresh silicon (Examples 8 and 9A) showed a weight loss: 73 g in Example 8 and 82 g in Example 9A. In contrast, Example 9B, which added cyclone solids, had a weight gain of 20 g. Using the hourly product composition and sample weight, it was calculated that 77 g of silicon was converted to allyl chlorosilane in Example 9A and 62.8 g in Example 9B. So, a total of 82.8 g of polymer was formed in Example 9B and the adjusted silicon conversion was 49%.

[0212] Thus, additional phenothiazine was needed in Example 9B to completely pre- prevent polymer formation and enhance silicon conversion to allyl chlorosilane.

[0213] Table 13: Reaction conditions for direct synthesis of allyl chlorosilane from fresh silicon with (Example 9B) and without (Example 9A) cyclone solids, affected by phenothiazine

[0214]

[0215] Table 14: Summary of experimental data for Example 9A

[0216]

[0217] Table 15: Summary of experimental data for Example 9B

[0218]

Claims

1. The process for synthesizing alkenyl halosilanes includes: (1) In a heat-stable solvent, a slurry of copper-activated silicon is formed, wherein the copper-activated silicon is derived from at least one of the following: fresh silicon, cyclone-separated fine particles, cyclone-separated fine dust, ultrafine silicon particles, waste contact material from the direct synthesis of organohalosilanes, or mixtures thereof. (2) Stir the slurry; (3) In the presence of an additive exhibiting Lewis base properties, the stirred slurry is mixed with at least one of formula R 1 The reaction involves an unsaturated aliphatic or unsaturated cycloaliphatic organohalide of X, and optionally at least one organohalosilane or hydrogen halide, wherein the additive effectively inhibits the polymerization of the alkenyl halosilane, the reaction is carried out at a reaction time, reaction temperature and reaction pressure that effectively produce the alkenyl halosilane, the alkenyl halosilane having the formula R. 1 SiHX2, R 1 2SiHX、R 1 3SiX, R 1 SiX3 and R 1 2SiX2 or a mixture thereof, wherein R 1 It is an unsaturated aliphatic or cycloalkenyl group, and X is a halogen; and (4) The alkenyl halosilane is collected from the slurry.

2. The process according to claim 1, wherein R 1 X is allyl, vinyl, methanallyl, or cyclohexenyl, and X is fluorine, chlorine, bromine, or iodine.

3. The process according to claim 1, wherein the additive is selected from the following sulfur-containing additives: polymerization-inhibiting thiohydroxyl and thiols, thioethers, thioesters, disulfides, thioketones, thioamides, thioimidazoles, and mixtures thereof.

4. The process according to claim 1, wherein the additive is a cyclic sulfur-containing additive selected from the following: polymerization-inhibiting thiophene, phenothiazine, thiomorpholine and 1,4-oxothiacyclohexane and mixtures thereof.

5. The process according to claim 1, wherein the additive is selected from: urea, tetraalkylurea, thiourea, tetraalkylthiourea and mixtures thereof.

6. The process according to claim 1, wherein the additive comprises hexamethyldisiloxane.

7. The process according to claim 1, wherein the additive comprises hexamethyldisiloxane and additives selected from the group consisting of polymerization-inhibiting thiohydroxyl, thiols, thioethers, thioesters, disulfides, thioketones, thioamides, thioimidazoles, tetramethylurea, and mixtures thereof.

8. The process according to claim 1, wherein the solvent is selected from straight-chain or branched alkanes, cycloalkanes and mixtures thereof having a boiling point greater than 200°C under standard conditions.

9. The process according to claim 1, wherein the solvent is an alkane-type heat transfer fluid.

10. The process according to claim 1, wherein R 1 It is allyl or methanally, and the organohalosilane contains R. 1 SiX3 and R 1 A mixture of SiHX2, wherein optional hydrogen halide is present, and wherein the molar ratio of allyl halide to hydrogen halide in the reactant mixture of step (1) is about 0.8:1 or greater.

11. The process according to claim 5, wherein the molar ratio of alkenyl halide to hydrogen halide is about 1 to about 100 or higher.

12. The process of claim 1, wherein an additional amount of additive is added to the slurry during the reaction process.

13. The process of claim 1, wherein the molar ratio of the amount of additive added to the slurry during the reaction is based on the molar ratio of the additive to all Lewis acids formed in the slurry during the reaction, the ratio being from about 0.05:1 to about 15:

1.

14. The process of claim 1, wherein the ratio of the amount of additive added to the slurry during the reaction is based on the molar ratio of the additive to all Lewis acids formed in the slurry during the reaction, the ratio being about 2:1 to about 5:

1.

15. The process according to claim 1, wherein the additive is selected from: C8H 17 SH, C 12 H 25 SH, C 18 H 37 SH, C6H 13 C(CH3)2SH (tert-nonylthiol), p-heptylbenzyl-thiol, furfuryl thiol, grapefruit thiol (1-p-menthene-8-thiohydroxy), 1,5-pentanedithiohydroxy, HS(CH2)5SH, 2,2'-(ethylenedioxy)-diethylthiohydroxy, and HSCH2CH2OCH2CH2OCH2CH2SH, and the sulfide is dibutyl sulfide, (C4H9)2S or dodecyl methyl sulfide, CH3(CH2) 11 SCH3 and its mixtures.

16. The process according to claim 1, wherein the reaction temperature is greater than 180°C.

17. The process according to claim 1, wherein the alkenyl halide is an allyl chloride, and the reaction temperature range is from about 220°C to about 300°C.

18. The process according to claim 1, wherein the reaction pressure ranges from atmospheric pressure to about 10 atmospheres.

19. The process according to claim 1, wherein the reaction time is in the range of 0.1 to 100 hours.

20. The process according to claim 1, further comprising collecting the solvent from the slurry and reusing the solvent in a new step (1).

21. The process according to claim 1, further comprising, after the initial charge has been partially or completely converted, in a new step (1), introducing additional fresh silicon, fine dust from silicon milling, cyclone-separated fine particles, ultrafine particles and / or waste material into the reaction slurry, and continuing to react with alkenyl halides to produce additional alkenyl halosilanes, without first collecting or repairing the solvent.

22. The process according to claim 1, wherein a foam control agent is added to the reaction step.

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