2,770,634 United States Patent Office Patented Nov. 13, 1956 2 chloride and a silane of the formula RaSIHC3-a, where R is an alkyl radical of less than 5 C atoms or a phenyl 2,770,634 radical and a has a value from 0 to 1 inclusive, is reacted METHOD oF PRODUCING VINYLCHLORO. at a temperature of from 550 to 650°C, for at least SLANES two Seconds at a pressure below three atmospheres. The reaction of this invention may be represented by DonaldCorning R. Weyenberg,Corporation, Midland, Midland, Michassignor Mich., a corporation to Dow the following equation: of Michigan CH2=CHCl--RaSiHC3-a->( CH2=CH) RaSiCl3-a--HCl No Drawing. Application July 17, 1953, 10 When the above conditions are adhered to excellent Serial No. 368,822 yields of the corresponding vinylchlorosilanes are ob tained. However, commercially acceptable yields of the 5 Claims. (C. 260-448.2) desired vinylchlorosilanes are not obtained at tempera tures below 550° C. or above 650° C. At temperatures This invention relates to the production of vinylchlo 5 below 550 C., little or no reaction takes place while rosilanes by the reaction of vinylchloride with hydrogen at temperatures above 650° C. excessive decomposition containing silanes. and rearrangement occur to give undesirable by-products Heretofore, vinylchlorosilanes have been produced by Such as silicon tetrachloride and methyltrichlorosilane. a number of methods. These include the reaction of The pressure employed in this invention must be be vinylchloride with silicon, the reaction of acetylene with 20 low three atmospheres because above that pressure sat trichlorosilane and the cracking of propyl or butyl chloro isfactory results are not obtained. However, there is no silanes. critical lower limit to the pressure. Subatmospheric pres The first and last of these methods give relatively poor Sures may be employed if desired. In general, satisfac yields of vinylchlorosilanes. The second method is tory yields are obtained by carrying out the reaction at hampered by the fact that acetylene is a potentially haz 25 atmospheric pressures. However, the use of slightly in ardous material to handle and thus necessitates the use creased pressure improves the volume efficiency of the of rather elaborate equipment. The present invention apparatus and thus may be desirable in commercial op deals with a commercially feasible method of preparing eration. vinylchlorosilanes in excellent yields employing simple The time of reaction required at the temperatures of equipment. 30 this invention is at least two seconds. In general, opti The present method involves the reaction of vinyl mum yields are obtained at contact times ranging from chloride with certain hydrogen-containing silanes. Prior 5 to 20 Seconds although longer times may be employed to this invention the art taught that the reaction of an if desired. unsaturated organic compound with a hydrogen-contain Either trichlorosilane or organochlorosilanes in which ing silane would produce a product by the addition of a 35 the organic group is alkyl or phenyl can be employed in silicon and hydrogen of the silane across the double bond this invention. It is to be understood that either single of the unsaturated compound. For example, trichloro chlorosilanes or mixtures of two or more chlorosilanes silane plus ethylene gives ethyltrichlorosilane and tri can be used. Specific examples of organochlorosilanes chlorosilane plus allylchloride gives gammachloropropyl which are operative are methyldichlorosilane, ethyldi trichlorosilane. In accordance with this teaching it 40 chlorosilane, propyldichlorosilane, butyldichlorosilane would be expected that the reaction of vinylchloride with and phenyldichlorosilane. trichlorosilane would give monochloroethyltrichlorosi The reactants may be fed into the reaction zone sep lane. Applicant has found, however, that under the con arately or they may be fixed prior to the reaction. The ditions of this invention a different product is obtained. reactants may be added either as liquids or as vapors. It is known from C. L. Agre, JACS, 71 (1949), page 45 The relative proportions of vinylchloride and the silane 300, that dichlorovinyltrichlorosilane is obtained when are not critical although, in general the best yields of trichloroethylene is reacted with trichlorosilane at 500 vinylchlorosilanes are obtained when a ten to twenty mol C. It has been found, however, that serious decomposi percent excess of vinylchloride is employed. tion takes place when the temperature of the reaction is The reaction of this invention may be carried out in boosted substantially above 500° C. For example, when 50 any suitable apparatus. In general, it is sufficient to trichloroethylene is reacted with methyldichlorosilane at pass the reactants through a tube heated to the specified 550° C. at atmospheric pressure for a period from 10 temperatures. If desired, the tube may be packed with to 12 seconds, the product is an equi-molar mixture of inert packing Such as clay chips, glass wool, or diato dichlorovinyltrichlorosilane and methyltrichlorosilane. maceous earth. The reaction vessel may be of either Furthermore, pyrolytic decomposition of the reaction 55 ceramic or metal construction. mixture occurs to such an extent that the reaction tube The vinylchlorosilanes made by the method of this in will plug in about two hours. Thus, the reaction dis vention are useful per se for rendering ceramic materials closed by Agre cannot be carried out commercially at Water repellant and for sizing glass fabrics. They are 550 C. or above. also useful as intermediates in the preparation of vinyl Whereas, the yield of dichlorovinyltrichlorosilane de 60 polysiloxanes. creases rapidly, in the above reaction, when the tempera The following examples are illustrative only and should ture is raised above 500 C., applicant has found that not be construed as limiting the invention which is prop contrary to all expectations the reverse is true when vinyl erly delineated in the appended claims. chloride is reacted with hydrogen-containing silanes. EXAMPLE 1. Not only does the yield of the desired vinyltrichlorosil 65 ane increase rapidly with temperature but there is no Vinylchloride and the chlorosilanes specified in the coking. Consequently, the present method is eminently table below were fed separately into an electrically adaptable for commercial use. heated quartz tube having an inside diameter of 1' and The primary object of this invention is to provide a a length of 4'. The reaction products were condensed simple and cheap method for the production of vinyl 70 and identified by analytical distillation. In each of the chlorosilanes. runs, except run 1, the percent yield is based upon the In accordance with this invention a mixture of vinyl amount of chlorosilane added. In run 1 the yield is 2,770,634 3. 4. based upon the amount of vinylchloride employed. The 2. The method in accordance with claim 1 where the by-product in run 1 was silicontetrachloride, in runs 2, chlorosilane is trichlorosilane. 3, and 4 it was methyltrichlorosilane and in run 5 it was 3. The method in accordance with claim 1 where the phenyltrichlorosilane. The mol percent of by-product chlorosilane is methyldichlorosilane. is based upon the amount of chlorosilane employed. 5 4. The method in accordance with claim 1 where the For example, in run the amount of SiCl4 by-produced chlorosilane is ethyldichlorosilane. was equivalent to 5.4 mol percent of the HSiCl3 added to 5. The method in accordance with claim 1 where the the reaction vessel. chlorosilane, is phenyldichlorosilane. Table

Amt. of Reactants Mol Per in Granas Cont. Mol Mo cent Start Chloro- Temp. Time Products Percent Percenting Chloro silane in C in Secs. Yo... of By-Prod. silane Chloro- Vinyl- Prod, Recovered silane chloride l------SiCl3--- 688 90 600 14.2 WiSiCl3-...-- 53 5.4 33.9 2. - MeSiCls-- 958 693 550 5, 6 WiMeSiCla--- 22.4 ... 6 54.4 3. MeSiBC2- 840 : 60 600 10.5 WiMeSiCl2. 59. 1.9 17.1 4.-- MeSiHCl2-- 401 299 650 10, 2 WiMeSiCl,---- 35 3.6 9.5 5--- PhSiHC- 686 385 550 0.2. WiphSiCl 29, 3.3 36, 6 1 In run 5 the products were identified by infrared analysis. EXAMPLE.2 References Cited in the file of this patent When 5 mols of ethyldichlorosilane is reacted with 3 25 UNITED STATES PATENTS mols of vinylchloride at a temperature of 600° C. for 2,379,821 Miller ------July 3, 1945 10 seconds at atmospheric pressure, vinylethyldichloro 2,574,390 Hatcher ------Nov. 6, 1951 silane is obtained. 2,632,013 Wagner ------Mar. 17, 1953 That which is claimed is: 2,637,738 Wagner ------May 5, 1953 1. A-method of preparing vinylchlorosilanes which 30 comprises, heating a mixture of vinylchloride and a FOREIGN PATENTS chlorosilane of the formula RaSiHCl3-a, where R is 961,878 France ------Nov. 28, 1949 selected from the group consisting of alkyl radicals of less than .5 C atoms and phenyl radicals and a has a OTHER REFERENCES value from 0 to 1 inclusive, at a temperature of from sis Agre: “Jour. Am. Chem. Soc.,” vol. 71 (1949), pages 550°C. to 650°C. for at least two seconds at a pressure 300-304 below three atmospheres,