UNITED STATES PATENT OFFICE 2,647,136 PREPARATION of METHYLCELOROSLANES Robert O

Patented July 28, 1953 2,647,136

UNITED STATES PATENT OFFICE 2,647,136 PREPARATION OF METHYLCELOROSLANES Robert O. Sauer, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York No Drawing. Application January 22, 1948, Seria No. 3,835 3 Claims. (C. 260-448.2) 1. 2 This invention is concerned with a process for silicon atom to another as the result of effecting the preparation of alkylhalogenosilanes. More reaction at a temperature above 250° C. be particularly, this invention relates to a process tween (1) a compound corresponding to the gen Which comprises effecting reaction in the sub eral formula (R) mSi(X) 4-m and (2) a com Stantial absence of an alkyl halide at a tempera 5 pound corresponding to the general formula, ture above 250° C. between (1) a preformed com (R') nSi(X) 4-n, where R and R. are each lower pound corresponding to the general formula, alkyl radicals, X is a halogen, m is one of the (R) mSi(X) 4-m and (2) a preformed compound following: 1, 2, 3, and in corresponds to one of Corresponding to the general formula the following: 0, 1, 2 and 3. My invention differs from the work done by O Callingaert et al. in that I am able to effect not where R, and R, are each lower alkyl radicals, X is only the migration of an alkyl group, but also a halogen (e.g., bromine, chlorine, fluorine, etc.), the nigration of a halogen atom. Moreover, m is one of the following: 1, 2, 3 and in corre contrary to the random distribution encountered Sponds to One of the following: 0, 1, 2 and 3. in the reaction disclosed by . Callingaert et al., One Of the objects of this invention is to en 5 my reaction results in the establishment of an able one to prepare in a relatively easy manner equilibrium relationship whereby the distribu alkyl-substituted halogenosilanes wherein dif tion of the individual components comprising the ferent alkyl groups are attached directly to the final reaction products are present in a definite Silicon aton by carbon-Silicon linkages. and substantially predictable ratio, depending Another object of the invention relates to a 20 upon the starting ingredients; this equilibrium proceSS for preparing more desirable alkyl-Sub relationship is not in accord with the random Stituted halogenosilanes from less desirable al distribution theory. In addition, there is the kyl-Substituted halogenosilanes. sane number of carbon-silicon and Silicon-hao A further object of this invention is to enable gen bonds after rearrangement as there was be an interchange of both halogenS and alkyl groupS 25 fore. As an illustration of this point, there may to take place between different alkyl-substituted be mentioned the reaction between trimethyl halogenosilanes to yield alkyl-Substituted halo chlorosilane and methyltrichlorosilane which re genosilanes having a different numerical Con act as follows: figuration of alkyl groupS and halogens around the Silicon aton. 30 (CH3)3SiCl-, -CH3SiCl3(22(CH3) 2SiCl, A still further object of this invention is to It is desired to point out that although re effect a dealkylation of alkyl-Substituted halo action between different alkyl-substituted halo genosilanes So as to yield alkyl-substituted halo genosilanes may be effected in accordance with genosilanes containing the grouping Si-R-Si my claimed process disclosed in the first para where R is a Saturated alkylene linkage, e. g., a 35 graph of this specification, redistribution of al methylene (-CH2-) linkage. kyl groups and halogens may also be effected Other objects will become more apparent as where only one alkylhalogenosilane, for example, the description of this invention proceeds. dimethyldichlorosilane, is reacted with itself at It was known heretofore that tetraethylsilane temperatures above 250° C. This will be ap and tetrapropylsilane could be caused to react AO parent from the equilibrium relationship shown With each other to yield a reaction mixture Com in Equation I above as well as in the examples prising mixed ethylpropylsilanes in addition to which follow. the starting materials. Thus, Calingaert et al. The manner in which the exchange of both have previously disclosed that the above-de alkyl groups and halogen atoms is caused to scribed reaction between tetraethylsilane and 45 proceed to give reaction mixtures containing tetrapropylsilane proceeds in the presence of alu non-random concentrations of individual com minum chloride at a temperature of the order ponents is not clearly understood. However, it of about 175 to 180° C. See J. A. C. S. 62, is believed that these unexpected results may be 1104-1110 (1940); J. A. C. S. 61, 2748 (1939) J. explained by reference to the well-known ther The manner in which the ethyl and propyl groups 50 modynamic equation migrated and attached to the Silicon atoms was AF=AH-TAS stated by Calingaert to constitute a random by postulating that AH is not zero for the reac distribution pattern. tions under consideration. . . . I have now discovered that I am able to shift In addition to effecting. a rearrangement. of both alkyl groups and halogen atoms from one alkyl groups and halogen atoms under the Spec 2,647,136 3 4 ified conditions of reaction, there also occurs a num chloride employed in the reaction may be side reaction whereby dealkylation of an alkyl varied widely. I have found that good results oc halogenosilane takes place with the establish cur when from about 0.5 to 5 per cent, by Weight, ment of an Si-R-Si linkage wherein R is an aluminum chloride is used, based on the total alkylene grouping (i. e., a bivalent hydrocarbon 5 Weight of the halogenosilane (or silanes) emi radical). Under preferred conditions of tiline ployed. and temperature, the main reaction which oc Where normal pressures are employed in con curs is the redistribution of alkyl groups and hal ducting the reaction, the reactant or reactants ogen atoms. At temperatures of the order of are advantageously passed through a hot tube 400° C. or above, in addition to the products of heated at the required temperatures. The alu redistribution, from about 10 to 20 per cent of minum chloride catalyst may be suitably em the reaction product may comprise alkylhalo ployed within the tube in a manner so as to per mit passage of the halogenosilane or mixtures of genosilanes containing the aforementioned halogenosilanes while contacting the catalyst. Si-R-Si 5 The use of pressure equipment is preferable grouping. for conducting my reaction to give more intimate Among the compounds embraced by the afore contact between the coreacting molecules. Under mentioned general formula, (R) mSi(X) 4-in are such conditions, heating of the pressure equip e.g., methyltrichlorosilane, ethyltrichlorosilane, ment at the required temperature may cause the methyltribromosilane, butyltrichlorosilane, di- i. internal pressure to vary anywhere from about methyldichlorosilane, trimethylchlorosilane, di 500 p.s. i. to 2,000-3,000 p.s. i. The use of super methyldibromosilane, dimethylidifluorosilane, di atmospheric pressure also permits lower temper ethyldichlorosilane, triethylchlorosilane, dipro atures of reaction at slightly longer periods of pyldichlorosilane, di-isopropyldichlorosilane, tri time with the attendant advantage that undes propylbromosilane, dibutyldichlorosilane, tri-iso 25 sirable side reactions are minimized. butylchlorosilane, amyltrichlorosilane, etc. It is, of course, obvious that when a single The compound represented by the general for alkyl-substituted halogenosilane is employed, it mula (R') in Si(X) 4-n, in addition to being one is only necessary to treat this material under the of the alkylhalogenosilanes embraced by the for stipulated conditions, either with or without a mula in the preceding paragraph, may also be, catalyst. When mixtures of halogenosilanes, e.g., for example, silicon tetrachloride, silicon tetra trimethylchlorosilane and methyltrichlorosilane, bromide, silicon tetrafluoride, etc. or trimethylchlorosilane and silicon tetrachloride, The manner whereby my process may be prac etc., are employed, the proportions of these re ticed may be varied within wide limits. Al actants may be varied within broad limits. The though the reaction may be effected at atmos 35 actual proportions will depend, for instance, on pheric pressures, I prefer to use Superatmospheric such factors as the desired product, starting ma pressures in order to effect a more intimate con terials available, etc. It will, of course, be ap tact between the various molecules. parent to those skilled in the art that starting The temperature at which the reaction is mixtures containing more than two halogeno caused to proceed may also be varied depending 40 silane components may also be employed. upon such factors as, for example, the particu In Order that those skilled in the art hay lar alkylhalogenosilane (or silanes) employed, better understand how the present invention may whether a catalyst is used, the time of reaction, be practiced the following examples are given by the presence or absence of pressure, etc. I have way of illustration and not by way of limitation. found that good results are obtained if temper In all the following examples, unless stated atures of the order of from 250° to 500 C. Or even otherwise, the pressure equipment employed was 600° C. are employed. Temperatures above a 3-liter Aminco hydrogenation steel bomb which 500° C. may be employed provided shorter reac was provided with suitable arrangements where tion times are used to minimize undesirable losses by the bomb together with its contents could be due to side reactions. Insufficient reaction Oc 50 uniformly heated at elevated temperatures. curs at temperatures below 250° C. either with or Eacample i without a catalyst, to make the use of tempera tures below 250° C. of any practical value. About 849 grams (7.81 nois) trimethylchloro The time for effecting the reaction may ob silane and 20 grams aluminum chloride were viously be varied within wide limits depending charged to the Steel bomb. The bomb and its on the temperature employed, the presence or 55 contents were heated at 300° C. and 775 p.s. i. for absence of pressure, whether a catalyst is used 15.3 hours. The bomb WaS cooled and its con in the reaction, etc. At temperatures of the tents were fractionally distilled to yield 77 grams order of 250° to 400° C., in the presence of a cata." (0.60 mol) dimethyldichlorosilane, 66 grams lyst, my claimed reaction proceeds substantially (0.75 mol) silicon tetramethyl, and 648 grams to completion in from 3 to 15 or 20 hours. 60 (5.97 mois) recovered trimethyl-chlorosilane. Although, as stated previously, the reaction Neither methyltrichlorosilane nor Silicon tetra proceeds without a catalyst at elevated tempera chloride was present. tures, I have found that aluminum chloride, Eacample 2 preferably, though not essentially in the Sub stantially anhydrous state, may be used to good To the Sane Steel bomb employed in the pre advantage in accelerating the migration of the ceding example was added 855 grams (7.87 mols) alkyl groups and halogen atoms attemperatures trimethylchlorosilane (no catalyst). This charge ranging from about 250° to 400° C. Surpris Was heated at 450° C. and 1575 p.s. i. for 7 hours, ingly, aluminum chloride was the only catalyst the product cooled and filtered. Separation of found which would accelerate this reaction. the Solid matter and fractional distillation of the Thus, other common catalysts, for example, bOrOn filtrate yielded 96 grams (0.74 mol) dimethyldi trichloride, zinc chloride, iron chloride, copper chlorosilane and 621 grams (5.73 mols) trimeth chloride, etc., exerted no perceptible effect on the ylchlorosilane in addition to about 61 grams course of the reaction. The amount of alumi (0.69 mol) silicon tetramethyl. 2,647,136 5 6 Eacample 3. ... Eacample 8 In this example, 1006 grams (7.80 mols) di To the pressure reaction vessel were charged methyldichlorosilane and 20 grams. aluminum 993 grams methyltrichlorosilane and 20 grams chloride were charged to the pressure equip aluminum chloride. After heating the vessel at ment. After heating at 350° C. and 925 p.s. i. for 375° C. and 925 p. s. i., for 7 hours, fractional 7 hours, fractional distillation of the product distillation of the reaction product gave a trace mixture yielded 92 grams (0.85 mol) trimethyl of silicon tetrachloride, 906 grams methyltri chlorosilane and 126 grams (0.84 mol) methyl chlorosilane, and 30 grams dimethyldichloro trichlorosilane. The remainder of the reaction Silane. product comprised unchanged dimethyldichloro O Eacample 9 silane. No silicon tetramethyl nor silicon tetra To the pressure equipment were charged 446 chloride Was found. grams (3.45 mols) dimethyldichlorosilane, 576 Eacample 4 grams (3.39 mols) silicon tetrachloride, and 20 To the same pressure equipment employed in 15 grams aluminum chloride. After heating at the foregoing example were charged 417 grams 375°C; and 990 p.s. i. for 17 hours the bomb WaS (3.84 mols) trimethylchlorosilane, 576 grams cooled and the contents fractionally distilled to (3.85 mols) methyltrichlorosilane and 20 grams yield a trace of trimethylchlorosilane, 281 grams aluminum chloride. After heating at 375 C. for (2.18 mols) dimethyldichlorosilane, 213 grams 7 hours, fractional distillation of the reaction 20 (1.42 mols) methyltrichlorosilane and 381 grams product gave 82 grams (0.75 mol) trimethylchlo (2.24 mols) silicon tetrachloride. rosilane, 124 grams (0.83 mol) methyltrichloro Eacample 10 silane, and 713 grams (5.53 mols) dimethyldi In this example 462 grams (3.58 mols) dimeth chlorosilane. Again neither silicon tetramethyl 25 yldichlorosilane, 595 grams (3.50 mols) silicon nor silicon tetrachloride was detected in the tetrachloride and 20 grams aluminum chloride product. were charged to the bomb and the contents The results in this example seem to indicate heated at 450° C. and 1365 p.s. i. for 7 hours. that the equilibrium concentrations at 375 C. of Fractional distiluation of the reaction mixture equimolecular proportions of trimethylchloro 30 gave 95 grams (0.74 mol) dimethyldichlorosilane, silane and methyltrichlorosilane fall in the fol 490 grams (3.28 mols) methyltrichlorosilane, and lowing ranges: (CH3)3SiCl 10-12 mol per cent; 198grams (1.16 mols) silicon tetrachloride. A CHSiCl3 10-12 mol per cent; (CH3)2SiCl2 78-80 considerable volume of methane was formed and mol per cent. w at least 123 grams of residue boiling above 75 Eacample 5 C./760 mm. Was obtained. To the steel reactor were added 562 grams Distillation of the 123 gram residue showed it (5.18 mols) trimethylchlorosilane, 439 grams to be comprised predominantly of bis-(trichlo (2.58 mols) silicon tetrachloride, and 20 grams rosilyl) methane (C3Si-CH2-SiCl3) boiling at aluminum chloride, Aafter heating at 375 C. 40 about 185° C. This establishes that at the ele and 1075 p.s. i. for 23.5 hours the bomb and its wated temperatures employed in the presence of contents were cooled. Distillation of the reaction aluminum chloride, dealkylation of methyltri product gave 60 grams (0.55 mol) trimethylchlo chlorosilane occurred in accordance With the foll rosilane, 127 grams (0.85 mol) methyltrichloro lowing equation: silane, no silicon tetramethyl and a trace of sili con tetrachloride. The balance of the distilla 45 tion product comprised mainly dimethyldichlo This accounted for the evolution of methane rosilane. during the course of the reaction. Eacample 6 Eacample 11 To a 1.3-liter Aminco hydrogenation bomb About 1003 grams (7.79 mols) dimethyldi 50 similar to that employed in the previous exam chlorosilane and 20 grams aluminum chlo ples were added 530 grams (3.37 mois) diethyl ride were charged to the pressure equipment dichlorosilane and 10 grams aluminum chloride. and heated at 250° C. for 6 hours. Fract The bomb and its contents were heated at 300° tional distillation of the product yielded 4 grams C. for 8 hours. Fractional distillation of the res trimethylchlorosilane and 15 grams methyltri 55 idue gave approximately 33 grams ethyltrichlo chlorosilane, the balance of the charge compris rosilane, the balance of the residue comprising ing principally unchanged dimethyldichloro principally unchanged diethyldichlorosilane con silane. These results when compared with the results obtained in Example 3 establish that 250 taining about 10 per cent triethylchlorosilane. C. is essentially the lowest practical temperature 60 Eacample 12 limit at which my claimed process may be prac . To the pressure equipment described in Exam ticed. ple 11 were charged 235.5 grams (1.50 mols) di Eacample 7 ethyldichlorosilane, 255.5 grams (1.50 mols) sili In this example a mixture of 430 grams (3.96 65 con tetrachloride, and 10 grams aluminum chlo mols) trimethylchlorosilane, 668 grams (3.93 ride. After heating the reaction mixture at 375 C. and 100 p. S. i. for 7 hours, the reaction mass mols) silicon tetrachloride, and 30 grams alu was fractionally distilled to yield about 36 grams minum chloride were heated in the Aminco bomb (0.22 mol) ethyltrichlorosilane in addition to the at 375° C. and 1290 p.s. i. for 7.1 hours. Analy unchanged silicon tetrachloride and dimethyldi sis of the reaction product by fractional distilla O tion showed it to contain 12 grams (0.11 mol) chlorosilane, trimethylchlorosilane, 118 grams (0.70 mol) sili Eacample 13 contetrachloride, 285 grams (1.91 mols) methyl To an Aminco bomb of 180 cc. capacity were trichlorosilane and 473 grams (3.67 mols) di charged 0.5 gram aluminum chloride and 95.6 methyldichlorosilane. 5 grams of an equimolar mixture of trimethyl 2,847,188 8 bromosilane and methyltribromosilane (equiva chloride. The bomb and its contents were ent to 0.22 mol of each bromosilane component). heated at 450° C. for 7.0 hours. After cooling, The bomb and its contents were heated at the liquid contents were removed and subjected 310-320° C. for 6 hours. Fractional distillation to fractional distillation at atmospheric pressure of the reaction product showed it to contain 8.3 to yield 130 grams (0.77 mol) silicon tetrachlo grams trimethylbromosilane, 45.1 grams dimeth ride, 750 grams (5.03 mols) methyltrichloro yldibromosilane and 20.5 grams methyltribromo silarae, and 32 grams (0.25 mol) dimethyldi Silane. chlorosilane. A fraction weighing 108 grams Eacample 14 which was collected at a vapor temperature of 10 176-199° C. was carefully redistilled to give a To the pressure equipment employed in Ex fraction boiling between 185.3 to 185.5° C. This anaple 1 were charged 852 grams (7.85 mols) tri fraction, together with a small amount of sodium methylchlorosilane and 20 grams (0.015 mol) chloride, was heated at 200° C. for 2 hours and aluminum chloride. The mixture was heated at redistilled to yield 39 grams of a material having 375° C. at 1150 p.s. i. for 7 hours. Fractional a boiling point of 1843 to 186.3° C. A chlorine distillation of the reaction mass yielded 34 grams analysis of this material showed it to comprise a (0.039 mol) silicon tetramethyl, 596 grams (5.50 mixture of bis-(trichlorosily) methane and tri mols) unchanged trimethylchlorosilane, 68 chlorosilylmethyldichlorosilylmethane. This ex granas (0.53 mol) dinnethyldichlorosilane, and ample again illustrates the dealkylation, more 95 grams of a higher boiling residue. 20 particularly, the dennethylation, effected by Fractional distillation of the aforementioned means of my claimed process. higher boiling residue showed it to be com prised predominantly of bis-(dimethylchloro Eacample 17 silyl)methane boiling at about 176.8° C. at at To the pressure reactor employed in the fore mospheric pressure (approximately 754 mm.). going example were added 852 grams (7.85 mols) Analysis of the compound showed it to contain trimethylchlorosilane and 20 grams aluminum about 35.55 per cent chlorine (calculated chloride. The reactor was closed and heated at 35.25%). This example again illustrates that in 375 C. and 1150 p.s. i. for 7 hours. Distilla addition to effecting migration of alkyl groups tion of the reaction product at atmospheric pres and halogens, under the conditions of reaction, 30 Sure gave 34 grams (0.39 mol) Silicon tetra there also occurs a dimethylation with the Sub methyl, 596 grams (5.50 inhols) trimethylchloro sequent establishment of a methylene bridge be Silane, 68 grams (0.53 mol) dimethyldichloro tween the two silicon atoms. - Sikane and 95 grams of higher boiling substances. Careful distillation of the high-boiling fraction Eacample 15 yielded essentially pure bis-(dimethylchloro To a 1.3 liter Aminco autoclave were charged silyl)methane having a boiling point of about 198.5 grams (154 mois) dimethyldichlorosilane, 175.3 to 176.9° C. and showing a chlorine analy 249. grams (1.53 mols) ethyltrichlorosilane, sis of about 35.5 per cent (calculated 35.25 per and 10 grams aluminum chloride. The bomb cent chlorine), was closed and heated at 375 C. for 5 hours. I have also found that I can effect rearrange Thereafter, 30 grams sodium chloride were ment of alkyl radicals and halogens attached to added and the mixture again heated in the Silicon in the presence of arylhalogenosilanes, closed bomb at 225 C. for 3.25 hours. The bomb consisting of aryl radicals and silicon and halo was cooled and the liquid product was decanted gen atoms, wherein from 1 to 3 aryl groups are from the sodium chloroaluminate-sodium chlo 45 attached directly to silicon by a carbon-silicon ride cake, and the product fractionally distilled bond. More particularly, I have found that I to reneove the unreacted methyltrichlorosilane, an able to effect the above-described reaction and Small amounts of dimethyldichlorosilane between (1) Compounds corresponding to the and Silicon tetrachloride. The residue which general formula (R) Six-u where R is a lower "comprised a 130 gram mixture of ethyltrichloro 50 alkyl radical, X is a halogen, and u is one of the silane and ethylmethyldichlorosilane was con following: 2, 3, and (2) a compound correspond verted to the respective ethoxy derivatives by ing to the general formula (R') Six- where treatment with absolute ethanol. This proce R’ is an aryl radical, for example, phenyl, tolyl, dure yielded a fraction comprising ethylmethyl Xylyl, naphthyl, etc., X is a halogen, and u) is diethoxysilane having a boiling point of 140 C. 55 a Value equal to one of the following: 1, 2. It and no 1.3950. Analysis of this compound Should be noted in the aforementioned reaction showed it to contain 51.75 per cent carbon and that there is no detachment or migration of the 11.0 per cent hydrogen (theoretical 51.81 per aryl radicals, the alkyl radicals of the alkyl halo cent carbon and 11.18 per cent hydrogen). genosilanes acting as alkylating agents. In order to establish conclusively that ethyl 60 The above-described reaction is effected either methyldichlorosilane had been obtained, about with or without aluminum chloride as a catalyst 33 grams of the ethylmethyldiethoxysilane ob at temperatures of the same order as those em stained above was added to 46 grames phosphorus ployed in the case where none of the coreactants tribromide and the mixture refluxed for six contain an aryl radical attached directly to the hours. The ethyl bromide formed was removed 85 silicon aton by a silicon-carbon bond. The foll by distillation and essentially pure ethylmethyl lowing examples illustrate the reaction between dibromosilane Was obtained. This material had phenyltrichlorosilane and either a dialkyldihalo a boiling point of 139-141° C. and upon analysis genosilane or a trialkylnonohalogenosilane. was shown to contain 69.65 per cent bromine Eacample 18 -(theoretical 68.90 per cent bromine). 70 Into a 3-liter Aminco autoclave were charged Eacample 16 396 grams (1.87 mols) phenyltrichlorosilane, 207 To the pressure equipment employed in Ex grams (1.90 mols) trimethylchlorosilane and 5 ample 1 were charged 1193 grams (8.02 mols) grams anhydrous aluminum chloride. This mix methyltrichlorosilane and 20 grams aluminum is ture was heated at 325° C. for four hours during 2,647, 186 9 10 which time the autogenous pressure rose from 500 absolute ethanol and anhydrous hydrogen fluo p.s. i. to 600 p.s. i. The bomb was cooled, the ride in the Same manner as described in Example contents removed, and about 30 grams sodium 19 to yield ethylphenylidifluorosilane, B. P. 163 chloride were added thereto and the total mix 164 C., thus establishing the presence in the orig ture distilled until a pot temperature of 175° C. inal reaction mixture of ethylphenyldichlorosi was obtained. This distillate (328 grams) Was lane. shown by analysis to comprise 16 grams trimeth My claimed process is useful in connection with ylchlorosilane, 60 grams methyltrichlorosilane, the azeotropic mixture of silicon tetrachloride 201 grams dimethyldichlorosilane and 28 grams and trimethylchlorosilane obtained as a result of benzene. the direct reaction of silicon and methyl chloride The residue was distilled at atmospheric pres O in accordance with the process described and sure yielding 102 grams of a liquid distilling With claimed in Rochow Patent 2,380,995, issued Aug in the boiling point range of from 190° C. to 205 ust 7, 1945, and assigned to the same assignee as C. and which contained 40.6 per cent hydrolyzable the present invention. Great difficulty has been chlorine. Analysis of this liquid showed it to experienced in separating the two components of comprise a mixture of phenyltrichlorosilane, B. P. 15 this azeotropic mixture in view of the close boil 201.5° C. (50.3 per cent chlorine), and methyl ing points of the components. By means of my phenyldichlorosilane, B. P. 204 C. (34.1 per cent invention, it is now possible to utilize this azeo chlorine), as evidenced by the following experi tropic mixture by converting it to a Composition ment: The mixture of chlorosilanes was convert containing increased amounts of methylchloro ed to the corresponding ethoxy silanes by slowly 20 Silanes which can be more readily separated by adding 58.5 grams anhydrous ethanol to the usual distillation procedures and which have chlorosilane mixture which was thereafter heated great utility as, for instance, in the preparation at 70-100° C. About 4 cc. dry quinoline were added of resins, lubricating oils, synthetic rubbers, etc. to neutralize traces of acid and the mixture of The dealkylated products, for example, bis ethoxy silanes distilled over a free flame. Dilu 25 (dimethylchlorosilyl)methane (which is more tion of the distillate with pentane followed by particularly disclosed in my COpending applica cooling caused the separation of quinoline hy tion Serial No. 3,836, now U.S. Patent 2,491,833, drochloride which had distilled with the ethoxy filed concurrently herewith and assigned to the silanes. Redistillation gave 50 grams of meth Sane assignee as the present invention), bis-(tri ylphenyldiethoxysilane, B. P. 217.5-223 C. (theo 30 chlorosilyl) methane, etc., are also useful as in retical B. P. 221.5° C.). Since phenyltriethoxy termediates in the preparation of resins, oils and silane boils at 235-237 C., the evidence estab Synthetic elastomers. lished that reaction between the methylchloro What I claim as new and desire to secure by silane and the phenylchlorosilane had resulted in Letters Patent of the United States is: the formation of methylphenyldichlorosilane. l. The method for the production of methyl chlorosilanes which comprises reacting dimethy Eacample 19 dichlorosilane with a compound corresponding Into a 1.3 liter Aminco autoclave were charged to the general formula 212.5 grams (1.00 mol) phenyltrichlorosilane, 259 grams (2.01 mols.) dimethyldichlorosilane and 10 40 (CH3) nSi(C1)- grams aluminum chloride. The autoclave Was Where n is one of the following: 0, 1, at a tem closed and heated at 350° C. (825 p.s. i.) for four perature from 300° to 500° C. and under a pres hours. After cooling, 30 grams sodium chloride Sure of at least about 925 pounds per square inch were added to the reaction mixture and the bomb in the presence of aluminum trichloride. and contents heated at 225° C. for two hours with 45 2. The method of preparing trimethylchloro shaking. The liquid product was decanted, fil Silane which comprises reacting dimethyldichlo tered and fractionally distilled to yield a higher rosilane and methyltrichlorosilane at a tempera boiling portion comprising phenyltrichlorosilane ture of from 300° to 500° C. and under a pressure and methylphenyldichlorosilane containing about 9f at least about 925 pounds per square inch in 60 per cent, by weight, of the latter. This mix 50 the presence of aluminum trichloride. ture was treated with absolute ethanol and then 3. The method for the production of methyl with anhydrous hydrogen fluoride to convert the trichlorosilane which comprises reacting dimeth chlorosilanes to the fluorosilanes. The conver yldichlorosilane and silicon tetrachloride at 3. sion product was shaken and extracted with pen temperature of from 300° to 5000 C. and under tane, and the pentane removed by distillation to 55 a pressure of at least about 925 pounds per Square yield about 29 grams methylphenylidifluorosilane, inch in the presence of aluminum trichloride, B. P. 141-142° C. containing 23.5 per cent flu ROBERT. O. SAUER. orine (theoretical 24.02 per cent fluorine). References Cited in the file of this patent Eacample 20 60 Into the pressure equipment described in Ex UNITED STATES PATENTS ample 19 were charged 422 grams (1.99 mois) Number Name Date phenyltrichlorosilane, 313 grams (1.99 mols) di 2,403,370 Hurd ------July 2, 1946 ethyldichlorosilane, and 15 grams aluminum chlo 2,406,605 Hurd ------Aug. 27, 1946 ride. After heating at 350° C. for 4.7 hours, 30 65 2,421,653 Sauer ------June 3, 1947 grams Sodium chloride were added and the mix ture heated for an additional 3.5 hours at 225° C. OTHER REFERENCES The 720 grams of liquid product removed from Stokes, "Am. Chem. Journal,' vol. 13, pages the bomb comprised 28.2 grams (0.17 mol) sili 244-53 (1891). con tetrachloride, 57.0 grams (0.73 mol) benzene, 70 Ipat'ev et al., "Jour. Gen. Chemistry'' (U. S. 149 grams (0.91 mol) ethyltrichlorosilane, 178.5 S. R.), Vol. 1 (1931). grams (1.13 mols) diethyldichlorosilane and 111.5 Callingaert et al., "Jour. Amer. Chem. Soc.” grams (0.53 mol) phenyltrichlorosilane. The res Vol. 62, pages 1107-10 (1940). idue on distillation yielded a fraction boiling be Post, "Chemistry of Aliphatic Ortho-Esters' tween 230-268 C. This fraction was treated with 5 (1943), pages 133-136, Reinhold, N.Y., publisher.