US2519926A - Resolution of chlorosilane mixtures - Google Patents

Resolution of chlorosilane mixtures Download PDF

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US2519926A
US2519926A US736990A US73699047A US2519926A US 2519926 A US2519926 A US 2519926A US 736990 A US736990 A US 736990A US 73699047 A US73699047 A US 73699047A US 2519926 A US2519926 A US 2519926A
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Winton I Patnode
John R Elliott
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General Electric Co
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
    • C07F7/02—Silicon compounds
    • C07F7/08—Compounds having one or more C—Si linkages
    • C07F7/20—Purification, separation

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  • the present invention relates to a process for resolving mixtures of tetrachlorosilane (silicon tetrachloride) and trimethylchlorosilane, particularly azeotropic or constant boiling mixtures of these "two chlorosilanes. More particularly, the invention is concerned with the process which comprises (1) hydrolyzing a mixture of tetrachlorosilane and trimethylchlorosilane "and (2) contacting the hydrolysis reaction product in an aqueous mediumwith an alkali-metal hydroxide, preferably in the form of an aqueous solution, therebyto obtain a layer comprising hexamethyl disiloxane.
  • chlorosilanes cannot be completely separated into their various components by fractional distillation because tetrachlorosilane (B. P. 516C. at 760 mm.) and trimethylchlorosilane .(B. P. 575 C. at 760 mm.) not only have approximately the same boiling points, but also form a constant boiling mixture or .azeotrope which-consists substantially of about 45'to 55 mol per cent trimethylchlorosilane and'55 .to 45 mol per cent tetrachlorosilane. Usually these two chlorosilanes are present in approximately equimolecular proportions in a constant boiling mixture whichdistills at about 545 C.at 760 mm. and contains about 65.8 per cent by weightof chlorine.
  • Vzarious standard methods are known for resolving an azeotrope.
  • One of the more common methods is to fractionally'distill the azeotrope at pressures other than atmospheric pressure.
  • Another method involves fractionally distilling the mixture of chlorosilanes in the presence of a nitrile selected from the group consisting of acetonitrile and acrylonitrile as disclosed and claimed in Sauer et a1.
  • Patent 2,388,575 issued November .6, 1945, and assigned to the same -assignee as the present invention.
  • This latter method is, however, complicated by the fact that because of the corrosion of the iron equipment by the ingredients employed in this method, it has .beennecessary to use an all glass still which is expensive.
  • the "stepswhereby our claimed process may be carried out may be varied.
  • the mixture of chlorosilanes may-be hydrolyzed by either adding water to the mixture or adding the mixture to water.
  • the amount of alkali-metal hydroxide employed is preferably equal to at least that necessary to convert the silicic acid or its condensation products obtained in the hydrolysis to an alkalimetal silicate, e. g., sodium silicate (NazSiOs). From the foregoing it will be apparent that the minimum amount of alkali-metal hydroxide which may be employed comprises a molar ratio of at least 2 mols of the alkali-metal hydroxide per mol of silicon tetrachloride.
  • the aforementioned alkalizing step effects separation of the mass into an aqueous layer and a non-aqueous or oily layer which comprises hexamethyl disiloxane and smaller amounts of other substituted siloxanes, for example, tetra (trimethylsiloxy) silane.
  • the reaction product after the addition of the solution of the alkali-metal hydroxide under the proper conditions, separates so readily into two layers, it is more practical to remove the aqueous layer prior to isolation of the hexamethyl disiloxane.
  • the methyl-substituted siloxanes may be removed from the alkaline reaction mass by other methods, for example, by steam distillation or by solvent extraction with non-polar solvents, e. g., benzene, toluene, xylene, petroleum ether, diethyl ether, etc.
  • Hexamethyl disiloxane obtained in the practice of our claimed invention is useful for making liquid, oily, linear hydrocarbon-substituted (e. g., methyl-substituted) polysiloxanes of the type disclosed and claimed in Patnode application Serial No. 463,814, filed October 29, 1942 (now U. S. 2,469,888, issued May 10, 1949), and assigned to the same assignee as the present invention.
  • These liquid polysiloxanes, which are useful for lubricating purposes generally have from about 2.001 to 2.2 hydrocarbon groups per 4 silicon atom.
  • condensation products of trimethyl silanol and silicic acid are also useful as a source of trimethyl siloxy groups ((CHa): Si-O) for terminating the ends of hydrocarbon-substituted polysiloxane chains having a ratio of about 2 hydrocarbon groups per silicon atom, for example, two methyl groups per silicon atom, by effecting rearrangement by the process of cleavage and condensation between the hydrolysis product of a dihydrocarbon-substituted dihalogenosilane and the aforementioned condensation product of trimethyl silanol and silicic acid (see the aforementioned Patnode application as well as Sprung et a1.
  • application Serial No. 702,590 filed October 11, 1946 (now U. S. 2,483,158, issued September 27, 1949), and assigned to the same assignee as the instant application).
  • a dilute acid for example, a dilute aqueous hydrochloric acid solution, for instance, a 5 per cent solution
  • This acidification step effects condensation of free silanol groups present in the mass thereby increasing the yields and simplifies the distillation of, e. g., hexamethyl disiloxane.
  • Tetra trimethylsi ox ila iewas i elat dirom with-watera mixture of tetrachlorosilane and trithe residue.
  • COP-taming th u stantially n h eq -e s umn of the table refers to the number of methyl 3o Port-ion resulting m e hydrolysi p in ps p r Silicon atom of the non-aqueous with a concentrated aqueous solution of an alkalioily layer obtained as in the example after the m tal hyd x d the latter being p s nt in a alkalizing step.
  • the number 2.4 in the same molar ratio of from 2 to 8.6 mols of the alkalicolumn refers to the number of methyl groups metal hydroxide per mol of the tetrachlorosilane, per silicon atom of tetra (trimethylsiloxy) silane. 3s nd (4) separating t resulting Substantially
  • the term tetramer refers o Oc amethyl tetranon-aqueous layer from the reaction mass in (3) SIIOXaIle havlng the Structural formula and isolating the hexamethyl disiloxane present (CH3), therein.
  • the process which comprises 1) hydrolyzing with water a mixture of tetrachlorosilane and trimethyl chlorosilane, (2) contacting the hydrolysis reaction product in an aqueous medium with an alkali-metal hydroxide thereby to obtain a layer comprising hexamethyl disiloxane, the alkali-metal hydroxide being present in a ratio of from 2 to 8.6 mols of the latter per mol tetrachlorosilane, and (3) isolating the hexamethyldisiloxane present in the aforesaid layer.
  • process comprises (1) hydrolyzing the azeotropic calculated as necessary for the complete hydrolysis of the two components, (2) removing the resulting aqueous layer from the hydrolysis mixture, (3) thoroughly mixing the remaining substantially non-aqueous powdery portion with a concentrated aqueous solution of sodium hydroxide, the latter being present in the molar ratio of from 2 to 8.6 mols of the sodium hydroxide per mol of the tetrachlorosilane, (4) separating the resulting substantially non-aqueous liquid layer from the 2.
  • the process which comprises (1) hydrolyzing aqueous layer, and (5) isolating hexamethyl disiloxane from the non-aqueous layer obtained in (4).
  • the process for separating the components of an azeotropic mixture consisting substantially of about 45 to 55 mol per cent trimethylchlorosilane and 55 to 45 mol per cent tetrachlorosilane thereby to obtain the former component in the form of hexamethyl disiloxane which process comprises (1) hydrolyzing the azeotropic mixture with water present, by weight, in an amount equal to from about 75 to 90 per cent of the total weight of water and azeotropic mixture of chlorosilanes, (2) separating the resulting substantially nonaqueous portion, (3) treating the latter non-aqueous portion with a concentrated aqueous solution of sodium hydroxide, the latter being present in a molar ratio of from 2 to 8.6 mols of the sodium hydroxide per mol of the tetrachlorosilane, and (4) isolating hexamethyl disiloxane from the non-aqueous phase resulting from the alkaline treatment in (3) '7.
  • the process which comprises (1) hydrolyzing an azeotropic mixture of tetrachlorosilane and trimethylchlorosilane with water present, by weight, in an amount equal to from about 75 to 90 per cent of the total Weight of water and azeotropic mixture of chlorosilanes, (2) separating the resulting substantially non-aqueous portion, (3) treating the latter non-aqueous portion with a. concentrated aqueous solution of sodium hy- REFERENCES CITED
  • the following references are of record in the file of this patent:

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Description

Aug. 22, 1950 w. PATNODE ETAL 2,519,925
RESOLUTION OF CHLOROSILANE MIXTURES Filed March 25, 1947 Tetrach/orosi/ane and Trim e thy/ch ior-o si/an e Mixture Water Se arate Aqueous Solution of an Alkali-Meta/ Aqueous Phase Non-Aqueous Phase H o r-oxide Se ar'te Hexamethy/ Other" Methyl- Substituted Dis i/oxane Si/oxanes Tetra (Tr/methy/sfiox 'S/Yane Inventors: Winton I. Pat'flode, John E. Eliiott,
Their Attorney.
Patented Aug. 22, 1950 RESOLUTION :OF CHLOROSILANE MIXTURES Winton I. Patnode, Richland, Wash.,-and John R.
Elliott, Schenectady, N. Y., as'signors to General Electric Company, a corporation of New York PATENT OFFICE Application Marcl125, 1947, Serial No. 736,990
(o1. zen-448.2)
'7 Claims.
The present invention relates to a process for resolving mixtures of tetrachlorosilane (silicon tetrachloride) and trimethylchlorosilane, particularly azeotropic or constant boiling mixtures of these "two chlorosilanes. More particularly, the invention is concerned with the process which comprises (1) hydrolyzing a mixture of tetrachlorosilane and trimethylchlorosilane "and (2) contacting the hydrolysis reaction product in an aqueous mediumwith an alkali-metal hydroxide, preferably in the form of an aqueous solution, therebyto obtain a layer comprising hexamethyl disiloxane.
Mixtures of the above-mentioned chlorosilanes cannot be completely separated into their various components by fractional distillation because tetrachlorosilane (B. P. 516C. at 760 mm.) and trimethylchlorosilane .(B. P. 575 C. at 760 mm.) not only have approximately the same boiling points, but also form a constant boiling mixture or .azeotrope which-consists substantially of about 45'to 55 mol per cent trimethylchlorosilane and'55 .to 45 mol per cent tetrachlorosilane. Usually these two chlorosilanes are present in approximately equimolecular proportions in a constant boiling mixture whichdistills at about 545 C.at 760 mm. and contains about 65.8 per cent by weightof chlorine.
Vzarious standard methods are known for resolving an azeotrope. One of the more common methods .is to fractionally'distill the azeotrope at pressures other than atmospheric pressure. However, with this method no appreciable change in the composition of the tetrachlorosilane-trimethylchlorosilane azeotrope is effected at practical superor sub-atmospheric pressures. Another method involves fractionally distilling the mixture of chlorosilanes in the presence of a nitrile selected from the group consisting of acetonitrile and acrylonitrile as disclosed and claimed in Sauer et a1. Patent 2,388,575, issued November .6, 1945, and assigned to the same -assignee as the present invention. This latter method is, however, complicated by the fact that because of the corrosion of the iron equipment by the ingredients employed in this method, it has .beennecessary to use an all glass still which is expensive.
In accordance with the process of our inven tion which is diagrammatically illustrated in the accompanying drawing, we have discovered a process for separating the components of a mix ture of tetrachlorosilane and trimethylchlorosilane thereby to obtain the latter component inthe :form of hexamethyl disiloxane substan- 2 tially freeof the former component, which process comprises first hydrolyzing the mixture of chlorosilanes with an amount of Water at least in excess of that calculated as necessary to effect complete hydrolysis of the chlorosilanes, secondly, removing the resulting aqueous layer from the hydrolysis mixtureand contacting the substantially non-aqueous phase resulting from the hydrolysis step with an aqueous solution, preferably a concentrated aqueous solution, of an alkalimetal "hydroxide, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, etc., and finally;-separat'ing the resulting substantially nonaqueous layer fromthe reaction product obtained infthe previous alkalizing step, and isolating the hexamet'hyl disiloxane present in the previously obtained non-aqueous layer, for instance, by frac tional "distillation.
The "stepswhereby our claimed process may be carried out may be varied. The mixture of chlorosilanes may-be hydrolyzed by either adding water to the mixture or adding the mixture to water. We have discovered that when an azeotropeof tetrachlorosilane and trimethylchlorosilane is employed in the process, 'it is desirable that the amount of water employed in hydrolyzing the mixture of chlorosilanes be present in an amountequal to, by weight, from about to 90, preferably from to 85, per cent of the total weight of Water and mixture of chlorosilanes. Stated alternatively, we prefer to use, on a weight basis, from 3 to 9 parts Water per part azeotropic mixture.
"If the above-stated'proportion'of water to mixture of chlorosilanes is employed, two layers separate-easily upon hydrolysis, one layer comprising-' -an acid aqueous phase, and the other layer comprising a non-aqueous phase consisting essentially" of a white powder which floats on the surfaceof the water. If toomuch water is employedinthe hydrolysis step, a soupy gel is usually obtained Which is'more difficult to separate into the two aforementioned aqueous and nonaqueous phases. If too little water is employed, there is obtained a mass which is diflicult to stir. We have found, in 'hydrolyzing the azeotrope, that the optimum weight ratio of water to azeotrope, on a weight basis, is approximately rectly-with a large excess of a concentrated 'aque- When separation of the hydrolysis product into 7 an aqueous phase and a non-aqueous phase has been accomplished, the former phase is removed and the latter phase is treated with the aqueous solution of the alkali-metal hydroxide wherein the alkali-metal hydroxide is preferably present in a concentrated form, for example, in the form of from about a 5 to normal solution. The amount of alkali-metal hydroxide employed is preferably equal to at least that necessary to convert the silicic acid or its condensation products obtained in the hydrolysis to an alkalimetal silicate, e. g., sodium silicate (NazSiOs). From the foregoing it will be apparent that the minimum amount of alkali-metal hydroxide which may be employed comprises a molar ratio of at least 2 mols of the alkali-metal hydroxide per mol of silicon tetrachloride.
The aforementioned alkalizing step effects separation of the mass into an aqueous layer and a non-aqueous or oily layer which comprises hexamethyl disiloxane and smaller amounts of other substituted siloxanes, for example, tetra (trimethylsiloxy) silane. Fractional distillation of the non-aqueous or oily layer results in good yields of trimethylchlorosilane in the form of hexamethyl disiloxane, as well as small amounts of trimethyl silanol (which condenses easily to form hexamethyl disiloxane) and varying amounts of condensation products of trimethyl silanol and silicic acid, for example, the aforementioned tetra (trimethylsiloxy) silane of the general formula:
ll'CHa):
Because the reaction product after the addition of the solution of the alkali-metal hydroxide, under the proper conditions, separates so readily into two layers, it is more practical to remove the aqueous layer prior to isolation of the hexamethyl disiloxane. However, instead of separating the layers, the methyl-substituted siloxanes may be removed from the alkaline reaction mass by other methods, for example, by steam distillation or by solvent extraction with non-polar solvents, e. g., benzene, toluene, xylene, petroleum ether, diethyl ether, etc.
Hexamethyl disiloxane obtained in the practice of our claimed invention is useful for making liquid, oily, linear hydrocarbon-substituted (e. g., methyl-substituted) polysiloxanes of the type disclosed and claimed in Patnode application Serial No. 463,814, filed October 29, 1942 (now U. S. 2,469,888, issued May 10, 1949), and assigned to the same assignee as the present invention. These liquid polysiloxanes, which are useful for lubricating purposes, generally have from about 2.001 to 2.2 hydrocarbon groups per 4 silicon atom. In addition, we have found that the condensation products of trimethyl silanol and silicic acid are also useful as a source of trimethyl siloxy groups ((CHa): Si-O) for terminating the ends of hydrocarbon-substituted polysiloxane chains having a ratio of about 2 hydrocarbon groups per silicon atom, for example, two methyl groups per silicon atom, by effecting rearrangement by the process of cleavage and condensation between the hydrolysis product of a dihydrocarbon-substituted dihalogenosilane and the aforementioned condensation product of trimethyl silanol and silicic acid (see the aforementioned Patnode application as well as Sprung et a1. application Serial No. 702,590, filed October 11, 1946 (now U. S. 2,483,158, issued September 27, 1949), and assigned to the same assignee as the instant application).
It is desirable to acidify the non-aqueous or oily layer obtained as a result of the alkalizing step with a dilute acid, for example, a dilute aqueous hydrochloric acid solution, for instance, a 5 per cent solution, prior to fractional distillation of the mass to isolate the hexamethyl disiloxane or other substituted methyl siloxanes. This acidification step effects condensation of free silanol groups present in the mass thereby increasing the yields and simplifies the distillation of, e. g., hexamethyl disiloxane.
In order that those skilled in the art may better understand how the present invention may be practiced, the following examples are given by way of illustration and not by way of limitation.
Example About 400 grams (containing 1.44 mols SiCl4) of an azeotrope of tetrachloro'silane and trimethylchlorosilane (the trimethylchlorosilane being equivalent to 103 grams hexamethyl dislloxane) was added with vigorous stirring through a dropping funnel to about 2000 parts water over a period of- 15 minutes. During the hydrolysis, the temperature rose spontaneously to about to C. If desired, the hydrolysis may be carried out with ice water to maintain a lower temperature, or other external cooling means may be employed to prevent the temperature from rising above the boiling point of the azeotrope.
After the mixture of chlorosilanes had been added, the stirring was continued for about one half hour to "powder the hydrolysis product and to whip air into the slurry in order to float the powder; After allowing the lower aqueous layer to settle completely, the latter layer was drained from the powder and the powder was washed twice with water.
A solution of about 500 grams (12.5 mols sodium hydroxide) sodium hydroxide dissolved in approximately 500 grams water was then added slowly through a dropping funnel to the washed powder, the sodium hydroxide thus being present in a molar ratio of approximately 8.6 mols of the latter per mol of S1014, taking into account the amount of SiCli in the azeotropic mixture. The powder dissolved with the evolution of heat and two layers separated immediately. The contents of the flask containing the reaction product was drained into a separatory funnel and the oily phase collected. Theyield of this non-aqueous or-oily phase which was about 117 grams, was subjected to a fractional distillation step to yield about 70 grams of an oily product which consisted essentially "of hexamethyl disiloxane..
Tetra (trimethylsi ox ila iewas i elat dirom with-watera mixture of tetrachlorosilane and trithe residue. This commune has the following methylchlorosilane, (2) contacting the nonaqueproperties: ous phaseof the hydrolysis product with an aque- B. P.=130.8-'l31;0 c. at 50 mm. Wewereefeeellelrmmhydroxide thereby N :13894 s to obtain a layer rich in hex-amethyl d1s1loxane, 01420203677 the alkali-metal hydroxide being present in a culated 2.40 methyl groups per silicon atom),
37.38 per cent carbon (calculated 3.71%), and 9.32 per cent hydrogen (calculated 9.43 per cent).
An oily or non-aqueous phase obtained in accordance with the process in the example imratio oflrom 2 to 8.6 mols ofthe latterper mol tetrachlorosilane, and (3) isolating the hexamethyldisilcxane present in the aforesaid layer.
3. The process which comprisesll) hydrolyz-ing with water an azeotropic mixture of tetrachlorosilence and trimethylchlorosilane, (2) contacting the non aqueous phase .of the hydrolysis product with an aqueous solution of sodium hydroxide,
mediately after the alkalizing step was found .to 1.6 thereby t0 Obtain a bstantially -aqueous have a methyl to silicon ratio .of 2.70. Varying layer P D-E h l ethyl disiloxane, the S0- amounts of .this oily phase and the tetra (tridium ydroxide bein p nt n a ol r atio of methylsiloxy) silane were eachsha-ken with octa- E0111 2 t0 3- 111015 t e t 'p r mol of tetramethyl tetrasiloxane (having a methyl to silicon 61112105112119, and (3) isolating e Xa et y ratio M20) in the presence .of asmall amount 2c disiloXene present in e non-aqueous ye of concentrated sulfuric. acid in accordance with The Process for Separating h p n -ts the method disclosed in the aforementioned Pat- Of a i u f tetraehloresilene and m t y node application. The oils-obtained were Washed chlm'osilane thereby 0 Obtain the latter "compo.- several times with water and centrifuged to remerit in the m of X methyl disiloxane-submove the last traces of water. The following stem-1am?" free of the firmer m-1 m which table shows the properties of the oils containing P196955 flompfisis (1) y olyzing with waterthe varying proportions of the aforementioned two mlxture of chklrosfianes, ramfiving'the eq compositions intercondensed with the octamethyl 5 ayer resulting from the hydrolysis mixture, tetrasiloxane. The number 2.7 in the first col- (3) COP-taming th u stantially n h eq -e s umn of the table refers to the number of methyl 3o Port-ion resulting m e hydrolysi p in ps p r Silicon atom of the non-aqueous with a concentrated aqueous solution of an alkalioily layer obtained as in the example after the m tal hyd x d the latter being p s nt in a alkalizing step. The number 2.4 in the same molar ratio of from 2 to 8.6 mols of the alkalicolumn refers to the number of methyl groups metal hydroxide per mol of the tetrachlorosilane, per silicon atom of tetra (trimethylsiloxy) silane. 3s nd (4) separating t resulting Substantially The term tetramer refers o Oc amethyl tetranon-aqueous layer from the reaction mass in (3) SIIOXaIle havlng the Structural formula and isolating the hexamethyl disiloxane present (CH3), therein.
F0 P 5. The process for separating the components of an azeotropic mixture of tetrachlorosilane and O Shaman trimethylchlorosilane thereby to obtain the latter oHer-si component in the form of hexamethyl disiloxane substantially free of the former component, which Table e ester are Type 011 Me/ S11 Chain I??? S 32 ature 00- Point smppe 150 o. 100 0 210 0. efiicient 2. 0033 0. 989 11.3 1, 320 43s 0. 668 -38 2. 0075 1. 037 11. 2 253 -43 Tetramer +2.4 2.0152 3. 933 12.4 3, 714 -45 2. 0222 5. 736 13. 7 51. 5 20. 7 0. 594 -e3 2. 0351 9. 073 17. 7 30. s 12. 5 0. 594 -67 2. 0068 1. 035 10. 7 565 230 0. 594 -3a 2. 0127 1. 939 11.5 171 66. 1 0. 604 Tetramer +2.7 2.0253 3.821 13.0 57.0 23.1 0.594 -43 2. 0376 5. 713 14. 9 32. 9 13. 5 0. 539 -45 2. 0605 9. 168 20.4 19. 5 s. 2 0. 520 -67 2. 0865 13. 070 27. e 14. 1 5. 54 0. 607 -70 1 This refers to the ratio of methyl groups to silicon atoms in the complete chain-stoppered oil. 2 This refers to the per cent, by weight, of the liquid oily phase or of tetra (trimethylsiloxy) silane intercondensed with the octamethyl tetrasiloxane.
What we claim as new and desire to secure by Letters Patent of the United States is:
1. The process which comprises 1) hydrolyzing with water a mixture of tetrachlorosilane and trimethyl chlorosilane, (2) contacting the hydrolysis reaction product in an aqueous medium with an alkali-metal hydroxide thereby to obtain a layer comprising hexamethyl disiloxane, the alkali-metal hydroxide being present in a ratio of from 2 to 8.6 mols of the latter per mol tetrachlorosilane, and (3) isolating the hexamethyldisiloxane present in the aforesaid layer.
process comprises (1) hydrolyzing the azeotropic calculated as necessary for the complete hydrolysis of the two components, (2) removing the resulting aqueous layer from the hydrolysis mixture, (3) thoroughly mixing the remaining substantially non-aqueous powdery portion with a concentrated aqueous solution of sodium hydroxide, the latter being present in the molar ratio of from 2 to 8.6 mols of the sodium hydroxide per mol of the tetrachlorosilane, (4) separating the resulting substantially non-aqueous liquid layer from the 2. The process which comprises (1) hydrolyzing aqueous layer, and (5) isolating hexamethyl disiloxane from the non-aqueous layer obtained in (4).
6. The process for separating the components of an azeotropic mixture consisting substantially of about 45 to 55 mol per cent trimethylchlorosilane and 55 to 45 mol per cent tetrachlorosilane thereby to obtain the former component in the form of hexamethyl disiloxane, which process comprises (1) hydrolyzing the azeotropic mixture with water present, by weight, in an amount equal to from about 75 to 90 per cent of the total weight of water and azeotropic mixture of chlorosilanes, (2) separating the resulting substantially nonaqueous portion, (3) treating the latter non-aqueous portion with a concentrated aqueous solution of sodium hydroxide, the latter being present in a molar ratio of from 2 to 8.6 mols of the sodium hydroxide per mol of the tetrachlorosilane, and (4) isolating hexamethyl disiloxane from the non-aqueous phase resulting from the alkaline treatment in (3) '7. The process which comprises (1) hydrolyzing an azeotropic mixture of tetrachlorosilane and trimethylchlorosilane with water present, by weight, in an amount equal to from about 75 to 90 per cent of the total Weight of water and azeotropic mixture of chlorosilanes, (2) separating the resulting substantially non-aqueous portion, (3) treating the latter non-aqueous portion with a. concentrated aqueous solution of sodium hy- REFERENCES CITED The following references are of record in the file of this patent:
. UNITED STATES PATENTS Number Name Date 2,211,704 Robinson Aug. 13, 1940 2,381,139. Sauer Aug. '7, 1945 2,388,575 Sauer Nov. 6, 1945 2,389,804 McGregor Nov. 27, 1945 2,412,470 Norton Dec. 10, 1946 2,441,320 Hyde May 11, 1948 2,453,092 Hyde et a1. Nov. 2, 1948 OTHER REFERENCES Bauer: J our. Amer. Chem. 800.," vol. 66 (1944), pages 1707-1710.
Mellor: Modern Inorganic Chemistry, 1939, Longmans, Green & 00., page 693.
Robison and Kipping: Journal Chem. Soc." (London), vol. 101 (1912) pages 2158, 2159.

Claims (1)

1. THE PROCESS WHICH COMPRISES (1) HYDROLYZING WITH WATER A MIXTURE OF TETRACHLORASILANE AND TRIMETHYL CHLOROSILANE, (2) CONTACTING THE HYDROLYSIS REACTION PRODUCT IN AN AQUEOUS MEDIUM WITH AN ALKALI-METAL HYDROXIDE THEREBY TO OBTAIN A LAYER COMPRISING HEXAMETHYL DISILOXANE, THE ALKALI-METAL HYDROXIDE BEING PRESENT IN A RATIO OF FROM 2 TO 8.6 MOLS OF THE LATTER PER MOL TETRACHLOROSILANE, AND (3) ISOLATING THE HEXAMETHYLDISILOXANE PRESENT IN THE AFORESAID LAYER.
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2752379A (en) * 1952-10-29 1956-06-26 Union Carbide & Carbon Corp Resolving chlorosilane mixtures
US2920044A (en) * 1957-10-07 1960-01-05 Dow Corning Organosiloxane fluids
US3114678A (en) * 1961-08-11 1963-12-17 Gen Electric Method for separating chlorosilanes from mixtures thereof
US3168542A (en) * 1957-05-15 1965-02-02 Union Carbide Corp Process for separating mixtures of chlorosilanes
CN102924493A (en) * 2012-11-05 2013-02-13 安徽九天硅业有限公司 Method for preparing hexamethyldisiloxane through separation of organosilicon azeotrope
CN103319519A (en) * 2013-05-31 2013-09-25 浙江合盛硅业有限公司 Method for producing hexamethyldisiloxane by utilization of organosilicon azeotrope
CN107629081A (en) * 2017-09-19 2018-01-26 荆州市江汉精细化工有限公司 A kind of synthetic method of four (trimethylsilane epoxide) silicon

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2211704A (en) * 1939-02-15 1940-08-13 Dow Chemical Co Process for treating friedel-crafts reaction liquors
US2381139A (en) * 1942-05-14 1945-08-07 Gen Electric Resolution of azeotropic mixtures of chlorosilanes
US2388575A (en) * 1943-06-23 1945-11-06 Gen Electric Resolution of mixtures of chlorosilanes
US2389804A (en) * 1945-11-27 Stabilizing organo-siloxanes
US2412470A (en) * 1943-02-22 1946-12-10 Gen Electric Production of water-repellent materials
US2441320A (en) * 1944-03-20 1948-05-11 Corning Glass Works Organo-siloxanes and methods of making them
US2453092A (en) * 1947-08-05 1948-11-02 Corning Glass Works Method of polymerizing organosiloxanes

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2389804A (en) * 1945-11-27 Stabilizing organo-siloxanes
US2211704A (en) * 1939-02-15 1940-08-13 Dow Chemical Co Process for treating friedel-crafts reaction liquors
US2381139A (en) * 1942-05-14 1945-08-07 Gen Electric Resolution of azeotropic mixtures of chlorosilanes
US2412470A (en) * 1943-02-22 1946-12-10 Gen Electric Production of water-repellent materials
US2388575A (en) * 1943-06-23 1945-11-06 Gen Electric Resolution of mixtures of chlorosilanes
US2441320A (en) * 1944-03-20 1948-05-11 Corning Glass Works Organo-siloxanes and methods of making them
US2453092A (en) * 1947-08-05 1948-11-02 Corning Glass Works Method of polymerizing organosiloxanes

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2752379A (en) * 1952-10-29 1956-06-26 Union Carbide & Carbon Corp Resolving chlorosilane mixtures
US3168542A (en) * 1957-05-15 1965-02-02 Union Carbide Corp Process for separating mixtures of chlorosilanes
US2920044A (en) * 1957-10-07 1960-01-05 Dow Corning Organosiloxane fluids
US3114678A (en) * 1961-08-11 1963-12-17 Gen Electric Method for separating chlorosilanes from mixtures thereof
CN102924493A (en) * 2012-11-05 2013-02-13 安徽九天硅业有限公司 Method for preparing hexamethyldisiloxane through separation of organosilicon azeotrope
CN103319519A (en) * 2013-05-31 2013-09-25 浙江合盛硅业有限公司 Method for producing hexamethyldisiloxane by utilization of organosilicon azeotrope
CN103319519B (en) * 2013-05-31 2016-02-10 合盛硅业股份有限公司 A kind of method utilizing organic silicon azeotrope production hexamethyldisiloxane
CN107629081A (en) * 2017-09-19 2018-01-26 荆州市江汉精细化工有限公司 A kind of synthetic method of four (trimethylsilane epoxide) silicon
CN107629081B (en) * 2017-09-19 2020-03-17 荆州市江汉精细化工有限公司 Synthetic method of tetra (trimethylsiloxy) silicon

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