CN116655679A - Hexamethyldisiloxane and preparation method thereof - Google Patents

Hexamethyldisiloxane and preparation method thereof Download PDF

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Publication number
CN116655679A
CN116655679A CN202310656681.6A CN202310656681A CN116655679A CN 116655679 A CN116655679 A CN 116655679A CN 202310656681 A CN202310656681 A CN 202310656681A CN 116655679 A CN116655679 A CN 116655679A
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hexamethyldisiloxane
gallium
solution
reaction
mixed
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徐聪
王毅
陈琪
孔超
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Jinhong Gas Co ltd
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Jinhong Gas Co ltd
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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 System
    • C07F7/02—Silicon compounds
    • C07F7/08—Compounds having one or more C—Si linkages
    • C07F7/0834—Compounds having one or more O-Si linkage
    • C07F7/0838—Compounds with one or more Si-O-Si sequences
    • C07F7/0872—Preparation and treatment thereof
    • C07F7/0876—Reactions involving the formation of bonds to a Si atom of a Si-O-Si sequence other than a bond of the Si-O-Si linkage
    • C07F7/0878—Si-C bond
    • 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 System
    • C07F7/02—Silicon compounds
    • C07F7/08—Compounds having one or more C—Si linkages
    • C07F7/0834—Compounds having one or more O-Si linkage
    • C07F7/0838—Compounds with one or more Si-O-Si sequences
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/584—Recycling of catalysts

Abstract

The invention discloses hexamethyldisiloxane and a preparation method thereof, wherein the preparation method of the hexamethyldisiloxane comprises the following steps: mixing octamethyl cyclotetrasiloxane, a gallium catalyst and methyl lithium to obtain a mixed reaction system; and (3) reacting, quenching and separating the mixed reaction system to obtain hexamethyldisiloxane. According to the preparation method of the hexamethyldisiloxane, disclosed by the embodiment of the invention, the hexamethyldisiloxane is prepared by the reaction of the mixed reaction system of the octamethyl cyclotetrasiloxane, the gallium catalyst and the methyl lithium, no extra chloride ions are introduced in the preparation process, the whole preparation process is mild and controllable in condition, the raw materials are easy to obtain, the gallium catalyst can be repeatedly used, a low-temperature reactor is not needed, the subsequent purification difficulty is low, and the purity of the prepared hexamethyldisiloxane is high.

Description

Hexamethyldisiloxane and preparation method thereof
Technical Field
The invention relates to the field of fine chemical synthesis, in particular to hexamethyldisiloxane and a preparation method thereof.
Background
In the traditional process, the hexamethyldisiloxane is synthesized by adopting trimethylchlorosilane, water and sodium hydroxide as raw materials and adopting an alkaline hydrolysis method. The unavoidable raw materials in the process contain chloride ions, which makes demands on the high-end application of hexamethyldisiloxane. The chloride ions can enhance the corrosion effect and greatly shorten the service life of the instrument, and the most obvious effect is that in an acidic cleaning agent, such as a pressure vessel manufactured by austenitic stainless steel, if a chloride solution exists, stress corrosion can occur, and even a trace amount of chloride ions can also occur. Hexamethyldisiloxane products having low silicon hydroxyl content and low chlorine content are desirable in both the downstream processing and high-end cleaning industries of silicones.
In addition, another major use of hexamethyldisiloxane is as a primary raw material for the synthesis of hexamethyldisilazane, an important pharmaceutical intermediate. At present, the purity of the hexamethyldisiloxane product sold in China is more than 99 percent, and the hexamethyldisiloxane product contains a plurality of impurities, including toluene, tetrahydrofuran and other organic solvents. This results in a great difference in the quality of hexamethyldisiloxane, which is difficult to be applied in demanding applications.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.
Disclosure of Invention
The invention aims to provide a preparation method of hexamethyldisiloxane, which has the advantages of no extra chloride ion introduced in the preparation process, mild and controllable reaction conditions, easily available raw materials and reusable gallium catalyst.
The invention also aims to provide hexamethyldisiloxane.
To achieve the above object, an embodiment of the present invention provides a method for preparing hexamethyldisiloxane, comprising the steps of:
mixing octamethyl cyclotetrasiloxane, a gallium catalyst and methyl lithium to obtain a mixed reaction system;
and (3) reacting, quenching and separating the mixed reaction system to obtain hexamethyldisiloxane.
In one or more embodiments of the invention, the gallium catalyst is selected from gallium, gallium salts, and gallium-containing complexes; and/or the number of the groups of groups,
the gallium catalyst accounts for 0.1 to 4mol percent of the total reaction system; and/or the number of the groups of groups,
the molar ratio of the methyl lithium to the octamethyl cyclotetrasiloxane is greater than or equal to 4:1.
in one or more embodiments of the present invention, the step of mixing octamethyl cyclotetrasiloxane, gallium catalyst and methyllithium comprises:
while stirring, octamethyl cyclotetrasiloxane and gallium catalyst were mixed and methyl lithium solution was added.
In one or more embodiments of the present invention, the step of adding a methyllithium solution includes:
and dropwise adding a methyl lithium solution into the mixed system of the octamethyl cyclotetrasiloxane and the gallium catalyst in a cooling environment.
In one or more embodiments of the present invention, the methyllithium solution is any one of an ether solution of methyllithium and a diethoxymethane solution of methyllithium.
In one or more embodiments of the invention, the reaction conditions of the mixed reaction system are: the reaction is carried out for 4 to 12 hours under the condition of stirring at the temperature of 100 to 180 ℃.
In one or more embodiments of the invention, the step of quenching includes:
after the reaction of the mixed reaction system, a quencher is added to quench the reaction.
In one or more embodiments of the invention, the quencher comprises one of an aqueous ethanol solution, an ice water mixture.
In one or more embodiments of the invention, the step of separating comprises:
and filtering and purifying the quenched mixed reaction system to obtain hexamethyldisiloxane.
The embodiment of the invention provides hexamethyldisiloxane, which is prepared by reacting a mixed reaction system of octamethyl cyclotetrasiloxane, a gallium catalyst and methyl lithium.
Compared with the prior art, according to the preparation method of the hexamethyldisiloxane, the hexamethyldisiloxane is prepared by the reaction of the mixed reaction system of the octamethyl cyclotetrasiloxane, the gallium catalyst and the methyl lithium, the preparation process is mild and controllable without introducing extra chloride ions, the raw materials are easy to obtain, the gallium catalyst can be reused, a low-temperature reactor is not needed, the subsequent purification difficulty is low, and the prepared hexamethyldisiloxane has high purity.
Drawings
FIG. 1 is a flow chart of a method of preparing hexamethyldisiloxane in accordance with an embodiment of the present invention;
Detailed Description
The following detailed description of embodiments of the invention is, therefore, to be taken in conjunction with the accompanying drawings, and it is to be understood that the scope of the invention is not limited to the specific embodiments.
Throughout the specification and claims, unless explicitly stated otherwise, the term "comprise" or variations thereof such as "comprises" or "comprising", etc. will be understood to include the stated element or component without excluding other elements or components.
As shown in fig. 1, a method for preparing hexamethyldisiloxane according to a preferred embodiment of the present invention comprises the steps of:
s1, mixing octamethyl cyclotetrasiloxane, a gallium catalyst and methyl lithium to obtain a mixed reaction system.
In step S1, the mixing process of octamethyl cyclotetrasiloxane, gallium catalyst and methyllithium may specifically be: while stirring, octamethyl cyclotetrasiloxane and gallium catalyst were mixed and methyl lithium solution was added.
It is understood that, because the methyl lithium is relatively active, the methyl lithium solution is added into the mixed system of octamethyl cyclotetrasiloxane and gallium catalyst to play a role of buffering. The methyllithium solution may be specifically any one of an ether solution of methyllithium and a diethoxymethane solution of methyllithium. Specifically, the methyl lithium solution is a commercially available diethyl ether solution of methyl lithium and a diethoxymethane solution of methyl lithium, wherein the concentration of methyl lithium in the diethyl ether solution of methyl lithium is 1.0-2.0 mol/L, and diethyl ether solutions of methyl lithium with concentrations of 1.0mol/L and 1.6mol/L are common. The concentration of methyl lithium in the diethoxymethane solution of methyl lithium is 2-3.1 mol/L.
Further, in order to avoid the severe reaction of the subsequent mixed reaction system, the step of adding the methyllithium solution may specifically include:
and dropwise adding a methyl lithium solution into the mixed system of the octamethyl cyclotetrasiloxane and the gallium catalyst in a cooling environment. The cooling environment is understood to mean that the octamethyltetrasiloxane and gallium catalyst mixed system is subjected to a circulating water cooling system. Namely, in the process of dropwise adding the methyl lithium solution into the mixed system of the octamethyl cyclotetrasiloxane and the gallium catalyst, a circulating water cooling system is used, so that the temperature in the dropwise adding process is ensured to be in a room temperature state as much as possible, and severe reaction is avoided.
It is understood that the above mixed reaction system is already in the process of the reaction in the process of dripping the methyllithium solution, and the cooling environment is the effect of timely removing the exothermic energy of the reaction. After the dripping of the methyl lithium solution is completed, the process of the subsequent step S2 can be carried out. The conditions of stirring and cooling environment are to reduce the possibility of severe reaction during mixing, and the actual reaction needs to be heated before starting.
In particular, the gallium catalyst may be selected from gallium, gallium salts and gallium-containing complexes. Wherein, the gallium salt can be any one of gallium nitrate and gallium oxide for new hydrogen production.
The gallium catalyst accounts for 0.1 to 4mol percent of the total reaction system.
S2, reacting, quenching and separating the mixed reaction system to obtain hexamethyldisiloxane, and quenching.
Wherein, the reaction conditions of the mixed reaction system in the step S2 are as follows: the reaction is carried out for 4 to 12 hours under the condition of stirring at the temperature of 100 to 180 ℃.
Specifically, the step of separating includes: and filtering and purifying the quenched mixed reaction system to obtain hexamethyldisiloxane.
Specifically, the quenching step includes: after the mixed reaction system is reacted, a quenching agent is added for quenching, thereby playing a role in stopping the reaction. The quenching agent may be slowly added until the temperature of the mixed reaction system is not raised, and the quenching reaction may be judged to be completed. When the reaction is completed (or the reaction time reaches a set time), the unreacted methyllithium in the mixed reaction system may cause danger, and then a quenching agent is added for quenching, so that the methyllithium is converted into lithium oxide/lithium hydroxide, and the danger is reduced.
Further, the quencher includes one of an ice-water mixture (0 ℃), an aqueous ethanol solution. For example, a 20% aqueous ethanol solution may be used as the quencher.
Further, the above filtration step may serve to separate the solid by-products, gallium catalyst, and other impurities. Among these, solid byproducts may include lithium oxide, lithium hydroxide, and the like. The process can play a role in separation, and the gallium catalyst in the process can be recovered and reused, so that the cost of the preparation method is reduced.
Further, the purification may be a simple distillation or a more complex rectification process, depending on the purity requirements of the final desired hexamethyldisiloxane.
The following is a reaction equation in the preparation of hexamethyldisiloxane in accordance with one embodiment of the present invention:
wherein RT means room temperature and Ga means a gallium catalyst.
According to the preparation method of the hexamethyldisiloxane, the octamethyltetrasiloxane is subjected to ring opening reaction under the action of a gallium catalyst and methyl lithium to obtain the hexamethyldisiloxane, so that based on the principle and the reaction equation, the molar ratio of the octamethyltetrasiloxane to the methyl lithium is preferably 1 in order to improve the purity and the yield of the product: 4, namely, octamethyl cyclotetrasiloxane and methyl lithium are just completely reacted, so that byproducts and side reactions are fewer. However, in the actual production process, it is difficult to achieve absolute 1:4, therefore, in the case of actual production, the amount of methyllithium will be slightly more, for example, the molar ratio of methyllithium to octamethyltetrasiloxane is 4.1:1, thereby reducing the amount of byproducts of the octamethyl cyclotetrasiloxane ring opening process.
The embodiment of the invention provides hexamethyldisiloxane, which can be prepared by reacting the mixed reaction system of octamethyl cyclotetrasiloxane, gallium catalyst and methyl lithium.
The hexamethyldisiloxane and the method for preparing the same according to the present invention will be described in detail with reference to specific examples.
Example 1
115.7g (0.39 mol) of octamethyltetrasiloxane and 0.28g (0.04 mol,1 mol%) of metallic gallium were charged into a 2000mL reaction vessel, and mixed with stirring for 30 minutes. 1L of 1.6mol/L methyl lithium solution is prepared, and the solution is slowly added dropwise into the octamethyl cyclotetrasiloxane solution under the condition that condensed water is cooled and kept at room temperature. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, the temperature was raised to 180℃and the reaction was stirred for 12 hours, 200mL of a mixture of quenching agent and ice water (0 ℃) was added, and after the system temperature was stabilized, the generated lithium oxide and lithium hydroxide were removed by filtration, and silver gallium was recovered. The remaining liquid was distilled to give 92.4g of 100-103℃component in 62.9% yield and 93.2% purity by GC-MS test.
Example 2
115.7g (0.39 mol) of octamethyltetrasiloxane and 0.56g (0.008 mol,2 mol%) of metallic gallium were put into a 2000mL reaction vessel and stirred and mixed for 30min. 1L of 1.6mol/L methyl lithium diethyl ether solution is prepared, the room temperature state is kept under the cooling of condensed water, and the solution is slowly added into the octamethyl cyclotetrasiloxane solution in a dropwise manner. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, the temperature was raised to 180℃and the reaction was stirred for 12 hours, 200mL of a mixture of quenching agent and ice water (0 ℃) was added, and after the system temperature was stabilized, the generated lithium oxide and lithium hydroxide were removed by filtration, and silver gallium was recovered. The remaining liquid was distilled to give 104.1g of 100-103℃component in 72.2% yield and 96.1% purity by GC-MS test.
Example 3
115.7g (0.39 mol) of octamethyltetrasiloxane and 1.12g (0.016 mol,4 mol%) of gallium were put into a 2000mL reaction vessel and stirred and mixed for 30min. 1L of 1.6mol/L methyl lithium diethyl ether solution is prepared, the room temperature state is kept under the cooling of condensed water, and the solution is slowly added into the octamethyl cyclotetrasiloxane solution in a dropwise manner. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, the temperature was raised to 180℃and the reaction was stirred for 12 hours, 200mL of a mixture of quenching agent and ice water (0 ℃) was added, and after the system temperature was stabilized, the generated lithium oxide and lithium hydroxide were removed by filtration, and silver gallium was recovered. . The remaining liquid was distilled to give 107.3g of 100-103℃component in 74.7% yield and 95.3% purity by GC-MS test.
Example 4
115.7g (0.39 mol) of octamethyltetrasiloxane and 0.028g (0.0004 mol,0.1 mol%) of metallic gallium were put into a 2000mL reaction vessel and stirred and mixed for 30 minutes. 1L of 1.6mol/L methyl lithium diethyl ether solution is prepared, the room temperature state is kept under the cooling of condensed water, and the solution is slowly added into the octamethyl cyclotetrasiloxane solution in a dropwise manner. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, the temperature was raised to 180℃and the reaction was stirred for 12 hours, 200mL of a mixture of quenching agent and ice water (0 ℃) was added, and after the system temperature was stabilized, the generated lithium oxide and lithium hydroxide were removed by filtration, and silver gallium was recovered. . The remaining liquid was distilled to give 59.7g of 100-103℃component in 39.2% yield and 91.7% purity by GC-MS test.
Example 5
115.7g (0.39 mol) of octamethyltetrasiloxane and 0.28g (0.04 mol,1 mol%) of metallic gallium were charged into a 2000mL reaction vessel, and mixed with stirring for 30 minutes. 1L of 1.6mol/L methyl lithium diethyl ether solution is prepared, the room temperature state is kept under the cooling of condensed water, and the solution is slowly added into the octamethyl cyclotetrasiloxane solution in a dropwise manner. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, the temperature was raised to 140℃and the reaction was stirred for 12 hours, 200mL of a mixture of quenching agent and ice water (0 ℃) was added, and after the system temperature was stabilized, the generated lithium oxide and lithium hydroxide were removed by filtration, and silver gallium was recovered. The remaining liquid was distilled to give 8.1g of the component at 100-103℃in a yield of 5.6% and a GC-MS test purity of 90.5%.
Example 6
115.7g (0.39 mol) of octamethyltetrasiloxane and 0.28g (0.04 mol,1 mol%) of metallic gallium were charged into a 2000mL reaction vessel, and mixed with stirring for 30 minutes. 1L of 1.6mol/L methyl lithium diethyl ether solution is prepared, the room temperature state is kept under the cooling of condensed water, and the solution is slowly added into the octamethyl cyclotetrasiloxane solution in a dropwise manner. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, the temperature was raised to 100℃and the reaction was stirred for 12 hours, 200mL of a mixture of quenching agent and ice water (0 ℃) was added, and after the system temperature was stabilized, the generated lithium oxide and lithium hydroxide were removed by filtration, and silver gallium was recovered. The remaining liquid was distilled to give 3.6g of the component at 100-103℃in 2.5% yield and 88.9% purity by GC-MS test.
Example 7
115.7g (0.39 mol) of octamethyltetrasiloxane and 0.28g (0.04 mol,1 mol%) of metallic gallium were charged into a 2000mL reaction vessel, and mixed with stirring for 30 minutes. 1L of 1.6mol/L methyl lithium diethyl ether solution is prepared, the room temperature state is kept under the cooling of condensed water, and the solution is slowly added into the octamethyl cyclotetrasiloxane solution in a dropwise manner. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, the temperature was raised to 180℃and the reaction was stirred for 4 hours, 200mL of a mixture of quenching agent and ice water (0 ℃) was added, and after the system temperature was stabilized, the generated lithium oxide and lithium hydroxide were removed by filtration, and silver gallium was recovered. Distillation gave 50.4g of 100-103℃component in 39.8% yield and 95.8% purity by GC-MS test.
Example 8
115.7g (0.39 mol) of octamethyltetrasiloxane and 0.28g (0.04 mol,1 mol%) of metallic gallium were charged into a 2000mL reaction vessel, and mixed with stirring for 30 minutes. 1L of 1.6mol/L methyl lithium diethyl ether solution is prepared, the room temperature state is kept under the cooling of condensed water, and the solution is slowly added into the octamethyl cyclotetrasiloxane solution in a dropwise manner. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, the temperature was raised to 180℃and the reaction was stirred for 8 hours, 200mL of a mixture of quenching agent and ice water (0 ℃) was added, and after the system temperature was stabilized, the generated lithium oxide and lithium hydroxide were removed by filtration, and silver gallium was recovered. . Distillation gave 85.6g of 100-103℃component in 59.4% yield and 92.6% purity by GC-MS test.
Example 9
115.7g (0.39 mol) of octamethyltetrasiloxane and 0.28g (0.04 mol,1 mol%) of metallic gallium were charged into a 2000mL reaction vessel, and mixed with stirring for 30 minutes. 1L of 1.6mol/L methyl lithium diethyl ether solution is prepared, the room temperature state is kept under the cooling of condensed water, and the solution is slowly added into the octamethyl cyclotetrasiloxane solution in a dropwise manner. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, the temperature was raised to 180℃and the reaction was stirred for 24 hours, 200mL of a mixture of quenching agent and ice water (0 ℃) was added, and after the system temperature was stabilized, the generated lithium oxide and lithium hydroxide were removed by filtration, and silver gallium was recovered. Distillation gave 102.6g of 100-103℃component in 71.3% yield and 93.7% purity by GC-MS test.
Example 10
115.7g (0.39 mol) of octamethyltetrasiloxane and 0.28g (0.04 mol,1 mol%) of metallic gallium were charged into a 1500mL reaction vessel and mixed with stirring for 30 minutes. 600mL of a diethoxymethane solution of 2.7mol/L methyllithium was prepared, and the solution was kept at room temperature under cooling with condensed water, and slowly added dropwise into the octamethyltetrasiloxane solution. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, the temperature was raised to 180℃and the reaction was stirred for 12 hours, 200mL of a mixture of quenching agent and ice water (0 ℃) was added, and after the system temperature was stabilized, the generated lithium oxide and lithium hydroxide were removed by filtration, and silver gallium was recovered. Distillation gave 94.6g of 100-103℃component in 74.7% yield and 89.7% purity by GC-MS test.
Example 11
115.7g (0.39 mol) of octamethyltetrasiloxane and 0.28g (0.04 mol,1 mol%) of metallic gallium were charged into a 2000mL reaction vessel, and mixed with stirring for 30 minutes. 1L of 1.6mol/L methyl lithium diethyl ether solution is prepared, the room temperature state is kept under the cooling of condensed water, and the solution is slowly added into the octamethyl cyclotetrasiloxane solution in a dropwise manner. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the dripping is completed, the temperature is raised to 180 ℃ and the stirring reaction is carried out for 24 hours, 250mL of 20% ethanol aqueous solution of a quenching agent is added, and after the system temperature is stable, the generated lithium oxide and lithium hydroxide are filtered and removed, and silver gallium is recovered. The reaction was stopped. The generated lithium oxide and lithium hydroxide are removed by filtration, and metallic gallium of silver color is recovered. Distillation gave 99.9g of 100-103℃component in 69.4% yield and 92.2% purity by GC-MS test.
Comparative example 1
115.7g (0.39 mol) of octamethyltetrasiloxane was added to a 2000mL reaction vessel and mixed with stirring for 30min. 1L of 1.6mol/L methyl lithium diethyl ether solution is prepared, the room temperature state is kept under the cooling of condensed water, and the solution is slowly added into the octamethyl cyclotetrasiloxane solution in a dropwise manner. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, 200mL of a solution of a quencher of 0℃in an ice-water mixture (0 ℃) was added after the reaction was stirred for 24 hours at 180℃and after the system temperature was stabilized, the reaction raffinate was collected after filtration, the reaction raffinate was separated, the organic phase was collected and distilled, and the 100 to 103℃component could not be obtained, and the product (hexamethyldisiloxane) was found to be hardly reacted by the separation filtration, because it was considered that almost no reaction occurred between octamethyltetrasiloxane and methyl lithium diethyl ether solution.
Comparative example 2
115.7g (0.39 mol) of octamethyltetrasiloxane and 0.28g (0.04 mol,1 mol%) of metallic gallium were charged into a 2000mL reaction vessel, and mixed with stirring for 30 minutes. 1L of 1.6mol/L methyl lithium diethyl ether solution is prepared, the room temperature state is kept under the cooling of condensed water, and the solution is slowly added into the octamethyl cyclotetrasiloxane solution in a dropwise manner. In the process, the temperature needs to be controlled not to be too high, and the whole stirring reaction is needed. After the completion of the dropwise addition, 200mL of a mixture of ice and water (0 ℃) of a quenching agent is added after the mixture is stirred and reacted for 12 hours, after the system temperature is stabilized, the reaction residual liquid is collected after filtration, the reaction residual liquid is separated, the organic phase is collected and distilled, 100-103 ℃ components meeting the test conditions cannot be collected, and the product (hexamethyldisiloxane) is almost not obtained by the separation filtration, because the octamethyltetrasiloxane and the methyl lithium diethyl ether solution can be considered to hardly react.
In summary, the preparation method of hexamethyldisiloxane according to the embodiment of the present invention has the following beneficial effects: the preparation process has no extra chloride ion introduced, the whole preparation process has mild and controllable conditions, the raw materials are easy to obtain, the gallium catalyst can be reused, a low-temperature reactor is not needed, the subsequent purification difficulty is low, and the purity of the prepared hexamethyldisiloxane is high.
In addition, the hexamethyldisiloxane prepared by the preparation method has low chloride ion content and other impurities are easy to separate because no extra chloride ion is introduced into the raw materials and the reaction system, and the subsequent purification process can be facilitated.
The foregoing descriptions of specific exemplary embodiments of the present invention are presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application to thereby enable one skilled in the art to make and utilize the invention in various exemplary embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims (10)

1. A method for preparing hexamethyldisiloxane, comprising the steps of:
mixing octamethyl cyclotetrasiloxane, a gallium catalyst and methyl lithium to obtain a mixed reaction system;
and (3) reacting, quenching and separating the mixed reaction system to obtain hexamethyldisiloxane.
2. The method of preparing hexamethyldisiloxane according to claim 1, wherein the gallium catalyst is selected from the group consisting of gallium, gallium salts, and gallium-containing complexes; and/or the number of the groups of groups,
the gallium catalyst accounts for 0.1-4 mol% of the total reaction system; and/or the number of the groups of groups,
the molar ratio of the methyl lithium to the octamethyl cyclotetrasiloxane is greater than or equal to 4:1.
3. the method of preparing hexamethyldisiloxane according to claim 1, wherein the step of mixing said octamethyl cyclotetrasiloxane, gallium catalyst and methyllithium comprises:
the octamethyl cyclotetrasiloxane and gallium catalyst are mixed with stirring and a solution of methyllithium is added.
4. A method of preparing hexamethyldisiloxane according to claim 3, wherein said step of adding a methyllithium solution comprises:
and dropwise adding a methyl lithium solution into the mixed system of the octamethyl cyclotetrasiloxane and the gallium catalyst in a cooling environment.
5. The method for producing hexamethyldisiloxane according to claim 4, wherein the methyllithium solution is any one of an ether solution of methyllithium and a diethoxymethane solution of methyllithium.
6. The method for preparing hexamethyldisiloxane according to claim 1, wherein the reaction conditions of said mixed reaction system are: the reaction is carried out for 4 to 12 hours under the condition of stirring at the temperature of 100 to 180 ℃.
7. The method of preparing hexamethyldisiloxane according to claim 1, wherein said step of quenching comprises:
after the reaction of the mixed reaction system, a quencher is added for quenching.
8. The method of preparing hexamethyldisiloxane according to claim 7, wherein the quencher comprises one of an aqueous ethanol solution and an ice-water mixture.
9. The method of preparing hexamethyldisiloxane according to claim 1, wherein said step of isolating comprises:
and filtering and purifying the quenched mixed reaction system to obtain the hexamethyldisiloxane.
10. The hexamethyldisiloxane is characterized by being prepared by the reaction of a mixed reaction system of octamethyl cyclotetrasiloxane, a gallium catalyst and methyl lithium.
CN202310656681.6A 2023-06-05 2023-06-05 Hexamethyldisiloxane and preparation method thereof Pending CN116655679A (en)

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