Method for efficiently synthesizing triethyl silane

Abstract

The invention discloses a method for efficiently synthesizing triethyl silane, which comprises the following steps: S1, synthesis reaction: under the protection of inert gas or nitrogen, taking a reducing agent sodium dihydrogen bis (2-methoxyethoxy) aluminate, stirring and dissolving the sodium dihydrogen bis (2-methoxyethoxy) aluminate in a dried solvent to prepare a sodium dihydrogen bis (2-methoxyethoxy) aluminate solution; dropwise adding triethyl chlorosilane into the prepared sodium dihydrogen bis (2-methoxyethoxy) aluminate solution to form a reaction solution, and continuously heating and stirring for reflux reaction; s2, separation and purification: carrying out solid-liquid separation in a filter pressing manner, removing filter residues, and retaining filtrate; and carrying out negative pressure distillation on the collected filtrate, and distilling out the recovered solvent to obtain the residual liquid, namely triethyl silane. The method is easy to process, cost-saving, less in generated by-products, high in yield and capable of realizing industrialization.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a method for efficiently synthesizing triethylsilane, in particular to a method for synthesizing triethylsilane by selecting a relatively stable hydrogenation reagent. Background Art

[0002] Triethylsilane is mainly used in organosilicon synthesis and is a common reducing agent. Its biggest feature is that it can be used as a reducing agent in an acidic environment. It is an intermediate in the production of oseltamivir, a drug used to treat the highly pathogenic avian influenza A (H1N1) worldwide. With the rapid development of the semiconductor industry and the continuous expansion of the specialty gas market, the market demand for triethylsilane will also grow rapidly.

[0003] Advantages and disadvantages of industrial synthesis methods:

[0004] Chinese patent CN102050833A discloses a method for preparing triethylsilane using a Grignard reagent method: using halogenated ethane and chlorosilane as raw materials, reacting with metal magnesium under anhydrous, oxygen-free, and carbon dioxide-free conditions to generate ethylmagnesium bromide; ethylmagnesium bromide reacts with trichlorodisilane in an ether solvent to generate crude triethylsilane. Due to the two-step reaction and the relatively harsh control conditions, the difficulty of industrialization is increased.

[0005] Chinese patent CN117700441A discloses a method and device for synthesizing triethylsilane using the carbene method: using chloromethylsilane, potassium metal, and sodium to generate a carbene reagent, and then adding a reducing agent and catalysts such as palladium, platinum, and rhodium. Precious metals involve recycling and other issues, and the process is complex and risky.

[0006] Reduction method: Use negative hydrogen metal hydrides such as lithium aluminum hydride to prepare triethylsilane. The disadvantages are high cost and poor solubility of metal hydrides in organic solvents. The chloride generated during the reaction affects further reactions and causes waste of raw materials.

[0007] Therefore, there is an urgent need for a method for synthesizing triethylsilane that is easy to handle, saves costs, produces fewer by-products, has a higher yield, and can be industrialized. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a method for efficiently synthesizing triethylsilane by using a reducing agent, sodium dihydrobis(2-methoxyethoxy)aluminate. The present invention is easy to handle, saves costs, produces fewer by-products, has a higher yield, and can be industrialized.

[0009] In order to achieve the purpose of the invention, the technical solution adopted by the present invention is as follows:

[0010] A method for efficiently synthesizing triethylsilane comprises the following steps:

[0011] S1. Synthesis reaction: Under the protection of inert gas or nitrogen (to avoid the influence of moisture on product yield and purity), take a reducing agent, sodium dihydrogen bis(2-methoxyethoxy)aluminate, and stir and dissolve it in a dried solvent to prepare a sodium dihydrogen bis(2-methoxyethoxy)aluminate solution;

[0012] Triethylchlorosilane is added dropwise to the prepared sodium dihydrogen bis(2-methoxyethoxy)aluminate solution to form a reaction solution, and the mixture is continuously heated, stirred and refluxed for reaction;

[0013] S2, separation and purification: solid-liquid separation by filter pressing, removal of filter residue, and retention of filtrate;

[0014] The collected filtrate is subjected to negative pressure distillation to evaporate the solvent, and the remaining liquid is triethylsilane.

[0015] Preferably, the solvent described in S1 is one of xylene, trimethylbenzene, methyl tert-butyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, or a mixed solvent.

[0016] Preferably, the solvent in S1 is dried using 3A-4A molecular sieves to make the water content of the solvent less than 150 ppm.

[0017] Preferably, the dropping speed of triethylchlorosilane in S1 is 1-5 mL / min.

[0018] Preferably, the concentration of the sodium dihydrobis(2-methoxyethoxy)aluminate solution in S1 is 30-70wt%, and the molar ratio of sodium dihydrobis(2-methoxyethoxy)aluminate to triethylchlorosilane is 0.5-1.5:1.

[0019] Preferably, the temperature of the reaction liquid in S1 is controlled at 60-150°C, and the condensation reflux temperature is -10 to 10°C.

[0020] Preferably, the reflux reaction time in S1 is 0.5-4h.

[0021] Preferably, the pressure of the solid-liquid separation in S2 is 0.2-3Mpa.

[0022] Preferably, the negative pressure distillation pressure in S2 is -0.1 to -0.05 MPa.

[0023] Preferably, the solvent evaporated in S2 is recovered and returned to S1 for use as a solvent.

[0024] Beneficial effects of the present invention:

[0025] The invention collects the filtrate and conducts negative pressure distillation to separate the solvent, a small amount of triethylsilane azeotrope, triethylsilane and other small amounts of impurities. The yield is 90%-95% and the purity is 89-99.5% as tested by chromatographic analysis.

[0026] The solvent of the invention can be recovered and reused.

[0027] The reducing agent sodium dihydrobis(2-methoxyethoxy)aluminate has attracted much attention due to its good solubility in organic solvents, stable storage, low cost and easy industrialization. Currently, a 70% toluene solution of sodium dihydrobis(2-methoxyethoxy)aluminate, commonly known as red aluminum, is widely sold on the market.

[0028] In the present invention, the boiling point of triethylsilane (107-108° C.) is large, and xylene, trimethylbenzene, methyl tert-butyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran and other solvents with large boiling point difference are selected to facilitate separation and purification.

[0029] The reducing agent raw material of the present invention is relatively stable in nature, strong in reducing property, strong in reaction activity, and has good solubility in organic solvents, so that the chloride generated by the reducing agent is prevented from being wrapped with the reducing agent during the reaction, resulting in waste of materials due to incomplete reaction. The reaction product of the present invention is very easy to handle, saves costs, generates fewer by-products, has a high yield, and can be industrialized. DETAILED DESCRIPTION

[0030] The synthesis method of triethylsilane provided by the present invention is described in detail below in conjunction with specific examples. The purpose of the present invention is to provide an efficient and inexpensive reducing agent for synthesizing triethylsilane.

[0031] Example 1

[0032] Under nitrogen protection, 90 g of sodium dihydrogen bis(2-methoxyethoxy)aluminate and 100 mL of dried and dehydrated xylene (dried with 4A molecular sieve, water content 50 ppm) were added to a 250 mL reaction bottle to prepare a 51% xylene solution. The reaction solution was heated to 150° C., the reflux condensate was controlled at 10° C., 130 g of triethylchlorosilane was added at a drip rate of 5 mL / min, and after the addition was completed, the reaction was refluxed for 4 hours.

[0033] The solid and liquid were separated by filtration at a pressure of 0.2 MPa, and then vacuum distillation was performed at a pressure of -0.05 MPa, and finally 75 ml of solvent was recovered, and 80 g of triethylsilane, that is, the yield was 90% and the purity was 99.3%.

[0034] Example 2

[0035] In a glove box, 80 g of sodium dihydrobis(2-methoxyethoxy)aluminate and 200 mL of dried and dehydrated tetrahydrofuran (dried with 3A molecular sieve, water content 100 ppm) were added to a 500 mL reactor to prepare a 31 wt% solution. The coolant was controlled at -5°C, the reaction liquid temperature was controlled at 60°C, 108 g of triethylchlorosilane was added at a rate of 2 mL / min, and the reaction liquid was refluxed for 0.5 hours after the addition was completed.

[0036] The solid and liquid were separated by filtration at a pressure of 1.5 MPa. The filtrate was subjected to reduced pressure distillation at a pressure of -0.1 MPa, and finally 165 mL of solvent was recovered, and 68.5 g of triethylsilane was obtained, with a yield of 92.3% and a purity of 90.8%.

[0037] Example 3

[0038] Under helium protection, 303 g of sodium dihydrobis(2-methoxyethoxy)aluminate and 400 mL of a mixed solvent of 2-methyltetrahydrofuran and xylene (dried with 4A molecular sieve, water content 150 ppm) after drying and dehydration were added to a 1 L reactor to prepare a 47 wt% solution. The reaction solution was heated to 90° C., the circulating coolant was -10° C., and 450 g of triethylchlorosilane was slowly added dropwise at 1 mL / min, and the reflux reaction was completed for 3.5 hours.

[0039] The solid and liquid were separated by filtration at a pressure of 3 MPa, and the filtrate was distilled under reduced pressure at a pressure of -0.1 MPa. Finally, 360 mL of solvent was recovered and 292 g of triethylsilane was obtained, with a yield of 94.5% and a purity of 99.1%.

[0040] Comparative Example 1

[0041] The difference between this comparative example and Example 1 is that this comparative example is not carried out under the protection of inert gas or nitrogen.

[0042] The yield was 55.2% and the purity was 72%.

[0043] Comparative Example 2

[0044] The only difference between this comparative example and Example 1 is that the solvent in this comparative example is not dried and has a water content of 200 ppm.

[0045] The yield was 40% and the purity was 63.4%.

[0046] Comparative Example 3

[0047] The difference between this comparative example and Example 1 is that the dropping speed of triethylchlorosilane in this comparative example is 20 mL / min.

[0048] The yield was 35% and the purity was 50%.

[0049] Comparative Example 4

[0050] The difference between this comparative example and Example 1 is that the solvent used in this comparative example is the recovered solvent in Example 1.

[0051] The yield was 92.5% and the purity was 98.2%.

[0052] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for efficiently synthesizing triethylsilane, characterized in that: The following steps are included: S1. Synthesis reaction: Under the protection of inert gas or nitrogen, take a reducing agent, sodium dihydrogen bis(2-methoxyethoxy)aluminate, and stir and dissolve it in a dried solvent to prepare a sodium dihydrogen bis(2-methoxyethoxy)aluminate solution; Triethylchlorosilane is added dropwise to the prepared sodium dihydrogen bis(2-methoxyethoxy)aluminate solution to form a reaction solution, and the mixture is continuously heated, stirred and refluxed for reaction; S2, separation and purification: solid-liquid separation by filter pressing, removal of filter residue, and retention of filtrate; The collected filtrate is subjected to negative pressure distillation to evaporate the solvent, and the remaining liquid is triethylsilane.

2. A method for efficiently synthesizing triethylsilane according to claim 1, characterized in that: The solvent in S1 is one of xylene, trimethylbenzene, methyl tert-butyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran or a mixed solvent.

3. A method for efficiently synthesizing triethylsilane according to claim 1, characterized in that: The solvent in S1 is dried with 3A-4A molecular sieves to make the water content of the solvent less than 150ppm.

4. A method for efficiently synthesizing triethylsilane according to claim 1, characterized in that: The dropping speed of triethylchlorosilane in S1 is 1-5 mL / min.

5. A method for efficiently synthesizing triethylsilane according to claim 1, characterized in that: The concentration of the sodium dihydrobis(2-methoxyethoxy)aluminate solution in S1 is 30-70wt%, and the molar ratio of sodium dihydrobis(2-methoxyethoxy)aluminate to triethylchlorosilane is 0.5-1.5:

1.

6. A method for efficiently synthesizing triethylsilane according to claim 1, characterized in that: The temperature of the reaction liquid in S1 is controlled at 60-150°C, and the condensation reflux temperature is -10 to 10°C.

7. A method for efficiently synthesizing triethylsilane according to claim 1, characterized in that: The reflux reaction time in S1 is 0.5-4h.

8. A method for efficiently synthesizing triethylsilane according to claim 1, characterized in that: The pressure of the solid-liquid separation in S2 is 0.2-3Mpa.

9. A method for efficiently synthesizing triethylsilane according to claim 1, characterized in that: The negative pressure distillation pressure in S2 is -0.1 to -0.05 MPa.

10. A method for efficiently synthesizing triethylsilane according to claim 1, characterized in that: The solvent evaporated in S2 is recovered and returned to S1 for use as solvent.