A method for the synthesis and purification of a pentadentate organosilicon compound

Abstract

The application relates to a synthesis and purification method of a pentacoordinated organosilicon compound. A silicon source and an inorganic base are added into ethylene glycol, heated to reflux under nitrogen protection to remove water, and the pentacoordinated organosilicon compound is obtained after distillation and purification. The application has wide raw material sources, simple synthesis method, short synthesis route and environmental friendliness.

Description

Technical Field

[0001] This invention belongs to the field of organic chemistry technology, specifically a method for the synthesis and purification of a five-coordinate organosilicon compound. Background Technology

[0002] Pentacoordinate organosilicon compounds exhibit high reactivity and can be used as raw materials to further synthesize conductive materials, high-performance ceramic glasses, anhydrous zeolites, and other silicon-containing polymers. Because pentacoordinate organosilicon compounds contain silicon-oxygen bonds, these materials also possess good temperature resistance, weather resistance, and stain resistance.

[0003] There are two main methods for preparing traditional five-coordinate organosilicon compounds. One method involves reacting amorphous silica with ethylene glycol under continuous heating and nitrogen purging in the presence of a 1-equivalent alkali metal (M) hydroxide catalyzed reaction, using the nitrogen flow to remove the water generated during the reaction. However, this method consumes a large amount of nitrogen, results in incomplete dehydration, and is complex. The other method involves heating and distilling amorphous silica with ethylene glycol under continuous heating and distillation in the presence of a 1-equivalent alkali metal (M) hydroxide catalyzed reaction, using the steam flow to remove the water generated during the reaction. However, this method is energy-intensive, results in incomplete dehydration, and is costly. Furthermore, amorphous silica is expensive, which is not conducive to industrial production, and the reaction products are prone to hydrolysis due to incomplete dehydration. A study on the direct synthesis of organosilicon compounds from amorphous silica (Zhou Aiping, Hefei University of Technology, 2003) used sodium hydroxide as an alkaline medium and precipitated silica, magnesium residue from serpentine extraction, and aluminum residue from bentonite extraction as silicon-containing raw materials, respectively, using continuous nitrogen purging to remove the water generated during the reaction to prepare organosilicon compounds. Documents recorded Figure 4-1 In the middle, at 2800-3000 cm -1 Between these, the five-ligand organosilicon compounds exhibit an asymmetric stretching vibration peak of CH at 900 cm⁻¹. -1 Typical Si-OC asymmetric bending vibration absorption peaks are present on both sides, at 1090 cm⁻¹. -1 The peak at this position is due to the Si-O stretching vibration. After the electron-connecting group, the peak shifts to the right and may produce a double peak. Summary of the Invention

[0004] The purpose of this invention is to provide a method for the synthesis and purification of five-coordinate organosilicon compounds. This method solves the problems of unconventional raw materials and incomplete dehydration in the synthesis of five-coordinate organosilicon compounds, and provides a new synthesis method. This method improves and optimizes existing synthesis methods, utilizes more common silicon materials, performs in vitro dehydration, improves reaction stability, and simplifies the process.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] A method for synthesizing a five-coordinate organosilicon compound, the method comprising the following steps:

[0007] S1: Add silicon source and inorganic base to ethylene glycol, heat the reaction under nitrogen protection, and then filter.

[0008] S2: The filtrate is replaced with nitrogen and then distilled under reduced pressure to remove excess ethylene glycol, yielding a solid pentacoordinate organosilicon compound.

[0009] Preferably, in step S1,

[0010] The silicon source is silicic acid or white zeolite;

[0011] The inorganic base is potassium hydroxide or sodium hydroxide;

[0012] The molar ratio of silicon source to inorganic base is 1:(1-2).

[0013] Preferably, in step S1, the heating temperature is 200-220 °C and the reaction time is 4-24 h.

[0014] In both silicic acid and white zeolite structures, silicon exists as silicate ions. Ethylene glycol, acting as a nucleophile, undergoes vigorous boiling and thorough contact with the silicon source under stirring and within this temperature range. Under the influence of a strong base, it reacts with the silicate ions. Below 200 °C, insufficient steam rises to remove the water produced in the reaction, hindering the reaction. Above 220 °C, the boiling of ethylene glycol becomes too vigorous; some ethylene glycol adheres to the adsorbent surface, while some undergoes polymerization. Insufficient ethylene glycol is detrimental to the reaction. Furthermore, silicic acid readily decomposes into water and silica above 150 °C. The newly formed silica at this temperature is highly reactive and readily reacts with ethylene glycol.

[0015] In step S1, during the heating reaction, water generated during the reaction process is removed promptly. Pentacoordinate organosilicon compounds are sensitive to water and easily hydrolyze in the presence of water. Using this dehydration device, ethylene glycol boils and enters the dehydration device through the steam riser. Upon cooling, the ethylene glycol liquefies and comes into full contact with the desiccant in the dehydration tube, remaining there for a period of time. When the liquid level in the dehydration tube is higher than the highest point of the siphon return tube, the liquid is siphoned back into the reaction flask. The long contact time between ethylene glycol and the desiccant ensures thorough water removal. Furthermore, this dehydration device employs external dehydration, proceeding simultaneously with the reaction, allowing for the timely removal of water generated during the reaction.

[0016] In step S1, the device used to remove water during the reaction process includes a dehydration body, which includes a dehydration pipe with a first opening at the upper end and a steam riser with a second opening at the lower end. The upper end of the steam riser is connected to the dehydration pipe, and the bottom of the dehydration pipe is connected to the siphon return pipe.

[0017] Preferably, the first opening is an internal ground joint and the second opening is an external ground joint; the diameter of the steam riser pipe is larger than that of the siphon return pipe.

[0018] Preferably, the connection point between the siphon reflux pipe and the dehydration pipe is located at the lowest point of the dehydration pipe; the top of the siphon reflux pipe is lower than the connection point between the steam riser pipe and the dehydration pipe; the first opening is connected to the condenser, and the second opening and the lower end of the siphon reflux pipe are inserted into the reaction flask.

[0019] An industrial device or equipment made based on the principle of the dehydration device.

[0020] Preferably, in step S2, the ethylene glycol obtained by distillation can be reused multiple times.

[0021] The method for purifying the solid five-coordinate organosilicon compound synthesized by the aforementioned method includes the following steps:

[0022] 1) Wash the pentacohesive organosilicon compound solid with ethanol to remove residual ethylene glycol, add dimethyl sulfoxide and stir for 1-2 h, then filter.

[0023] 2) After filtering, add methanol to the solid and stir for 1-2 hours, then filter again;

[0024] 3) The obtained solid was dried to obtain a five-coordinate organosilicon compound.

[0025] Preferably, anhydrous ethanol is used, dimethyl sulfoxide concentration is AR grade 99%, methanol is anhydrous methanol, and vacuum drying is performed at 55-65℃ for 22-26 hours.

[0026] Anhydrous ethanol must be used, and centrifugal washing is efficient and convenient. Ethanol can dissolve unreacted alkali and any residual ethylene glycol that may remain after distillation. Centrifugal washing involves a certain contact time, and multiple centrifugal washes can effectively remove unreacted alkali and residual ethylene glycol.

[0027] Dimethyl sulfoxide (DMSO) is used to leach solids. The silica produced by the pyrolysis of silicic acid is soluble in DMSO, and a small amount of unreacted silica is removed during leaching.

[0028] The solid is washed with methanol to remove dimethyl sulfoxide from its surface. Methanol has a low boiling point and is highly volatile; it can be removed by vacuum drying. The drying process in step three requires vacuum drying.

[0029] Existing technologies for preparing five-coordinate organosilicon compounds mainly utilize highly reactive silica such as silica gel, fused silica, or fumed silica with ethylene glycol, reacting under the catalysis of a 1-equivalent alkali metal (M) hydroxide (except Na). However, the use of reactive silica such as silica gel, fused silica, or fumed silica results in high costs. This invention uses silicic acid and zeolite, reducing costs. Furthermore, existing technologies suffer from incomplete dehydration. This invention employs external dehydration, utilizing boiling reflux of ethylene glycol through a desiccant to remove water generated during the reaction, promoting the reaction and improving product purity.

[0030] Compared with existing technologies, it has the following beneficial effects:

[0031] 1. This method uses silicic acid and white zeolite, which greatly reduces costs, shortens reaction time, and facilitates industrialization. The silicic acid used in this invention can be dried, and the white zeolite can be acidified with hydrochloric acid at 120-150 °C in a homogeneous reactor for 4-6 hours, which can increase the silicon content in the white zeolite and facilitate the reaction.

[0032] 2. This method utilizes a dehydration device to promptly remove water generated during the reaction. During the reaction, ethylene glycol boils and enters the dehydration device through a steam riser. Upon cooling, the ethylene glycol liquefies and comes into full contact with the desiccant in the dehydration tube, remaining there for a period of time. When the liquid level in the dehydration tube is higher than the highest point of the siphon return tube, the liquid is siphoned back into the reaction flask. The long contact time between ethylene glycol and the desiccant ensures thorough water removal. Furthermore, this dehydration device employs external dehydration, proceeding simultaneously with the reaction, effectively removing water generated during the reaction. Before adding this dehydration device, the yield of pentacoordinate organosilicon compounds prepared using silicic acid or white zeolite as the silicon source was less than 40%. With the addition of the dehydration device and prior drying or acidification of the raw materials, the yield can be increased to approximately 80%. Attached Figure Description

[0033] Figure 1 Infrared spectra of the products obtained from the reaction (dehydration) of silicic acid, sodium hydroxide and ethylene glycol;

[0034] Figure 2 Infrared spectra of the products obtained from the reaction of silicic acid, sodium hydroxide and ethylene glycol (without dehydration);

[0035] Figure 3 Infrared spectra of the products obtained from the reaction of white zeolite, sodium hydroxide and ethylene glycol;

[0036] Figure 4 Infrared spectra of the products obtained from the reaction of silicic acid, potassium hydroxide and ethylene glycol;

[0037] Figure 5 Schematic diagram of the dehydration device;

[0038] In the diagram: dehydration body 100, first opening 101, steam riser pipe 102, siphon return pipe 103, dehydration pipe 104, second opening 105. Detailed Implementation

[0039] To better understand the present invention, the following description, in conjunction with embodiments and accompanying drawings, further clarifies the content of the present invention. However, in order to enable those skilled in the art to fully understand the technical solutions and beneficial effects of the present invention, the following description, in conjunction with specific embodiments, provides further explanation. The embodiments are merely simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

[0040] Example 1: Synthesis of NaSi(OCH2CH2O)2OCH2CH2OH

[0041] Silicic acid and sodium hydroxide in a 1:1 molar ratio were mixed with excess ethylene glycol (ethylene glycol ≥ five times the molar amount of silicic acid). The mixture was heated to 220°C and stirred for 4 hours until the solid was completely dissolved, at which point the reaction was stopped. Water generated during the reaction was removed promptly. Excess ethylene glycol was removed by vacuum distillation to obtain a solid. The solid was washed with ethanol to remove residual ethylene glycol. The solid was then added to dimethyl sulfoxide and stirred for 1 hour before filtration. The filter cake was added to methanol and stirred for 1 hour before filtration. The filtered solid was dried to obtain a five-coordinate organosilicon compound. Anhydrous ethanol, 99% AR grade dimethyl sulfoxide, and anhydrous methanol were used. Vacuum drying was performed at 60°C for 24 hours. Figure 1 As shown, the infrared spectrum of the product is as follows: Figure 1 As shown in the figure. 1468 cm -1 The peak at 1351 cm⁻¹ represents the bending vibration of the methylene group. -1 The peak at 2916 cm⁻¹ represents the bending vibration of -C-CH₃. -1 The peak at 2951 cm⁻¹ represents the asymmetric stretching vibration of the methylene group. -1 The peak at 2864 cm⁻¹ represents the asymmetric stretching vibration of the methyl group. -1 The peak at 2836 cm⁻¹ represents the symmetric stretching vibration of the methyl group. -1 The peak at 1074 cm⁻¹ represents the symmetric stretching vibration of the methylene group. -1 and 898 cm -1 The peak value for the stretching vibration of Si-OC is 925 cm⁻¹. -1 Si-O at the site - Na + The stretching vibration peak indicates that the product is a five-coordinate organosilicon compound.

[0042] Comparative Example 1

[0043] A mixture of silicic acid and sodium hydroxide in a 1:1 molar ratio and excess ethylene glycol (ethylene glycol ≥ five times the molar amount of silicic acid) was heated to 220°C and stirred for 4 hours until the solid was completely dissolved. The reaction was then stopped. Excess ethylene glycol was removed by liquid distillation under reduced pressure to obtain a solid. The solid was washed with ethanol to remove residual ethylene glycol. The solid was added to dimethyl sulfoxide and stirred for 1 hour, then filtered. The filter cake was added to methanol and stirred for 1 hour, then filtered again. The filtered solid was dried to obtain a five-coordinate organosilicon compound. Anhydrous ethanol, 99% AR grade dimethyl sulfoxide, and anhydrous methanol were used. Vacuum drying was performed at 60°C for 24 hours. Figure 2 As shown, the infrared spectrum of the product is as follows: Figure 1 As shown in the figure. 1049 cm -1 and 879 cm -1 The stretching vibration peak of Si-OC is 1458 cm⁻¹. -1 The peak at 2951 cm⁻¹ represents the bending vibration of the methylene group. -1 The peak at 2884 cm⁻¹ represents the asymmetric stretching vibration of the methyl group. -1 The peak at 3000-3500 cm⁻¹ represents the symmetric stretching vibration of the methyl group. -1 The hydroxyl peak at water is relatively large, at 929 cm⁻¹. -1 Si-O - Na + The stretching vibration peaks are not obvious, indicating that the yield of the five-ligand organosilicon compound is low.

[0044] Example 2: Synthesis of NaSi(OCH2CH2O)2OCH2CH2OH

[0045] The silicon content in white zeolite was mixed with sodium hydroxide at a molar ratio of 1:1 and excess ethylene glycol (ethylene glycol ≥ five times the molar amount of silicon). The mixture was heated to 200℃ and stirred for 12 h. After the reaction was stopped, the mixture was filtered. The filtrate was distilled under reduced pressure to remove excess ethylene glycol, yielding a solid. The solid was washed with ethanol to remove residual ethylene glycol. The solid was added to dimethyl sulfoxide and stirred for 1.5 h. The filter cake was added to methanol and stirred for 1.5 h, then filtered. The filtered solid was dried to obtain the compound. Anhydrous ethanol was used, dimethyl sulfoxide was 99% AR grade, and methanol was anhydrous. Vacuum drying was performed at 60℃ for 24 h. The infrared spectrum of the obtained product is shown below. Figure 3 As shown, the infrared spectrum of the product obtained from the reaction with silicic acid, sodium hydroxide, and ethylene glycol is basically consistent. In the figure, 1467 cm⁻¹... -1 The peak at 2916 cm⁻¹ represents the bending vibration of the methylene group. -1 The peak at 2954 cm⁻¹ represents the asymmetric stretching vibration of the methylene group. -1 The peak at 2864 cm⁻¹ represents the asymmetric stretching vibration of the methyl group. -1The peak at 2836 cm⁻¹ represents the symmetric stretching vibration of the methyl group. -1 The peak at 1080 cm⁻¹ represents the symmetric stretching vibration of the methylene group. -1 and 898 cm -1 The peak value for the stretching vibration of Si-OC is 924 cm⁻¹. -1 Si-O at the site - Na + The stretching vibration peak indicates that the product is a five-coordinate organosilicon compound.

[0046] Example 3: Synthesis of KSi(OCH2CH2O)2OCH2CH2OH

[0047] Silicic acid and potassium hydroxide were mixed in a 1:1 molar ratio with excess ethylene glycol (ethylene glycol ≥ five times the molar amount of silicic acid). The mixture was heated to 200°C and stirred for 12 h. After the reaction was stopped, the mixture was filtered. The filtrate was distilled under reduced pressure to remove excess ethylene glycol, yielding a solid. The solid was washed with ethanol to remove residual ethylene glycol. The solid was added to dimethyl sulfoxide and stirred for 1.5 h, then filtered. The filter cake was added to methanol and stirred for 1.5 h, then filtered again. The filtered solid was dried to obtain the compound. Anhydrous ethanol was used, dimethyl sulfoxide was 99% AR grade, and methanol was anhydrous. Vacuum drying was performed at 60°C for 24 h. The infrared spectrum of the obtained product is shown below. Figure 4 As shown. 1472 cm -1 The peak at 1349 cm⁻¹ represents the methylene bending vibration. -1 The peak at 2946 cm⁻¹ is the bending vibration peak of -C-CH₃. -1 The peak at 2898 cm⁻¹ represents the asymmetric stretching vibration of the methyl group. -1 The peak at 2849 cm⁻¹ represents the symmetric stretching vibration of the methyl group. -1 The peak at 1070 cm⁻¹ represents the symmetric stretching vibration of the methylene group. -1 and 885 cm -1 The peak value for the stretching vibration of Si-OC is 1032 cm⁻¹. -1 The peak value for CO stretching vibration is 924 cm⁻¹. -1 Si-O at the site - K + The stretching vibration peak indicates that the product is a five-coordinate organosilicon compound.

[0048] Example 4

[0049] The dehydration device used in Examples 1-3 includes a dehydration body 100. The dehydration body 100 includes a dehydration pipe 104 with a first opening 101 at the upper end and a steam riser pipe 102 with a second opening 105 at the lower end. The upper end of the steam riser pipe 102 is connected to the dehydration pipe 104, and the bottom of the dehydration pipe 104 is connected to the siphon return pipe 103.

[0050] Preferably, the first opening 101 is an internal grinding opening, and the second opening 105 is an external grinding opening.

[0051] Preferably, the diameter of the steam riser pipe 102 is larger than that of the siphon return pipe 103, and its strength is sufficient to support the upper dehydration pipe.

[0052] Preferably, the connection point between the siphon return pipe 103 and the dehydration pipe 104 is located at the lowest point of the dehydration pipe 104.

[0053] Preferably, the top of the siphon return pipe 103 is lower than the point where the steam rise pipe 102 connects to the dehydration pipe 104.

[0054] Preferably, the first opening 101 is connected to the condenser, and the second opening 105 and the lower end of the siphon reflux pipe 103 are inserted into the reaction flask.

[0055] The steam riser pipe 102 is the steam rising channel of the reaction system, the siphon return pipe 103 is used for liquid reflux after dehydration, and the dehydration pipe 104 is used to place the desiccant.

[0056] The size of the first opening 101 and the second opening 105 can be adjusted as needed.

[0057] For specific examples, such as Figure 5 As shown, a suitable amount of 3A molecular sieve is placed in the dehydration tube 104 and installed between the reaction flask and the condenser tube. After the liquid in the flask boils, it rises to the condenser tube through the steam riser tube 102, liquefies upon cooling, and drips into the dehydration device (100). The liquid is in full contact with the molecular sieve. After the molecular sieve absorbs water, the liquid flows back to the reaction flask through the siphon reflux tube 103.

[0058] An industrial device or equipment made based on the principle of the dehydration device.

[0059] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The embodiments and features described in these embodiments can be arbitrarily combined without conflict. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for synthesizing a five-coordinate organosilicon compound, characterized in that: The synthesis method includes the following steps: S1: Add silicon source and inorganic base to ethylene glycol, heat under nitrogen protection for 4-24 h and then filter. The silicon source is silicic acid or white zeolite; the inorganic base is potassium hydroxide or sodium hydroxide; the molar ratio of silicon source to inorganic base is 1:(1-2); the heating temperature is 200-220 ℃; and the reaction time is 4-24 h. S2: The filtrate was replaced with nitrogen and then distilled under reduced pressure to remove excess ethylene glycol, yielding a solid pentacohesive organosilicon compound. In step S1, during the heating reaction, water is removed in a timely manner. The device used to remove water during the reaction includes a dehydration body (100), which includes a dehydration pipe (104) and a steam riser pipe (102). The upper end of the steam riser pipe (102) is connected to the dehydration pipe (104), and the bottom of the dehydration pipe (104) is connected to the siphon return pipe (103). The siphon return pipe (103) returns the water to the steam riser pipe (102). The bottom of the dehydration pipe (104) and the steam riser pipe (102) are not connected. The connection point between the siphon return pipe (103) and the dehydration pipe (104) is located at the lowest point of the dehydration pipe (104); the top of the siphon return pipe (103) is lower than the connection point between the steam riser pipe (102) and the dehydration pipe (104); The diameter of the steam riser pipe (102) is larger than that of the siphon return pipe (103).

2. The method for synthesizing the five-coordinate organosilicon compound according to claim 1, characterized in that, The dehydration pipe (104) has a first opening (101) at the upper end and a second opening (105) at the lower end of the steam riser pipe (102). The first opening (101) is connected to the condenser, and the second opening (105) and the lower end of the siphon reflux pipe (103) are inserted into the reaction flask.

3. The method for synthesizing the five-coordinate organosilicon compound according to claim 2, characterized in that, The first opening (101) is an internal grinding opening, and the second opening (105) is an external grinding opening.

4. The method for synthesizing the five-coordinate organosilicon compound according to claim 1, characterized in that, In step S2, the ethylene glycol obtained by distillation can be reused multiple times.

5. A method for purifying the solid five-coordinate organosilicon compound obtained by the method for synthesizing the five-coordinate organosilicon compound according to any one of claims 1-4, characterized in that, The purification method includes the following steps: 1) Wash the pentacohesive organosilicon compound solid with ethanol to remove residual ethylene glycol, add dimethyl sulfoxide and stir for 1-2 h, then filter. 2) After filtering, add methanol to the solid and stir for 1-2 hours, then filter again; 3) The obtained solid was dried to obtain a five-coordinate organosilicon compound.

6. A method for purifying the solid five-coordinate organosilicon compound synthesized by the method according to claim 5, characterized in that, The ethanol used is anhydrous ethanol, the dimethyl sulfoxide concentration is AR grade 99%, the methanol is anhydrous methanol, and the drying is carried out by vacuum drying at 55-65℃ for 22-26 hours.

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