Method for co-producing triphenylphosphine and silicon tetrachloride

Abstract

The invention discloses a method for co-producing triphenylphosphine and silicon tetrachloride, which comprises the following steps: S1, mixing triphenylphosphine oxide with a solvent, heating to 90-110 DEG C, and dropwise adding trichlorosilane to carry out reduction reaction; the reaction pressure is controlled to be 0.12 to 0.20 Mpa absolute pressure; s2, the reaction temperature is kept not lower than 90 DEG C, preferably 90-110 DEG C, meanwhile, the system pressure is adjusted to be negative pressure, and the reaction continues for 0.5-3 h; and after the reaction is completed, rectifying and separating out silicon tetrachloride, adding water into the residual reaction liquid for quenching, filtering out insoluble substances, and removing the solvent to obtain the triphenylphosphine. According to the method, high-purity triphenylphosphine can be obtained with high yield, the electronic-grade silicon tetrachloride is co-produced, the generation of silicon dioxide is reduced, the gel coating problem of the silicon dioxide and the product loss are reduced, the post-treatment is more convenient, and the method is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to a co-production method, in particular to a method for co-producing triphenylphosphine and silicon tetrachloride. Background Art

[0002] Triphenylphosphine (TPP) is a white crystalline solid and an important organic intermediate. It can be used as a nucleophilic reagent to participate in catalytic reduction, nucleophilic substitution and many other reactions. At the same time, as a phosphorus ligand, triphenylphosphine is widely used in coordination chemistry and transition metal catalytic reactions to catalyze the synthesis of chemicals such as menthol and adiponitrile. Triphenylphosphine is also used in the medical field for the synthesis of certain drugs; at the same time, in some fields of polymer chemistry and materials science, triphenylphosphine has also shown certain application potential.

[0003] At present, some manufacturers use the Grignard process to produce triphenylphosphine, using chlorobenzene, magnesium chips, and phosphorus trichloride as the main raw materials, undergoing Grignard reaction in a mixed solvent, distillation, and then crystallizing in methanol to obtain the product. However, the conversion rate of the existing production method is low, generally only reaching 60-70%, resulting in limited industrial application.

[0004] The applicant has found in the continuous research in this field that the reaction using triphenylphosphine in industrial production is usually accompanied by the formation of triphenylphosphine oxide (TPPO) which has low utilization value, resulting in the problem of low atom economy. The reduction of triphenylphosphine oxide to regenerate triphenylphosphine can improve atom economy, which is of significant significance.

[0005] According to known reports, BASF uses phosgene to reduce triphenylphosphine oxide, first converting it into dichloride, and then using red phosphorus to reduce it to triphenylphosphine. The raw material is highly toxic and has a low yield, and some triphenylphosphine oxides are not suitable for use and have a low conversion rate. In addition, silane can also be used as a reducing agent, among which only trichlorosilane has a cost advantage, obvious economic benefits, and a relatively mild reaction process. However, this method generates a molecule of triphenylphosphine while generating a molecule of silicon dioxide. Silicon dioxide is difficult to be reused, and the overall atomic economy is poor. How to improve the production efficiency of triphenylphosphine and reduce the generation of silicon dioxide is a technical problem that is still being addressed. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a method for co-producing triphenylphosphine and silicon tetrachloride. The yield of triphenylphosphine in this method is as high as 95% or more, and silicon tetrachloride is co-produced, which reduces the generation of silicon dioxide. The silicon tetrachloride has high purity and can be used as electronic grade silicon tetrachloride, which significantly improves the added value of the product.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A method for co-producing triphenylphosphine and silicon tetrachloride comprises the following steps:

[0009] S1. Mix triphenylphosphine oxide and a solvent, raise the temperature to 90-120° C., and dropwise add trichlorosilane to carry out a reduction reaction; control the reaction pressure to be 0.12-0.20 MPa absolute pressure;

[0010] S2. Keep the reaction temperature not lower than 90°C, preferably 90-120°C, and adjust the system pressure to negative pressure, and continue the reaction for 0.5-3h. After the reaction is completed, separate silicon tetrachloride by distillation, quench the remaining reaction solution with water, filter out insoluble matter, remove solvent, and obtain triphenylphosphine.

[0011] The inventors found in the study of the process for synthesizing triphenylphosphine that in the process of adding trichlorosilane for reduction reaction, the conventional reaction process is that triphenylphosphine oxide and trichlorosilane react to generate dichlorosilane and hydrogen chloride, as shown in the following formula:

[0012]

[0013] The method of the present invention can produce triphenylphosphine and co-produce silicon tetrachloride by adjusting the reduction reaction conditions and steps, thereby reducing the amount of silicon dioxide and the generation of HCl. According to the GC-MS analysis results of the product, it is inferred that the possible reaction mechanism is that step S1 tends to generate triphenylphosphine and polysilicon ether structures (such as hexachlorosilane Cl3SiOSiCl3) under higher reaction temperature, pressure and raw material ratio, and after step S2 reduces the reaction pressure to negative pressure, the polysilicon ether can be further decomposed into silicon tetrachloride and dichlorosilane, and stably exists in the system, thereby obtaining the co-product silicon tetrachloride by simple distillation. The silicon tetrachloride has a higher purity and can be used as a high value-added electronic grade product. Dichlorosilane generates silicon dioxide after adding water to quench, and the output is reduced.

[0014] In step S2, the reaction temperature needs to be maintained at 90°C or above. Silicon tetrachloride is in a gaseous state at this temperature. By further reducing the reaction pressure, the reaction is prompted to move in the direction of generating gas, thereby generating silicon tetrachloride and silicon dichloride. After the silicon dichloride is subsequently quenched by adding water, it quickly undergoes a hydrolysis reaction to generate silicon dioxide.

[0015] In some preferred examples of the present invention, the molar ratio of trichlorosilane to triphenylphosphine oxide is 2-5.

[0016] In some preferred examples of the present invention, the dripping time of trichlorosilane is 0.15 to 2.5 hours.

[0017] In some preferred examples of the present invention, in step S1, after the trichlorosilane is added, the reaction is continued for 0.5 to 5 hours.

[0018] In some preferred examples of the present invention, the reaction solvent in step S1 is one or more of toluene, chlorobenzene, xylene, and ethylbenzene.

[0019] Preferably, the amount of the solvent used is 3 to 10 times the mass of triphenylphosphine oxide.

[0020] In some preferred examples of the present invention, the reaction pressure in step S2 is 75-95 KPa absolute pressure.

[0021] The invention proposes a new synthesis route, which can obtain triphenylphosphine with a purity of more than 99% with a yield of more than 95% and co-produce electronic-grade silicon tetrachloride, while reducing the generation of silicon dioxide by 50%, reducing the problem of gel coating of silicon dioxide and product loss, making post-processing more convenient and suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the gas chromatography-mass spectrometry analysis spectrum of the reaction solution obtained after the reaction in step S2 of Example 1. DETAILED DESCRIPTION

[0023] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0024] The main raw materials in the following examples of the present invention are as follows. Other raw materials, unless otherwise specified, can be purchased from commercial sources.

[0025] Trichlorosilane: Alfa Aesar (China) Chemical Co., Ltd.

[0026] Triphenylphosphine oxide: Shanghai Yien Chemical Technology Co., Ltd.

[0027] The main test methods involved in the following embodiments of the present invention are as follows:

[0028] (1) Analysis of the composition of substances in the reaction solution by liquid chromatography

[0029] Liquid phase analysis column: Agilent ZORBAX SB phenyl (Phenyl) liquid chromatography column (StableBond), 250mm*4.6mm*5um (80A).

[0030] Chromatographic conditions: column temperature: 40°C; detector: UV260nm; flow rate: 1.0ml / min; mobile phase: methanol and pure water.

[0031] TPPO conversion rate: (TPPO feed amount - remaining TPPO in the reaction solution) / TPPO feed amount;

[0032] TPP yield: TPP mass in reaction solution / theoretical TPP mass.

[0033] (2) The silicon dioxide content shall be determined in accordance with HG / T 3066-2008.

[0034] [Example 1]

[0035] S1. Add 20.82g of triphenylphosphine oxide and 62.46g of toluene to a 500ml reactor, heat to 90°C, slowly drop 20.27g of trichlorosilane, add for about 10min, maintain the system pressure at 0.12MPa after the addition, and react for 5h. During the experiment, bubbles can be observed in the system when trichlorosilane is added, but no bubbles are formed after the addition, indicating that the amount of HCl generated is reduced.

[0036] S2. Slowly open the vacuum valve, adjust the reaction pressure to 95Kpa, maintain the temperature at 90℃, and keep the reaction for 2h. The reaction solution is analyzed by gas chromatography-mass spectrometry (GC-MS). The spectrum is as follows: Figure 1 As shown, it can be seen that a certain amount of silicon hexachloride remains in the reaction solution and a large amount of silicon tetrachloride is generated, which indirectly verifies the reaction mechanism shown above.

[0037] After the reaction was complete as detected by liquid chromatography, the temperature was raised to 110°C for atmospheric distillation to separate 6.14g of electronic grade silicon tetrachloride (purity 99%). The remaining reaction solution was quenched with water to generate white solid silicon dioxide, which was filtered to remove the solid, and the solvent was evaporated. After cooling, a white solid was immediately precipitated. After drying, the mass of triphenylphosphine was detected to be 18.95g, and the purity was greater than 99% by HPLC, the reaction conversion rate was 98.54%, and the reaction yield was 96.57%.

[0038] [Example 2]

[0039] S1. Add 200.42 g of triphenylphosphine oxide and 1302.73 g of toluene into a 5 L reactor. After heating to 120°C, slowly drop 487.71 g of trichlorosilane for about 120 min. After the dropwise addition is completed, maintain the system pressure at 0.20 MPa and react for 1 h.

[0040] S2, slowly open the vacuum valve, adjust the reaction pressure to 75Kpa, and keep the reaction warm for 0.5h. After the liquid chromatography detection reaction is complete, the temperature is raised to 120°C for atmospheric distillation, and 94.64g (purity 99%) of electronic grade silicon tetrachloride is separated. The remaining reaction solution is quenched with water to generate white solid silicon dioxide, the solid is filtered to remove the solid, the solvent is evaporated, and the white solid is immediately precipitated after cooling. After drying, the mass of triphenylphosphine is detected to be 182.65g, and the purity detected by HPLC is greater than 99%, the reaction conversion rate is 98.66%, and the reaction yield is 96.69%.

[0041] [Example 3]

[0042] S1. Add 100.42 g of triphenylphosphine oxide and 1004.20 g of toluene into a 5 L reactor. After heating to 110°C, slowly drop 171.06 g of trichlorosilane for about 80 min. After the dropwise addition is completed, maintain the system pressure at 0.16 MPa and react for 3 h.

[0043] S2, slowly open the vacuum valve, adjust the reaction pressure to 85Kpa, and keep the reaction for 1h. After the reaction is complete by liquid chromatography, the temperature is raised to 120°C for rectification, and 43.97g (purity 99%) of electronic grade silicon tetrachloride is separated. The remaining reaction solution is quenched with water to generate white solid silicon dioxide, the solid is filtered to remove the solid, the solvent is evaporated, and a white solid is precipitated immediately after cooling. After drying, the mass of triphenylphosphine is detected to be 90.52g, and the purity detected by HPLC is greater than 99%, the reaction conversion rate is 97.59%, and the reaction yield is 95.64%.

[0044] [Comparative Example 1]

[0045] Add 20.92g triphenylphosphine oxide and 62.76g toluene to a 500ml reactor, heat to 90°C, slowly drip 20.36g trichlorosilane, the dripping time is about 10min, react at normal pressure for 7h after the dripping is completed, and bubbles continue to form during the reaction stage. After liquid chromatography detection, heat to 110°C for distillation, and no silicon tetrachloride is detected. Add water to the remaining reaction solution to quench, generate white solid silicon dioxide, filter to remove solids, rotary evaporate the solvent, and immediately precipitate a white solid after cooling. After drying, the mass of triphenylphosphine is detected to be 15.62g, the purity is 80% by HPLC, the reaction conversion rate is 80.83%, and the reaction yield is 79.22%.

[0046] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A method for co-producing triphenylphosphine and silicon tetrachloride, characterized in that: The following steps are involved: S1. Mix triphenylphosphine oxide and a solvent, raise the temperature to 90-120° C., and dropwise add trichlorosilane to carry out a reduction reaction; control the reaction pressure to be 0.12-0.20 MPa absolute pressure; S2. Keep the reaction temperature not lower than 90°C, preferably 90-120°C, and adjust the system pressure to negative pressure, and continue the reaction for 0.5-3h. After the reaction is completed, separate silicon tetrachloride by distillation, quench the remaining reaction solution with water, filter out insoluble matter, remove solvent, and obtain triphenylphosphine.

2. The method for co-producing triphenylphosphine and silicon tetrachloride according to claim 1, characterized in that: The molar ratio of trichlorosilane to triphenylphosphine oxide is 2-5.

3. The method for co-producing triphenylphosphine and silicon tetrachloride according to claim 1 or 2, characterized in that: The dropping time of the trichlorosilane is 0.15 to 2.5 hours.

4. The method for co-producing triphenylphosphine and silicon tetrachloride according to any one of claims 1 to 3, characterized in that: In step S1, after the trichlorosilane is added dropwise, the reaction is continued for 0.5 to 5 hours.

5. The method for co-producing triphenylphosphine and silicon tetrachloride according to any one of claims 1 to 4, characterized in that: The reaction solvent in step S1 is one or more of toluene, chlorobenzene, xylene and ethylbenzene.

6. The method for co-producing triphenylphosphine and silicon tetrachloride according to any one of claims 1 to 5, characterized in that: The reaction pressure in step S2 is 75 to 95 KPa absolute pressure.

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