CN117683067A - Preparation method of bistriphenylsilyl chromate - Google Patents

Abstract

The invention discloses a preparation method of bistriphenylsilane chromate. The preparation method includes: using triphenylsilanol, triphenylchlorosilane and potassium dichromate as raw materials, glacial acetic acid and cyclohexane as raw materials. The solvent, acetic anhydride is used as a water-absorbing agent, reacts under light-proof conditions, and is filtered and distilled under reduced pressure to obtain the crude bistriphenylsilane chromate ester, which is then washed and dried to obtain bistriphenylsilane chromate. The preparation method of bistriphenylsilyl chromate of the present invention has the advantages of high atomic utilization, high yield and purity, reduced Cr(VI) post-processing pressure, and low post-processing cost. The carbon content is determined by elemental analysis and theory. The minimum value difference can reach 3‰, and the yield can reach more than 90%.

Description

Preparation method of ditriphenylsilane chromate

Technical Field

The invention belongs to the technical field of polyolefin catalysts, and particularly relates to a preparation method of ditriphenylsilane chromate.

Background

With the continued development of global economies, the use of polyethylene has grown. Catalysts are one of the key technologies for polyolefin synthesis, and the most commonly used polyolefin catalysts on the market at present are Ziegler-Natta catalysts and chromium-based catalysts. The chromium-based catalyst can synthesize high-density polyethylene with wide molecular weight due to simple preparation and high catalytic activity, and is used for manufacturing large-scale hollow containers, and has been widely applied to the synthesis of polyolefin since the last fifty years (M.P.McDaniel, chapter 3-A Review of the Phillips Supported Chromium Catalyst and Its Commercial Use for Ethylene Polymerization, in: B.C.gates, H).(eds.) Advances in Catalysis, academic Press,2010, pp.123-606.) chromium-based catalysts find application in many polyethylene units, such as the widely used united states Union Carbide Corporation (UCC) Unipol fluidized bed reactor process. (F.J. Karol, in: macromolecular Symposia, wiley Online Library,1995, pp.563-575.). Bis-triphenylsilane chromates are an important active component precursor for the preparation of chromium-based catalysts.

US 2863891 discloses a synthesis method of ditriphenylsilane chromate, which uses triphenyl silanol, chromium trioxide and glacial acetic acid as raw materials to prepare the ditriphenylsilane chromate product with the yield of only 85%.

The united states union carbide company reports that ditrityl chromate product was obtained in 60% yield (L.M.Baker, W.L.Carrick, the Journal of Organic Chemistry,35 (1970) 774-776.) with triphenylsilanol and 4.5 times its molar amount of chromium trioxide starting material, carbon tetrachloride as solvent, anhydrous magnesium sulfate as water scavenger, and stirring at room temperature for 24 hours.

The Czech patent CS 175856 takes triphenylsilanol and chromium trioxide as raw materials, acetonitrile and butyronitrile are adopted as solvents, the yield is still low and is between 41 and 71 percent, and the toxicity of the solvents acetonitrile and butyronitrile is higher.

The raw materials adopted by the method are basically the same, the use of solvents is changed, water is inevitably generated in the reaction product, and water is required to be washed for desalting in the post-treatment process, so that the hydrolysis of the ditriphenylsilyl chromate is caused, and the purity of the product is reduced. Although the method of the American Union carbon company can remove water generated by the reaction, the solid mixture after the reaction contains unreacted chromium trioxide and magnesium sulfate containing crystal water, which are difficult to separate, so that the utilization rate of atoms is reduced, and meanwhile, the chromium trioxide is more harmful to the environment.

The soviet patent SU 689192 proposes another synthetic route for synthesizing ditriphenylsilane chromate, wherein triphenylchlorosilane and potassium dichromate are used as raw materials to react according to a molar ratio of 2:1.1, glacial acetic acid is used as a solvent, and the reaction is carried out for 1.5 hours at 50 ℃, wherein the yield of the ditriphenylsilane chromate is 94.2 percent based on the chlorosilane. However, the post-treatment difficulty of the technology leads to the influence of the purity of the product, the melting point of the product is lower, the atomic utilization rate of Cr (VI) is low, and the byproduct Cr (VI) cannot be recovered.

Wang Jun by using triphenylchlorosilane and potassium dichromate as raw materials, mixing glacial acetic acid and cyclohexane as solvents according to a molar ratio of 1:0.6, reacting for two hours at 30 ℃, filtering the reaction system to remove insoluble substances, evaporating the filtrate under the condition of reducing pressure at 50 ℃, and washing the residual solid with 5ml of glacial acetic acid and cyclohexane respectively, wherein the final product yield is only 80%, and the utilization ratio of chromium atoms is far lower than 50% (Wang Jun, li Yun, li Cuiqin, zhang Huaizhi, chemical industry and engineering, 29 (2012) 21-25.). However, the technology has low utilization rate of chromium atoms, and the byproduct chromium cannot be recovered.

Patent CN 1143082 also uses triphenylchlorosilane and potassium dichromate as raw materials, adopts a mixture of glacial acetic acid and hydrocarbon (n-hexane, cyclohexane and the like) as a solvent, adds an oxide, hydroxide or carbonate of alkali metal sodium or potassium to promote the conversion of the triphenylchlorosilane into triphenylsilanol, can react with generated chromium trioxide to generate chromate, is heated for five hours under the stirring condition of 50-60 ℃, generally has the yield of more than 90 percent according to the measurement of the triphenylchlorosilane, and has a melting point range which is wider according to the reaction condition (from 154 to 161 ℃). However, the carbon content of the sample prepared in the technical embodiment is generally lower than the theoretical value by more than 1%, the purity of the prepared product is not high, and the post-treatment process is still complex.

Disclosure of Invention

The invention aims to solve the technical problems that the utilization rate of chromium atoms is not high in the process of preparing the ditriphenylsilane chromate, and the purity and the yield of products are affected. The invention aims to provide a preparation method of ditriphenylsilane chromate, which has the advantages of high atom utilization rate, high yield and purity, reduced Cr (VI) post-treatment pressure, low post-treatment cost and the like, and the carbon content is as low as 3 per mill from the theoretical value by element analysis, and the yield can reach more than 90 percent.

In order to achieve the above object, the present invention provides a method for preparing ditriphenylsilane chromate, comprising: the method comprises the steps of taking triphenylsilanol, triphenylchlorosilane and potassium dichromate as raw materials, taking glacial acetic acid and cyclohexane as solvents, taking acetic anhydride as a water absorbent, reacting under a light-proof condition, filtering, distilling under reduced pressure to obtain a crude product of ditolylsilane chromate, and washing and drying to obtain ditolylsilane chromate.

The preparation method of the ditriphenylsilane chromate has the following reaction equation (1):

in one embodiment, the molar ratio of the triphenylchlorosilane to the triphenylsilanol can be, for example, 1:0.5 to 1.5, and more preferably 1:0.8 to 1.2; the molar ratio of triphenylchlorosilane to potassium dichromate can be, for example, 1:0.1 to 1.1, more preferably 1:0.4 to 0.8; the volume ratio of glacial acetic acid to cyclohexane can be, for example, 1:0.2 to 1.2, and more preferably 1:0.4 to 0.8; the molar ratio of acetic anhydride to triphenylchlorosilane can be, for example, 1:0.2 to 4.5, more preferably 1:0.5 to 4. However, the present invention is not limited thereto, and in other embodiments, the addition amount of the triphenylsilanol, the triphenylchlorosilane, the potassium dichromate, the glacial acetic acid, the cyclohexane, and the acetic anhydride may be adjusted according to actual production needs.

In one embodiment, the temperature of the reaction may be, for example, 20 to 100 ℃ for a period of time, for example, 0.5 to 24 hours, and more preferably, the temperature of the reaction is 40 to 80 ℃ for a period of time of 4 to 8 hours; the acetic anhydride may be added, for example, from 0 to 2.5 hours of reaction. However, the present invention is not limited thereto, and the reaction time may be appropriately prolonged as the reaction mass increases.

The method for producing ditriphenylsilane chromates of the present invention is not particularly limited to the operation steps or operation conditions of filtration, and the filtration may be carried out using steps and conditions commonly used in the art.

In one embodiment, the reduced pressure distillation is performed at 20 to 80 ℃, more preferably 40 to 60 ℃, but the present invention is not limited thereto.

In one embodiment, the washing is performed sequentially with water, glacial acetic acid, and cyclohexane, wherein the water and cyclohexane are used in an amount of 1 to 5 times, more preferably 1 to 3 times, the volume of glacial acetic acid, respectively, but the present invention is not limited thereto. The temperature and the number of times of washing are not particularly limited, and the washing may be performed at room temperature, may be performed at other temperatures, and may be performed 2 times, or may be performed 1, 3 or more times.

In one embodiment, the drying is, for example, vacuum drying at 0 to 100℃for 0.5 to 12 hours, more preferably at 20 to 80℃for 2 to 8 hours, but the present invention is not limited thereto.

The invention relates to a preparation method of ditriphenylsilane chromate. The preparation method is characterized in that triphenyl silanol, triphenyl chlorosilane and potassium dichromate are used as raw materials, glacial acetic acid and hydrocarbon compounds are used as solvents, acetic anhydride is used as a water absorbent, an active intermediate regulation and control technology is adopted, and the addition of the active intermediate triphenyl silanol breaks through the original reaction balance, promotes the reaction, improves the reaction efficiency and the product yield, obviously improves the utilization rate of chromium atoms, and reduces the treatment cost of Cr (VI); acetic anhydride is used as water absorbent and can react with generated water to generate acetic acid, inorganic salt is not introduced while hydrolysis of the product is avoided, and the purity of the product is improved. According to the preparation method, when the potassium dichromate is excessive by 5-20%, the yield of the obtained ditriphenylsilane chromate product can reach more than 90%, and the highest melting point can reach 156-157 ℃.

Detailed Description

The present invention will be specifically described below by way of examples. It is noted herein that the following examples are given solely for the purpose of illustration and are not to be construed as limiting the scope of the invention, as many insubstantial modifications and variations of the invention will become apparent to those skilled in the art in light of the above disclosure.

Raw material or equipment source:

evaluation analysis method: DSC differential thermal measurement and hydrocarbon element analysis.

Example 1

1.47g of triphenylchlorosilane, 0.88g of potassium dichromate and 1.38g of triphenylsilanol were placed in a 100ml flask, followed by addition of a mixed solvent of 20ml of glacial acetic acid and 10ml of cyclohexane, stirring at 50℃for 5h, and addition of 0.5ml of acetic anhydride at 0.5 h. After the completion of the reaction, cyclohexane was removed by concentration at 50℃using a rotary evaporator, followed by filtration to obtain a crude ditriphenylsilane chromate product. The crude product was washed 2 times with 10ml of water, 5ml of glacial acetic acid and 5ml of cyclohexane in sequence, and finally the solid was dried in vacuo at 50℃for 5h, all over the course of the above procedure protected from light. 3.06g of ditriphenylsilane chromate is obtained, the yield is 96.3%, the melting point is determined to be 157 ℃, and the elemental analysis result is C68.41% and H4.84%; calculated C68.12%, H4.73%.

Example 2

1.47g of triphenylchlorosilane, 0.88g of potassium dichromate and 1.38g of triphenylsilanol were placed in a 100ml flask, followed by addition of a mixed solvent of 20ml of glacial acetic acid and 10ml of cyclohexane, stirring at 40℃for 4h, and addition of 0.5ml of acetic anhydride at 0.5 h. After the completion of the reaction, cyclohexane was removed by concentration at 40℃using a rotary evaporator, followed by filtration to obtain a crude ditriphenylsilane chromate product. The crude product was washed 2 times with 15ml of water, 5ml of glacial acetic acid and 10ml of cyclohexane in sequence, and finally the solid was dried in vacuo at 80℃for 2h, all from light. 2.93g of ditriphenylsilane chromate is obtained, the yield is 92.3%, the melting point is determined to be 153 ℃, and the elemental analysis result is C68.54% and H4.71%; calculated C68.12%, H4.73%.

Example 3

1.47g of triphenylchlorosilane, 0.59g of potassium dichromate and 1.66g of triphenylsilanol were placed in a 100ml flask, followed by addition of a mixed solvent of 20ml of glacial acetic acid and 10ml of cyclohexane, stirring at 50℃for 8h, and addition of 0.5ml of acetic anhydride at 0.5 h. After the completion of the reaction, cyclohexane was removed by concentration at 55℃using a rotary evaporator, followed by filtration to obtain a crude ditriphenylsilane chromate product. The crude product was washed 2 times with 10ml of water, 10ml of glacial acetic acid and 5ml of cyclohexane in sequence, and finally the solid was dried in vacuo at 60℃for 4.5h, all from light. 2.43g of ditriphenylsilane chromate is obtained, the yield is 95.7%, the melting point is 155 ℃ and the elemental analysis result is C68.56% and H4.69%; calculated C68.12%, H4.73%.

Example 4

1.47g of triphenylchlorosilane, 1.18 g of potassium dichromate and 1.10g of triphenylsilanol were placed in a 100ml flask, followed by addition of a mixed solvent of 20ml of glacial acetic acid and 16ml of cyclohexane, stirring at 50℃for 5h, and addition of 0.5ml of acetic anhydride at 0.5 h. After the completion of the reaction, cyclohexane was removed by concentration at 50℃using a rotary evaporator, followed by filtration to obtain a crude ditriphenylsilane chromate product. The crude product was washed 2 times with 10ml of water, 5ml of glacial acetic acid and 10ml of cyclohexane in sequence, and finally the solid was dried in vacuo at 45℃for 7h, all over the course of the above procedure protected from light. 2.45g of ditriphenylsilane chromate is obtained, the yield is 96.5%, the melting point is determined to be 156 ℃, and the elemental analysis result is C68.42% and H4.83%; calculated C68.12%, H4.73%.

Example 5

1.47g of triphenylchlorosilane, 0.88g of potassium dichromate and 1.38g of triphenylsilanol were placed in a 100ml flask, followed by addition of a mixed solvent of 20ml of glacial acetic acid and 8ml of cyclohexane, stirring at 50℃for 5h, and addition of 2ml of acetic anhydride at 2.5 h. After the completion of the reaction, cyclohexane was removed by concentration at 50℃using a rotary evaporator, followed by filtration to obtain a crude ditriphenylsilane chromate product. The crude product was washed 3 times with 5ml of water, 5ml of glacial acetic acid and 5ml of cyclohexane in sequence, and finally the solid was dried in vacuo at 65℃for 8h, all from light. 2.88g of ditriphenylsilane chromate is obtained, the yield is 90.7%, the melting point is 152 ℃ and the elemental analysis result is 68.57% and 4.68% of H; calculated C68.12%, H4.73%.

Example 6

1.47g of triphenylchlorosilane, 0.88g of potassium dichromate and 1.38g of triphenylsilanol were placed in a 100ml flask, followed by addition of a mixed solvent of 20ml of glacial acetic acid and 8ml of cyclohexane, stirring at 40℃for 5h, and addition of 0.5ml of acetic anhydride at 0.5 h. After the completion of the reaction, cyclohexane was removed by concentration at 60℃using a rotary evaporator, followed by filtration, to obtain a crude ditriphenylsilane chromate product. The crude product was washed 2 times with 15ml of water, 15ml of glacial acetic acid and 30ml of cyclohexane in sequence, and finally the solid was dried in vacuo at 45℃for 7h, all over the course of the above procedure protected from light. 2.89g of ditriphenylsilane chromate is obtained, the yield is 91.2%, the melting point is 152 ℃ and the elemental analysis result is C68.53% and H4.72%; calculated C68.12%, H4.73%.

Example 7

1.47g of triphenylchlorosilane, 1.18 g of potassium dichromate and 1.10g of triphenylsilanol were placed in a 100ml flask, followed by addition of a mixed solvent of 20ml of glacial acetic acid and 10ml of cyclohexane, stirring at 80℃for 5 hours, and 0.5ml of acetic anhydride was added at 0 h. After the completion of the reaction, cyclohexane was removed by concentration at 45℃using a rotary evaporator, followed by filtration to obtain a crude ditriphenylsilane chromate product. The crude product was washed 1 time with 30ml of water, 15ml of glacial acetic acid and 45ml of cyclohexane in sequence, and finally the solid was dried in vacuo at 20℃for 8h, all over the course of the above procedure protected from light. 2.34g of ditriphenylsilane chromate is obtained, the yield is 91.6%, the melting point is determined to be 154 ℃, and the elemental analysis result is C68.48% and H4.77%; calculated C68.12%, H4.73%.

Example 8

2.94g of triphenylchlorosilane, 1.76g of potassium dichromate and 2.76g of triphenylsilanol were placed in a 100ml flask, followed by addition of a mixed solvent of 40ml of glacial acetic acid and 20ml of cyclohexane, stirring at 50℃for 8h, and addition of 1.00ml of acetic anhydride at 0.5 h. After the completion of the reaction, cyclohexane was removed by concentration at 50℃using a rotary evaporator, followed by filtration to obtain a crude ditriphenylsilane chromate product. The crude product was washed 2 times with 20ml of water, 10ml of glacial acetic acid and 10ml of cyclohexane in sequence, and finally the solid was dried in vacuo at 50℃for 5h, all over the course of the procedure protected from light. 5.94g of ditriphenylsilane chromate is obtained, the yield is 93.7%, the melting point is determined to be 156 ℃, and the elemental analysis result is C68.46% and H4.79%; calculated C68.12%, H4.73%.

Comparative example 1

1.47g of triphenylchlorosilane, 0.88g of potassium dichromate and 1.38g of triphenylsilanol were placed in a 100ml flask, followed by adding a mixed solvent of 20ml of glacial acetic acid and 10ml of cyclohexane, and stirring at 50℃for 5 hours. After the completion of the reaction, cyclohexane was removed by concentration at 50℃using a rotary evaporator, followed by filtration to obtain a crude ditriphenylsilane chromate product. The crude product was washed 2 times with 10ml of water, 5ml of glacial acetic acid and 5ml of cyclohexane in sequence, and finally the solid was dried in vacuo at 50℃for 5h, all over the course of the above procedure protected from light. 2.82g of ditriphenylsilane chromate is obtained, the yield is 89.0%, the melting point is determined to be 153 ℃, and the elemental analysis result is C66.46% and H4.36%; calculated C68.12%, H4.73%.

Comparative example 2

10.00g of triphenylchlorosilane and 4.00g of potassium dichromate were placed in a 100ml flask, followed by addition of 120ml of glacial acetic acid and stirring at 45℃for 5h. After the reaction is completed, the reactants are filtered to obtain a crude product of the ditriphenylsilane chromate. The crude product was washed 2 times with 240ml of water, 240ml of glacial acetic acid and 240ml of hexane in sequence, and finally the solid was dried in vacuo at 50℃for 5h, all over the course of the procedure protected from light. 8.83g of ditriphenylsilane chromate is obtained, the yield is 86.0%, the melting point is 145 ℃ and the elemental analysis result is C65.99% and H4.90%; calculated C68.12%, H4.76%.

Comparative example 3

10.00g of triphenylchlorosilane, 4.30g of potassium dichromate and 1.00g of potassium hydroxide were placed in a 100ml flask, followed by pouring a mixed solvent of 20ml of glacial acetic acid and 27ml of n-hexane, and stirring at 55℃for 5 hours. After the reaction is completed, the reactants are filtered to obtain a crude product of the ditriphenylsilane chromate. The crude product was washed by suction filtration with 47ml of water, 24ml of glacial acetic acid and 24ml of n-hexane, and finally dried under vacuum at 50℃for 4h to give the final product, all under light-protected conditions. 8.80g of ditriphenylsilane chromate is finally obtained, the yield is 94.8%, the melting point is 129 ℃ and the elemental analysis result is 65.40% and 4.50%; calculated C68.12%, H4.73%.

Comparative example 4

5.53g of triphenylchlorosilanol and 1.00g of chromium trioxide were placed in a 100ml flask, followed by addition of 20ml of glacial acetic acid as a reaction solvent, and reacted at 50℃for 5 hours, followed by filtration to give a crude ditriphenylsilane chromate product. Washing the crude product with water to be neutral, drying, and recrystallizing with carbon tetrachloride to obtain orange solid ditriphenylsilane chromate, wherein the whole process is protected from light to obtain 4.50g of ditriphenylsilane chromate, the yield is 70.9%, the melting point is 152 ℃, and the elemental analysis result is C61.38% and H4.10%; calculated C68.12%, H4.76%.

Comparative example 5

3.00g of triphenylsilanol, 3.00g of chromium trioxide and 5.00g of anhydrous magnesium sulfate were placed in a 250ml round bottom flask, followed by addition of 90ml of carbon tetrachloride and stirring at room temperature in the absence of light for 24h. After the reaction was completed, the filtrate was collected by filtration. Spin-drying at 50deg.C, and recrystallizing with 30ml n-heptane to obtain dark red needle-like crystal bis-triphenylsilane chromate. 2.58g of ditriphenylsilane chromate is finally obtained, the yield is 75.0%, the melting point is determined to be 151 ℃, and the elemental analysis result is C65.27% and H4.62%; calculated C68.12%, H4.76%.

Comparative example 6

3.00g of triphenylsilanol, 3.00g of chromium trioxide and 1.00ml of acetic anhydride were placed in a 250ml round bottom flask, followed by addition of 90ml of carbon tetrachloride and stirring at room temperature in the dark for 24h. After the reaction was completed, the filtrate was collected by filtration. Spin-drying at 50deg.C, and recrystallizing with 30ml n-heptane to obtain dark red needle-like crystal bis-triphenylsilane chromate. 2.75g of ditriphenylsilane chromate is finally obtained, the yield is 80.0%, the melting point is 152 ℃ and the elemental analysis result is C66.41% and H4.74%; calculated C68.12%, H4.76%.

Of course, the present invention is capable of other various embodiments and modifications thereof, and various changes and modifications can be made by one skilled in the art without departing from the spirit and scope of the invention, which is limited only by the appended claims.

Claims (10)

1. A method for preparing ditriphenylsilane chromate, comprising the steps of: the method comprises the steps of taking triphenylsilanol, triphenylchlorosilane and potassium dichromate as raw materials, taking glacial acetic acid and cyclohexane as solvents, taking acetic anhydride as a water absorbent, reacting under a light-proof condition, filtering, distilling under reduced pressure to obtain a crude product of ditolylsilane chromate, and washing and drying to obtain ditolylsilane chromate.

2. The preparation method according to claim 1, wherein the molar ratio of the triphenylchlorosilane to the triphenylsilanol is 1:0.5-1.5; the molar ratio of the triphenylchlorosilane to the potassium dichromate is 1:0.1-1.1; the volume ratio of the glacial acetic acid to the cyclohexane is 1:0.2-1.2; the molar ratio of the acetic anhydride to the triphenylchlorosilane is 1:0.2-4.5.

3. The preparation method according to claim 2, wherein the molar ratio of the triphenylchlorosilane to the triphenylsilanol is 1:0.8-1.2; the mole ratio of the triphenylchlorosilane to the potassium dichromate is 1:0.4-0.8; the volume ratio of the glacial acetic acid to the cyclohexane is 1:0.4-0.8; the molar ratio of the acetic anhydride to the triphenylchlorosilane is 1:0.5-4.

4. The method according to claim 1, wherein the reaction is carried out at a temperature of 20 to 100 ℃ for a time of 0.5 to 24 hours.

5. The process according to claim 4, wherein the reaction is carried out at a temperature of 40 to 80℃for a period of 4 to 8 hours.

6. The process according to claim 1, wherein the acetic anhydride is added at 0 to 2.5 hours of the reaction.

7. The process according to claim 1, wherein the reduced pressure distillation is carried out at 20 to 80 ℃.

8. The preparation method according to claim 1, wherein the washing is carried out by sequentially using water, glacial acetic acid and cyclohexane, and the water and the cyclohexane are respectively 1-5 times of the volume of the glacial acetic acid.

9. The method according to claim 7, wherein the amount of water and cyclohexane is 1 to 3 times the amount of glacial acetic acid by volume, respectively, and the number of times of washing is 2.

10. The method according to claim 1, wherein the drying is vacuum drying at 0 to 100 ℃ for 0.5 to 12 hours.