CN117683067B - Preparation method of ditriphenylsilane chromate - Google Patents

Abstract

This invention discloses a method for preparing bis(triphenylsilane) chromate. The method includes: using triphenylsilanol, triphenylchlorosilane, and potassium dichromate as raw materials, glacial acetic acid and cyclohexane as solvents, and acetic anhydride as a dehydrating agent, reacting under light-protected conditions, followed by filtration and vacuum distillation to obtain a crude bis(triphenylsilane) chromate product, which is then washed and dried to obtain the final bis(triphenylsilane) chromate. The method for preparing bis(triphenylsilane) chromate of this invention has advantages such as high atom utilization, high yield and purity, reduced Cr(VI) post-processing pressure, and low post-processing cost. The carbon content, as determined by elemental analysis, deviates from the theoretical value by as little as 3‰, and the yield can reach over 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 catalyst has simple preparation and high catalytic activity, can synthesize high-density polyethylene with wide molecular weight, is used for manufacturing large hollow containers, and is widely applied to polyolefin synthesis 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 Company (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 uses triphenylsilanol and chromium trioxide as raw materials, acetonitrile and butyronitrile are used 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 union patent SU 689192 proposes another synthetic route for synthesizing ditriphenylsilane chromate, which takes triphenylchlorosilane and potassium dichromate as raw materials to react according to the molar ratio of 2:1.1, takes glacial acetic acid as solvent, and reacts for 1.5 hours at 50 ℃, wherein the yield of the ditriphenylsilane chromate is 94.2 percent measured by 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 and the like, triphenylchlorosilane and potassium dichromate are used as raw materials, the molar ratio is 1:0.6, glacial acetic acid and cyclohexane are used as solvents, the reaction is carried out for two hours at 30 ℃, insoluble substances are removed by filtration of the reaction system, the solvents are distilled off from the filtrate under the condition of 50 ℃ and the pressure reduction, the residual solids are washed by 5ml of glacial acetic acid and 5ml of cyclohexane respectively, and finally the 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 hydrocarbons (n-hexane, cyclohexane, etc.) 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, and is heated for five hours under the stirring condition of 50-60 ℃, the yield measured by the triphenylchlorosilane can generally reach more than 90%, and the melting point range of the product 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.

The invention provides a preparation method of ditriphenylsilane chromate, which 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 water absorbent, reacting under the condition of avoiding light, filtering, distilling under reduced pressure to obtain a ditriphenylsilane chromate crude product, washing and drying to obtain ditriphenylsilane chromate.

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

In the preparation method of the ditriphenylsilane chromate, in an embodiment, the molar ratio of the triphenylchlorosilane to the triphenylsilanol may be, for example, 1:0.5-1.5, more preferably 1:0.8-1.2, the molar ratio of the triphenylchlorosilane to the potassium dichromate may be, for example, 1:0.1-1.1, more preferably 1:0.4-0.8, the volume ratio of the glacial acetic acid to the cyclohexane may be, for example, 1:0.2-1.2, more preferably 1:0.4-0.8, and the molar ratio of the acetic anhydride to the triphenylchlorosilane may be, for example, 1:0.2-4.5, more preferably 1:0.5-4. 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 reaction temperature may be, for example, 20 to 100 ℃, the reaction time may be, for example, 0.5 to 24 hours, and more preferably, the reaction temperature may be 40 to 80 ℃ and the reaction time may be 4 to 8 hours, and the acetic anhydride may be added, for example, at the reaction time of 0 to 2.5 hours. 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 ℃, and more preferably at 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 respectively 1-5 times, more preferably 1-3 times, the volume of glacial acetic acid, but the 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, and more preferably vacuum drying 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 method uses triphenyl silanol, triphenyl chlorosilane and potassium dichromate as raw materials, glacial acetic acid and hydrocarbon compounds as solvents, acetic anhydride as water absorbent, adopts an active intermediate regulation technology, breaks the original reaction balance through adding the active intermediate triphenyl silanol, promotes the reaction, improves the reaction efficiency and the product yield, obviously improves the utilization ratio of chromium atoms, reduces the treatment cost of Cr (VI), and can react with the generated water to generate acetic acid by using the acetic anhydride as the water absorbent, thereby avoiding the hydrolysis of the product, avoiding introducing inorganic salt and improving the purity of the product. 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:

the evaluation and analysis method comprises 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 using a rotary evaporator at 50℃and then filtered 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 under vacuum at 50 ℃ for 5h, all over the course of the above procedure protected from light. 3.06g of ditriphenylsilane chromate was obtained, the yield was 96.3%, the melting point was found to be 157℃and the elemental analysis result was found to be C68.41%, H4.84% and calculated to be C68.12% and 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 using a rotary evaporator at 40 ℃, 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 under vacuum at 80 ℃ for 2h, all over the course of the above procedure protected from light. 2.93g of ditriphenylsilane chromate was obtained, the yield was 92.3%, the melting point was found to be 153℃and the elemental analysis result was found to be C68.54%, H4.71%, calculated as C68.12% and 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 using a rotary evaporator at 55℃and then filtered 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 under vacuum at 60℃for 4.5h, all over the course of the above procedure protected from light. 2.43g of ditriphenylsilane chromate was obtained, the yield was 95.7%, the melting point was found to be 155℃and the elemental analysis result was found to be 68.56% for H4.69% and 68.12% for calculated C, 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 using a rotary evaporator at 50℃and then filtered 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 under vacuum at 45℃for 7h, all from light. 2.45g of ditriphenylsilane chromate was obtained, the yield was 96.5%, the melting point was 156℃as determined, and the results of elemental analysis were 68.42% and 4.83% as calculated for C68.12% and 4.73%.

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 using a rotary evaporator at 50℃and then filtered 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 under vacuum at 65℃for 8h, all from light. 2.88g of ditriphenylsilane chromate was obtained, the yield was 90.7%, the melting point was 152℃as determined, and the results of elemental analysis were 68.57%, H4.68% and calculated as 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 using a rotary evaporator at 60℃and then filtered 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 under vacuum at 45℃for 7h, all from light. 2.89g of ditriphenylsilane chromate was obtained, the yield was 91.2%, the melting point was 152℃as determined, and the elemental analysis result C68.53%, H4.72% and the calculated value C68.12%, H4.73% were obtained.

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 5h, and 0.5ml of acetic anhydride at 0 h. After the completion of the reaction, cyclohexane was removed by concentration using a rotary evaporator at 45℃and then filtered 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 under vacuum at 20 ℃ for 8h, all over the course of the above procedure protected from light. 2.34g of ditriphenylsilane chromate was obtained, the yield was 91.6%, the melting point was determined to be 154 ℃, the elemental analysis result was C68.48%, H4.77%, and the calculated value was 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 using a rotary evaporator at 50℃and then filtered 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 under vacuum at 50 ℃ for 5h, all over the course of the above procedure protected from light. 5.94g of ditriphenylsilane chromate was obtained, the yield was 93.7%, the melting point was 156℃as determined, the elemental analysis result C68.46%, H4.79% and the calculated value 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 addition of 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 using a rotary evaporator at 50℃and then filtered 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 under vacuum at 50 ℃ for 5h, all over the course of the above procedure protected from light. 2.82g of ditriphenylsilane chromate was obtained, the yield was 89.0%, the melting point was found to be 153℃and the elemental analysis result C66.46%, H4.36% and the calculated value 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 under vacuum at 50 ℃ for 5h, all over the course of the above procedure protected from light. 8.83g of ditriphenylsilane chromate was obtained, the yield was 86.0%, the melting point was found to be 145℃and the elemental analysis result was found to be C65.99%, H4.90% and calculated as C68.12% and 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 yield the final product, all under the condition of avoiding light. 8.80g of ditriphenylsilane chromate is finally obtained, the yield is 94.8%, the melting point is measured to be 129 ℃, the elemental analysis result C is 65.40%, H4.50%, and the calculated value C is 68.12%, 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. The crude product was washed with water to neutrality, dried, and recrystallized with carbon tetrachloride to give ditriphenylsilane chromate as an orange solid, which was protected from light throughout the above operation to give ditriphenylsilane chromate 4.50g in 70.9% yield, measured at 152 ℃ melting point, elemental analysis results C61.38%, 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 of 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 measured to be 151 ℃, the elemental analysis result C65.27%, H4.62% and the calculated value C68.12% and 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 of 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 C66.41%, H4.74% and the calculated value C68.12% and H4.76% are determined.

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 preparation method of ditriphenylsilane chromate is characterized by comprising the steps of taking triphenylsilanol, triphenylchlorosilane and potassium dichromate as raw materials, taking glacial acetic acid and cyclohexane as solvents and acetic anhydride as water absorbent, reacting under the condition of avoiding light, filtering, distilling under reduced pressure to obtain a ditriphenylsilane chromate crude product, and washing and drying to obtain ditriphenylsilane chromate.

2. The preparation method of the triphenylchlorosilane-to-triphenylsilanol compound, which is characterized by comprising the steps of enabling a molar ratio of triphenylchlorosilane to triphenylsilanol to be 1:0.5-1.5, enabling a molar ratio of triphenylchlorosilane to potassium dichromate to be 1:0.1-1.1, enabling a volume ratio of glacial acetic acid to cyclohexane to be 1:0.2-1.2, and enabling a molar ratio of acetic anhydride to triphenylchlorosilane to be 1:0.2-4.5.

3. The preparation method of the aqueous solution of the acetic anhydride and the triphenylsilanol is characterized in that the molar ratio of the triphenylchlorosilane to the triphenylsilanol is 1:0.8-1.2, the molar 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, and 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 method according to claim 4, wherein the reaction temperature is 40-80 ℃ and the reaction time is 4-8 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 method according to claim 1, wherein the reduced pressure distillation is performed at 20 to 80 ℃.

8. The preparation method of claim 1, wherein the washing is performed sequentially by 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 8, wherein the water and cyclohexane are used in an amount of 1 to 3 times the volume of glacial acetic acid, 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.