CN114516887A - Preparation method of triisopropyl borate - Google Patents

Abstract

The invention discloses a method for preparing triisopropyl borate, which comprises the steps of taking trimethyl borate as a starting material, carrying out ester exchange reaction with isopropanol under the catalysis of acid, and carrying out post-treatment by simple rectification separation to obtain the triisopropyl borate with high purity and high yield. The method has mild reaction conditions, simple system after the reaction is finished and few components, and only simple rectification equipment is used for continuous rectification once, thereby greatly reducing the requirements on the equipment, simplifying the process operation, improving the production safety, greatly shortening the production period, improving the production efficiency and being particularly suitable for large-scale industrial production.

Description

A kind of preparation method of triisopropyl borate

technical field

The invention relates to a preparation method of triisopropyl borate, and belongs to the technical field of organic synthesis.

Background technique

Triisopropyl borate is a colorless and transparent liquid. It is mainly used as a solvent and a semiconductor boron diffusion source. It is a very important organic boron fine chemical raw material.

At present, the production method of triisopropyl borate is to use boric anhydride or boric acid as the starting material, react with isopropanol, and obtain high-purity triisopropyl borate through complex binary batch rectification and ternary batch rectification. . For example, the paper "Improvement of the Synthesis Method of Triisopropyl Borate" published in "Chemical Reagent" discloses a method for synthesizing triisopropyl borate by using calcium hydride as a dehydrating agent and using boron anhydride and isopropanol as raw materials.

Chinese patent CN201210009269.7 discloses a production method of high-purity triisopropyl borate. The specific method is to add reactants boron anhydride, water, isopropanol and cyclohexane into the tower kettle, and cyclohexane is used as an azeotrope , boric anhydride and water react at a pressure of 0.1 MPa and a temperature of 80 to 100 °C to generate boric acid, and the boric acid is subjected to reactive distillation with isopropanol and cyclohexane to obtain a crude product containing triisopropyl borate, The crude triisopropyl borate is continuously subjected to binary batch rectification and ternary batch rectification in the column still, to separate cyclohexane and isopropanol, reflux at the top of the column, separate moisture, and separate cyclohexane in a separation tank The mixture with isopropanol is sent to the mixture recovery box, and then re-enters the tower kettle for rectification reaction, and the triisopropyl borate is separated into the finished product recovery box to collect the finished product.

Chinese patent CN200710179716.2 also discloses a production method of high-purity triisopropyl borate, specifically using boric acid and isopropanol as raw materials, and a mixture of benzene, toluene and cyclohexane as an azeotrope. Reactive rectification is carried out in the device, and then water and azeotrope are separated by binary batch rectification, and then isopropanol is separated by ternary batch azeotrope rectification. The patent adopts the reactive distillation technology of adding azeotrope to separate the by-product water from the reaction system, which improves the conversion rate of the reaction, and solves the shortcomings of inconvenient operation of calcium hydride dehydrating agent, difficult solid waste treatment, and high operational risk; The crude product is refined by the new batch rectification technology with storage tank at the top of the tower, and high-purity triisopropyl borate can be obtained, and the recovered isopropanol and azeotrope can be recycled.

As can be seen from the above prior art, the preparation of triisopropyl borate at present all use boric anhydride or boric acid as the starting material, and after the completion of the reaction with isopropanol, it needs to pass through relatively complicated binary batch rectification and ternary rectification. Only batch distillation can obtain high-purity triisopropyl borate, so the required equipment and equipment are complicated, and the process operation is cumbersome; and in the subsequent separation process, flammable and explosive hazardous chemicals such as benzene and cyclohexane will be involved. Therefore, the safety of the production process is poor. Due to the complicated operation, the production cycle of the prior art is relatively long, and it generally takes 24 to 48 hours to complete one cycle. In addition, water will be generated in the reaction process. If the water is not removed in time or not completely, the reaction will be incomplete, and mono- and di-substituted products will easily appear, which will affect the purity of the product.

How to solve these problems existing in the prior art, simplify the production process of triisopropyl borate, reduce the requirements for equipment, shorten the production cycle, and improve the safety, it is a technical problem to be solved by those skilled in the art.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a preparation method of triisopropyl borate, using trimethyl borate as starting material, under acid catalysis, carrying out transesterification reaction with isopropanol, and after-treatment is only separated by simple rectification Triisopropyl borate with high purity and high yield can be obtained. The reaction conditions of the invention are mild, the requirements for equipment are greatly reduced, the process operation is simplified, the production safety is improved, the production cycle is greatly shortened, and the invention has great advantages in large-scale industrial production.

The invention provides a preparation method of triisopropyl borate, which is characterized in that, under the condition of acid catalysis, trimethyl borate shown in formula (I) and isopropanol undergo transesterification to obtain formula (II) ) triisopropyl borate

According to a specific but non-limiting embodiment of the present invention, the preparation method includes: under the protection of an inert gas, adding isopropanol and a catalyst acid to the reaction vessel, controlling the temperature at 30-70° C., slowly adding the formula The trimethyl borate shown in (I) is kept at 30 to 70° C. for 3 to 4 hours, and after completion of the reaction, separation and purification by ordinary rectification is performed to obtain triisopropyl borate shown in formula (II).

According to a specific but non-limiting embodiment of the present invention, wherein, the rectification temperature is controlled at 20-60° C. and the pressure is carried out under the conditions of -0.1--0.07mpa, and triisopropyl borate is obtained by rectification.

According to a specific but non-limiting embodiment of the present invention, the post-treatment adopts one continuous rectification.

According to a specific but non-limiting embodiment of the present invention, wherein, the rectification is accomplished using a common rectification column.

According to a specific but non-limiting embodiment of the present invention, the excess isopropanol is recovered by rectification, and is directly applied to the next reaction without treatment.

According to a specific but non-limiting embodiment of the present invention, the molar ratio of isopropanol to trimethyl borate is 3-5:1.

According to a specific but non-limiting embodiment of the present invention, wherein the catalyst acid is selected from at least one of p-toluenesulfonic acid, methanesulfonic acid, concentrated sulfuric acid, sodium hydrogen sulfate, phosphoric acid and concentrated hydrochloric acid.

According to a specific but non-limiting embodiment of the present invention, the molar ratio of catalyst acid to trimethyl borate is 0.02˜1:1.

According to a specific but non-limiting embodiment of the present invention, the molar ratio of isopropanol to trimethyl borate is 4.3:1; the molar ratio of catalyst acid to trimethyl borate is 0.03:1.

The beneficial effects of the present invention are mainly reflected in:

1. the present invention uses trimethyl borate to prepare triisopropyl borate by transesterification with isopropanol under acid catalysis instead, the system after the reaction is complete is simple, the components are few, and only simple distillation equipment is used to pass through a continuous process. High-purity and high-yield products can be obtained by rectification, which greatly simplifies the process operation, reduces the requirements for equipment, and is especially suitable for large-scale industrial production.

2. In the post-processing and separation process of the present invention, in addition to the product, there are only the generated methanol and the remaining trace amount of isopropanol, and no inflammable and explosive dangerous goods are involved, so the safety degree is high.

3. The method of the present invention is simple, and one production cycle time is only 16-20 hours, compared with 24-48 hours per cycle in the prior art, the time is greatly shortened, and the production efficiency is improved.

4. The present invention avoids the problems of water generation and water removal through transesterification, and easily obtains high-purity products.

Description of drawings

Fig. 1 is the nuclear magnetic spectrum of triisopropyl borate prepared in Example 1 of the present invention.

Detailed ways

Specific embodiments are provided below to further illustrate the present invention, but the present invention is not limited to the following embodiments.

The invention provides a preparation method of triisopropyl borate, which is suitable for industrial production, comprising: under the condition of acid catalysis, transesterification of trimethyl borate shown in formula (I) with isopropanol to obtain formula Triisopropyl borate shown in (II). Reaction formula of the present invention is as follows:

The reaction mechanism of the present invention is as follows:

An oxygen atom on trimethyl borate first combines with a hydrogen ion to form an oxonium ion, and then isopropanol conducts a nucleophilic attack on the boron atom. At the same time, a methanol molecule is lost, completing the substitution of isopropoxy to methoxy. reaction. In the same way, the other two methoxy groups are substituted by isopropoxy groups accordingly, and finally triisopropyl borate is obtained.

The system after the reaction of the present invention is simple, and the components are only triisopropyl borate (boiling point 139° C.), generated methanol (boiling point 65.4° C.) and remaining isopropanol (boiling point 82° C.). Because the boiling points of the three are quite different, they can be separated by simple rectification, which greatly reduces the requirements for equipment and simplifies the original cumbersome process operation.

Specifically, the preparation method of the present invention comprises: under the protection of an inert gas, adding isopropanol and a catalyst acid to a reaction vessel, controlling the temperature at 30-70° C., slowly adding trimethyl borate represented by formula (I), and The temperature is kept at 30-70° C. for 3-4 hours, and after completion of the reaction, separation and purification by ordinary rectification is performed to obtain triisopropyl borate represented by formula (II).

Wherein, the rectification is carried out under the control temperature of 20～60℃ and the pressure of -0.1～-0.07mpa, and triisopropyl borate is obtained by rectification.

Isopropanol is both a reactant and a solvent. The molar ratio of isopropanol to trimethyl borate is usually 3-5:1; preferably 4.3:1.

The catalyst acid may be selected from at least one of p-toluenesulfonic acid, methanesulfonic acid, concentrated sulfuric acid, sodium hydrogen sulfate, phosphoric acid, and concentrated hydrochloric acid, and p-toluenesulfonic acid is preferably used. The molar ratio of catalyst acid to trimethyl borate is usually 0.02-1:1; preferably 0.03:1. The catalyst acid has an important influence on the reaction, which can make the reaction complete the tri-substitution smoothly, and ensure that the main product obtained is the tri-substitute instead of the mono- and di-substitutes.

It is found through experiments that when the molar ratio of catalyst acid and trimethyl borate reaches 0.03:1, and the molar ratio of isopropanol to trimethyl borate reaches 4.3:1, the conversion rate of the reaction just reaches 100%.

Because the system after the reaction is simple and the components are few, the post-treatment of the present invention can be separated after one continuous rectification to obtain high-purity triisopropyl borate, without the need for multiple rectifications, and excessive isopropanol It can be recycled through rectification, and can be directly applied to the next reaction without treatment. In large-scale industrial production, the present invention can complete the separation and purification of products by using a common rectifying tower, has very simple requirements on equipment and devices, and is extremely simple and convenient in process operation.

Except for the product triisopropyl borate, the reacted system of the present invention only contains the generated methanol and a trace amount of unreacted isopropanol, and does not involve flammable and explosive dangerous goods such as benzene, toluene and cyclohexane. The production process Security is good.

In the present invention, trimethyl borate and isopropanol are used to prepare triisopropyl borate through transesterification, and water is not generated during the reaction, thereby avoiding the problem of water removal and the generation of impurities such as mono- and di-substitutes. The product has high purity and high yield. Experiments show that when the method of the invention is used to prepare triisopropyl borate, the yield can reach over 90% and the purity can reach over 99.5%. Usually, a production cycle of the present invention only takes 16-20 hours, while a production cycle of the prior art requires 24-48 hours. The present invention significantly shortens the production time and improves the production efficiency.

The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

The experimental methods used in the above and the following examples are conventional methods unless otherwise specified.

The materials, reagents, etc. used in the above and the following examples can be obtained from commercial sources unless otherwise specified.

Example 1

Under nitrogen protection, 500 g of isopropanol and 10 g of p-toluenesulfonic acid were added to a 1L four-neck flask, the temperature was raised to 55° C., and 200 g of trimethyl borate was slowly added. After the addition was completed, the temperature was kept at 50° C. for 3.5 hours, and the sample was taken to the gas phase. The trimethyl borate was completely converted to triisopropyl borate, and the reaction was completed. The temperature is controlled at 40～50℃, and the pressure is at -0.1～-0.07mpa, and 333.0 g of triisopropyl borate is obtained by ordinary rectification, the yield is 92%, and the GC purity is 99.5%. And recover isopropanol by rectification, and the recovered isopropanol is directly applied to the next reaction. Fig. 1 is the nuclear magnetic spectrum of triisopropyl borate prepared in Example 1.

Example 2

Under nitrogen protection, to a 1L four-necked flask, add 600g of isopropanol (part of which is the reclaimed isopropanol in Example 1), 10g of p-toluenesulfonic acid, be warming up to 60°C, and slowly add 200g of trimethyl borate. After the addition was completed, the temperature was kept at 60° C. for 3.5 hours, and the sample was taken to the gas phase. The trimethyl borate was completely converted to triisopropyl borate, and the reaction was completed. The temperature is controlled at 40～50℃, and the pressure is -0.1～-0.07mpa, and 334.1 g of triisopropyl borate is obtained by ordinary rectification, the yield is 92.3%, and the GC purity is 99.6%. And recover isopropanol by rectification, and the recovered isopropanol is directly applied to the next reaction.

Example 3

Industrial scale-up preparation

Under nitrogen protection, 500Kg of isopropanol and 10Kg of p-toluenesulfonic acid were added to the 1000L reactor, the temperature was raised to 55°C, and 200Kg of trimethyl borate was slowly added. After the addition was completed, the temperature was kept at 50° C. for 3.5 h, and the sample was taken for gas phase delivery. The trimethyl borate was completely converted to triisopropyl borate, and the reaction was completed. Through an ordinary 5-meter-high rectifying tower, the temperature is controlled at 40-50°C, and the pressure is -0.1--0.07mpa, and 336.0Kg of triisopropyl borate is obtained by rectification, the yield is 92.8%, and the GC purity is 99.6%. And recover isopropanol by rectification, and the recovered isopropanol is directly applied to the next reaction.

The above are only specific application examples of the present invention, and do not constitute any limitation to the protection scope of the present invention. All technical solutions formed by equivalent transformation or equivalent replacement fall within the protection scope of the present invention.

Claims (10)

1. The preparation method of triisopropyl borate is characterized in that trimethyl borate shown in formula (I) and isopropanol are subjected to transesterification reaction under the acid catalysis condition to obtain triisopropyl borate shown in formula (II)

2. The production method according to claim 1, comprising: under the protection of inert gas, adding isopropanol and catalyst acid into a reaction container, controlling the temperature at 30-70 ℃, slowly adding trimethyl borate shown in the formula (I), preserving heat at 30-70 ℃ for 3-4 hours, and after the reaction is finished, separating and purifying through common rectification to obtain triisopropyl borate shown in the formula (II).

3. The production process according to claim 2, wherein the rectification is carried out at a temperature of 20 to 60 ℃ and a pressure of-0.1 to-0.07 mpa to obtain triisopropyl borate by rectification.

4. The production process according to any one of claims 1 to 3, wherein the post-treatment employs a single continuous rectification.

5. The production method according to any one of claims 1 to 3, wherein the rectification is performed using one common rectification column.

6. The production process according to any one of claims 1 to 3, wherein the excess isopropyl alcohol is recovered by rectification without being disposed of directly for the next reaction.

7. The production method according to any one of claims 1 to 3, wherein the molar ratio of isopropanol to trimethyl borate is 3 to 5: 1.

8. the production method according to any one of claims 1 to 3, wherein the catalyst acid is at least one selected from the group consisting of p-toluenesulfonic acid, methanesulfonic acid, concentrated sulfuric acid, sodium hydrogensulfate, phosphoric acid and concentrated hydrochloric acid.

9. The production method according to any one of claims 1 to 3, wherein the molar ratio of the catalyst acid to trimethyl borate is 0.02 to 1: 1.

10. the production method according to claim 3, wherein the molar ratio of isopropanol to trimethyl borate is 4.3: 1; the molar ratio of the catalyst acid to trimethyl borate is 0.03: 1.

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