阅读说明：本技术 一种乙硼烷的制备方法 (Preparation method of diborane ) 是由 廖仕学 康卫兵 李芳� 陆华文 段良鹏 于 2020-12-28 设计创作，主要内容包括：本发明提供了一种乙硼烷的制备方法,其解决了现有制备方法不合理,存在原料价格昂贵、产品提纯操作复杂、成本高、收率低、不适合工业化生产的技术问题,本发明的乙硼烷的制备方法,以氢化钠、硼酸三甲酯和三氯化硼为起始原料,以四氢呋喃为反应溶剂,经过缩合反应和复分解反应得到乙硼烷。本发明可广泛应用于乙硼烷制备技术领域。(The invention provides a preparation method of diborane, which solves the technical problems of unreasonable preparation method, high raw material price, complex product purification operation, high cost, low yield and unsuitability for industrial production. The method can be widely applied to the technical field of diborane preparation.)

1. A preparation method of diborane is characterized by comprising the following steps:

(1) condensation reaction: the method comprises the following steps of introducing nitrogen into sodium hydride as a starting material to displace air in a reaction kettle, adding tetrahydrofuran, cleaning mineral oil in the sodium hydride twice, dropwise adding trimethyl borate into a sodium hydride-tetrahydrofuran mixed material, controlling the temperature to be 68 ℃, carrying out condensation reaction, condensing fractions, completely refluxing into the reaction kettle, preserving heat for 5 hours to obtain sodium trimethoxyborohydride, and distilling excessive trimethyl borate, wherein a specific chemical reaction equation is as follows:

NaH+B(OCH₃)₃＝NaBH(OCH₃)₃；

(2) double decomposition reaction: adding a boron trichloride tetrahydrofuran solution into the tetrahydrofuran solution of sodium trimethylborohydride in the step (1), controlling the temperature and time, carrying out double decomposition reaction to obtain a diborane crude product, cooling by adopting a three-stage ultralow temperature emptying condenser, circulating the collected unreacted boron trichloride fraction to a reaction kettle for continuous reaction, collecting uncondensed gas to obtain a diborane finished product, wherein the specific chemical reaction equation is as follows:

NaBH(OCH₃)₃+2BCl₃＝6NaCl+6B(OCH₃)₃+B₂H₆。

2. the method for producing diborane according to claim 1, wherein in step (1), the condensation reaction is carried out after replacing the air in the reaction vessel with nitrogen gas for 2 to 3 times.

3. The method for preparing diborane according to claim 1, wherein in step (1), the mass ratio of sodium hydride to tetrahydrofuran is 1: (1-2).

4. The method for preparing diborane according to claim 1, wherein in step (2), the molar ratio of the sodium trimethoxyborohydride to the boron trichloride is 1: (0.4-0.8).

5. The method for producing diborane according to claim 1, wherein in step (2), the temperature of said metathesis reaction is 50 to 100 ℃.

6. The method for preparing diborane according to claim 1, wherein in step (2), the time for the metathesis reaction is 5 to 10 hours.

7. The method for preparing diborane according to claim 1, wherein after the metathesis reaction in step (2) is completed, the reaction solution is filtered, and the obtained filtrate is heated to remove the excess boron trichloride, and then the mother liquor is applied to step (1).

Technical Field

The invention relates to the technical field of diborane preparation, in particular to a preparation method of diborane.

Background

Diborane (B2H6) is used as a dopant for gaseous impurity source, ion implantation and boron doping oxidation diffusion in the electronic industry, is mainly used as a dopant in the production of a P-type semiconductor chip, and is widely applied to industries such as semiconductor integrated circuits, liquid crystal displays, semiconductor light-emitting devices, solar cells and the like; because of high-value energy, the fuel can also be used as a high-energy fuel for rockets and missiles; due to the electron-deficient characteristic, the compound can be used for producing various complexes with Lewis base, such as boron-tetrahydrofuran and various amine boranes, the substances are used for preparing selective reducing agents commonly used in organic synthesis, and the compound has wide application in the fields of organic synthesis, metal welding, pharmacy and fine ceramics.

There are a number of reports on the preparation of diborane, most typically the reaction of boron trifluoride with sodium borohydride in ether solvents such as diethyl ether, diglyme and the like.

Patent US2544472 proposes to use metal hydride to react with boron trifluoride, which is beneficial to increase the reaction speed in organic solvent, such as ethylene glycol, methyl ether, butyl ether, etc. The reaction is as follows:

6MeH+2BX₃→B₂H₆+6MeX

6MeH+8BX₃→B₂H₆+6MeBX₄

due to the physicochemical property of boron trifluoride and the complexation between diborane and an ether solvent, boron trifluoride doped in a diborane product and the complex are extremely difficult to separate, and a great deal of resources are consumed for product purification.

Patent US2543511 proposes the use of a metal borohydride in reaction with a boron halide, the reaction being as follows:

3NaBH(OCH₃)₃+4B(BF₃·C₂H₅OC₂H₅→3B(OCH₃)₃+3NaBF₄+4B₂H₆+4(C₂H₅)_2O

the diborane produced by the method is easy to decompose.

Patent US3142538 proposes the use of metal hydrides to react with boron halides, among which mention is made of NaBH₄And BCl₃In a tetraglyme solvent, the reaction is as follows:

3MBH₄+BX₃→2B₂H₆+3MX

in practical commercial application, sodium borohydride is obtained by a Schlesinger method, namely sodium hydride and trimethyl borate are hydrolyzed after high-temperature reaction, and are extracted and concentrated by isopropylamine, wherein the sodium borohydride is a high-value product, and the methods have the problems of long working procedures and high cost.

Disclosure of Invention

The invention aims to solve the defects in the prior art and provides a preparation method of diborane

Therefore, the invention provides a preparation method of diborane, which comprises the following steps:

(1) condensation reaction: the method comprises the following steps of introducing nitrogen into sodium hydride as a starting material to displace air in a reaction kettle, adding tetrahydrofuran, cleaning mineral oil in the sodium hydride twice, dropwise adding trimethyl borate into a sodium hydride-tetrahydrofuran mixed material, controlling the temperature to be 68 ℃, carrying out condensation reaction, condensing fractions, completely refluxing into the reaction kettle, preserving heat for 5 hours to obtain sodium trimethoxyborohydride, and distilling excessive trimethyl borate, wherein a specific chemical reaction equation is as follows:

NaH+B(OCH₃)₃＝NaBH(OCH₃)₃；

(2) double decomposition reaction: adding a boron trichloride tetrahydrofuran solution into the tetrahydrofuran solution of sodium trimethylborohydride in the step (1), controlling the temperature and time, carrying out double decomposition reaction to obtain a diborane crude product, cooling by adopting a three-stage ultralow temperature emptying condenser, circulating the collected unreacted boron trichloride fraction to a reaction kettle for continuous reaction, collecting uncondensed gas to obtain a diborane finished product, wherein the specific chemical reaction equation is as follows:

NaBH(OCH₃)₃+2BCl₃＝6NaCl+6B(OCH₃)₃+B₂H₆。

preferably, in the step (1), the condensation reaction is performed after replacing 2 to 3 times with nitrogen and removing air in the reaction kettle.

Preferably, in the step (1), the mass ratio of sodium hydride to tetrahydrofuran is 1: (1-2).

Preferably, in the step (2), the molar ratio of sodium trimethoxyborohydride to boron trichloride is 1: (0.4-0.8).

Preferably, in the step (2), the temperature of the double decomposition reaction is 50 to 100 ℃.

Preferably, in the step (2), the time of the double decomposition reaction is 5-10 h.

Preferably, after the double decomposition reaction in the step (2) is finished, the reaction liquid is filtered, and the obtained filtrate is heated to remove the excessive boron trichloride, and then the mother liquid is applied to the step (1).

The invention has the beneficial effects that:

(1) the invention adopts a brand new synthetic route to prepare the diborane, takes sodium hydride, trimethyl borate and boron trichloride as initial raw materials and tetrahydrofuran as a reaction solvent, and obtains the diborane through condensation reaction and double decomposition reaction, and the total yield is up to 96.64%. Sodium hydride is used as a raw material, and a product is prepared through condensation and double decomposition reactions, so that the raw material is low in price, high in safety and simple in production process. Compared with other synthesis methods, the method has the advantages that low-value sodium hydride is used for replacing sodium borohydride, and tetrahydrofuran is added, so that on one hand, the tetrahydrofuran is used for cleaning mineral oil in the sodium hydride, on the other hand, the tetrahydrofuran is used as a reaction solvent, the yield of double decomposition reaction is further improved, and the yield of diborane is further improved.

(2) According to the invention, boron trichloride is used to replace boron trifluoride in the prior art, the diborane crude product obtained by the method contains impurities such as tetrahydrofuran, trimethyl borate and boron trichloride, three-stage emptying condensers are connected in series by utilizing the difference of boiling points of the impurities, the obtained diborane crude product is condensed and recovered, and the recovered tetrahydrofuran, trimethyl borate, boron trichloride and trace diborane are subjected to cyclic reversion decomposition reaction, so that the purification of diborane can be completed without further processing. Not only can save cost and simplify purification process, but also the total yield of the diborane still reaches a higher level.

(3) The mother liquor obtained after the filtrate obtained after the double decomposition reaction is heated to remove the excessive boron trichloride is recycled to the condensation reaction, so that the raw material cost in other processes is saved, the economic benefit is obviously improved, and the method is suitable for industrial production.

Detailed Description

The invention will be better understood from the following examples. However, those skilled in the art will readily appreciate that the description of the embodiments is only for illustrating the present invention and should not be taken as limiting the invention as described in the claims.

Example 1

A preparation method of diborane specifically comprises the following steps:

(1) condensation reaction: adding 40g of sodium hydride into a 1000mL four-neck flask, introducing nitrogen, replacing air in the flask with the nitrogen for 2-3 times, adding 60g of tetrahydrofuran, stirring, standing for 1h, pressing the tetrahydrofuran out of the flask with the nitrogen, and repeating the steps once. 200g of tetrahydrofuran is taken and added into a flask, the oil bath is slowly heated to 68 ℃, 109.12g of trimethyl borate is slowly dripped, the dripping is completed within 1.5h, the total reflux and heat preservation are carried out for 5h, the sodium hydride solution is changed from silver white to grey white, 125.93g of sodium trimethoxyborohydride is obtained, and the yield is 99.12 percent according to the calculation of sodium hydride.

(2) Double decomposition reaction: controlling the temperature of the mixed solution of trimethoxy sodium borohydride and tetrahydrofuran to be 70 ℃, slowly dripping 384.48g of 20% boron trichloride tetrahydrofuran solution, finishing dripping within 1.5h, and carrying out total reflux and heat preservation for 7h to obtain a crude diborane product. And (3) cooling by adopting a three-stage ultralow temperature emptying condenser, controlling the cooling temperature to be below 20 ℃ below zero, circulating the collected unreacted boron trichloride fraction to the reaction kettle for continuous reaction, collecting uncondensed gas to obtain 4.46g of diborane finished product, and calculating the yield by using sodium trimethoxyborohydride to be 97.50%.

(3) And (3) after the double decomposition reaction is finished, filtering the reaction liquid, and heating the obtained filtrate to remove the excessive boron trichloride so as to apply the mother liquid in the step (1).

The total yield of the reaction for preparing diborane is 96.64 percent.

Example 2

A preparation method of diborane specifically comprises the following steps:

(1) condensation reaction: adding 40g of sodium hydride into a 1000mL four-neck flask, replacing with nitrogen for 2-3 times, slowly heating to 68 ℃, slowly dropwise adding 109.12g of trimethyl borate, completing dropwise adding for 1.5 hours, carrying out total reflux and heat preservation for 5 hours, changing a sodium hydride solution from silver white to off-white to obtain 121.40g of sodium trimethoxyborohydride, wherein the yield is 95.55% calculated according to the sodium hydride.

(2) Double decomposition reaction: controlling the temperature of the mixed solution of trimethoxy sodium borohydride and tetrahydrofuran to be 70 ℃, slowly dripping 335.93g of 20% boron trichloride tetrahydrofuran solution, finishing dripping within 1.5h, and carrying out total reflux and heat preservation for 7h to obtain a crude diborane product. Cooling by a three-stage ultralow temperature emptying condenser, controlling the cooling temperature to be below 20 ℃ below zero, circulating the collected unreacted boron trichloride fraction to a reaction kettle for continuous reaction, collecting uncondensed gas to obtain 2.31g of diborane finished product, calculating the yield according to sodium trimethoxyborohydride of 52.39%,

(3) and (3) after the double decomposition reaction is finished, filtering the reaction liquid, and heating the obtained filtrate to remove the excessive boron trichloride so as to apply the mother liquid in the step (1).

The total yield of the reaction for preparing the diborane is 50.06 percent.

Example 3

A preparation method of diborane specifically comprises the following steps:

(1) condensation reaction: adding 40g of sodium hydride into a 1000mL four-neck flask, replacing for 2-3 times with nitrogen, adding 120g of tetrahydrofuran, stirring, standing for 1h, pressing the tetrahydrofuran out of the flask with nitrogen, and repeating once. 200g of tetrahydrofuran is added into a flask, the temperature of an oil bath is slowly raised to 68 ℃, 109.12g of trimethyl borate are slowly dripped, the dripping is completed within 1.5h, the total reflux and heat preservation are carried out for 5h, the sodium hydride solution is changed from silver white to grey white, 123.68g of sodium trimethoxyborohydride is obtained, and the yield is 97.35 percent according to the calculation of sodium hydride.

(2) Double decomposition reaction: controlling the temperature of the mixed solution of trimethoxy sodium borohydride and tetrahydrofuran to be 70 ℃, slowly dripping 342.25g of 20% boron trichloride tetrahydrofuran solution, finishing dripping within 1.5h, and carrying out total reflux and heat preservation for 7h to obtain a crude diborane product. And (3) cooling by adopting a three-stage ultralow temperature emptying condenser, controlling the cooling temperature to be below 20 ℃ below zero, circulating the collected unreacted boron trichloride fraction to the reaction kettle for continuous reaction, collecting uncondensed gas to obtain 4.02g of diborane finished product, and obtaining the yield of 89.45% according to the calculation of sodium trimethoxyborohydride.

(3) And (3) after the double decomposition reaction is finished, filtering the reaction liquid, and heating the obtained filtrate to remove the excessive boron trichloride so as to apply the mother liquid in the step (1).

The total yield of the reaction for preparing diborane is 87.08 percent.

Example 4

A preparation method of diborane specifically comprises the following steps:

(1) condensation reaction: adding 40g of sodium hydride into a 1000mL four-neck flask, replacing for 2-3 times with nitrogen, adding 60g of tetrahydrofuran, stirring, standing for 1h, pressing the tetrahydrofuran out of the flask with nitrogen, and repeating once. 200g of tetrahydrofuran is taken and added into a flask, the oil bath is slowly heated to 65 ℃, 109.12g of trimethyl borate is slowly dripped, the dripping is completed within 1.5h, the total reflux and heat preservation are carried out for 5h, the sodium hydride solution is changed from silver white to grey white, 125.80g of sodium trimethoxyborohydride is obtained, and the yield is 98.89% according to the calculation of sodium hydride.

(2) Double decomposition reaction: controlling the temperature of the mixed solution of trimethoxy sodium borohydride and tetrahydrofuran to be 70 ℃, slowly dripping 579.45g of 20% boron trichloride tetrahydrofuran solution, finishing dripping within 1.5h, and carrying out total reflux and heat preservation for 7h to obtain a crude diborane product. Cooling by a three-stage ultralow temperature emptying condenser, controlling the cooling temperature to be below 20 ℃ below zero, circulating the collected unreacted boron trichloride fraction to a reaction kettle for continuous reaction, collecting uncondensed gas to obtain 4.12g of diborane finished product, calculating the yield by using sodium trimethoxyborohydride to be 90.25 percent,

(3) and (3) after the double decomposition reaction is finished, filtering the reaction liquid, and heating the obtained filtrate to remove the excessive boron trichloride so as to apply the mother liquid in the step (1).

The total yield of the reaction for preparing the diborane is 89.25 percent.

Example 5

A preparation method of diborane specifically comprises the following steps:

(1) condensation reaction: adding 40g of sodium hydride into a 1000mL four-neck flask, replacing for 2-3 times with nitrogen, adding 60g of tetrahydrofuran, stirring, standing for 1h, pressing the tetrahydrofuran out of the flask with nitrogen, and repeating once. 200g of tetrahydrofuran is taken and added into a flask, the oil bath is slowly heated to 68 ℃, 109.12g of trimethyl borate is slowly dripped, the dripping is completed within 1.5h, the total reflux and heat preservation are carried out for 5h, the sodium hydride solution is changed from silver white to grey white, 125.80g of sodium trimethoxyborohydride is obtained, and the yield is 99.02 percent according to the calculation of sodium hydride.

(2) Double decomposition reaction: controlling the temperature of the mixed solution of trimethoxy sodium borohydride and tetrahydrofuran to be 120 ℃, slowly dripping 348.12g of 20% boron trichloride tetrahydrofuran solution, finishing dripping within 1.5h, and carrying out total reflux and heat preservation for 7h to obtain a crude diborane product. And (3) cooling by adopting a three-stage ultralow temperature emptying condenser, controlling the cooling temperature to be below 20 ℃ below zero, circulating the collected unreacted boron trichloride fraction to the reaction kettle for continuous reaction, and collecting uncondensed gas to obtain 3.29g of diborane finished product, wherein the yield is 72.14% according to the calculation of sodium trimethoxyborohydride.

(3) And (3) after the double decomposition reaction is finished, filtering the reaction liquid, and heating the obtained filtrate to remove the excessive boron trichloride so as to apply the mother liquid in the step (1).

The total yield of the reaction for preparing diborane is 71.43 percent.

Example 6

A preparation method of diborane specifically comprises the following steps:

(1) condensation reaction: adding 40g of sodium hydride into a 1000mL four-neck flask, replacing for 2-3 times with nitrogen, adding 60g of tetrahydrofuran, stirring, standing for 1h, pressing the tetrahydrofuran out of the flask with nitrogen, and repeating once. 200g of tetrahydrofuran is added into a flask, the temperature of an oil bath is slowly raised to 68 ℃, 125.87g of trimethyl borate are slowly dripped, the dripping is completed within 1.5h, the total reflux and heat preservation are carried out for 5h, the sodium hydride solution is changed from silver white to grey white, 125.87g of sodium trimethoxyborohydride is obtained, and the yield is 99.07% according to the calculation of sodium hydride.

(2) Double decomposition reaction: controlling the temperature of the mixed solution of trimethoxy sodium borohydride and tetrahydrofuran to be 70 ℃, slowly dripping 348.30g of 20% boron trichloride tetrahydrofuran solution, finishing dripping within 1.5h, and carrying out total reflux and heat preservation for 7h to obtain a crude diborane product. And (3) cooling by adopting a three-stage ultralow temperature emptying condenser, controlling the cooling temperature to be below 20 ℃ below zero, and collecting uncondensed gas to obtain 2.30g of diborane finished product, wherein the yield is 50.26% according to the calculation of sodium trimethoxyborohydride.

(3) And (3) after the double decomposition reaction is finished, filtering the reaction liquid, and heating the obtained filtrate to remove the excessive boron trichloride so as to apply the mother liquid in the step (1).

The total yield of the reaction for preparing the diborane is 49.79 percent.

The following further analysis of the experimental data and yield statistics in the above examples is summarized as follows:

(1) the data parameters and results for the experiments of examples 1-6 are summarized below in Table 1:

TABLE 1 EXAMPLES 1-6 summary of data parameters and results

As can be seen from the data results in the summary tables of the experimental parameters and results of examples 1 to 6, in the condensation reaction in step (1), firstly, tetrahydrofuran is added, and secondly, the mass ratio of sodium hydride to tetrahydrofuran is increased; in the double decomposition reaction in the step (2), factors such as the molar ratio of the sodium trimethoxyborohydride to the boron trichloride, the double decomposition reaction temperature, the double decomposition reaction time and the like respectively have certain influence on the yield of the double decomposition reaction, wherein the influence of the addition of tetrahydrofuran in the condensation reaction on the yield of the double decomposition reaction is the largest, and the influence of the double decomposition reaction time on the yield of the double decomposition reaction is larger, so that the full double decomposition reaction, the addition of tetrahydrofuran in the condensation reaction and the double decomposition reaction time are fully influenced, and the influence on the total reaction yield is finally caused.

(2) Examples 7-14 since the overall reaction steps and reaction parameters are similar to those of example 1, except for individual parameter changes, the specific experimental steps are not detailed one by one, and the parameters and results of the experimental data for examples 1 and 7-14 are summarized as follows, as shown in table 2:

TABLE 2 summary of parameters and results of the experimental data for example 1 and examples 7-14

From the data and results in the summary table of the experimental data parameters and results of examples 1 and 7 to 14, it can be seen that in the condensation reaction of step (1), the mass ratio of (i) sodium hydride to tetrahydrofuran is 1: (1-2); in the double decomposition reaction in the step (2), the molar ratio of the trimethoxy sodium borohydride to the boron trichloride is 1: (0.4-0.8), when the temperature of the double decomposition reaction is 50-100 ℃, the time of the double decomposition reaction is 5-10 h and the like, the preparation method of the diborane with high yield can be realized, wherein the combination of experimental parameters in the embodiment 1 is excellent, and the total yield of the diborane reaches 96.64%.

The invention adopts a brand new synthetic route to prepare the diborane, takes sodium hydride, trimethyl borate and boron trichloride as initial raw materials and tetrahydrofuran as a reaction solvent, and obtains the diborane through condensation reaction and double decomposition reaction, and the total yield is up to 96.64%. Sodium hydride is used as a raw material, and a product is prepared through condensation and double decomposition reactions, so that the raw material is low in price, high in safety and simple in production process. Compared with other synthesis methods, the method has the advantages that low-value sodium hydride is used for replacing sodium borohydride, and tetrahydrofuran is added, so that on one hand, the tetrahydrofuran is used for cleaning mineral oil in the sodium hydride, on the other hand, the tetrahydrofuran is used as a reaction solvent, the yield of double decomposition reaction is further improved, and the yield of diborane is further improved.

According to the invention, boron trichloride is used to replace boron trifluoride in the prior art, the diborane crude product obtained by the method contains impurities such as tetrahydrofuran, trimethyl borate and boron trichloride, three-stage emptying condensers are connected in series by utilizing the difference of boiling points of the impurities, the obtained diborane crude product is condensed and recovered, and the recovered tetrahydrofuran, trimethyl borate, boron trichloride and trace diborane are subjected to cyclic reversion decomposition reaction, so that the purification of diborane can be completed without further processing. The preparation method of the invention not only can save cost and simplify purification process, but also can ensure that the total yield of the diborane still reaches a higher level.

In addition, the mother liquor obtained after the filtrate obtained after the double decomposition reaction is heated to remove the excessive boron trichloride is recycled to the condensation reaction, so that the raw material cost in other processes is saved, the economic benefit is obviously improved, and the method is suitable for industrial production.

In conclusion, the preparation method of diborane has the advantages of simple process, few types of raw materials required by production, cheap and easily available raw materials, high safety, capability of recycling part of raw materials, simple purification process, high product yield and low cost, and is suitable for industrial production.

However, the above description is only exemplary of the present invention, and the scope of the present invention should not be limited thereby, and the replacement of the equivalent components or the equivalent changes and modifications made according to the protection scope of the present invention should be covered by the claims of the present invention.