阅读说明：本技术 一种制备2,6-二氟苯腈的方法 (Method for preparing 2, 6-difluorobenzonitrile ) 是由 席亚男 张俊 于 2021-08-03 设计创作，主要内容包括：本发明公开了一种制备2,6-二氟苯腈的方法,包括以下步骤：S1：配置原料液：配置2,6-二氯苯腈原料液备用；S2：装填催化剂；将固体氟反应催化剂和填料装填至反应器中备用；S3：氟化反应：用柱塞泵将原料液抽入固定床反应器中,并同时通入氟气进行氟化反应,反应液流入到接收釜中；S4：精馏产品：将反应液进行精馏处理,得到2,6-二氟苯腈。本发明提供的一种制备2,6-二氟苯腈的方法,采用固定床反应器的方法生产2,6-二氟苯腈,反应条件可控,所装填的固体氟催化剂寿命高,催化能力强,一次装填可长时间使用,大大降低了催化剂的成本。本方法得到的产品纯度＞99％,收率＞95％,与其他工艺相比均有较高竞争力。(The invention discloses a method for preparing 2, 6-difluorobenzonitrile, which comprises the following steps: s1: preparing a raw material liquid: preparing a 2, 6-dichlorobenzonitrile raw material liquid for later use; s2: filling a catalyst; filling a solid fluorine reaction catalyst and a filler into a reactor for later use; s3: fluorination reaction: pumping the raw material liquid into a fixed bed reactor by using a plunger pump, introducing fluorine gas for fluorination reaction at the same time, and allowing the reaction liquid to flow into a receiving kettle; s4: and (3) rectification products: rectifying the reaction liquid to obtain the 2, 6-difluorobenzonitrile. According to the method for preparing the 2, 6-difluorobenzonitrile, provided by the invention, the 2, 6-difluorobenzonitrile is produced by adopting a fixed bed reactor method, the reaction condition is controllable, the service life of the filled solid fluorine catalyst is long, the catalytic capability is strong, the catalyst can be used for a long time after being filled once, and the cost of the catalyst is greatly reduced. The purity of the product obtained by the method is more than 99 percent, the yield is more than 95 percent, and the method has higher competitiveness compared with other processes.)

1. A method for preparing 2, 6-difluorobenzonitrile is characterized in that: the invention provides a method for preparing 2, 6-difluorobenzonitrile by a fixed bed reactor method, which comprises the following operation steps:

s1: preparing a raw material liquid: adding a solvent into the fully dried reaction kettle, then controlling the temperature to be 10-30 ℃, adding 2, 6-dichlorobenzonitrile, and uniformly stirring for later use;

s2: filling a catalyst; uniformly mixing a solid fluorine reaction catalyst and a filler, and filling the mixture into a fixed bed reactor for later use;

s3: fluorination reaction: setting the temperature and the pressure of the fixed bed reactor in the step S2 to reaction requirement values, after the temperature and the pressure are stable, pumping the raw material liquid in the step S1 into the fixed bed reactor by using a plunger pump, introducing fluorine gas for fluorination reaction at the same time, and allowing the reaction liquid to flow into a receiving kettle;

s4: and (3) rectification products: and (4) vacuumizing and carrying out gradient temperature rise on the receiving kettle in the step S3, and collecting fractions of different temperature sections to obtain a product and a recovered solvent.

2. The method for preparing 2, 6-difluorobenzonitrile according to claim 1, wherein: in the step S1, the solvent is one or more of N, N-dimethylformamide, dimethyl sulfoxide or sulfolane; the mass percentage of the 2, 6-dichlorobenzonitrile in the raw material liquid is 10-40%.

3. The method for preparing 2, 6-difluorobenzonitrile according to claim 1, wherein: the solid fluorine catalyst in the step S2 is one or two of aluminum fluoride and chromium fluoride; the filler is one or two of glass beads or stainless steel balls, and the size of the filler is 1.0-1.5 mm.

4. The process according to claim 3, wherein the reaction mixture comprises at least one of the following compounds: the mass percentage of the solid fluorine catalyst in the filler in the step S2 is 3-30%.

5. The method for preparing 2, 6-difluorobenzonitrile according to claim 1, wherein: in the step S3, the reaction temperature is 30-45 ℃; the reaction time is 0.5-2 h; the reaction pressure is 2-2.5 Mpa; the molar ratio of the 2, 6-dichlorobenzonitrile to the fluorine gas is 1:1.2 to 1: 2.0.

6. The method for preparing 2, 6-difluorobenzonitrile according to claim 1, wherein: in the step S4, the vacuum degree is 0.08-0.1 MPa; the temperature is increased to 100-105 ℃ in a gradient manner, the temperature fraction is collected, and then the temperature is increased to 115-130 ℃ for collection.

7. The method for preparing 2, 6-difluorobenzonitrile according to claim 1, wherein: the fraction at 100-105 ℃ is the product 2, 6-difluorobenzonitrile, and the fraction at 115-130 ℃ is the solvent; and when the mass percent content of the 2, 6-difluorobenzonitrile in the fraction at the temperature of 100-105 ℃ is more than or equal to 98%, starting to receive the main fraction, and when the mass percent content of the 2, 6-difluorobenzonitrile in the main fraction is less than 98%, stopping receiving the main fraction.

Technical Field

The invention relates to the field of pesticide preparation, and particularly relates to a method for preparing 2, 6-difluorobenzonitrile.

Background

2, 6-difluorobenzonitrile is a specific insect growth regulator and is a necessary intermediate of phentolamine pesticides such as diflubenzuron and chlorfluazuron. The benzoyl urea compound plays a role by inhibiting the synthesis of chitin, and has the advantages of strong selectivity, small dosage, no harm to human, environmental friendliness and the like, so that the benzoyl urea compound is known as a green pesticide in the 21 st century and has wide application value. Therefore, the development of a process which is simple and suitable for large-scale production has wide market prospect

Therefore, in order to meet the requirement of modern enterprises on the 2, 6-difluorobenzonitrile, the development of the preparation method of the 2, 6-difluorobenzonitrile, which has the advantages of simple process, short reaction time, mild reaction process and high yield, has great significance.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a method for preparing 2, 6-difluorobenzonitrile.

The invention provides a method for preparing 2, 6-difluorobenzonitrile by a fixed bed reactor method, which comprises the following operation steps:

s1: preparing a raw material liquid: adding a solvent into the fully dried reaction kettle, then controlling the temperature to be 10-30 ℃, adding 2, 6-dichlorobenzonitrile, and uniformly stirring for later use;

s2: filling a catalyst; uniformly mixing a solid fluorine reaction catalyst and a filler, and filling the mixture into a fixed bed reactor for later use;

s3: fluorination reaction: setting the temperature and the pressure of the fixed bed reactor in the step S2 to reaction requirement values, after the temperature and the pressure are stable, pumping the raw material liquid in the step S1 into the fixed bed reactor by using a plunger pump, introducing fluorine gas for fluorination reaction at the same time, and allowing the reaction liquid to flow into a receiving kettle;

s4: and (3) rectification products: and (4) vacuumizing and carrying out gradient temperature rise on the receiving kettle in the step S3, and collecting fractions of different temperature sections to obtain a product and a recovered solvent.

Preferably, the solvent is one or more of N, N-dimethylformamide, dimethyl sulfoxide or sulfolane; the mass percentage of the 2, 6-dichlorobenzonitrile in the raw material liquid is 10-40%.

Preferably, the solid fluorine catalyst is one or two of aluminum fluoride and chromium fluoride; the filler is one or two of glass beads or stainless steel balls, and the size of the filler is 1.0-1.5 mm.

Preferably, the mass percent of the solid fluorine catalyst in the filler is 3-30%.

Preferably, in step S3, the reaction temperature is 30-45 ℃; the reaction time is 0.5-2 h; the reaction pressure is 2-2.5 Mpa; the molar ratio of the 2, 6-dichlorobenzonitrile to the fluorine gas is 1:1.2 to 1: 2.0.

Preferably, in the step S4, the vacuum degree is 0.08-0.1 MPa; the temperature is increased to 100-105 ℃ in a gradient manner, the temperature fraction is collected, and then the temperature is increased to 115-130 ℃ for collection.

Preferably, the fraction at 100-105 ℃ is the product 2, 6-difluorobenzonitrile, and the fraction at 115-130 ℃ is the solvent; and when the mass percent of the 2, 6-difluorobenzonitrile in the fraction at the temperature of 100-105 ℃ is more than or equal to 98%, starting to receive the main fraction, and when the mass percent of the 2, 6-difluorobenzonitrile in the main fraction is less than 98%, stopping receiving the main fraction. Compared with the prior art, the invention has the beneficial effects that:

(1) according to the method for preparing the 2, 6-difluorobenzonitrile, the 2, 6-difluorobenzonitrile is produced by adopting a fixed bed reactor method, the reaction condition is controllable, the service life of the filled solid fluorine catalyst is long, the catalytic capability is strong, the solid fluorine catalyst can be used for a long time after being filled once, and the cost of the catalyst is greatly reduced;

(2) the purity of the product obtained by the method is more than 99 percent, the yield is more than 95 percent, and the method has higher competitiveness compared with other processes.

The specific implementation mode is as follows:

the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

a method for preparing 2, 6-difluorobenzonitrile comprises the following operation steps in sequence:

s1: preparing a raw material liquid: adding sulfolane into a fully dried reaction kettle, then controlling the temperature to be 10-30 ℃, adding 2, 6-dichlorobenzonitrile, wherein the mass percentage of the 2, 6-dichlorobenzonitrile in the sulfolane is 30%, and uniformly stirring for later use;

s2: filling a catalyst; uniformly mixing chromium fluoride serving as a solid fluorine reaction catalyst and a filler (glass beads with the diameter of 1-1.5 mm), and filling the mixture into a fixed bed reactor, wherein the mass percent of the chromium fluoride serving as the solid fluorine catalyst in the filler is 5%;

s3: fluorination reaction: setting the temperature of the fixed bed reactor in the step S2 to be 40 ℃ and the pressure to be 2Mpa, after the temperature and the pressure are stable, pumping the raw material liquid in the step S1 into the fixed bed reactor by using a plunger pump, reacting for 1h, introducing fluorine gas for fluorination reaction at the same time, wherein the molar ratio of 2, 6-dichlorobenzonitrile to the fluorine gas is 1:1.5, and flowing the reaction liquid into a receiving kettle;

s4: and (3) rectification products: and (4) vacuumizing the reaction kettle in the step S3 to 0.1MPa, heating to 100-105 ℃, collecting fractions at the temperature, and heating to 115-130 ℃ to collect fractions.

As a result: 7.85kg of product is obtained in total, the purity is 99.5%, the quantitative nuclear magnetism is 99.3%, and the calculated yield is 96.1%.

Example 2:

a method for preparing 2, 6-difluorobenzonitrile comprises the following operation steps in sequence:

s1: preparing a raw material liquid: adding sulfolane into a fully dried reaction kettle, then controlling the temperature to be 10-30 ℃, adding 2, 6-dichlorobenzonitrile, wherein the mass percentage of the 2, 6-dichlorobenzonitrile in the sulfolane is 25%, and uniformly stirring for later use;

s2: filling a catalyst; uniformly mixing chromium fluoride serving as a solid fluorine reaction catalyst and a filler (glass beads with the diameter of 1-1.5 mm), and filling the mixture into a fixed bed reactor, wherein the mass percent of the chromium fluoride serving as the solid fluorine catalyst in the filler is 5%;

s3: fluorination reaction: setting the temperature of the fixed bed reactor in the step S2 to be 40 ℃ and the pressure to be 2Mpa, after the temperature and the pressure are stable, pumping the raw material liquid in the step S1 into the fixed bed reactor by using a plunger pump, reacting for 1h, introducing fluorine gas for fluorination reaction at the same time, wherein the molar ratio of 2, 6-dichlorobenzonitrile to the fluorine gas is 1:1.4, and flowing the reaction liquid into a receiving kettle;

s4: and (3) rectification products: and (4) vacuumizing the reaction kettle in the step S3 to 0.1MPa, heating to 100-105 ℃, collecting fractions at the temperature, and heating to 115-130 ℃ to collect fractions.

As a result: 7.78kg of product was obtained in total, with a purity of 99.5%, a quantitative nuclear magnetism of 99.4%, and a calculated yield of 95.7%.

Example 3:

a method for preparing 2, 6-difluorobenzonitrile comprises the following operation steps in sequence:

s1: preparing a raw material liquid: adding sulfolane into a fully dried reaction kettle, then controlling the temperature to be 10-30 ℃, adding 2, 6-dichlorobenzonitrile, wherein the mass percentage of the 2, 6-dichlorobenzonitrile in the sulfolane is 30%, and uniformly stirring for later use;

s2: filling a catalyst; uniformly mixing chromium fluoride serving as a solid fluorine reaction catalyst and a filler (glass beads with the diameter of 1-1.5 mm), and filling the mixture into a fixed bed reactor, wherein the mass percentage of the chromium fluoride serving as the solid fluorine catalyst in the filler is 10%;

s3: fluorination reaction: setting the temperature of the fixed bed reactor in the step S2 to be 40 ℃ and the pressure to be 2Mpa, after the temperature and the pressure are stable, pumping the raw material liquid in the step S1 into the fixed bed reactor by using a plunger pump, reacting for 1h, introducing fluorine gas for fluorination reaction at the same time, wherein the molar ratio of 2, 6-dichlorobenzonitrile to the fluorine gas is 1:1.4, and flowing the reaction liquid into a receiving kettle;

s4: and (3) rectification products: and (4) vacuumizing the reaction kettle in the step S3 to 0.1MPa, heating to 100-105 ℃, collecting fractions at the temperature, and heating to 115-130 ℃ to collect fractions.

As a result: 7.79kg of product with a purity of 99.5%, a quantitative nuclear magnetism of 99.3% and a calculated yield of 95.7% are obtained.