阅读说明：本技术 一种二氟乙酸的合成方法 (Synthetic method of difluoroacetic acid ) 是由 王瑞英 魏刚 燕东 邹冉 王通 崔传博 于 2020-12-31 设计创作，主要内容包括：本发明涉及一种二氟乙酸的合成方法,属于有机氟化工技术领域。本发明的二氟乙酸的合成方法,以1,1-二氟乙烷(R152a)与过氧化氢为原料,一步制备二氟乙酸,未反应的1,1-二氟乙烷(R152a)经回收后循环使用,目标产物的选择性和转化率高,对设备无腐蚀,安全环保。所用催化剂为固体酸催化剂,催化效率高,可反复使用,反应完成后易于与反应体系分离,尤其适合用于以1,1-二氟乙烷(R152a)与过氧化氢为原料制备二氟乙酸。所采用的原料均为常见试剂,来源广、价格便宜、反应条件温和、反应过程易于控制。所制得的二氟乙酸产品产率较高,适合工业化生产。(The invention relates to a synthetic method of difluoroacetic acid, belonging to the technical field of organic fluorine chemical industry. The synthesis method of difluoroacetic acid takes 1, 1-difluoroethane (R152 a) and hydrogen peroxide as raw materials to prepare difluoroacetic acid in one step, unreacted 1, 1-difluoroethane (R152 a) is recycled, and the method has the advantages of high selectivity and conversion rate of target products, no corrosion to equipment, safety and environmental protection. The catalyst is a solid acid catalyst, has high catalytic efficiency, can be repeatedly used, is easy to separate from a reaction system after the reaction is finished, and is particularly suitable for preparing difluoroacetic acid by taking 1, 1-difluoroethane (R152 a) and hydrogen peroxide as raw materials. The adopted raw materials are common reagents, the sources are wide, the price is low, the reaction conditions are mild, and the reaction process is easy to control. The prepared difluoroacetic acid product has high yield and is suitable for industrial production.)

1. A synthetic method of difluoroacetic acid is characterized by comprising the following steps:

1) putting a solid catalyst and hydrogen peroxide into a reaction kettle, and introducing nitrogen to replace air in the reaction kettle;

2) stirring and heating to 135-145 ℃, wherein the stirring speed is 200-300 r/min;

3) introducing R152a into the bottom of the reaction kettle for reaction;

condensing and collecting gas-phase products until no liquid flows out from a gas-phase outlet of the reaction kettle;

5) and carrying out rectification operation on the generated product to obtain the difluoroacetic acid.

2. A process for the synthesis of difluoroacetic acid as claimed in claim 1, characterized in that: the solid catalyst in the step 1) is any one of strong acid ion exchange resin, tungstic acid complex and heteropoly acid.

3. A process for the synthesis of difluoroacetic acid as claimed in claim 2, characterized in that: the strongly acidic ion exchange resin in the step 1) is any one of dry hydrogen ion exchange resin and perfluorinated sulfonic acid resin.

4. A process for the synthesis of difluoroacetic acid as claimed in claim 2, characterized in that: the tungstic acid complex in the step 1) is any one of tungstic acid inorganic acid ligand and tungstic acid organic acid ligand.

5. A process for the synthesis of difluoroacetic acid as claimed in claim 1, characterized in that: the heteropoly acid in the step 1) is any one or a mixture of more of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid.

6. A process for the synthesis of difluoroacetic acid as claimed in claim 1, characterized in that: the hydrogen peroxide in step 1) is 30wt% of H₂O₂。

7. A process for the synthesis of difluoroacetic acid as claimed in claim 1, characterized in that: the flow rate of the R152a in the step 3) is 30 ml/min-100 ml/min.

8. A process for the synthesis of difluoroacetic acid as claimed in claim 1, characterized in that: the condensation collection mode in the step 4) is cooling water condensation.

9. A process for the synthesis of difluoroacetic acid as claimed in any of claims 1 to 9, characterized by comprising the following steps:

1) 20g of perfluorosulfonic acid resin catalyst and 600g of 30wt% hydrogen peroxide are put into a 1L reaction kettle, and nitrogen is introduced to replace the air in the reaction kettle;

2) stirring the reaction kettle, heating to 140 ℃, and stirring at the rotating speed of 200-300 r/min;

3) introducing R152a into the bottom of the reaction kettle at the speed of 60ml/min for reaction;

4) condensing and collecting gas-phase products by using cooling water until no liquid flows out from a gas-phase outlet of the reaction kettle;

5) the resultant was subjected to a rectification operation to obtain difluoroacetic acid.

Technical Field

The invention relates to a synthetic method of difluoroacetic acid, belonging to the technical field of organic fluorine chemical industry.

Background

Difluoroacetic acid is a fluorine-containing intermediate with wide application, is widely used in the industrial fields of pharmacy and agricultural chemicals, and can also be used as a raw material for a fluorine-containing liquid crystal and glass coating process; is a catalyst for esterification and condensation reaction, and a protective agent for hydroxyl and amino, and is used for synthesizing sugar and polypeptide; is a good solvent for a plurality of organic compounds and a good solvent for organic reaction, and has good market prospect.

The prior art processes for the preparation of difluoroacetic acid have safety problems, as is known from Japanese patent JP06228043, for example, for the preparation of difluoroacetic acid by reaction between N, N-dichloroacetamide and potassium fluoride in ethylene glycol at 150 ℃. The disadvantage of the above process is that it involves amide type substrates. In EP0694523, the preparation of difluoroacetic acid fluorides or esters thereof is described, which is carried out by reaction of 1-alkoxy-1, 1,2, 2-tetrafluoroethane in the gas phase in the presence of a catalyst of the metal oxide type. This method has the disadvantage of requiring a gaseous substrate which is explosive in air.

Chinese patent CN103201245A provides a method for preparing difluoroacetic acid from tetrafluoroethylene. The process comprises reacting tetrafluoroethylene with an aqueous solution of an inorganic base, optionally in the presence of an organic solvent. The method has the defect that the tetrafluoroethylene raw material is combustible, inert gas needs to be introduced for dilution in the reaction process for preventing the tetrafluoroethylene from being burnt, and the reaction time is longer.

In order to overcome the problem of safety defect of the preparation method of difluoroacetic acid in the prior art, a synthesis method of difluoroacetic acid, which has mild reaction conditions, simple method and easy realization of industrial production, is urgently needed to be developed.

Disclosure of Invention

In order to overcome the problem of safety defect of the preparation method of difluoroacetic acid in the prior art, the invention takes gas-phase 1, 1-difluoroethane (R152 a) as a raw material to react with liquid-phase hydrogen peroxide in the presence of a solid-phase catalyst, the product is separated in a way of distilling out of a reaction system while generating, and the unreacted R152a can be recycled. The raw materials and the process related by the invention are safer, almost do not generate hazardous waste and are easy to treat. The method has high selectivity and conversion rate, simple process and suitability for industrial production.

In order to achieve the above object, the technical solution adopted by the present invention to solve the technical problem is a method for synthesizing difluoroacetic acid, comprising the following steps:

(1) putting a solid catalyst and hydrogen peroxide into a reaction kettle, and introducing nitrogen to replace air in the reaction kettle;

(2) stirring and heating to 135-145 ℃, wherein the stirring speed is 200-300 r/min;

(3) introducing R152a into the bottom of the reaction kettle for reaction;

(4) condensing and collecting gas-phase products until no liquid flows out from a gas-phase outlet of the reaction kettle.

(5) The resultant was subjected to a rectification operation to obtain difluoroacetic acid.

Preferably, the solid catalyst in the step (1) is any one of strong acid ion exchange resin, tungstic acid complex and heteropoly acid.

Preferably, the strongly acidic ion exchange resin in step (1) is any one of a dry hydrogen ion exchange resin and a perfluorosulfonic acid resin.

Preferably, the tungstic acid complex in the step (1) is any one of tungstic acid inorganic acid ligand and tungstic acid organic acid ligand.

Preferably, the heteropoly acid in the step (1) is one or a mixture of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid.

Preferably, the hydrogen peroxide in step (1) is 30wt% H₂O₂。

Preferably, the flow rate of R152a in step (3) is 30ml/min to 100 ml/min.

Preferably, the condensing and collecting manner in the step (4) is cooling water condensation.

The synthesis method of difluoroacetic acid comprises the steps of putting a catalyst and hydrogen peroxide into a reaction kettle, introducing nitrogen to replace air in the reaction kettle, stirring and heating to a specified temperature. Then 1, 1-difluoroethane (R152 a) is fed into the bottom of the reaction kettle at a certain flow rate for reaction, and cooling water is used for condensing and collecting gas-phase products until no liquid flows out from a gas-phase outlet of the reaction kettle. The unreacted 1, 1-difluoroethane (R152 a) is recycled after being recovered, and the product collected by condensation is rectified to obtain the product difluoroacetic acid.

The invention has the beneficial technical effects that:

1. the synthesis method of difluoroacetic acid takes 1, 1-difluoroethane (R152 a) and hydrogen peroxide as raw materials to prepare difluoroacetic acid in one step, unreacted 1, 1-difluoroethane (R152 a) is recycled, and the method has the advantages of high selectivity and conversion rate of target products, no corrosion to equipment, safety and environmental protection.

2. The synthesis method of difluoroacetic acid uses the solid acid catalyst, has high catalytic efficiency, can be repeatedly used, is easy to separate from a reaction system after the reaction is finished, and is particularly suitable for preparing the difluoroacetic acid by using 1, 1-difluoroethane (R152 a) and hydrogen peroxide as raw materials.

3. The synthesis method of difluoroacetic acid adopts common reagents as raw materials, has wide sources, low price, mild reaction conditions and easily controlled reaction process. The prepared difluoroacetic acid product has high yield and is suitable for industrial production.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to limit the invention.

Example 1:

(1) 20g of perfluorosulfonic acid resin catalyst and 600g of 30wt% hydrogen peroxide are put into a 1L reaction kettle, and nitrogen is introduced to replace the air in the reaction kettle;

(2) stirring the reaction kettle, heating to 135 ℃, and stirring at the rotating speed of 200-300 r/min;

(3) introducing R152a into the bottom of the reaction kettle at the speed of 50ml/min for reaction;

(4) the gas phase product was collected by condensing with cooling water until no liquid flowed out of the gas phase outlet of the reaction vessel, and the reaction results are shown in Table 1.

(5) The resultant was subjected to a rectification operation to obtain difluoroacetic acid.

Example 2:

(1) 20g of perfluorosulfonic acid resin catalyst and 600g of 30wt% hydrogen peroxide are put into a 1L reaction kettle, and nitrogen is introduced to replace the air in the reaction kettle;

(2) stirring the reaction kettle, heating to 140 ℃, and stirring at the rotating speed of 200-300 r/min;

(3) introducing R152a into the bottom of the reaction kettle at the speed of 60ml/min for reaction;

(4) the gas phase product was collected by condensing with cooling water until no liquid flowed out of the gas phase outlet of the reaction vessel, and the reaction results are shown in Table 1.

(5) The resultant was subjected to a rectification operation to obtain difluoroacetic acid.

Example 3:

(1) 20g of perfluorosulfonic acid resin catalyst and 600g of 30wt% hydrogen peroxide are put into a 1L reaction kettle, and nitrogen is introduced to replace the air in the reaction kettle;

(2) stirring the reaction kettle, heating to 145 ℃, and stirring at the rotating speed of 200-300 r/min;

(3) introducing R152a into the bottom of the reaction kettle at the speed of 70ml/min for reaction;

(4) the gas phase product was collected by condensing with cooling water until no liquid flowed out of the gas phase outlet of the reaction vessel, and the reaction results are shown in Table 1.

(5) The resultant was subjected to a rectification operation to obtain difluoroacetic acid.

Example 4:

(1) 20g of Pd-SiW₁₂ /SiO₂Putting a catalyst and 600g of 30wt% hydrogen peroxide into a 1L reaction kettle, and introducing nitrogen to replace the air in the reaction kettle;

(2) stirring the reaction kettle, heating to 135 ℃, and stirring at the rotating speed of 200-300 r/min;

(3) introducing R152a into the bottom of the reaction kettle at the speed of 70ml/min for reaction;

(4) the gas phase product was collected by condensing with cooling water until no liquid flowed out of the gas phase outlet of the reaction vessel, and the reaction results are shown in Table 1.

(5) The resultant was subjected to a rectification operation to obtain difluoroacetic acid.

Example 5:

(1) 20g of Pd-SiW₁₂ /SiO₂Putting a catalyst and 600g of 30wt% hydrogen peroxide into a 1L reaction kettle, and introducing nitrogen to replace the air in the reaction kettle;

(2) stirring the reaction kettle, heating to 140 ℃, and stirring at the rotating speed of 200-300 r/min;

(3) introducing R152a into the bottom of the reaction kettle at the speed of 50ml/min for reaction;

(4) the gas phase product was collected by condensing with cooling water until no liquid flowed out of the gas phase outlet of the reaction vessel, and the reaction results are shown in Table 1.

(5) The resultant was subjected to a rectification operation to obtain difluoroacetic acid.

Example 6:

(1) 20g of Pd-SiW₁₂ /SiO₂Putting a catalyst and 600g of 30wt% hydrogen peroxide into a 1L reaction kettle, and introducing nitrogen to replace the air in the reaction kettle;

(2) stirring the reaction kettle, heating to 145 ℃, and stirring at the rotating speed of 200-300 r/min;

(3) introducing R152a into the bottom of the reaction kettle at the speed of 60ml/min for reaction;

(4) the gas phase product was collected by condensing with cooling water until no liquid flowed out of the gas phase outlet of the reaction vessel, and the reaction results are shown in Table 1.

(5) The resultant was subjected to a rectification operation to obtain difluoroacetic acid.

Example 7:

(1) 20g H₃[PW₁₂O₄₀]•xH₂Putting an O catalyst and 600g of 30wt% hydrogen peroxide into a 1L reaction kettle, and introducing nitrogen to replace the air in the reaction kettle;

(2) stirring the reaction kettle, heating to 135 ℃, and stirring at the rotating speed of 200-300 r/min;

(3) introducing R152a into the bottom of the reaction kettle at the speed of 60ml/min for reaction;

(4) the gas phase product was collected by condensing with cooling water until no liquid flowed out of the gas phase outlet of the reaction vessel, and the reaction results are shown in Table 1.

(5) The resultant was subjected to a rectification operation to obtain difluoroacetic acid.

Example 8:

(1) 20g H₃[PW₁₂O₄₀]•xH₂Putting an O catalyst and 600g of 30wt% hydrogen peroxide into a 1L reaction kettle, and introducing nitrogen to replace the air in the reaction kettle;

(2) stirring the reaction kettle, heating to 140 ℃, and stirring at the rotating speed of 200-300 r/min;

(3) introducing R152a into the bottom of the reaction kettle at the speed of 70ml/min for reaction;

(4) the gas phase product was collected by condensing with cooling water until no liquid flowed out of the gas phase outlet of the reaction vessel, and the reaction results are shown in Table 1.

(5) The resultant was subjected to a rectification operation to obtain difluoroacetic acid.

Example 9:

(1) 20g H₃[PW₁₂O₄₀]•xH₂Putting an O catalyst and 600g of 30wt% hydrogen peroxide into a 1L reaction kettle, and introducing nitrogen to replace the air in the reaction kettle;

(2) stirring the reaction kettle, heating to 145 ℃, and stirring at the rotating speed of 200-300 r/min;

(3) introducing R152a into the bottom of the reaction kettle at the speed of 50ml/min for reaction;

(4) the gas phase product was collected by condensing with cooling water until no liquid flowed out of the gas phase outlet of the reaction vessel, and the reaction results are shown in Table 1.

(5) The resultant was subjected to a rectification operation to obtain difluoroacetic acid.

EXAMPLES 1-9 comparison of reaction conditions and yield and conversion of target product

As can be seen from the experimental results in table 1, in the synthesis methods of difluoroacetic acid of the present invention, in examples 1 to 9, the conversion rate of R152a was 86% or more, the yield was 75% or more, and the selectivity and conversion rate of the target product were high. The preparation process is simple, convenient to control, good in repeatability, capable of continuously feeding and easy to realize large-scale industrial production.

It should be noted that the above-mentioned preferred embodiments are merely illustrative of the technical concepts and features of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.