阅读说明：本技术 熔融结晶制备超高纯2,4’-二氟二苯甲酮的方法 (Method for preparing ultra-pure 2,4' -difluorobenzophenone by melt crystallization ) 是由 王彦飞 杨鹏辉 马立强 许史杰 任建军 张伟 于 2021-09-24 设计创作，主要内容包括：本发明属于化学提纯领域,具体涉及熔融结晶制备超高纯2,4’-二氟二苯甲酮的方法,包括以下步骤：1)液相进料：将固态2,4′-二氟二苯甲酮粗料加入到层式熔融结晶器在熔化温度下进行化料,熔化到液态；2)降温结晶：对液态2,4′-二氟二苯甲酮粗料进行降温,降温速率为1～30K/h；降温终温为15～25℃；恒温0.5h；3)发汗：待排出未结晶母液后,对晶体进行发汗,升温速率为1～20K/h,升温至27～35℃,恒温0.5h,将发汗液排出；4)化料。本发明方法适用于质量百分含量≥70％,优先适用于90％以上2,4′-二氟二苯甲酮粗品,不外加溶剂,降低了操作成本,简化了操作,环境友好无三废产生,得到纯度大于99.9％甚至超过99.99％的2,4′-二氟二苯甲酮纯品。(The invention belongs to the field of chemical purification, and particularly relates to a method for preparing ultra-high-purity 2,4' -difluorobenzophenone by melt crystallization, which comprises the following steps: 1) liquid-phase feeding: adding the solid 2,4' -difluorobenzophenone coarse material into a layer-type melt crystallizer for melting at a melting temperature to be melted into a liquid state; 2) cooling and crystallizing: cooling the liquid 2,4' -difluorobenzophenone coarse material at a cooling rate of 1-30K/h; the final temperature of the cooling is 15-25 ℃; keeping the temperature for 0.5 h; 3) sweating: after discharging the non-crystallized mother liquor, sweating the crystals at a heating rate of 1-20K/h to 27-35 ℃, keeping the temperature for 0.5h, and discharging the sweating liquid; 4) and (5) melting materials. The method is suitable for more than or equal to 70 percent of 2,4' -difluorobenzophenone crude products, preferably more than 90 percent of 2,4' -difluorobenzophenone crude products, does not add any solvent, reduces the operation cost, simplifies the operation, is environment-friendly, does not generate three wastes, and obtains 2,4' -difluorobenzophenone pure products with the purity of more than 99.9 percent and even more than 99.99 percent.)

1. A method for preparing ultra-pure 2,4' -difluorobenzophenone by melt crystallization is characterized by comprising the following steps: the method comprises the following steps:

step 1) liquid phase feeding: adding the solid 2,4' -difluorobenzophenone coarse material into a layer-type melt crystallizer for melting at a melting temperature to be melted into a liquid state;

step 2), cooling and crystallizing: cooling the liquid 2,4' -difluorobenzophenone coarse material with the percentage content of more than or equal to 90%, wherein the cooling rate is controlled to be 1-30K/h, and the final cooling temperature is 15-25 ℃; keeping the temperature for 0.5-1 h;

step 3), sweating: after discharging the non-crystallized mother liquor, sweating the crystals at a heating rate of 1-20K/h to 27-35 ℃, keeping the temperature for 0.5-1 h, discharging the sweating liquid, and using the sweating liquid as the next raw material for application;

step 4), material melting: heating the material to melt completely after the sweat is discharged, and obtaining the 2,4 '-difluorobenzophenone with the purity of more than 99.99 percent, which is the ultra-high purity 2,4' -difluorobenzophenone.

2. The method of claim 1, wherein: the crude material of the 2,4 '-difluorobenzophenone in the step 1) is a crude product of the 2,4' -difluorobenzophenone obtained by an organic synthesis method.

3. The method of claim 1, wherein: the mass percentage content of the 2,4' -difluorobenzophenone coarse material in the step 1) is more than or equal to 90%.

4. The method of claim 1, wherein: more than two-stage crystallization is adopted.

5. The method of claim 4, wherein: adopting secondary crystallization, wherein primary mother liquor enters a secondary crystallizer, primary perspiration liquid flows back to the primary crystallizer to be used as a raw material, and a primary product is produced by the primary crystallizer; and mixing the secondary sweat and the primary mother liquor, pumping into the secondary crystallizer again, mixing the secondary product with the raw material and the primary sweat, and pumping into the primary crystallizer again.

Technical Field

The invention belongs to the field of chemical purification, relates to a purification method of 2,4' -difluorobenzophenone, and particularly relates to a method for preparing ultra-high-purity 2,4' -difluorobenzophenone by melting and crystallizing 2,4' -difluorobenzophenone coarse materials.

Background

The 2,4' -difluorobenzophenone product is mainly used as an intermediate of pesticide flutriafol. The preparation method of 2,4' -difluorobenzophenone reported in domestic literature and patents mainly uses aluminium trichloride as a catalyst and adopts one or more complex solvents for catalytic reaction synthesis. The substances and homologues reported in the literature and the patent are purified by adopting modes of rectification, solution crystallization and the like.

Patent CN 103449986A discloses a method for preparing high-purity 2,4' -difluorobenzophenone, which comprises using one or more compound solvents such as fluorobenzene, dichloromethane, dichloroethane, n-hexane, nitrobenzene during synthesis, taking o-fluorobenzoyl chloride and fluorobenzene as raw materials, taking anhydrous aluminum trichloride as a catalyst, after reaction, hydrolyzing for desolventizing, post-treating, and recrystallizing the solution to obtain a high-purity target product; wherein o-fluorobenzoyl chloride: fluorobenzene is taken as a raw material: the mass portion ratio of the anhydrous aluminum trichloride is 1: 1-3: 0.5-1.5. Solution recrystallization requires the use of methanol, ethanol, ethylene glycol, a mixture of isopropanol and water, petroleum ether, methyl ether, tetrahydrofuran or n-hexane as solvent.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for preparing high-purity 2,4' -difluorobenzophenone by layered melt crystallization, which does not need solvent, has safe process, no three wastes and high product purity.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing ultra-high-purity 2,4' -difluorobenzophenone by melt crystallization comprises the following steps:

step 1) liquid phase feeding: adding solid 2,4' -difluorobenzophenone coarse material with the mass percentage of more than or equal to 90% into a layer-type melt crystallizer for melting at the melting temperature to be liquid;

step 2), cooling and crystallizing: cooling the liquid 2,4' -difluorobenzophenone coarse material with the percentage content of more than or equal to 90%, wherein the cooling rate is controlled to be 1-30K/h, and the final cooling temperature is 15-25 ℃; keeping the temperature for 0.5-1 h;

step 3), sweating: after discharging the non-crystallized mother liquor, sweating the crystals at a heating rate of 1-20K/h to 27-35 ℃, keeping the temperature for 0.5-1 h, discharging the sweating liquid, and using the sweating liquid as the next raw material for application;

step 4), material melting: heating the material to melt completely after the sweat is discharged, and obtaining the 2,4 '-difluorobenzophenone with the purity of more than 99.99 percent, which is the ultra-high purity 2,4' -difluorobenzophenone.

And the 2,4 '-difluorobenzophenone crude material in the step 1) is a 2,4' -difluorobenzophenone crude product obtained by an organic synthesis method.

Furthermore, more than two stages of crystallization can be employed according to the process requirements. If secondary crystallization is adopted, the primary mother liquor enters a secondary crystallizer, primary sweat flows back to the primary crystallizer to serve as a raw material, and a primary product is produced by the primary crystallizer; and mixing the secondary sweat and the primary mother liquor, pumping into the secondary crystallizer again, mixing the secondary product with the raw material and the primary sweat, and pumping into the primary crystallizer again.

The method for separating and purifying the 2,4 '-difluorobenzophenone is suitable for crude products (the percentage content is more than or equal to 70 percent, and the percentage content is preferably more than or equal to 90 percent) of the 2,4' -difluorobenzophenone, raw materials of the process enter a separation process, and except secondary mother liquor obtained by recrystallization of the mother liquor, materials obtained in other steps can be used as primary raw materials or secondary raw materials.

The invention has the advantages and beneficial effects that:

1. the invention adopts a melt crystallization mode for purification, can purify to obtain the ultra-pure product with the purity of 99.9 percent or even more than 99.99 percent, has the advantages of no solvent, safe process, no three wastes, high product purity and the like, and is a green separation and purification process.

2. The 2,4' -difluorobenzophenone can be recovered except for secondary mother liquor, and the recovery rate of the raw material with the purity of over 90 percent can be more than 97 percent at present.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following detailed description of the present invention is provided in conjunction with the best embodiment.

Example 1

491.17g of a 2,4' -difluorobenzophenone crude product with the content of 97.69 percent is put into a 500ml layer-type melt crystallizer, the temperature is raised to 30 ℃ until the material is completely melted into liquid, the temperature is reduced according to the cooling rate of 20K/h, and the final temperature of the temperature reduction is 23 ℃; discharging the mother liquor, and heating the materials to 29.7 ℃ at a heating rate of 14K/h for sweating; discharging the perspiration; heating and melting, discharging, and obtaining the product with the purity of 99.69%. The single-pass yield was 64.27%.

Example 2

238.38g of a 2,4' -difluorobenzophenone crude product with the content of 97.85 percent is put into a 500ml layer-type melt crystallizer, the temperature is raised to 30 ℃ until the material is completely melted into liquid, the temperature is reduced according to the cooling rate of 22K/h, and the final temperature of the temperature reduction is 21 ℃; discharging the mother liquor, and heating the materials to 31 ℃ at the heating rate of 12K/h for sweating; discharging the perspiration; heating and melting, and discharging. The purity of the obtained product is 99.94%. The single-pass yield was 42.99%.

Embodiment 3

397.34g of a 2,4' -difluorobenzophenone crude product with the content of 98.55 percent is put into a 500ml layer-type melt crystallizer, the temperature is raised to 30 ℃ until the material is completely melted into liquid, the temperature is reduced according to the cooling rate of 20K/h, and the final temperature of the temperature reduction is 21.5 ℃; discharging the mother liquor, heating the materials to 29 ℃ at the heating rate of 13K/h, sweating, and keeping the final temperature of sweating constant for 3 hours; discharging the perspiration; heating and melting, and discharging. The purity of the obtained product is 100.00%. The single-pass yield was 62.21%.

Example 4

Putting the mother liquor obtained in the embodiment 2 into a 300ml layered melt crystallizer, wherein 126.02g of crude 2,4' -difluorobenzophenone with the content of 91.73 percent is heated to 24 ℃ until the materials are completely melted into liquid, cooling according to the cooling rate of 18K/h, keeping the temperature constant when the temperature reaches 15 ℃, and cooling to the final temperature of 15 ℃; discharging the mother liquor, and heating the materials to 28 ℃ at a heating rate of 14K/h to perform sweating; discharging the perspiration; heating and melting, discharging, and recrystallizing the mother liquor to obtain the product with the purity of 98.03%. The one-way yield is 59.3%, and if the sweat and the product are applied in the embodiment 3, the total yield can reach 97%.

Example 5

450.31g of a 2,4' -difluorobenzophenone crude product with the content of 98.91 percent is put into a 500ml layer-type melt crystallizer, the temperature is raised to 29 ℃ until the material is completely melted into liquid, the temperature is reduced according to the cooling rate of 17K/h, and the final temperature of the temperature reduction is 19.2 ℃; discharging the mother liquor, and heating the materials to 30.2 ℃ at the heating rate of 12K/h for sweating; discharging the perspiration; heating and melting, discharging, and obtaining the product with the purity of 100.00%. The single-pass yield thereof was found to be 47.13%.

Example 6

399.16g of 98.36 percent crude 2,4' -difluorobenzophenone is put into a 500ml layered melt crystallizer, the temperature is raised to 30 ℃ until the materials are completely melted into liquid, and the temperature is reduced according to the cooling rate of 28K/h, wherein the final temperature of the temperature reduction is 23.2 ℃; discharging the mother liquor, and heating the materials to 30.5 ℃ at a heating rate of 14K/h for sweating; discharging the perspiration; heating and melting, and discharging. The purity of the obtained product is 99.97%, and the single-pass yield is 71.46%.

Example 7

405.16g of 70.05 percent crude 2,4' -difluorobenzophenone is put into a 500ml layered melt crystallizer, the temperature is raised to 30 ℃ until the materials are completely melted into liquid, and the temperature is reduced according to the cooling rate of 15K/h, wherein the final temperature of the temperature reduction is 20.2 ℃; discharging the mother liquor, and heating the materials to 30.5 ℃ at a heating rate of 14K/h for sweating; discharging the perspiration; heating and melting, and discharging. The purity of the obtained product is 99.90%, and the once-through yield is 21.46%.

The foregoing is only a preferred embodiment of the invention, and the description should not be construed as limiting the invention as described herein, since variations in the detailed description and the scope of the application will occur to those skilled in the art and may be made in accordance with the teachings of the present invention.