Method for preparing high-purity DC and simultaneously recovering KCL

Abstract

The invention provides a method for preparing high-purity DC and recovering KCL at the same time. The method comprises the following steps: adding a solvent into a crude product DC, heating and dissolving to obtain a first crystal mixture; adding a surfactant and a crystal form guiding agent into the first crystal mixture to obtain a second crystal mixture; carrying out gradient cooling crystallization on the second crystallization mixture to purify DC, and when the crystallization end point is reached, carrying out suction filtration, washing and drying to obtain a solid which is a third crystallization mixture and a liquid which is a fourth crystallization mixture; and concentrating and rectifying the fourth crystallized mixture, and collecting fractions to obtain a first rectified mixture KCL. According to the method, the crystallization yield is high, the product DC purity is high, the KCL content is smaller than 0.001%, no crystallization additive is left in crystals, the rectification recovery rate of the high-added-value product KCL is high, and the method is suitable for industrial preparation.

Description

Technical Field

[0001] This invention relates to the field of organic compound crystallization and purification technology, specifically to a method for preparing high-purity DC while simultaneously recovering KCL. Background Technology

[0002] α,α'-Dihydroxy-1,3-diisopropylbenzene (DC) is derived from the peroxide intermediates of upstream diisopropylbenzene, 2-hydroxy-2-propyl-hydroperoxyisopropylbenzene (HHP) and diisopropylbenzene disperoxyisopropylbenzene (DHP). The hydrogenation product of these two is DC.

[0003]

[0004] DC, a key intermediate in many fine chemicals, reacts with tert-butyl peroxide to produce di-(tert-butylperoxyisopropyl)benzene (BIPB), a odorless plastic crosslinking agent. European regulations are pushing for BIPB to replace dicumyl peroxide (DCP), a type of plastic crosslinking agent, because products using DCP release acetophenone, a substance with a pungent odor that is extremely harmful to human health. The global demand for BIPB is expected to significantly increase compared to DCP in the future. Furthermore, the diene produced from the dehydration of DC can be further reacted to obtain TMXDI, which can be used to produce water-based automotive coatings, with a price as high as 300,000 RMB per ton.

[0005]

[0006] Due to process issues, the preparation of DC inevitably introduces the impurity 3-(2-hydroxyisopropyl)acetophenone (KCL). Because KCL has a high structural similarity to the target product DC, it is difficult to separate it effectively during the crystallization process.

[0007]

[0008] Traditional crystallization processes (CN 114945548 A) typically employ a single solvent system for cooling crystallization, but this process suffers from the following technical drawbacks:

[0009] 1. Due to the similar molecular polarity and high lattice parameter matching between DC and KCL, co-crystallization is prone to occur during the crystal growth stage, resulting in a large amount of KCL (>0.2%) in the product DC. Since pure KCL is a pale yellow solid, this seriously affects the purity, color and downstream applications of DC.

[0010] 2. KCl is mainly used in the biopharmaceutical field as an important pharmaceutical intermediate. The final product can be used as an inhibitor of inosine-5'-monophosphate dehydrogenase (IMPDH), selectively inhibiting parasitic IMPDH, and is used to treat bacterial infections and parasites in birds and mammals (CN 109134222 A). However, in the existing crystallization process, KCl and DC form a solid solution, which is difficult to separate, resulting in the waste of high-value-added components.

[0011] 3. Lattice defects caused by impurities can lead to a yellowing of the DC product. In high-end applications, additional post-processing steps such as activated carbon decolorization are required, increasing production costs. Furthermore, approximately 75% of KCl is trapped inside the DC crystals and cannot be removed by conventional washing. Multi-stage countercurrent washing or high-pressure crystallization techniques could be attempted to reduce the KCl content, but these solutions suffer from technical bottlenecks such as significantly increased organic solvent consumption, substantial increases in equipment investment costs, decreased product yield, and the inability to recover KCl.

[0012] Therefore, developing a novel crystallization process that can simultaneously achieve deep product purification and targeted enrichment of impurities has significant industrial value. Summary of the Invention

[0013] To address the shortcomings of existing technologies, one of the objectives of this invention is to provide a method for preparing high-purity α,α'-dihydroxy-1,3-diisopropylbenzene (DC) while simultaneously recovering 3-(2-hydroxyisopropyl)acetophenone (KCL). This method has a high crystallization yield, high DC purity, KCL content <0.001%, no residue of crystallization additives in the crystals, and high KCL distillation recovery rate, making it suitable for industrial-scale preparation.

[0014] To achieve the above objectives, the present invention adopts the following technical solution:

[0015] A method for preparing high-purity α,α'-dihydroxy-1,3-diisopropylbenzene DC while simultaneously recovering 3-(2-hydroxyisopropyl)acetophenone KCl, the method comprising the following steps:

[0016] S1: Crude DC is dissolved in solvent and heated to obtain the first crystalline mixture;

[0017] S2: Add a surfactant and a crystal-directing agent to the first crystallization mixture to obtain the second crystallization mixture;

[0018] S3: The second mixture for crystallization is subjected to gradient cooling crystallization to purify DC. When the crystallization endpoint is reached, it is filtered, washed, and dried. The solid is the third mixture for crystallization, and the liquid is the fourth mixture for crystallization.

[0019] Optionally, S4: Crystallize the fourth mixture, concentrate, distill, and collect the fraction to obtain the first mixture KCL.

[0020] The inventors discovered that by using additives, crystal growth kinetics and interfacial properties can be controlled to achieve the directional separation of DC and KCL, and then coupled with subsequent processes to obtain high-purity KCL. This invention is based on the fact that crystal form-inducing additives can be adsorbed onto specific crystal faces via hydrogen bonding, inducing directional crystal growth, preferentially occupying growth sites on DC crystal faces, changing the anisotropic growth rate of the crystal, increasing the specific surface area several times over, and significantly reducing internal inclusion defects. Simultaneously, surface-active additives can regulate the crystallization process; their hydrophobic ends can selectively adsorb KCL molecules, forming a dynamic repulsion layer on the crystal surface, preventing KCL from entering the DC lattice. This results in high-purity DC crystals, which are then coupled with subsequent processes to obtain high-purity KCL.

[0021] In one embodiment of the present invention, the solvent in S1 is a polar solvent, preferably comprising one or more of methyl isobutyl ketone, toluene, and ethyl acetate.

[0022] In one embodiment of the present invention, the effective concentration of DC in the first crystalline mixture of S1 is 25wt%-30wt%.

[0023] In one embodiment of the present invention, the first crystalline mixture of S1 contains 0.5 wt%-2 wt% KCl, 1 wt%-2 wt% heavy components, and 1 wt%-2 wt% water, based on the total mass of the mixture.

[0024] In one embodiment of the present invention, the holding temperature in S1 is 90℃-110℃. This temperature is the initial crystallization temperature.

[0025] In one embodiment of the present invention, the crystal-directing agent in S2 comprises a sterically hindered alkyl phosphonate, preferably one or more of 1-butyl-3-methylimidazolium dibutylphosphonate, 1-tert-butyl-3-methylimidazolium dibutylphosphonate, methyltributylphosphonate, and methyltriisopropylphosphonate, more preferably crystalline methyltributylphosphonate.

[0026] In one embodiment of the present invention, the surfactant in S2 comprises natural glycolipids and / or synthetic glycolipids, preferably one or more of rhamnolipids, sophorolipids, acetylated sophorolipids, trehalolipids, and alkylated sophorolipids, more preferably acetylated sophorolipids.

[0027] In one embodiment of the present invention, the total w / w concentration of the crystal-directing agent and the surfactant in S2 is 0.002%-2%, preferably 0.05%-0.5%.

[0028] In one embodiment of the present invention, the mass ratio of the crystal-directing agent to the surfactant in S2 is 10:1 to 1:10.

[0029] In one embodiment of the present invention, the initial crystallization temperature range in S2 is 90°C-110°C.

[0030] In one embodiment of the present invention, the gradient cooling in S3 includes a primary nucleation stage and a secondary growth stage; preferably, the cooling rate of the primary nucleation stage is 1-5℃ / h, and the cooling range is 90℃-110℃; preferably, the cooling rate of the secondary growth stage is 12-15℃ / h, and the cooling range is 65℃-75℃.

[0031] In one embodiment of the present invention, the crystallization endpoint temperature in S3 is 18-25°C.

[0032] In one embodiment of the present invention, the negative pressure of the filtration in S3 is 30 kPaA-50 kPaA.

[0033] In one embodiment of the present invention, the solvent used for washing in S3 is a moderately polar solvent, preferably one or more of methyl isobutyl ketone, toluene, and ethyl acetate; preferably, the amount of solvent used for washing is 30%-50% of the mass of the wet filter cake, and the number of washing times is 1-3.

[0034] In one embodiment of the present invention, the drying temperature in S3 is 30-50°C and the drying pressure is 10 kPaA-100 kPaA.

[0035] In one embodiment of the present invention, the concentration temperature in S4 is 50-70°C and the pressure is 20 kPaA-50 kPaA.

[0036] In one embodiment of the invention, S4 is concentrated to 10%-30% of its original volume.

[0037] In one embodiment of the present invention, the theoretical plate number of distillation in S4 is 10-15, the distillation pressure is 2 kPaA-20 kPaA, and the reflux ratio is 1:2 to 2:1.

[0038] Another object of the present invention is to provide an application of a method for preparing high-purity α,α'-dihydroxy-1,3-diisopropylbenzene DC while simultaneously recovering 3-(2-hydroxyisopropyl)acetophenone KCL.

[0039] Application of a method for preparing high-purity α,α'-dihydroxy-1,3-diisopropylbenzene (DC) while simultaneously recovering 3-(2-hydroxyisopropyl)acetophenone (KCL), wherein the method is the method described above, and the method is used to prepare high-purity α,α'-dihydroxy-1,3-diisopropylbenzene while simultaneously recovering 3-(2-hydroxyisopropyl)acetophenone.

[0040] Compared with the prior art, the positive effects of the present invention are as follows:

[0041] By adding two additives, a crystal form inducer and a surfactant, during the crystallization process, a high-value-added product, KCL, with a purity >99.5% and a single-pass yield >85%, can be recovered. Detailed Implementation

[0042] Key information about raw materials:

[0043]

[0044]

[0045] Analysis method:

[0046] Analytical characterization was performed using liquid chromatography (HPLC) with a manufacturer: SHIMADZU (Japan), model: SIL-20AXR. An SB-PHENYL (4.6*250mm, 5μm) column was used at 40℃ with gradient elution of methanol and water. The content was determined using external standard analysis.

[0047] Example 1

[0048] 1036.52 g of crude DC (25% purity) containing solvent and impurities was added to a 2 L jacketed crystallizer and heated to 95 °C until completely dissolved. 547 mg of crystallization directant methyltributylphosphine dibutylphosphonate and 5023 mg of surfactant acetylated sophorolipid were added. The temperature was lowered to 75 °C at a rate of 3 °C / h and maintained for 45 min to promote crystal growth; then, the temperature was lowered to 18 °C at a rate of 15 °C / min and maintained for 30 min. The mixture was then filtered under vacuum at 49 kPaA. The filter cake was washed twice with 120 g of toluene and dried at 30 °C and 10 kPaA until its mass no longer changed. The resulting solid was 229.17 g of DC crystals, with a DC purity of 99.54%, a KCl content of 8 ppm, and a crystallization yield of 88.03%. The filtrate without washing liquid was concentrated to 30% of its original volume at 50℃ and 50 kPaA. Then, in a distillation system with 15 theoretical plates, the boiling point of the fraction was collected at 135℃ under controlled pressure of 2 kPaA and reflux ratio of 1:2. This fraction was KCl, totaling 15.99 g with a purity of 99.61% and a KCl recovery rate of 90.39%.

[0049] Example 2

[0050] 1054.63 g of crude DC (30% purity) containing solvent and impurities was added to a 2 L jacketed crystallizer and heated to 110 °C until completely dissolved. 5003 mg of crystallization directant methyltributylphosphine dibutylphosphonate and 534 mg of surfactant rhamnolipid were added. The temperature was lowered to 65 °C at a rate of 5 °C / h and maintained for 45 min to promote crystal growth; then the temperature was lowered to 25 °C at a rate of 12 °C / min and maintained for 30 min. The mixture was then filtered under vacuum at 30 kPaA. The filter cake was washed three times with 200 g of methyl isobutyl ketone and dried at 48 °C and 95 kPaA until its mass no longer changed. The resulting solid was 281.35 g of DC crystals with a purity of 99.67%, a KCl content of 8 ppm, and a crystallization yield of 88.63%. The filtrate without washing liquid was concentrated to 12% of its original volume at 70℃ and 22 kPaA. Then, in a distillation system with 10 theoretical plates, the fraction with a boiling point of 135℃ was collected under controlled pressure of 2 kPaA and a reflux ratio of 2:1. This fraction was KCl, totaling 5.72 g with a purity of 99.73% and a KCl recovery rate of 90.15%.

[0051] Example 3

[0052] 1037.11 g of crude DC (28% purity) containing solvent and impurities was added to a 2 L jacketed crystallizer and heated to 100 °C until completely dissolved. 2456 mg of crystallization directing agent 1-tert-butyl-3-methylimidazolium dibutylphosphonate and 2689 mg of surfactant rhamnolipid were added. The temperature was lowered to 70 °C at a rate of 1 °C / h and maintained for 45 min to promote crystal growth; then, the temperature was lowered to 22 °C at a rate of 13 °C / min and maintained for 30 min. The mixture was then filtered under vacuum at 40 kPaA. The filter cake was washed three times with 160 g of ethyl acetate and dried at 41 °C and 60 kPaA until its mass no longer changed. The resulting solid was 256.78 g of DC crystals, with a DC purity of 99.61%, a KCl content of 8 ppm, and a crystallization yield of 88.08%. The filtrate without washing liquid was concentrated to 21% of its original volume at 61℃ and 35 kPaA. Then, in a distillation system with 13 theoretical plates, the fraction with a boiling point of 140℃ was collected under controlled pressure of 4 kPaA and a reflux ratio of 1:1. This fraction was KCl, totaling 11.15 g with a purity of 99.69% and a KCl recovery rate of 89.31%.

[0053] Comparative Example 1

[0054] Compared with Example 1, the only difference is that only a crystal-directing agent is added; otherwise, it is the same as Example 1.

[0055] 1049.11 g of crude DC (25% purity) containing solvent and impurities was added to a 2 L jacketed crystallizer and heated to 95 °C until completely dissolved. 539 mg of the crystallization directing agent methyltributylphosphine dibutylphosphonate was added, and the temperature was lowered to 75 °C at a rate of 3 °C / h and maintained for 45 min to promote crystal growth; then, the temperature was lowered to 18 °C at a rate of 15 °C / min and maintained for 30 min. The mixture was then filtered under vacuum at 49 kPaA. The filter cake was washed twice with 123 g of toluene and dried at 30 °C and 10 kPaA until its mass no longer changed. The resulting solid was 215.17 g of DC crystals, with a DC purity of 95.13%, a KCl content of 875 ppm, and a crystallization yield of 78.04%. The filtrate without washing liquid was concentrated to 30% of its original volume at 50℃ and 50 kPaA. Then, in a distillation system with 15 theoretical plates, the boiling point of the fraction was collected at 135℃ under controlled pressure of 2 kPaA and reflux ratio of 1:2. This fraction was KCl, totaling 14.75 g with a purity of 90.19% and a KCl recovery rate of 74.59%.

[0056] Comparative Example 2

[0057] Comparative Example 2 is compared with Example 2, except that no crystal form inducing agent was added, otherwise it is the same as Example 2.

[0058] 1058.03 g of crude DC (30% purity) containing solvent and impurities was added to a 2 L jacketed crystallizer and heated to 110 °C until completely dissolved. 598 mg of the surfactant rhamnolipid was added, and the temperature was lowered to 65 °C at a rate of 5 °C / h and maintained for 45 min to promote crystal growth; then the temperature was lowered to 25 °C at a rate of 12 °C / min and maintained for 30 min. The mixture was then filtered under vacuum at 30 kPaA. The filter cake was washed three times with 205 g of methyl isobutyl ketone and dried at 48 °C and 95 kPaA until its mass no longer changed. The resulting solid was 266.49 g of DC crystals, with a DC purity of 94.62%, a KCl content of 913 ppm, and a crystallization yield of 79.44%. The filtrate without washing liquid was concentrated to 12% of its original volume at 70℃ and 22 kPaA. Then, in a distillation system with 10 theoretical plates, the fraction with a boiling point of 135℃ was collected under controlled pressure of 2 kPaA and a reflux ratio of 2:1. This fraction was KCl, totaling 5.22 g with a purity of 90.41% and a KCl recovery rate of 74.34%.

[0059] Comparative Example 3

[0060] Comparative Example 3 is compared with Example 3, except that no crystal form inducer was added, otherwise it is the same as Example 3.

[0061] 1041.76 g of crude DC (28% purity) containing solvent and impurities was added to a 2 L jacketed crystallizer and heated to 100 °C, maintaining the temperature until complete dissolution. The temperature was then lowered to 70 °C at a rate of 1 °C / h and maintained for 45 min to promote crystal growth; subsequently, the temperature was lowered to 22 °C at a rate of 13 °C / min and maintained for 30 min. The mixture was then filtered under vacuum at 40 kPaA. The filter cake was washed three times with 163 g of ethyl acetate and dried at 41 °C and 60 kPaA until its mass no longer changed. The resulting solid was 242.48 g of DC crystals with a purity of 90.31% and a KCl content of 1593 ppm, yielding a crystallization rate of 75.07%. Under these conditions, KCl could not be recovered.

[0062] Example and comparative data table:

[0063]

[0064] In summary, this invention patent incorporates crystallization additives—surfactants and crystal form inducers—during the crystallization process. By synergistically regulating the crystallization process with these two additives, the KCl impurity content in the crystalline DC is reduced to below 10 ppm, the DC purity is greater than 99.5%, and the recovery purity of the key byproduct KCl is greater than 99.5%, with a recovery rate greater than 89%.

Claims

1. A method for producing high-purity α,α'-dihydroxy-1,3-diisopropylbenzene DC while recovering 3-(2-hydroxyisopropyl)acetophenone KCL, characterized by, The method comprises the following steps: S1: crude DC is dissolved in a solvent to obtain a crystallization first mixture; S2: a surfactant and a crystal form guiding agent are added to the crystallization first mixture to obtain a crystallization second mixture; S3: the crystallization second mixture is subjected to gradient cooling crystallization purification of DC, and when the crystallization endpoint is reached, filtration, washing, and drying are performed, and a solid is a crystallization third mixture and a liquid is a crystallization fourth mixture; Optionally, S4: the crystallization fourth mixture is concentrated and rectified to obtain a rectification first mixture KCL.

2. The method of claim 1, wherein, In S1, the solvent is a polar solvent, preferably one or more of methyl isobutyl ketone, toluene, and ethyl acetate; In the crystallization first mixture of S1, the effective concentration of DC is 25wt%-30wt%; In the crystallization first mixture of S1, the content of KCL is 0.5wt%-2wt%, the content of heavy components is 1wt%-2wt%, and the content of water is 1wt%-2wt%, based on the total mass of the mixture; In S1, the temperature is 90°C-110°C.

3. The method of claim 1, wherein, In S2, the crystal form guiding agent comprises an alkyl phosphonic acid salt with steric hindrance, preferably one or more of 1-butyl-3-methylimidazolium dibutyl phosphonate, 1-tert-butyl-3-methylimidazolium dibutyl phosphonate, methyl tributyl phosphonium dibutyl phosphonate, and methyl triisopropyl phosphonium dibutyl phosphonate, and more preferably methyl tributyl phosphonium dibutyl phosphonate; In S2, the surfactant comprises a natural glycolipid and / or a synthetic glycolipid, preferably one or more of rhamnolipid, sophorolipid, acetylated sophorolipid, trehalose lipid, and alkylated sophorolipid, and more preferably acetylated sophorolipid; In S2, the total w / w concentration of the crystal form guiding agent and the surfactant is 0.002%-2%, preferably 0.05%-0.5%; In S2, the mass ratio of the crystal form guiding agent to the surfactant is 10:1-1:10; In S2, the initial crystallization temperature interval is 90°C-110°C.

4. The method of claim 1, wherein, In S3, the gradient cooling comprises a primary nucleation stage and a secondary growth stage; In the primary nucleation stage, the cooling rate is 1-5°C / h, and the cooling interval is 90°C-110°C; In the secondary growth stage, the cooling rate is 12-15°C / h, and the cooling interval is 65°C-75°C; In S3, the crystallization endpoint temperature is 18-25°C; In S3, the negative pressure of the filtration is 30kpaA-50kpaA; In S3, the solvent used for the washing is a moderately polar solvent, preferably one or more of methyl isobutyl ketone, toluene, and ethyl acetate; Preferably, the solvent used for the washing is used in an amount of 30%-50% of the mass of the wet filter cake, and the washing is performed 1-3 times; In S3, the drying temperature is 30-50°C, and the drying pressure is 10kpaA-100kpaA.

5. The method of claim 1, wherein, In S4, the concentration temperature is 50-70°C, and the pressure is 20kpaA-50kpaA; In S4, the concentration is performed to 10%-30% of the original volume; In S4, the theoretical plate number of the rectification is 10-15, the rectification pressure is 2kpaA-20kpaA, and the reflux ratio is 1:2-2:

1.

6. Use of a process for the preparation of high purity α,α'-dihydroxy-1,3-diisopropylbenzene DC with simultaneous recovery of 3-(2-hydroxyisopropyl)acetophenone KCL, said process being the process according to any one of claims 1 to 5, for a process for the preparation of high purity α,α'-dihydroxy-1,3-diisopropylbenzene with simultaneous recovery of 3-(2-hydroxyisopropyl)acetophenone.

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