CN117986104A - Crystallization method of 1, 3-cyclohexanedione - Google Patents
Crystallization method of 1, 3-cyclohexanedione Download PDFInfo
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- CN117986104A CN117986104A CN202410164482.8A CN202410164482A CN117986104A CN 117986104 A CN117986104 A CN 117986104A CN 202410164482 A CN202410164482 A CN 202410164482A CN 117986104 A CN117986104 A CN 117986104A
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- cyclohexanedione
- protonic acid
- sodium salt
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- 238000002425 crystallisation Methods 0.000 title claims abstract description 47
- HJSLFCCWAKVHIW-UHFFFAOYSA-N cyclohexane-1,3-dione Chemical compound O=C1CCCC(=O)C1 HJSLFCCWAKVHIW-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 239000002253 acid Substances 0.000 claims abstract description 41
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 40
- 230000008025 crystallization Effects 0.000 claims abstract description 38
- 239000007864 aqueous solution Substances 0.000 claims abstract description 33
- KYIBHFNJISEQRB-UHFFFAOYSA-N cyclohexane-1,3-dione;sodium Chemical compound [Na].O=C1CCCC(=O)C1 KYIBHFNJISEQRB-UHFFFAOYSA-N 0.000 claims abstract description 27
- 238000001816 cooling Methods 0.000 claims abstract description 24
- 159000000000 sodium salts Chemical class 0.000 claims abstract description 21
- 238000003756 stirring Methods 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 17
- 239000007788 liquid Substances 0.000 claims abstract description 16
- 230000003068 static effect Effects 0.000 claims abstract description 14
- 238000001035 drying Methods 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 8
- 239000000498 cooling water Substances 0.000 claims description 13
- 238000002386 leaching Methods 0.000 claims description 11
- 239000002002 slurry Substances 0.000 claims description 9
- 238000004321 preservation Methods 0.000 claims description 7
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 6
- 229910017604 nitric acid Inorganic materials 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 6
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 claims description 4
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 2
- 239000013078 crystal Substances 0.000 abstract description 8
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 239000012535 impurity Substances 0.000 abstract description 3
- 238000009776 industrial production Methods 0.000 abstract description 3
- 238000005265 energy consumption Methods 0.000 abstract 1
- 238000002347 injection Methods 0.000 abstract 1
- 239000007924 injection Substances 0.000 abstract 1
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 24
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 8
- WQDUMFSSJAZKTM-UHFFFAOYSA-N Sodium methoxide Chemical compound [Na+].[O-]C WQDUMFSSJAZKTM-UHFFFAOYSA-N 0.000 description 8
- 238000002360 preparation method Methods 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 239000000243 solution Substances 0.000 description 6
- 239000003795 chemical substances by application Substances 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- AVVPOKSKJSJVIX-UHFFFAOYSA-N methyl 5-oxohexanoate Chemical compound COC(=O)CCCC(C)=O AVVPOKSKJSJVIX-UHFFFAOYSA-N 0.000 description 4
- 230000020477 pH reduction Effects 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000011780 sodium chloride Substances 0.000 description 4
- 239000005578 Mesotrione Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- KPUREKXXPHOJQT-UHFFFAOYSA-N mesotrione Chemical compound [O-][N+](=O)C1=CC(S(=O)(=O)C)=CC=C1C(=O)C1C(=O)CCCC1=O KPUREKXXPHOJQT-UHFFFAOYSA-N 0.000 description 2
- 239000005618 Sulcotrione Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229940035676 analgesics Drugs 0.000 description 1
- 239000000730 antalgic agent Substances 0.000 description 1
- 239000003416 antiarrhythmic agent Substances 0.000 description 1
- 239000002111 antiemetic agent Substances 0.000 description 1
- 239000003420 antiserotonin agent Substances 0.000 description 1
- 229940127217 antithrombotic drug Drugs 0.000 description 1
- NPAKNKYSJIDKMW-UHFFFAOYSA-N carvedilol Chemical compound COC1=CC=CC=C1OCCNCC(O)COC1=CC=CC2=NC3=CC=C[CH]C3=C12 NPAKNKYSJIDKMW-UHFFFAOYSA-N 0.000 description 1
- 229960004195 carvedilol Drugs 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 239000004009 herbicide Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- -1 material monomers Chemical class 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 239000012450 pharmaceutical intermediate Substances 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000001226 reprecipitation Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- PQTBTIFWAXVEPB-UHFFFAOYSA-N sulcotrione Chemical compound ClC1=CC(S(=O)(=O)C)=CC=C1C(=O)C1C(=O)CCCC1=O PQTBTIFWAXVEPB-UHFFFAOYSA-N 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000012873 virucide Substances 0.000 description 1
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a crystallization method of 1, 3-cyclohexanedione, which belongs to the technical field of crystallization, and comprises the steps of adding a part of protonic acid into a crystallization kettle in advance, stirring and cooling; then the residual protonic acid is quickly and evenly mixed with 1, 3-cyclohexanedione sodium salt aqueous solution in a static mixer; finally, injecting the mixed feed liquid into a crystallization kettle with protonic acid, cooling, growing crystals, and centrifugally drying; according to the invention, most of the protonic acid is mixed with the sodium salt aqueous solution through the static mixer, so that the production efficiency is improved; the rapid mixing and the direct injection of the mixed feed liquid into the residual hydrochloric acid prevent the 1, 3-cyclohexanedione from staying for a long time in an unstable pH region and inhibit the generation of impurities; the method has the advantages of high crystallization efficiency, high purity of the crystallized product, large granularity of the crystals, simple and convenient operation, low energy consumption and suitability for industrial production.
Description
Technical Field
The invention belongs to the technical field of crystallization, and particularly relates to a crystallization method of 1, 3-cyclohexanedione.
Background
1, 3-Cyclohexanedione is a very important pharmaceutical intermediate and can be used for preparing antiarrhythmic drugs, antithrombotic drugs carvedilol, antiemetic drugs anthracenexel, analgesics, virucides, 5-HT antagonists, herbicides sulcotrione and mesotrione, mesotrione and other pesticides. Meanwhile, the 3-cyclohexanedione is an important fine chemical product and can be used for synthesizing various organic compounds such as material monomers, curing agents, solvents and the like.
The crystallization technology adopted at present mainly comprises the steps of adding acid drop into 1, 3-cyclohexanedione sodium salt aqueous solution, cooling to 0-5 ℃ for crystal growth and centrifuging. In the patent CN1275922C, a 50 ℃ sodium salt aqueous solution is transferred into a container, concentrated hydrochloric acid is added dropwise under stirring, acidification is carried out at room temperature, the reaction solution is cooled to 0-5 ℃, and crystallization, filtration and drying are carried out. The acidification step of the patent application CN 106083545A is divided into two stages, wherein the first stage is to dropwise add hydrochloric acid, and the temperature is controlled to be 20-25 ℃; the second stage is cooling crystallization, and the temperature is reduced from 20 ℃ to 5-10 ℃. The patent application CN110818540A drops hydrochloric acid into the sodium salt aqueous solution, the reaction temperature is controlled to be 25-30 ℃, the pH is controlled to be 2-2.5 as the end point, the temperature is reduced to be 0-5 ℃, the temperature is kept for 5-6 h, and the mixture is centrifugally dried after acidification rearrangement.
However, the existing technology mainly has the following problems: the acid dripping time is too long, and the production efficiency is low; the acid of the feed liquid is regulated from a strong alkali environment to an acid environment, and the feed liquid is subjected to a buffer interval with a long-time pH value of 3-7, and a 1, 3-cyclohexanedione product is unstable in the buffer interval and is easy to generate polymeric impurities (the structural formula is shown below), so that the product quality is influenced; the crystallization temperature is higher, and the crystallization rate is lower.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a crystallization method of 1, 3-cyclohexanedione. The method can solve the problems of long production period, low crystallization yield, poor product quality and the like caused by long-time acidification, and is suitable for industrial production.
The invention aims to achieve the aim, and the aim is achieved by the following technical scheme:
a method for crystallizing 1, 3-cyclohexanedione, comprising the steps of:
1) The temperature of the aqueous solution of protonic acid and 1, 3-cyclohexanedione sodium salt is reduced to 10-20 ℃ in advance;
The protonic acid is hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid or perchloric acid;
the mass concentration of the 1, 3-cyclohexanedione sodium salt aqueous solution is 15-40%;
The molar ratio of the protonic acid to the sodium salt in the 1, 3-cyclohexanedione sodium salt aqueous solution is 1: 1-1.2;
2) Dividing the protonic acid subjected to cooling treatment in the step 1) into two parts, wherein the first part of protonic acid is added into a crystallization kettle, and cooling to-15 ℃ under stirring at 20-200 r/min; introducing the second part of protonic acid and the 1, 3-cyclohexanedione sodium salt aqueous solution subjected to cooling treatment in the step 1) into a static mixer, and uniformly mixing to obtain mixed feed liquid;
the first part of protonic acid is 30-70% of the total amount of the required protonic acid;
The second part of protonic acid and the 1, 3-cyclohexanedione sodium salt aqueous solution subjected to cooling treatment are simultaneously introduced into a static mixer, and the total time for introduction is 0.1 min-24 h;
3) Introducing the mixed feed liquid obtained in the step 2) into a crystallization kettle with protonic acid, and cooling to-15 to-5 ℃ under stirring at 100-800 r/min; and (3) preserving heat for 0.5-24 h, centrifuging the obtained slurry after the heat preservation is finished, leaching the obtained solid for 2-3 times by using cooling water, and drying to obtain the 1, 3-cyclohexanedione.
Preferably, the protonic acid in step 1) is hydrochloric acid.
Preferably, in the step 1), the mass concentration of the 1, 3-cyclohexanedione sodium salt aqueous solution is 25-35%.
Preferably, in the step 2), the first part of protonic acid is 50-70% of the total amount of the required protonic acid.
Preferably, in the step 2), the temperature is reduced under 50-100 r/min of stirring.
Preferably, in the step 3), the temperature is reduced to-10 to-5 ℃ under the stirring of 200-500 r/min.
Preferably, the heat preservation in the step 3) is carried out for 1-3 hours.
The temperature of the cooling water in the step 3) is 0-5 ℃, and the leaching amount of the cooling water is 5-30% of the total amount of the protonic acid.
And 3) the pH value of the slurry in the step 3) is 0.5-2.
Preferably, the leaching amount of the cooling water in the step 3) is 5-15% of the total amount of the protonic acid.
Compared with the prior art, the invention has the following advantages:
The crystallization method of 1, 3-cyclohexanedione of the invention divides the protonic acid into two parts, and uses firstly
Injecting 30-70% of the total acid into a static mixer to be mixed with 1, 3-cyclohexanedione sodium salt aqueous solution, so as to ensure that 1, 3-cyclohexanedione is not crystallized in the static mixer and avoid the consequences such as blockage; meanwhile, the static mixer is used for rapid mixing, so that the 1, 3-cyclohexanedione is further prevented from staying in an unstable pH range (pH is 3-7) for a long time, the generation of polymerization impurities is inhibited, and the purity of the product is improved.
According to the crystallization method of 1, 3-cyclohexanedione, part of protonic acid is added into a crystallization kettle in advance
And the mixed solution discharged from the static mixer is directly injected into a crystallization kettle to form a crystallization process of precipitation, dissolution and re-precipitation, so that the precipitated product has large particles, crystal types and high product quality.
According to the crystallization method of 1, 3-cyclohexanedione, crystallization is carried out at a lower temperature (-15 to-5 ℃) under the condition that slurry is not frozen, and the crystallization rate and the product yield are improved.
The crystallization method of the 1, 3-cyclohexanedione is suitable for laboratories and industrial production, has the characteristics of high crystallization efficiency, high yield and good quality of crystallization products, and is simple to operate, mild in process, low in production cost and environment-friendly.
Detailed Description
The foregoing is further elaborated by the following description of embodiments of the present invention, which are given by way of example only, and should not be construed as limiting the scope of the present invention. All techniques implemented based on the above description of the invention are within the scope of the invention.
Example 1 preparation of sodium 1, 3-cyclohexanedione aqueous salt solution:
Methyl 5-oxo-hexanoate (1.77 kg of feed) is taken as a raw material, sodium methoxide is taken as a condensing agent, and methanol is taken as a solvent to prepare a1, 3-cyclohexanedione sodium salt alcohol solution, wherein the sodium salt content is 20%. After methanol was distilled off, water was added to prepare a sodium salt aqueous solution having a sodium salt concentration of 30%.
Preparation of 1, 3-cyclohexanedione:
1.42kg of hydrochloric acid with the mass concentration of 31% and 1, 3-cyclohexanedione sodium salt aqueous solution with the mass concentration of 30% are cooled to 15 ℃ in advance; adding 0.57kg of 31% hydrochloric acid into a crystallization kettle, and cooling to 0 ℃ under stirring at 80 r/min; introducing the rest 0.85kg of 31% hydrochloric acid and 5.4kg of 1, 3-cyclohexanedione sodium salt aqueous solution into a static mixer at the speed of 28.5g/min and 180g/min respectively, uniformly mixing to obtain mixed liquid, introducing the obtained mixed liquid into a crystallization kettle with hydrochloric acid, and cooling to-10 ℃ under 300r/min stirring; preserving heat for 1h, after the heat preservation is finished, the pH value of the obtained slurry is 1.65, centrifuging, leaching the obtained solid for 2 times by using 0.15kg of cooling water (4 ℃), and drying to obtain 1.3kg of 1, 3-cyclohexanedione product, wherein the sodium chloride content is 0.21%, and the water content is 0.14%. The crystallization product has white color, good crystal form and one-time crystallization rate of 94.5 percent.
Example 2 preparation of 1, 3-cyclohexanedione sodium salt aqueous solution:
Methyl 5-oxo-hexanoate (2.93 kg of the feed) is taken as a raw material, sodium methoxide is taken as a condensing agent, and methanol is taken as a solvent to prepare a1, 3-cyclohexanedione sodium salt alcohol solution, wherein the sodium salt content is 20%. After methanol was distilled off, water was added to prepare a sodium salt aqueous solution having a sodium salt concentration of 28%.
Preparation of 1, 3-cyclohexanedione:
2.36kg of hydrochloric acid with the mass concentration of 31% and 1, 3-cyclohexanedione sodium salt aqueous solution with the mass concentration of 28% are cooled to 10 ℃ in advance; adding 0.71kg of 31% hydrochloric acid into a crystallization kettle, and cooling to-15 ℃ under stirring at 20 r/min; introducing the rest 1.65 kg of 31% hydrochloric acid and 9.6kg of 1, 3-cyclohexanedione sodium salt aqueous solution into a static mixer at the speed of 52g/min and 300g/min respectively, uniformly mixing to obtain mixed feed liquid, introducing the obtained mixed feed liquid into a crystallization kettle with hydrochloric acid, and cooling to-15 ℃ under stirring at 100 r/min; preserving heat for 0.5h, after the heat preservation is finished, the pH value of the obtained slurry is 1.2, centrifuging, leaching the obtained solid for 3 times by using 0.12kg of cooling water (0 ℃), and drying to obtain 2.1kg of 1, 3-cyclohexanedione product, wherein the sodium chloride content is 0.37% and the water content is 0.18%. The crystallization product has white color, good crystal form and one-time crystallization rate of 92.3 percent.
Example 3 preparation of 1, 3-cyclohexanedione sodium salt aqueous solution:
Methyl 5-oxo-hexanoate (2.73 kg of feed) is used as a raw material, sodium methoxide is used as a condensing agent, and methanol is used as a solvent to prepare a1, 3-cyclohexanedione sodium salt alcohol solution, wherein the sodium salt content is 20%. After methanol was distilled off, water was added to prepare a sodium salt aqueous solution having a sodium salt concentration of 34%.
Preparation of 1, 3-cyclohexanedione:
2.86kg of hydrochloric acid with the mass concentration of 31% and 1, 3-cyclohexanedione sodium salt aqueous solution with the mass concentration of 34% are cooled to 16 ℃ in advance; adding 1.43kg of 31% hydrochloric acid into a crystallization kettle, and cooling to 10 ℃ under stirring at 100 r/min; introducing the rest 1.43kg of 31% hydrochloric acid and 9.6kg of 1, 3-cyclohexanedione sodium salt aqueous solution into a static mixer at the speed of 71.5g/min and 480g/min respectively, uniformly mixing to obtain mixed liquid, introducing the obtained mixed liquid into a crystallization kettle with hydrochloric acid, and cooling to-8 ℃ under 300r/min stirring; and (3) preserving heat for 2 hours, after the heat preservation is finished, the pH value of the obtained slurry is 1.96, centrifuging, leaching the obtained solid for 3 times by using 0.43kg of cooling water (2 ℃), and drying to obtain 2.0kg of 1, 3-cyclohexanedione product, wherein the sodium chloride content is 0.15% and the water content is 0.12%. The crystallization product has white color, good crystal form and one-time crystallization rate of 95.0 percent.
Example 4 preparation of 1, 3-cyclohexanedione sodium salt aqueous solution:
Methyl 5-oxo-hexanoate (1.95 kg of feed) is taken as a raw material, sodium methoxide is taken as a condensing agent, and methanol is taken as a solvent to prepare a1, 3-cyclohexanedione sodium salt alcohol solution, wherein the sodium salt content is 20%. After methanol was distilled off, water was added to prepare a sodium salt aqueous solution having a sodium salt concentration of 25%.
Preparation of 1, 3-cyclohexanedione:
1.55kg of nitric acid with the mass concentration of 31% and 1, 3-cyclohexanedione sodium salt aqueous solution with the mass concentration of 25% are cooled to 20 ℃ in advance; adding 0.6kg of 31% nitric acid into a crystallization kettle, and cooling to 15 ℃ under stirring at 200 r/min; introducing the rest 0.95 kg of 31% nitric acid and 7.2kg of 1, 3-cyclohexanedione sodium salt aqueous solution into a static mixer at the speed of 26.4g/min and 200g/min respectively, uniformly mixing to obtain mixed liquid, introducing the obtained mixed liquid into a crystallization kettle with nitric acid, and cooling to-5 ℃ under 800r/min stirring; and (3) preserving heat for 24 hours, after the heat preservation is finished, the pH of the obtained slurry is 2, centrifuging, leaching the obtained solid for 3 times by using 0.46kg of cooling water (5 ℃), and drying to obtain 1.4kg of 1, 3-cyclohexanedione product, wherein the sodium chloride content is 0.22% and the water content is 0.22%. The crystallization product has white color, good crystal form and one-time crystallization rate of 92.0 percent.
While the foregoing describes the embodiments of the present invention, it is not intended to limit the scope of the present invention, and various modifications or variations may be made by those skilled in the art without the need for inventive effort on the basis of the technical solutions of the present invention.
Claims (10)
1. A method for crystallizing 1, 3-cyclohexanedione, characterized by: the method comprises the following steps:
1) The temperature of the aqueous solution of protonic acid and 1, 3-cyclohexanedione sodium salt is reduced to 10-20 ℃ in advance;
The protonic acid is hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid or perchloric acid;
the mass concentration of the 1, 3-cyclohexanedione sodium salt aqueous solution is 15-40%;
The molar ratio of the protonic acid to the sodium salt in the 1, 3-cyclohexanedione sodium salt aqueous solution is 1: 1-1.2;
2) Dividing the protonic acid subjected to cooling treatment in the step 1) into two parts, wherein the first part of protonic acid is added into a crystallization kettle, and cooling to-15 ℃ under stirring at 20-200 r/min; introducing the second part of protonic acid and the 1, 3-cyclohexanedione sodium salt aqueous solution subjected to cooling treatment in the step 1) into a static mixer, and uniformly mixing to obtain mixed feed liquid;
The first part of protonic acid is 30-70% of the total amount of protonic acid;
The second part of protonic acid and the 1, 3-cyclohexanedione sodium salt aqueous solution subjected to cooling treatment are simultaneously introduced into a static mixer, and the total time for introduction is 0.1 min-24 h;
3) Introducing the mixed feed liquid obtained in the step 2) into a crystallization kettle with protonic acid, and cooling to-15 to-5 ℃ under stirring at 100-800 r/min; and (3) preserving heat for 0.5-24 h, centrifuging the obtained slurry after the heat preservation is finished, leaching the obtained solid for 2-3 times by using cooling water, and drying to obtain the 1, 3-cyclohexanedione.
2. The method for crystallizing 1, 3-cyclohexanedione as claimed in claim 1, wherein: the protonic acid in the step 1) is hydrochloric acid.
3. The method for crystallizing 1, 3-cyclohexanedione as claimed in claim 1, wherein: and in the step 1), the mass concentration of the 1, 3-cyclohexanedione sodium salt aqueous solution is 25-35%.
4. The method for crystallizing 1, 3-cyclohexanedione as claimed in claim 1, wherein: the first part of protonic acid in the step 2) is 50-70% of the total amount of the required protonic acid.
5. The method for crystallizing 1, 3-cyclohexanedione as claimed in claim 1, wherein: and in the step 2), cooling under stirring at 50-100 r/min.
6. The method for crystallizing 1, 3-cyclohexanedione as claimed in claim 1, wherein: and in the step 3), cooling to-10 to-5 ℃ under stirring at 200-500 r/min.
7. The method for crystallizing 1, 3-cyclohexanedione as claimed in claim 1, wherein: and 3) preserving heat for 1-3 hours in the step 3).
8. The method for crystallizing 1, 3-cyclohexanedione as claimed in claim 1, wherein: the temperature of the cooling water in the step 3) is 0-5 ℃, and the leaching amount of the cooling water is 5-30% of the total amount of the protonic acid.
9. The method for crystallizing 1, 3-cyclohexanedione as claimed in claim 1, wherein: and 3) the pH value of the slurry in the step 3) is 0.5-2.
10. The method for crystallizing 1, 3-cyclohexanedione as claimed in claim 1, wherein: and 3) leaching the cooling water, wherein the leaching dosage of the cooling water is 5-15% of the total amount of the protonic acid.
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