Continuous washing method of pesticide intermediate and application

Abstract

The invention discloses a continuous washing method of a pesticide intermediate, which comprises the following steps: S1, mixing and dissolving the pesticide intermediate and an organic solvent to obtain an intermediate solution; s2, feeding an intermediate solution, carrying out three-stage continuous series extraction, and enabling a lower-layer heavy phase obtained after extraction separation to enter an extraction water phase tank; and S3, continuously performing centrifugal extraction on the extracted and separated upper-layer light phase, performing reverse acid pickling on the acid solution and the upper-layer light phase, and performing two-stage acid pickling to realize separation of the light phase and the heavy phase. After kettle type intermittent extraction layering is changed into continuous extraction, program control can be achieved, workers only need to itinerate regularly, and the workload of the workers is reduced. And meanwhile, subjective misjudgment caused by layering judgment by naked eyes of personnel is avoided. The method reduces the production loss, reduces the COD value of the wastewater, avoids the use of dichloromethane or trichloromethane in the traditional process, and is green and environment-friendly in process.

Description

Technical Field

[0001] This invention relates to the field of separation methods, specifically to a continuous water washing method for pesticide intermediates and its application. Background Technology

[0002] In the separation and purification stages of pesticide intermediates during production, static settling is required. However, in large-scale factory production, this process takes a considerable amount of time, and the manual determination of the separation interface by operators is subjective and prone to batch-to-batch variations, leading to inconsistent product quality. Therefore, developing a method for the efficient separation, purification, and washing of pesticide intermediates is crucial.

[0003] Chinese invention patent CN109705184B discloses a continuous method for extracting high-purity cholesterol from fish oil residue. The method involves countercurrent extraction of a saponified liquid using a mixed solvent of n-heptane and ethyl acetate in a multi-stage series centrifugal extractor to obtain an extract. The extract is then countercurrently washed in the multi-stage series centrifugal extractor with a mixed solvent of water, methanol, and acetic acid. This continuous extraction of fish oil residue using a multi-stage series centrifugal extractor produces high-purity cholesterol with good separation efficiency and high product purity. However, the flow rate of the feed liquid is relatively small, making it unsuitable for mass production in the chemical industry. Chinese utility model patent CN219072137U discloses a continuous extraction device for dimethyl 3-methylpentadecanedioic acid. This device uses multiple centrifugal extractors for continuous extraction instead of the current intermittent extraction method with static stratification in extraction tanks. This reduces the residual amount of dimethyl 3-methylpentadecanedioic acid in the wastewater after extraction, significantly saves extraction time, improves production efficiency, and achieves continuous and automated production. However, the final product contains a high amount of salt, resulting in low purity of the separated product. Summary of the Invention

[0004] To develop a method for the efficient separation, purification, and water washing of pesticide intermediates, a first aspect of the present invention provides a continuous water washing method for pesticide intermediates, comprising the following steps:

[0005] S1: Mix and dissolve the pesticide intermediate with an organic solvent to obtain an intermediate solution;

[0006] S2: The intermediate solution is subjected to three-stage continuous series centrifugal extraction, and the lower heavy phase after extraction and separation enters the extraction aqueous phase tank.

[0007] S3: After extraction and separation, the upper light phase is further centrifuged and extracted. The acid solution and the upper light phase are then reverse-biased for acid washing. After two stages of acid washing, the light and heavy phases are separated.

[0008] As one embodiment, the pesticide intermediate includes, but is not limited to, at least one of the following: N-methyl-N-isopropylsulfonic acid (an intermediate for pyrimisulfonamide), diacetic acid monochloroamine (an intermediate for acetochlor), methyl isocyanate (an intermediate for prothioconazole), and phenoxyacetic acid (an intermediate for 2,4-D herbicides).

[0009] In one embodiment, the flow rate of the intermediate solution in step S2 during three-stage continuous series centrifugal extraction is 180-350 L / h.

[0010] In one embodiment, the flow rate of the intermediate solution in step S2 during three-stage continuous series centrifugal extraction is 200-300 L / h.

[0011] In one embodiment, the flow rate of the intermediate solution in step S2 during the three-stage continuous series centrifugal extraction is 270 L / h.

[0012] In one embodiment, the centrifugal extraction frequency is 35-45 Hz.

[0013] In one embodiment, the centrifugal extraction frequency is 40 Hz.

[0014] In one embodiment, the mass concentration of the acid solution is 1-5 wt%.

[0015] In one embodiment, the mass concentration of the acid solution is 2-4 wt%.

[0016] In one embodiment, the mass concentration of the acid solution is 3 wt%.

[0017] In one embodiment, the flow rate ratio of the acid solution to the upper light phase in step S3 is (540-1000):(180-350).

[0018] In one embodiment, the flow rate ratio of the acid solution to the upper light phase in step S3 is (600-900):(200-300).

[0019] In one embodiment, the flow ratio of the acid solution to the oil phase in step S3 is 810:270.

[0020] In one embodiment, the acid solution includes, but is not limited to, at least one of hydrochloric acid solution, sulfuric acid solution, nitric acid solution, chloric acid solution or bromic acid solution.

[0021] As one implementation method, the two-stage pickling time is 20-60 minutes.

[0022] In one implementation, the two-stage pickling time is 20-45 minutes.

[0023] In one implementation, the two-stage pickling time is 27 minutes.

[0024] During the experiment, the inventors discovered that the intermediate phase in the extraction process contains a large amount of potassium carbonate, which has low solubility in the heavy phase and does not easily enter the lower heavy phase, thus hindering the separation of the light and heavy phases. This invention introduces an acid solution to convert the carbonate into a highly soluble salt, promoting the entry of the salt into the lower heavy phase and thereby improving the extraction and separation effect.

[0025] In one implementation, the total time for centrifugal extraction in steps S2 and S3 is 40-50 hours.

[0026] In one implementation, the total time for centrifugal extraction in steps S2 and S3 is 48 hours.

[0027] In one embodiment, the organic solvent is at least one of ketone solvents or ester solvents.

[0028] In one embodiment, the ketone solvent includes, but is not limited to, at least one of acetone, methyl isobutyl ketone, cyclohexanone, methyl ethyl ketone, diisobutyl ketone, or dipentanone.

[0029] In one embodiment, the ester solvent includes, but is not limited to, at least one of ethyl acetate, butyl acetate, isopropyl acetate, methyl propionate, ethyl butyrate, ethyl propionate, or propyl acetate.

[0030] In one embodiment, the organic solvent is added intermittently, and the amount of organic solvent added is 2m. 3 / 8h.

[0031] In one embodiment, after step S3, the moisture content in the light phase is 0.1-1.5 wt%, and the organic solvent content in the heavy phase is 0.01-0.1 wt%.

[0032] This invention involves mixing and dissolving organic solvents in a washing vessel with pesticide intermediates in an intermediate storage tank, then sequentially feeding the mixture into a primary centrifugal extractor, a secondary centrifugal extractor, and a tertiary centrifugal extractor. After the tertiary centrifugal extractor, the upper light phase enters a quaternary centrifugal extractor, while the lower heavy phase enters an aqueous extraction tank. The acid solution in a dilute hydrochloric acid tank undergoes a quintuple centrifugal extractor, where it is counter-currently acid-washed with the upper light phase. This process is then repeated through the quintuple centrifugal extractor, achieving separation of the light and heavy phases. The light phase then enters an oil extraction tank.

[0033] This invention's continuous water washing process for pesticide intermediates avoids the use of dichloromethane as the extractant in centrifugal extractors. Instead, the light and heavy phases are directly separated in a centrifugal extractor through three stages to obtain a lighter extractant with relatively low water content. Simultaneously, 3% dilute hydrochloric acid is introduced at the end of the centrifugal extractor for automatic acid washing of the light phase. The wastewater after washing is drawn from between the third and fourth centrifugal extractors to the aqueous phase extraction tank, while the oil phase is drawn from the fifth centrifugal extractor to the oil phase extraction tank for settling and later use.

[0034] This scheme achieves automated and continuous operation of the water washing and acid washing steps of the intermediate through multi-stage series centrifugal extractors, avoiding the use of dichloromethane or trichloromethane as the extractant in traditional processes.

[0035] The second aspect of the present invention provides an application of a continuous water washing method for pesticide intermediates, which is applied to the industrial separation of pesticide intermediates.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The continuous water washing method for pesticide intermediates described in this invention, after changing from batch extraction to continuous extraction, can achieve program control, and staff only need to conduct regular inspections, reducing the workload of personnel. At the same time, it avoids subjective misjudgment caused by personnel visually judging the layering.

[0038] (2) The continuous water washing method for pesticide intermediates described in this invention, after changing the batch extraction layering method to continuous extraction, can avoid subjective misjudgment caused by personnel visually judging the layering. Compared with the traditional process, the yield loss is reduced from 2% to 0.1%.

[0039] (3) The continuous water washing method for pesticide intermediates described in this invention improves the quality of the oil phase, reduces the water content in the oil phase, and increases the yield of pesticide intermediates in the oil phase through three-stage continuous centrifugal extraction and two-stage centrifugal acid washing extraction.

[0040] (4) The continuous water washing method for pesticide intermediates described in this invention adds an acid washing step after continuous centrifugal extraction, which reduces the COD value of wastewater from 31,000 ppm in the traditional process to 17,000 ppm, resulting in better environmental protection.

[0041] (5) The continuous water washing method for pesticide intermediates described in this invention achieves automatic and continuous operation of the water washing and acid washing steps of intermediates through multi-stage series centrifugal extraction, avoiding the use of dichloromethane or trichloromethane in the traditional process, and the process is green and environmentally friendly. Attached Figure Description

[0042] Figure 1 This is a flowchart of the apparatus for continuous water washing of pesticide intermediates in Embodiment 1 of the present invention.

[0043] In the diagram: 1. Washing vessel; 2. Intermediate storage tank; 3. First-stage centrifugal extractor; 4. Second-stage centrifugal extractor; 5. Third-stage centrifugal extractor; 6. Fourth-stage centrifugal extractor; 7. Fifth-stage centrifugal extractor; 8. Aqueous phase extraction tank; 9. Dilute hydrochloric acid tank; 10. Oil phase extraction tank; 11. Heavy phase outlet; 12. Light phase outlet; 13. Heavy phase inlet; 14. Light phase inlet. Detailed Implementation

[0044] Example 1

[0045] A continuous water washing method for pesticide intermediates includes the following steps:

[0046] S1: Mix and dissolve the pesticide intermediate with an organic solvent to obtain an intermediate solution;

[0047] S2: The intermediate solution is subjected to three-stage continuous series centrifugal extraction, and the lower heavy phase after extraction and separation enters the extraction aqueous phase tank.

[0048] S3: The upper light phase after separation is further centrifuged and extracted. The acid solution and the upper light phase are then reverse-biased for acid washing. After two stages of acid washing, the light and heavy phases are separated.

[0049] See the device flow chart. Figure 1 In this invention, the organic solvent in the washing vessel 1 is mixed and dissolved with the pesticide intermediate in the intermediate storage tank 2. The mixture then sequentially enters a primary centrifugal extractor 3, a secondary centrifugal extractor 4, a tertiary centrifugal extractor 5, and so on, through the light phase inlet 14. The upper light phase from the tertiary centrifugal extractor 5 enters a quaternary centrifugal extractor 6, while the lower heavy phase enters an aqueous extraction tank 8 through the heavy phase outlet 11. The acid solution in the dilute hydrochloric acid tank 9 enters a quinary centrifugal extractor 7 through the heavy phase inlet 13, where it undergoes a counter-current acid wash with the upper light phase. The mixture then passes through the quinary centrifugal extractor 7, achieving separation of the light and heavy phases. The light phase then enters an oil extraction tank 10 through the light phase outlet 12.

[0050] The pesticide intermediate is N-methyl-N-isopropylsulfonic acid, an intermediate of pyrimisulfonamide.

[0051] In step S2, the flow rate for the intermediate solution during three-stage continuous series centrifugal extraction is 180 L / h.

[0052] The centrifugal extraction frequency is 40 Hz.

[0053] The acid solution has a mass concentration of 3 wt%, and the acid solution is a hydrochloric acid solution.

[0054] In step S3, the flow rate of the acid solution is 540 L / h.

[0055] The two-stage pickling time is 41 minutes.

[0056] The total time for centrifugal extraction in steps S2 and S3 is 48 hours.

[0057] The organic solvent is methyl isobutyl ketone.

[0058] The organic solvent is added intermittently, and the amount of organic solvent added is 2m. 3 / 8h.

[0059] Example 2

[0060] A continuous water washing method for pesticide intermediates, the specific implementation method is the same as in Example 1, except that the flow rate is 270 L / h when the intermediate solution is subjected to three-stage continuous series centrifugal extraction in step S2.

[0061] The centrifugal extraction frequency is 40 Hz.

[0062] The acid solution has a mass concentration of 3 wt%, and the acid solution is a hydrochloric acid solution.

[0063] The flow rate of the acid solution in step S3 is 810 L / h.

[0064] The two-stage pickling time is 27 minutes.

[0065] The total time for centrifugal extraction in steps S2 and S3 is 48 hours.

[0066] The organic solvent is methyl isobutyl ketone.

[0067] The organic solvent is added intermittently, once every 5.3 hours.

[0068] Example 3

[0069] A continuous water washing method for pesticide intermediates, the specific implementation method is the same as in Example 1, the difference being that the flow rate is 350 L / h when the intermediate solution is subjected to three-stage continuous series centrifugal extraction in step S2.

[0070] The centrifugal extraction frequency is 40 Hz.

[0071] The acid solution has a mass concentration of 3 wt%, and the acid solution is a hydrochloric acid solution.

[0072] In step S3, the flow rate of the acid solution is 1000 L / h.

[0073] The two-stage pickling time is 22 minutes.

[0074] The total time for centrifugal extraction in steps S2 and S3 is 48 hours.

[0075] The organic solvent is methyl isobutyl ketone.

[0076] The organic solvent is added intermittently, once every 4 hours.

[0077] Comparative Example 1

[0078] A continuous water washing method for pesticide intermediates is implemented in the same way as in Example 3, except that hydrochloric acid solution is replaced with industrial water.

[0079] Comparative Example 2

[0080] A continuous water washing method for pesticide intermediates, the specific implementation method is the same as in Example 3, except that the frequency of the centrifugal extraction is 30Hz.

[0081] Performance testing

[0082] The moisture content in the light phase, the recovery rate of intermediates in the light phase, the methyl isobutyl ketone (MIBK) content in the heavy phase, and the recovery rate of potassium salts in the heavy phase were tested. The results are shown in Table 1.

[0083] Moisture content was determined using the Karl Fischer moisture analyzer method; MIBK content was determined using the gas chromatography internal standard method; intermediate content was determined using the liquid chromatography internal standard method; and potassium salt content was determined using the potassium tetraphenylborone gravimetric method.

[0084]

[0085] Table 1

[0086] Moisture content / % Intermediate recovery rate / % MIBK content / % Potassium salt recovery rate / % Example 1 1.2 99.61 0.11 99.7 Example 2 0.2 99.75 0.075 99.94 Example 3 0.2 99.75 0.075 99.94 Comparative Example 1 1.2 97.54 0.75 96.10 Comparative Example 2 5.6 87.84 3.7 96.21

Claims

1. A continuous water washing method for pesticide intermediates, characterized in that, Includes the following steps: S1: Mix and dissolve the pesticide intermediate with an organic solvent to obtain an intermediate solution; S2: The intermediate solution is subjected to three-stage continuous series centrifugal extraction, and the lower heavy phase after extraction and separation enters the extraction aqueous phase tank. S3: After extraction and separation, the upper light phase is further centrifuged and extracted. The acid solution and the upper light phase are then reverse-biased for acid washing. After two stages of acid washing, the light and heavy phases are separated.

2. The continuous water washing method for pesticide intermediates according to claim 1, characterized in that, In step S2, the flow rate for the intermediate solution during three-stage continuous series centrifugal extraction is 180-350 L / h.

3. The continuous water washing method for pesticide intermediates according to claim 1, characterized in that, The centrifugal extraction frequency is 35-45 Hz.

4. The continuous water washing method for pesticide intermediates according to claim 1, characterized in that, The mass concentration of the acid solution is 1-5%.

5. The continuous water washing method for pesticide intermediates according to claim 4, characterized in that, In step S3, the flow rate ratio of the acid solution to the upper light phase is (540-1000):(180-350).

6. The continuous water washing method for pesticide intermediates according to claim 1, characterized in that, The two-stage pickling time is 20-60 minutes.

7. The continuous water washing method for pesticide intermediates according to claim 6, characterized in that, The total time for centrifugal extraction in steps S2 and S3 is 40-50 hours.

8. The continuous water washing method for pesticide intermediates according to claim 1, characterized in that, The organic solvent is at least one of ketone solvents or ester solvents.

9. The continuous water washing method for pesticide intermediates according to claim 1, characterized in that, After step S3, the moisture content in the light phase is 0.1-1.5 wt%, and the organic solvent content in the heavy phase is 0.01-0.1 wt%.

10. The application of a continuous water washing method for pesticide intermediates according to any one of claims 1-9, characterized in that, It is used in the industrial separation of pesticide intermediates.

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