Method for separating and purifying byproduct phenazine of rtp

Abstract

The present application relates to the technical field of chemical separation, in particular to a separation and purification method of RT pes by-product oxazepine, which comprises: (1) heating RT pes by-product waste residue, then adding ethanol to carry out first hot filtration to obtain filtrate and crude oxazepine, and washing the crude oxazepine with alcohol to obtain oxazepine coarse crystal and flushing liquid; (2) recrystallizing the oxazepine coarse crystal and mixed solvent to obtain oxazepine crystalline crystal with purity ≥99.9wt% and crystallization mother liquor; wherein the mixed solvent is selected from good solvent and poor solvent, wherein 1 part by weight of oxazepine sample is placed in 10 parts by weight of solvent to dissolve at T1=25±5℃ and T2=75±5℃, if the oxazepine sample is not dissolved at T1 and T2, the solvent is a poor solvent; otherwise, it is a good solvent. The method not only effectively improves the purity and recovery rate of oxazepine crystalline crystal, but also realizes the resource utilization of RT pes by-product waste residue.

Description

Technical Field

[0001] This invention relates to the field of chemical separation technology, specifically to a method for separating and purifying phenazine, a byproduct of RT-based terpenoids, and the application of the phenazine crystals obtained by this method. Background Technology

[0002] 4-Aminodiphenylamine (4-ADPA), commonly known as RT-based additives, is mainly used in the rubber additives field as an antioxidant, stabilizer, or anti-degradation agent. The main synthesis methods include the aniline method, diphenylamine method, formylaniline method, and nitrobenzene method. Currently, the newest and most important preparation method internationally is the nitrobenzene method, which is a clean and green production process. However, the production of RT-based additives using the nitrobenzene method generates phenazine as a byproduct. Direct discharge of phenazine waste will pollute the environment, while disposal by professional solid waste companies will increase production costs. Separating and recovering phenazine from the RT-based additive byproduct is not only environmentally friendly and cost-effective, but also achieves rational resource utilization, resulting in significant economic and social benefits.

[0003] The phenazine waste residue, a byproduct of RT (Retrieval of Particulate Residue) production, mainly contains components such as aniline, azobenzene, phenazine, and o-aminodiphenylamine. Currently, the main processes for separating and purifying phenazine from RT byproduct waste residue in China include solvent extraction, melt crystallization, a combination of extraction and melt crystallization, and distillation.

[0004] CN200810099916.1 discloses a method for extracting phenazine from RT product waste. The method involves sequentially dissolving and extracting the RT product waste, separating solids and liquids, recrystallizing, drying, distilling, and rectifying the waste. The waste is then dissolved and extracted with ethanol, which is recovered and recycled. The phenazine is then purified by recrystallization. The recovery rate of phenazine from the RT product waste reaches over 97%, and the recovery rate of the solvent ethanol can reach 95%.

[0005] CN201310217173.4 discloses a method for extracting refined phenazine from RT-based waste. The method involves two extractions, two recrystallizations, drying, solvent (ethanol) recovery, and melt crystallization to obtain refined phenazine with a purity that can be consistently maintained above 99.5%. This purification method, after two extractions and two recrystallizations, produces a product with high purity, but the yield is not high.

[0006] CN201410233493.3 discloses a method for extracting high-purity phenazine from RT product by-product waste, including the following steps: heating separation, extraction, primary crystallization, secondary decolorization crystallization, drying, primary distillation crystallization, secondary solvent distillation, and decolorization with activated carbon to make the phenazine product have a brighter appearance and a stable purity of ≥99.8%.

[0007] All of the above methods use ethanol as a recrystallization solvent, which requires a large amount of ethanol. Experiments have shown that to dissolve phenazine under reflux conditions, more than 16 times the mass of ethanol is needed, resulting in excessive ethanol consumption. Even if the ethanol is recovered, the content of phenazine and impurities in the ethanol solution of each dissolution and extraction step is different, so it cannot be centrally distilled and recovered, thus increasing the amount of recovery equipment and energy consumption. Summary of the Invention

[0008] The purpose of this invention is to overcome the above-mentioned technical problems and provide a method for separating and purifying phenazine, a by-product of RT-based permethrin, and an application of the phenazine crystals obtained by this method. This method not only effectively improves the purity and recovery rate of phenazine crystals, but also realizes the resource utilization of RT-based permethrin by-product waste residue.

[0009] To achieve the above objectives, the first aspect of the present invention provides a method for separating and purifying phenazine, a byproduct of RT-pestos, the method comprising: (1) After heating the by-product waste residue of RT-Plast, ethanol is added for the first hot filtration to obtain filtrate and crude phenazine. The crude phenazine is washed with alcohol to obtain crude phenazine crystals and washing liquid. (2) The crude phenazine crystals and the mixed solvent are recrystallized to obtain phenazine crystals with a purity ≥99.9wt% and a mother liquor for crystallization; The mixed solvent is selected from good solvents and bad solvents. One part by weight of phenazine sample is placed in 10 parts by weight of solvent and dissolved at T1=25±5℃ and T2=75±5℃ respectively. If the phenazine sample does not dissolve at either T1 or T2, the solvent is a bad solvent; otherwise, it is a good solvent.

[0010] The second aspect of this invention provides the application of phenazine crystals obtained by the method provided in the first aspect in the manufacture of dyes, pharmaceuticals, and organic synthesis intermediates.

[0011] The method provided by this invention, using RT product by-product waste residue as raw material, employs heating, hot filtration, alcohol washing, and recrystallization techniques in sequence, combined with a specific mixed solvent, to obtain phenazine crystals with high purity (≥99.9wt%) and high recovery rate (≥60%). In particular, by controlling the heating temperature and the mass ratio of good to bad solvents in the mixed solvent, the amount of bad solvent used is effectively reduced, and the filtrate is recycled, resulting in a purity of ≥99.9wt% and a recovery rate of ≥75% for the phenazine crystals. Furthermore, this method simplifies the process flow, facilitates industrial production, and realizes the resource utilization of RT product by-product waste residue. Detailed Implementation

[0012] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0013] In this invention, unless otherwise specified, "first" and "second" do not indicate a sequence or limit the specific materials or steps; they are merely used to distinguish or indicate that these are not the same material or step. For example, in "first hot filtration" and "second hot filtration," "first" and "second" are used only to indicate that these are not the same hot filtration process.

[0014] The first aspect of this invention provides a method for separating and purifying phenazine, a byproduct of RT-pestos, the method comprising: (1) After heating the by-product waste residue of RT-Plast, ethanol is added for the first hot filtration to obtain filtrate and crude phenazine. The crude phenazine is washed with alcohol to obtain crude phenazine crystals and rinsing solution. (2) The crude phenazine crystals and the mixed solvent are recrystallized to obtain phenazine crystals with a purity ≥99.9wt% and a mother liquor for crystallization; The mixed solvent is selected from good solvents and bad solvents. One part by weight of phenazine sample is placed in 10 parts by weight of solvent and dissolved at T1=25±5℃ and T2=75±5℃ respectively. If the phenazine sample does not dissolve at either T1 or T2, the solvent is a bad solvent; otherwise, it is a good solvent.

[0015] The inventors of this invention discovered that by utilizing the difference in melting points between impurities and phenazine in the by-product waste of RT-Purpose, the RT-Purpose by-product waste is heated until the impurities are in a molten state. Ethanol is then added for hot filtration, removing most of the impurities and yielding crude phenazine rich in phenazine. Since the impurity content varies from batch to batch, if the impurity content is low, without adding ethanol, the liquid impurities cannot be filtered out or are not filtered cleanly, leaving a large amount of impurities in the crude phenazine crystals. Therefore, adding ethanol not only facilitates filtration but also significantly reduces the impurities in the crude phenazine crystals. Because the phenazine in the RT-Purpose by-product waste is black and viscous, the filter cake (crude phenazine) after hot filtration is washed with alcohol, carrying the black color into the filtrate. This not only restores the color of the crude phenazine crystals but also prevents the filtrate from becoming too dark, which is beneficial for subsequent filtrate reuse.

[0016] Meanwhile, during the recrystallization stage, in addition to the undesirable solvent (preferably ethanol), another good solvent is added to form a mixed solvent. By using the mixed solvent in combination with multiple recrystallization, phenazine is separated and purified from the crude phenazine crystals. This significantly reduces the amount of undesirable solvent (ethanol) used, stabilizes the purity of phenazine at ≥99.9 wt%, and allows the mother liquor to be reused, resulting in a phenazine recovery rate of ≥75%.

[0017] In this invention, unless otherwise specified, the RT product by-product waste residue contains impurities such as aniline, azobenzene, o-aminodiphenylamine and p-aminodiphenylamine in addition to phenazine.

[0018] In one specific embodiment of the present invention, 1g of phenazine sample is placed in 10g of solvent and dissolved at T1=25±5℃ and T2=75±5℃ respectively. If the phenazine sample does not completely dissolve at T1 and does not completely dissolve at T2, then the solvent is a poor solvent; otherwise, if the phenazine sample does not completely dissolve at T1 but completely dissolves at T2, then the solvent is a good solvent.

[0019] In some embodiments of the present invention, preferably, in step (1), the phenazine content in the RT-based by-product waste residue is ≥50wt%, preferably 50-70wt%. In the present invention, the phenazine content parameter is determined by gas chromatography (analytical conditions: gas chromatograph: Agilent 6890 / 7820; chromatographic column: HP-5 chromatograph 30m×0.32mm×0.5μm; chromatographic conditions: column temperature 90℃ (programmed temperature rise: first-stage temperature rise rate 15℃ / min, rise to 280℃, second-stage hold for 20min), vaporization temperature 300℃, FID detector, detector temperature 300℃; quantitative method: area normalization method).

[0020] In this invention, the melting point difference between impurities and phenazine in the RT-based by-product waste residue is utilized to set the dissolution temperature, ensuring that most of the impurities are in a molten state. Preferably, the RT-based by-product waste residue is heated to 70-90°C, for example, 70°C, 75°C, 80°C, 85°C, 90°C, or any value within a range of any two of these values, with a preferred temperature of 75-85°C.

[0021] In some embodiments of the present invention, preferably, in step (1), the mass ratio of the RT product by-product waste residue to ethanol is 0.01-0.5:1, for example, 0.01:1, 0.05:1, 0.08:1, 0.1:1, 0.11:1, 0.15:1, 0.16:1, 0.18:1, 0.2:1, 0.5:1, and any value within the range of any two values, preferably 0.05-0.2:1.

[0022] In some embodiments of the present invention, preferably, the temperature of the first thermal filtration is 70-90°C, for example, 70°C, 75°C, 80°C, 85°C, 90°C, and any value in any range of any two values, preferably 75-85°C.

[0023] In this invention, the alcohol washing is intended to further remove residual impurities from the crude phenazine. Preferably, the alcohol washing process includes washing the crude phenazine with ethanol to obtain crude phenazine crystals and a rinsing solution.

[0024] In some embodiments of the present invention, preferably, in step (1), the mass ratio of the crude phenazine to ethanol, based on the by-product waste residue of the RT pyrene, is 1:0.5-3, for example, 1:0.5, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:3, and any value within the range of any two values, preferably 1:1-2.

[0025] In this invention, unless otherwise specified, the recrystallization is intended to dissolve the crude phenazine crystals in a mixed solvent and then cool and crystallize them to obtain phenazine crystalline crystals and a mother liquor for crystallization.

[0026] In this invention, the recrystallization aims to further refine and purify the crude phenazine crystals to obtain phenazine crystalline crystals with a purity ≥ 99.9 wt%. Preferably, in step (2), the recrystallization process includes: (2-i) performing a primary crystallization of the crude phenazine crystals and a mixed solvent to obtain primary phenazine crystals and a primary crystallization mother liquor; (2-ii) performing a secondary crystallization of the primary phenazine crystals and a mixed solvent to obtain secondary phenazine crystals and a secondary crystallization mother liquor; ... (2-iii) performing an N-time crystallization of the (N-1)th phenazine crystals and a mixed solvent to obtain Nth phenazine crystals and an Nth crystallization mother liquor; wherein, N is selected from natural numbers ≥ 1; wherein, the Nth phenazine crystals are used as the phenazine crystalline crystals; and the mixture of the primary crystallization mother liquor, the secondary crystallization mother liquor, ..., the Nth crystallization mother liquor is used as the crystallization mother liquor.

[0027] In one specific embodiment of the present invention, the recrystallization process includes: performing a primary crystallization of the crude phenazine crystals and a mixed solvent to obtain primary phenazine crystals and a primary crystallization mother liquor; performing a secondary crystallization of the primary phenazine crystals and a mixed solvent to obtain secondary phenazine crystals and a secondary crystallization mother liquor; and performing a tertiary crystallization of the secondary phenazine crystals and a mixed solvent to obtain tertiary phenazine crystals and a tertiary crystallization mother liquor; wherein the tertiary phenazine crystals are used as the phenazine crystals; and the mixture of the primary crystallization mother liquor, the secondary crystallization mother liquor, and the tertiary crystallization mother liquor is used as the crystallization mother liquor.

[0028] In some embodiments of the present invention, preferably, in step (2), the mass ratio of the crude phenazine crystals to the mixed solvent is 1:1-10, for example, 1:1, 1:3, 1:4, 1:5, 1:6, 1:8, 1:10, and any value within the range of any two values, preferably 1:4-8. Using the preferred mass ratio is more conducive to improving the purity of the phenazine crystals and controlling the yield.

[0029] In this invention, unless otherwise specified, the amount of mixed solvent used in the N crystallization processes satisfies the condition described above: "the mass ratio of the crude phenazine crystals to the mixed solvent is 1:1-10, preferably 1:4-8".

[0030] In some embodiments of the present invention, preferably, in step (2), the recrystallization conditions include: a dissolution temperature of 70-100℃, for example, 70℃, 80℃, 85℃, 90℃, 100℃, and any value within the range of any two values, preferably 80-90℃; and a crystallization temperature of 0-20℃, for example, 0℃, 5℃, 8℃, 10℃, 20℃, and any value within the range of any two values, preferably 0-10℃.

[0031] In some embodiments of the present invention, preferably, the method further includes: filtering the recrystallized product to obtain the phenazine crystals and the mother liquor.

[0032] In some embodiments of the present invention, preferably, the mass ratio of good solvent to poor solvent in the mixed solvent is 1:2-15, for example, 1:2, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:7, 1:8, 1:10, 1:12, 1:15, and any value within any range of any two values, preferably 1:4-10, more preferably 1:4-6. A mass ratio satisfying the above range not only effectively improves the purity of phenazine but also significantly reduces the amount of poor solvent used.

[0033] In some embodiments of the present invention, preferably, the good solvent is selected from at least one of organic acids, chlorinated alkanes, amides, epoxides and benzene homologues.

[0034] In some embodiments of the present invention, preferably, the undesirable solvent is selected from organic alcohols, more preferably from C1-C5 alcohols, more preferably from ethanol and / or propanol, and most preferably from ethanol.

[0035] In some specific embodiments of the present invention, preferably, the organic acid is selected from C1-C5 acids, more preferably from acetic acid and / or propionic acid; the chloroalkanes are selected from at least one of chloroform, dichloromethane and 1,2-dichloroethane; the amides are selected from N,N'-dimethylformamide and / or N,N'-dimethylacetamide; the epoxides are selected from C3-C6 epoxides, more preferably from 1,4-dioxane; and the benzene homologues are selected from toluene and / or xylene.

[0036] In a preferred embodiment of the present invention, the mixed solvent is composed of ethanol and a good solvent in a mass ratio of 1:4-6, wherein the good solvent is selected from at least one of organic acids, chlorinated alkanes, amides, epoxides and benzene homologues.

[0037] In some embodiments of the present invention, preferably, the method further includes: mixing the filtrate and the rinsing liquid and then distilling to obtain a circulating solvent and a residue, and subjecting the residue to a second hot filtration to obtain a phenazine-containing filter cake; more preferably, returning the circulating solvent and performing the first hot filtration and / or alcohol washing; and returning the phenazine-containing filter cake for recrystallization.

[0038] In some embodiments of the present invention, preferably, the method further includes: reusing the crystallization mother liquor; or, when the impurity content in the crystallization mother liquor is ≥5wt%, the crystallization mother liquor is distilled and recovered, the obtained solvent is returned and mixed into the mixed solvent, and the remaining solid obtained from distillation is returned and recrystallized.

[0039] The second aspect of this invention provides the application of phenazine crystals obtained by the method provided in the first aspect in the manufacture of dyes, pharmaceuticals, and organic synthesis intermediates.

[0040] According to a particularly preferred embodiment of the present invention, a method for separating and purifying phenazine byproducts of RT-pestos is provided, the method comprising: (1) After heating the by-product waste residue of RT-Plast, ethanol is added for the first hot filtration to obtain filtrate and crude phenazine. The crude phenazine is washed with alcohol to obtain crude phenazine crystals and rinsing solution. (2) The crude phenazine crystals and the mixed solvent are recrystallized to obtain phenazine crystals with a purity ≥99.9wt% and a mother liquor for crystallization; (3) The mother liquor of crystallization is recycled; or, when the impurity content in the mother liquor of crystallization is ≥5wt%, the mother liquor of crystallization is distilled and recovered, the obtained solvent is returned and mixed into the mixed solvent, and the remaining solid obtained from distillation is returned and recrystallized. The mixed solvent is selected from a good solvent and ethanol in a mass ratio of 1:2-15, wherein the good solvent is selected from at least one of organic acids, chlorinated alkanes, amides, epoxides and benzene homologues.

[0041] The present invention will be described in detail below through embodiments.

[0042] In the examples and comparative examples, the phenazine content in the RT-based byproduct phenazine waste residue was 62.8 wt%.

[0043] Example 1 (1) Take 30.5g of the phenazine waste residue by-product of the above RT-pes and heat it to 85°C. Add 6.1g of ethanol, stir and perform hot filtration to obtain filtrate and crude phenazine. Wash the above crude phenazine with 61g of ethanol to obtain 16.8g of crude phenazine crystals and washing liquid. Collect the filtrate and washing liquid. (2) The above crude phenazine crystals were crystallized once in a mixed solvent (67.2g ethanol, 16.8g acetic acid) (dissolution temperature 85℃, crystallization temperature 5℃) and filtered to obtain 15.6g of primary phenazine crystals and primary crystallization mother liquor; The above-mentioned phenazine primary crystals were subjected to secondary crystallization in a mixed solvent (62.4 g ethanol, 15.6 g acetic acid) (dissolution temperature 85℃, crystallization temperature 5℃), and filtered to obtain 14.1 g of phenazine secondary crystals and secondary crystallization mother liquor; The above-mentioned phenazine secondary crystals were subjected to tertiary crystallization in a mixed solvent (56.4 g ethanol, 14.1 g acetic acid) (dissolution temperature 85 °C, crystallization temperature 5 °C), and filtered to obtain 12.5 g of phenazine tertiary crystals and tertiary crystallization mother liquor. The above-mentioned tertiary phenazine crystals were taken as phenazine crystalline crystals S1. Gas chromatography analysis showed that the purity of phenazine crystalline crystals S1 was 99.9 wt%, and the phenazine recovery rate was 65.2%.

[0044] Example 2 (1) Take 30.3g of the phenazine waste residue byproduct of the above RT-pes and heat it to 80°C. Add 3.6g of ethanol, stir and perform hot filtration to obtain filtrate and crude phenazine. Wash the above crude phenazine with 30.3g of ethanol to obtain 17.2g of crude phenazine crystals and washing liquid. Collect the filtrate and washing liquid. (2) The above crude phenazine crystals were subjected to primary crystallization in a mixed solvent (103.2g ethanol, 8.6g xylene) (dissolution temperature 80℃, crystallization temperature 0℃) and filtered to obtain 15.8g primary phenazine crystals and primary crystallization mother liquor; The above-mentioned phenazine primary crystals were subjected to secondary crystallization in a mixed solvent (94.8 g ethanol, 7.9 g xylene) (dissolution temperature 80 °C, crystallization temperature 0 °C), and filtered to obtain 14.6 g of phenazine secondary crystals and secondary crystallization mother liquor; The above-mentioned phenazine secondary crystals were subjected to tertiary crystallization in a mixed solvent (87.6 g ethanol, 7.3 g xylene) (dissolution temperature 80 °C, crystallization temperature 0 °C), and filtered to obtain 13.5 g of phenazine tertiary crystals and tertiary crystallization mother liquor; The above-mentioned tertiary phenazine crystals were taken as phenazine crystalline crystals S2. Gas chromatography analysis showed that the purity of phenazine crystalline crystals S2 was 99.9 wt%, and the phenazine recovery rate was 70.9%.

[0045] Example 3 (1) Take 29.2g of the phenazine waste residue by-product of the above RT-pes and heat it to 75°C. Add 1.5g of ethanol, stir and perform hot filtration to obtain filtrate and crude phenazine. Wash the above crude phenazine with 35g of ethanol to obtain 17.8g of crude phenazine crystals and washing liquid. Collect the filtrate and washing liquid. (2) The above crude phenazine crystals were subjected to a first crystallization in a mixed solvent (71.2g ethanol, 26.7g 1,4-dioxane) (dissolution temperature 75℃, crystallization temperature 10℃), and filtered to obtain 16g of primary phenazine crystals and primary crystallization mother liquor; The above-mentioned phenazine primary crystals were subjected to secondary crystallization in a mixed solvent (64g ethanol, 24g 1,4-dioxane) (dissolution temperature 75℃, crystallization temperature 10℃), and filtered to obtain 13.8g of phenazine secondary crystals and secondary crystallization mother liquor; The above-mentioned phenazine secondary crystals were subjected to tertiary crystallization in a mixed solvent (55.2 g ethanol, 20.7 g 1,4-dioxane) (dissolution temperature 75℃, crystallization temperature 10℃) and filtered to obtain 11.2 g of phenazine tertiary crystals and tertiary crystallization mother liquor; The above-mentioned tertiary phenazine crystals were taken as phenazine crystalline crystals S3. Gas chromatography analysis showed that the purity of phenazine crystalline crystals S3 was 99.9 wt%, and the phenazine recovery rate was 60.5%.

[0046] Example 4 (1) Take 29.5g of the phenazine waste residue byproduct of the above RT-pes and heat it to 75°C. Add 3.2g of ethanol, stir and perform hot filtration to obtain filtrate and crude phenazine. Wash the above crude phenazine with 58.5g of ethanol to obtain 16.6g of crude phenazine crystals and washing liquid. Collect the filtrate and washing liquid. (2) The above crude phenazine crystals were subjected to a first crystallization in a mixed solvent (83g ethanol, 13.3g N,N'-dimethylformamide) (dissolution temperature 75℃, crystallization temperature 4℃) and filtered to obtain 15.4g of primary phenazine crystals and primary crystallization mother liquor; The above-mentioned phenazine primary crystals were subjected to secondary crystallization in a mixed solvent (77g ethanol, 12.3g N,N'-dimethylformamide) (dissolution temperature 75℃, crystallization temperature 4℃), and filtered to obtain 14.4g of phenazine secondary crystals and secondary crystallization mother liquor; The above-mentioned phenazine secondary crystals were subjected to tertiary crystallization in a mixed solvent (72g ethanol, 11.5g N,N'-dimethylformamide) (dissolution temperature 75℃, crystallization temperature 4℃), and filtered to obtain 12.7g of phenazine tertiary crystals and tertiary crystallization mother liquor; The above-mentioned tertiary phenazine crystals were taken as phenazine crystalline crystals S4. Gas chromatography analysis showed that the purity of phenazine crystalline crystals S3 was 99.9 wt%, and the phenazine recovery rate was 68.5%.

[0047] Example 5 (1) Take 31.1g of the phenazine waste residue by-product of the above RT-pes and heat it to 75°C. Add 5g of ethanol, stir and perform hot filtration to obtain filtrate and crude phenazine. Wash the above crude phenazine with 40.9g of ethanol to obtain 17.1g of crude phenazine crystals and washing liquid. Collect the filtrate and washing liquid. (2) The above crude phenazine crystals were subjected to a single crystallization in a mixed solvent (100.5g ethanol, 12.4g 1,2-dichloroethane) (dissolution temperature 75℃, crystallization temperature 4℃) and filtered to obtain 16.3g of primary phenazine crystals and primary crystallization mother liquor; The above-mentioned primary phenazine crystals were subjected to secondary crystallization in a mixed solvent (96.1 g ethanol, 10.2 g 1,2-dichloroethane) (dissolution temperature 75 °C, crystallization temperature 4 °C), and filtered to obtain 14.3 g of secondary phenazine crystals and secondary crystallization mother liquor; The above-mentioned phenazine secondary crystals were subjected to tertiary crystallization in a mixed solvent (84g ethanol, 9.8g 1,2-dichloroethane) (dissolution temperature 75℃, crystallization temperature 4℃), and filtered to obtain 11.6g of phenazine tertiary crystals and tertiary crystallization mother liquor; The above-mentioned tertiary phenazine crystals were subjected to quaternary crystallization in a mixed solvent (69.5 g ethanol, 8.1 g 1,2-dichloroethane) (dissolution temperature 75 °C, crystallization temperature 4 °C) and filtered to obtain 10.2 g of tertiary phenazine crystals and the mother liquor of the quaternary crystallization. The above-mentioned phenazine quaternary crystals were taken as phenazine crystalline crystals S5. Gas chromatography analysis showed that the purity of phenazine crystalline crystals S5 was 99.9 wt%, and the phenazine recovery rate was 61.4%.

[0048] Repeat the above steps, and use the mixture of the first crystallization mother liquor, the second crystallization mother liquor, the third crystallization mother liquor and the fourth crystallization mother liquor as the crystallization mother liquor for recycling. After recycling 3 times, the crystal purity is still maintained at 99.9 wt%, and the phenazine recovery rate is 79.8%.

[0049] Example 6 The method according to Example 1 differs in that it further includes: The mixture of 831.8g of filtrate and rinsing solution obtained in step (1) was distilled to obtain 520.2g of ethanol. The purity of ethanol was 99.2wt% according to gas chromatography analysis. It was basically free of separated substances and transparent in color. It could be reused. The residue at the bottom of the vessel was hot filtered. The filtrate was collected and processed. The filter cake was washed with ethanol and a total of 11.5g was collected. After analyzing the content (the purity of phenazine was 93.1wt%), it was returned and used together with crude phenazine as raw material for primary crystallization in the crystallization vessel for crystallization. The other conditions were the same, and phenazine crystal S6 was obtained. Gas chromatography analysis showed that the purity of phenazine crystal S6 was 99.9wt%.

[0050] Comparative Example 1 The method is the same as in Example 1, except that in step (2), During the first crystallization process, the mixed solvent (67.2 g ethanol, 16.8 g acetic acid) was replaced with a mixed solvent (79.8 g ethanol, 4.2 g acetic acid), and the other conditions remained the same. Phenazine crystals DS1 were obtained. Gas chromatography analysis showed that the purity of phenazine crystals DS1 was 98.8 wt%, and the recovery rate of phenazine was 67.8%.

[0051] Comparative Example 2 The method is the same as in Example 1, except that in step (2), In the first crystallization process, the mixed solvent (67.2g ethanol, 16.8g acetic acid) was replaced with 84g ethanol; in the second crystallization process, the mixed solvent (62.4g ethanol, 15.6g acetic acid) was replaced with 78g ethanol; in the third crystallization process, the mixed solvent (56.4g ethanol, 14.1g acetic acid) was replaced with 70.5g ethanol; all other conditions remained the same, and phenazine crystals DS2 were obtained. Gas chromatography analysis showed that the purity of phenazine crystals DS2 was 94.3wt% (with this amount of added ethanol, phenazine could not be completely dissolved and could not be recrystallized, resulting in poor purity).

[0052] Compared with Comparative Examples 1-2, Examples 1-6 adopted the method provided by the present invention, using RT product by-product waste residue as raw material to obtain phenazine crystals with a purity ≥99.9wt% and a recovery rate ≥60%; at the same time, by recycling the filtrate, the purity of the phenazine crystals was ≥99.9wt% and the recovery rate was ≥75%.

[0053] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for separating and purifying phenazine, a byproduct of RT-peptide production, characterized in that, The method includes: (1) After heating the by-product waste residue of RT-Plast, ethanol is added for the first hot filtration to obtain filtrate and crude phenazine. The crude phenazine is washed with alcohol to obtain crude phenazine crystals and washing liquid. (2) The crude phenazine crystals and the mixed solvent are recrystallized to obtain phenazine crystals with a purity ≥99.9wt% and a mother liquor for crystallization; (3) The mother liquor of crystallization is recycled; or, when the impurity content in the mother liquor of crystallization is ≥5wt%, the mother liquor of crystallization is distilled and recovered, the obtained solvent is returned and mixed into the mixed solvent, and the remaining solid obtained from distillation is returned and recrystallized. (4) The filtrate and rinsing solution are mixed and then distilled to obtain a circulating solvent and residue. The residue is then subjected to a second hot filtration to obtain a filter cake containing phenazine. (5) Return the recycled solvent and perform the first hot filtration and / or alcohol washing; return the phenazine-containing filter cake and perform the recrystallization; The mixed solvent is selected from a good solvent and ethanol in a mass ratio of 1:2-15, wherein the good solvent is selected from at least one of organic acids, chlorinated alkanes, amides, epoxides and benzene homologues.

2. The method according to claim 1, wherein, The mass ratio of good solvent to ethanol in the mixed solvent is 1:4-10.

3. The method according to claim 2, wherein, The mass ratio of good solvent to ethanol in the mixed solvent is 1:4-6.

4. The method according to claim 1, wherein, The organic acids are selected from C1-C5 acids; And / or, the chloroalkanes are selected from at least one of chloroform, dichloromethane, and 1,2-dichloroethane; And / or, the amides are selected from N,N'-dimethylformamide and / or N,N'-dimethylacetamide; And / or, the epoxy hydrocarbons are selected from C3-C6 epoxy hydrocarbons; And / or, the benzene homologues are selected from toluene and / or xylene.

5. The method according to claim 4, wherein, The organic acids are selected from acetic acid and / or propionic acid; And / or, the epoxy hydrocarbons are selected from 1,4-dioxane.

6. The method according to any one of claims 1-5, wherein, In step (1), The phenazine content in the by-product waste residue of RT-pes is ≥50wt%; And / or, heat the RT product by-product waste residue to 70-90°C.

7. The method according to claim 6, wherein, In step (1), The phenazine content in the by-product waste residue of RT-Pyrate is 50-70 wt%. And / or, heat the RT product by-product waste to 75-85°C.

8. The method according to any one of claims 1-5, wherein, In step (1), The mass ratio of the RT product by-product waste residue to ethanol is 0.01-0.5:1; And / or, the temperature of the first thermal filter is 70-90°C.

9. The method according to claim 8, wherein, In step (1), The mass ratio of the RT product by-product waste residue to ethanol is 0.05-0.2:1; And / or, the temperature of the first thermal filter is 75-85°C.

10. The method according to any one of claims 1-5, wherein, In step (1), The alcohol washing process includes washing the crude phenazine with ethanol to obtain crude phenazine crystals and a rinsing solution.

11. The method according to claim 10, wherein, In step (1), the mass ratio of crude phenazine to ethanol, based on the by-product waste residue of the RT pyrene, is 1:0.5-3.

12. The method according to claim 11, wherein, In step (1), the mass ratio of crude phenazine to ethanol, based on the by-product waste residue of the RT pyrimethamine, is 1:1-2.

13. The method according to any one of claims 1-5, wherein, In step (2), the recrystallization process includes: (2-i) The crude phenazine crystals and the mixed solvent are subjected to primary crystallization to obtain primary phenazine crystals and primary crystallization mother liquor; (2-ii) The phenazine primary crystal and the mixed solvent are subjected to secondary crystallization to obtain phenazine secondary crystals and secondary crystallization mother liquor; (2-iii) Phenazine (N-1) sub-crystallization and mixed solvent were subjected to N-crystallization to obtain N-crystallization of phenazine and N-crystallization mother liquor; Where N is selected from natural numbers greater than 1; Specifically, the Nth crystal of phenazine is used as the phenazine crystal; and the mixture of the primary crystallization mother liquor, the secondary crystallization mother liquor, and the Nth crystallization mother liquor is used as the crystallization mother liquor.

14. The method according to claim 13, wherein, The mass ratio of the crude phenazine crystals to the mixed solvent is 1:1-10; And / or, the recrystallization conditions include: a dissolution temperature of 70-100°C; and a crystallization temperature of 0-20°C; And / or, the method further includes: filtering the recrystallized product to obtain the phenazine crystals and the mother liquor.

15. The method according to claim 14, wherein, The mass ratio of the crude phenazine crystals to the mixed solvent is 1:4-8; And / or, the recrystallization conditions include: a dissolution temperature of 80-90°C; and a crystallization temperature of 0-10°C.