Preparation method of salazosulfapyridine impurity B
Compounds I and Compound III are used as starting materials to synthesize sulfasalazine impurity B in two steps, solving the problem of lack of effective preparation methods in the prior art, achieving high-purity product preparation, and providing test samples for sulfasalazine research.
Patent Information
- Application Number
- CN202510275546.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-10
- Publication Date
- 2025-05-06
AI Technical Summary
The lack of effective preparation method for sulfasalazine impurity B in the prior art has resulted in limited application in drug research.
Compounds I and Compound III were used as starting materials to synthesize sulfasalazine impurity B through two-step reaction, and simple and easy-to-get reagents were used to control the reaction conditions to obtain high-purity products.
The high purity (more than 96.5%) preparation of sulfasalazine impurity B was achieved, providing test samples for sulfasalazine research. The overall preparation method has strong operability and high yield.
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Figure CN119930507A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of drug impurity synthesis, and in particular to a method for preparing sulfasalazine impurity B. Background Art
[0002] Sulfasalazine is a sulfonamide antibiotic. Its English name is Sulfasalazine and its chemical name is 5-[p-(2-pyridylaminesulfonyl)phenyl]azosalicylic acid. Its CAS number is 599-79-1 and its molecular formula is C 18 H 14 N 4 O 5 S, molecular weight is 398.39 g / mol. Structural formula:
[0003]
[0004] Sulfasalazine was originally used for inflammatory bowel disease, namely Crohn's disease and ulcerative colitis, and has dual anti-inflammatory and antibacterial effects. It is an oral sulfonamide that is not easily absorbed. After the 1970s, it was found that it can improve joint pain, swelling and stiffness in ankylosing spondylitis, and can reduce serum IgA levels and other laboratory activity indicators. It is particularly suitable for improving peripheral arthritis in patients with ankylosing spondylitis, and has the effect of preventing recurrence and alleviating lesions for anterior uveitis complicated by this disease. With the progress of research, it has gradually been applied to rheumatoid arthritis. To date, sulfasalazine has been widely used in the treatment of rheumatoid arthritis and spondyloarthritis.
[0005] Sulfasalazine impurity B is an impurity produced during the synthesis of sulfasalazine. Its alias is sulfasalazine EP impurity B. Its CAS number is 1391062-49-9. Its chemical name is: 2-hydroxy-3,5-bis((4-(N-(pyridin-2-yl)sulfamoyl)phenyl)diazenyl)benzoic acid. Its molecular weight is 658.66 and its molecular formula is C 29 H 22 N 8 O 7 S 2 , the structural formula is as follows:
[0006]
[0007] Relevant pharmacology and pharmacokinetics research on sulfasalazine impurity B can provide control samples for the quality control of the raw material sulfasalazine, thereby promoting the research of sulfasalazine. Sulfasalazine impurity B has an additional azosulfapyridine structure compared to the raw material. The synthesis method of sulfasalazine impurity B is still unclear.
[0008] Therefore, it is necessary to develop a targeted preparation method for sulfasalazine impurity B to obtain high-purity sulfasalazine impurity B and provide test samples for sulfasalazine research. Summary of the invention
[0009] Purpose of the invention: In view of the shortcomings and defects of the prior art, the present invention provides a method for preparing sulfasalazine impurity B, using compound I and compound III as starting materials, and synthesizing sulfasalazine impurity B through two-step reactions; using simple and readily available reagents, a sulfasalazine impurity B product with a purity of more than 96.5% is obtained, providing a test sample for sulfasalazine research; the overall preparation method has strong operability and high yield.
[0010] Technical solution: A method for preparing sulfasalazine impurity B of the present invention is characterized by comprising the following steps:
[0011] 1) Compound I is suspended in water, hydrochloric acid is added to dissolve and clarify it, sodium nitrite aqueous solution is added dropwise under ice bath, and the reaction solution is continuously stirred until all solids are precipitated; the structural formula of Compound I is as follows:
[0012]
[0013] 2) The precipitated solid is filtered, washed and dried to obtain an intermediate product II. The structural formula of the intermediate product II is as follows:
[0014]
[0015] 3) Compound III was suspended in water, and NaOH aqueous solution was added to dissolve and clarify it. The intermediate product II obtained in step 2) was added in batches under ice bath, and the pH value of the reaction solution was controlled to be ≥9 by dropping NaOH aqueous solution. The ice bath was maintained until the reaction was completed to obtain a black suspension. The structural formula of compound III is as follows:
[0016]
[0017] 4) adding hydrochloric acid aqueous solution dropwise under ice bath to adjust the pH of the reaction solution to 3-4, and a brown-black solid precipitates in the reaction solution; filtering, washing, and drying the solid to obtain a crude product; the crude product is purified by column chromatography and crystallization to obtain the final product IV, i.e., sulfasalazine impurity B; the structural formula of the final product IV is as follows:
[0018]
[0019] Wherein, in the step 1), the volume ratio of compound I to water is 1:10 to 1:15; the molar ratio of compound I, hydrochloric acid and sodium nitrite is 1:3.3:1 to 1:5.5:1.1.
[0020] Furthermore, in the step 1), the volume ratio of compound I to water is 1:12.18; the molar ratio of compound I, hydrochloric acid and sodium nitrite is 1:4.5:1.05; the hydrochloric acid is concentrated hydrochloric acid with a mass fraction of 35%; and the mass fraction of the sodium nitrite aqueous solution is 22.6%.
[0021] Wherein, in the step 1), an ice bath is performed after the solid is precipitated to increase the reaction yield, and the ice bath time is 30 min to 60 min.
[0022] Furthermore, in the step 1), the ice bath time is 30 minutes.
[0023] Among them, in the step 2), the intermediate product II is unstable and needs to be handled carefully and slowly with a horn spoon after drying, while taking protective measures to avoid contact with metal, heating, vibration and collision.
[0024] Wherein, in the step 2), the volume ratio of compound III to water is 1:5 to 1:7; the molar ratio of intermediate product II, compound III and NaOH aqueous solution is 1:0.3:2.6 to 1:0.6:4.5.
[0025] Wherein, in the step 2), the volume ratio of compound III to water is 1:5.33; the molar ratio of intermediate product II, compound III and NaOH aqueous solution is 1:0.5:3.74; and the mass fraction of NaOH aqueous solution is 30%.
[0026] Wherein, in the step 3), the pH value of the reaction solution is controlled to be ≥9 by adding NaOH aqueous solution. It should be noted that each time the intermediate product II is added, a few drops of NaOH aqueous solution should be added at the same time to prevent the local pH value of the reaction solution from being lower than 9.
[0027] Wherein, in the step 4), the ice bath is maintained for 2 hours to 6 hours.
[0028] Furthermore, in the step 4), the ice bath is maintained for 2 hours, and the molar concentration of the aqueous hydrochloric acid solution is 1 mol / L.
[0029] Wherein, in the step 4), during the column chromatography refining and purification, the column chromatography stationary phase is 200-400 mesh silica gel.
[0030] Furthermore, in the step 4), in the column chromatography refining and purification, the column chromatography stationary phase is 200-300 mesh silica gel; the mobile phase is dichloromethane and methanol, the volume ratio is 10:1; the solvent for crystallization purification is tetrahydrofuran and water.
[0031] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the present invention screens out the optimal synthesis steps and reaction conditions through a large number of experiments; uses compound I and compound III as starting materials, and synthesizes sulfasalazine impurity B through two-step reactions; uses simple and readily available reagents to obtain sulfasalazine impurity B products with a purity of more than 96.5%, providing test samples for sulfasalazine research; the overall preparation method has strong operability, high yield, high implementation value and social and economic benefits; and provides a reference substance for analysis and research for comprehensive analysis of the clinical, pharmacology, pharmacokinetics, toxicology and new drug development of sulfasalazine. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 It is a synthesis diagram of compound IV of the present invention;
[0033] Figure 2 is the mass spectrum of compound IV of the present invention;
[0034] Figure 3 is the NMR image of compound IV of the present invention;
[0035] Figure 4 is the liquid phase diagram of compound IV of the present invention;
[0036] Figure 5 is the LC-MS chart of compound IV of the present invention;
[0037] Figure 6 It is the IR chart of compound IV of the present invention. DETAILED DESCRIPTION
[0038] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.
[0039] The compound I of the present invention is sulfapyridine, and the compound III is sulfasalazine, both of which are directly purchased from the market.
[0040] Embodiment 1:
[0041] Synthesis of Compound II in this example: 13.10 g of Compound I (CAS: 144-83-2) was suspended in 159.6 mL of water, 19.5 mL of 35% concentrated hydrochloric acid was added to dissolve and clarify it, 16.77 g of 22.6% sodium nitrite aqueous solution was slowly added dropwise under ice bath, and a light yellow solid gradually precipitated from the reaction solution until stirring stopped. After continuing to maintain the ice bath for 30 minutes, the precipitated solid was filtered and washed with a small amount of water, and dried to obtain 15.30 g of off-white solid II, with a yield of 98.12%.
[0042] Synthesis of compound IV: 10.47g of compound III (CAS: 599-79-1) was suspended in 55.8mL of water, and 26.2g of 30% NaOH aqueous solution was added to dissolve and clarify it. 15.30g of compound II was slowly added in batches under ice bath. At the same time, 30% NaOH aqueous solution (about 6.24g in total) was slowly added to make the pH value of the reaction solution ≥9. The reaction solution gradually turned into a black suspension, and the ice bath was continued for two hours. TLC spot plate monitoring showed that there was less raw material remaining. 1M hydrochloric acid aqueous solution was slowly added under ice bath to adjust the pH of the reaction solution to 3-4. A large amount of brown-black solid precipitated in the reaction solution. It was filtered and washed with water and acetonitrile, and dried to obtain a crude product. The crude product was further purified by column chromatography, wherein the column chromatography stationary phase was 200-300 mesh silica gel, and the mobile phase was dichloromethane and methanol (containing HCl) in a volume ratio of 10:1. A dark brown solid was separated and further purified by crystallization with THF and water, and finally 2.37 g of dark brown solid IV was obtained, with a yield of 13.69%.
[0043] like Figure 1 The mass spectrum of compound IV is [MH]-: 657.0. Figure 2 The H NMR data of compound IV are: 1H NMR (400MHz, DMSO-d6) δ8.56 (d, 1H), 8.28 (d, 1H), 8.10-7.99 (m, 10H), 7.79 (m, 2H), 7.25 (m, 2H), 6.87 (m, 2H). Figure 3 , the liquid phase purity of compound IV is: 96.68%. Figure 4 The LC-MS spectrum of compound IV showed that the main peak mass spectrum of the product was: [MH]-: 657.1. Figure 5 The IR spectrum of compound IV is: 3444.45-3053.91cm-1(-NH, -OH, -COOH); 1673.94cm-1(C=O); 1629.55-1595.92cm-1(C=C).
[0044] Embodiment 2:
[0045] Synthesis of Compound II in this example: 12.50 g of Compound I (CAS: 144-83-2) was suspended in 125.0 mL of water, 13.8 mL of 35% concentrated hydrochloric acid was added to dissolve and clarify it, 15.31 g of 22.6% sodium nitrite aqueous solution was slowly added dropwise under ice bath, and yellow solid gradually precipitated from the reaction solution until stirring stopped, and the ice bath was continued for 1 hour. The precipitated solid was filtered and washed with a small amount of water, and dried to obtain 14.19 g of off-white solid II, with a yield of 95.37%.
[0046] Synthesis of compound IV: 5.99g of compound III was suspended in 30.0mL of water, 17.38g of 30% NaOH aqueous solution was added to dissolve and clarify it, 14.19g of compound II was slowly added in batches under ice bath, and at the same time, 30% NaOH aqueous solution (about 3.33g in total) was slowly added to make the pH value of the reaction solution ≥9, the reaction solution gradually turned into a black suspension, and the ice bath was continued for four hours. TLC spot plate monitoring showed that there was less raw material remaining, 1M hydrochloric acid aqueous solution was slowly added under ice bath, and the pH of the reaction solution was adjusted to 3-4, and a large amount of brown-black solid was precipitated in the reaction solution. It was filtered and washed with water and acetonitrile, and dried to obtain a crude product. The crude product was further refined and purified by column chromatography, wherein the column chromatography stationary phase was 200-300 mesh silica gel, and the mobile phase was dichloromethane and methanol (containing HCl) in a volume ratio of 10:1. A dark brown solid was separated and further purified by crystallization with THF and water, and finally 1.27 g of dark brown solid IV was obtained, with a yield of 12.82%, HPLC: 96.59%.
[0047] Embodiment 3:
[0048] Synthesis of Compound II of this Example: 13.50 g of Compound I (CAS: 144-83-2) was suspended in 202.5 mL of water, 24.8 mL of 35% concentrated hydrochloric acid was added to dissolve and clarify it, 18.19 g of 22.6% aqueous sodium nitrite solution was slowly added dropwise under ice bath, and a light yellow solid gradually precipitated from the reaction solution until stirring stopped. The ice bath was maintained for 45 minutes, the precipitated solid was filtered and washed with a small amount of water, and dried to obtain 15.01 g of off-white solid II, with a yield of 93.41%.
[0049] Synthesis of compound IV: 12.94g of compound III was suspended in 90.6mL of water, 32.49g of 30% NaOH aqueous solution was added to dissolve and clarify it, 15.01g of compound II was slowly added in batches under ice bath, and at the same time, 30% NaOH aqueous solution (about 7.16g in total) was slowly added to make the pH value of the reaction solution ≥9, the reaction solution gradually turned into a black suspension, and the ice bath was continued for six hours. TLC spot plate monitoring showed that there was less raw material remaining, 1M hydrochloric acid aqueous solution was slowly added under ice bath, and the pH of the reaction solution was adjusted to 3-4, and a large amount of brown-black solid was precipitated in the reaction solution. It was filtered and washed with water and acetonitrile, and dried to obtain a crude product. The crude product was further purified by column chromatography, wherein the column chromatography stationary phase was 300-400 mesh silica gel, and the mobile phase was dichloromethane and methanol (containing HCl) in a volume ratio of 10:1. A dark brown solid was separated and further purified by crystallization with THF and water to finally obtain 2.19 g of dark brown solid IV with a yield of 10.23%, HPLC: 96.61%.
[0050] The invention screens out the optimal synthesis steps and reaction conditions through a large number of experiments; uses compound I and compound III as starting materials, and synthesizes sulfasalazine impurity B through two-step reactions; uses simple and readily available reagents to obtain sulfasalazine impurity B products with a purity of more than 96.5%, and provides test samples for sulfasalazine research; the overall preparation method has strong operability, high yield, high implementation value and social and economic benefits; and provides a reference substance for analysis and research for comprehensive analysis of the clinical, pharmacology, pharmacokinetics, toxicology and new drug research and development of sulfasalazine.
Claims
1. A method for preparing sulfasalazine impurity B, characterized in that: The steps include: 1) Compound I is suspended in water, hydrochloric acid is added to dissolve and clarify it, sodium nitrite aqueous solution is added dropwise under ice bath, and the reaction solution is continuously stirred until all solids are precipitated; the structural formula of Compound I is as follows: 2) The precipitated solid is filtered, washed and dried to obtain an intermediate product II. The structural formula of the intermediate product II is as follows: 3) Compound III was suspended in water, and NaOH aqueous solution was added to dissolve and clarify it. The intermediate product II obtained in step 2) was added in batches under ice bath, and the pH value of the reaction solution was controlled to be ≥9 by dropping NaOH aqueous solution. The ice bath was maintained until the reaction was completed to obtain a black suspension. The structural formula of compound III is as follows: 4) adding hydrochloric acid aqueous solution dropwise under ice bath to adjust the pH of the reaction solution to 3-4, and a brown-black solid precipitates in the reaction solution; filtering, washing, and drying the solid to obtain a crude product; the crude product is purified by column chromatography and crystallization to obtain the final product IV, i.e., sulfasalazine impurity B; the structural formula of the final product IV is as follows:
2. The method for preparing sulfasalazine impurity B according to claim 1, characterized in that: In the step 1), the volume ratio of compound I to water is 1:10 to 1:15; the molar ratio of compound I, hydrochloric acid and sodium nitrite is 1:3.3:1 to 1:5.5:1.
1.
3. The method for preparing sulfasalazine impurity B according to claim 2, characterized in that: In the step 1), the volume ratio of compound I to water is 1:12.18; the molar ratio of compound I, hydrochloric acid and sodium nitrite is 1:4.5:1.05; the hydrochloric acid is concentrated hydrochloric acid with a mass fraction of 35%; and the mass fraction of the sodium nitrite aqueous solution is 22.6%.
4. The method for preparing sulfasalazine impurity B according to claim 1, characterized in that: In the step 1), an ice bath is performed after the solid is precipitated, and the ice bath time is 30 min to 60 min.
5. The method for preparing sulfasalazine impurity B according to claim 1, characterized in that: In the step 2), the volume ratio of compound III to water is 1:5 to 1:7; the molar ratio of intermediate product II, compound III and NaOH aqueous solution is 1:0.3:2.6 to 1:0.6:4.
5.
6. The method for preparing sulfasalazine impurity B according to claim 5, characterized in that: In the step 2), the volume ratio of compound III to water is 1:5.33; the molar ratio of intermediate product II, compound III and NaOH aqueous solution is 1:0.5:3.74; and the mass fraction of NaOH aqueous solution is 30%.
7. The method for preparing sulfasalazine impurity B according to claim 1, characterized in that: In the step 4), the ice bath is maintained for 2 hours to 6 hours.
8. The method for preparing sulfasalazine impurity B according to claim 7, characterized in that: In the step 4), the ice bath is maintained for 2 hours, and the molar concentration of the hydrochloric acid aqueous solution is 1 mol / L.
9. The method for preparing sulfasalazine impurity B according to claim 1, characterized in that: In the step 4), during the column chromatography refining and purification, the column chromatography stationary phase is 200-400 mesh silica gel.
10. The method for preparing sulfasalazine impurity B according to claim 1, characterized in that: In the step 4), in the column chromatography refining and purification, the column chromatography stationary phase is 200-300 mesh silica gel; the mobile phase is dichloromethane and methanol, the volume ratio is 10:1; the solvent for crystallization purification is tetrahydrofuran and water.