Method for recovering camphorsulfonic acid from sulfonation mother liquor

Abstract

The invention relates to a method for recovering camphorsulfonic acid from sulfonation mother liquor. The method comprises the following steps: (1) adding water into mother liquor for dilution, and then starting reduced pressure distillation to recover acetic acid and water; continuously adding water in the process until most acetic acid is evaporated; (2) adding 1%-5% of a decolorizing agent into the mother liquor, stirring and decolorizing at a certain temperature, and filtering; (3) adding a resolving agent into the decoloring solution, heating to perform salt forming reaction, cooling to crystallize, and performing suction filtration to obtain double salt; (4) adding water into the double salt, dropwise adding ammonia water to carry out hydrolysis reaction, cooling and carrying out suction filtration, taking a filter cake as a resolving agent, drying and then applying mechanically, and taking a filtrate as an ammonium camphorsulfonate solution; (5) adsorbing the ammonium camphorsulfonate solution through cation exchange resin, and removing ammonia to obtain a camphorsulfonic acid solution; and (6) finally, concentrating the camphorsulfonic acid solution under reduced pressure until no water is evaporated, adding acetic acid for crystallization, and performing suction filtration and drying. According to the method, 80-90% of camphorsulfonic acid in the mother liquor can be recovered, and considerable economic benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemical industry, and particularly relates to a method for recovering camphor sulfonic acid from a sulfonated mother liquor containing camphor sulfonic acid generated in a production process of camphor sulfonic acid. Background Art

[0002] Camphorsulfonic acid, as a fine chemical, has a wide range of applications. It has a chiral structure and can be divided into left-handed, right-handed and mixed camphorsulfonic acid according to its chiral properties, namely left-handed camphorsulfonic acid (L-(-)-camphorsulfonic acid), right-handed camphorsulfonic acid (D-(+)-camphorsulfonic acid) and mixed camphorsulfonic acid (D,L-(+,-)-camphorsulfonic acid).

[0003] Among them, L-camphorsulfonic acid is often used as a chiral splitting agent and is often used in the field of pharmaceutical synthesis, such as the chiral splitting of clopidogrel intermediates and voriconazole intermediates. D-camphorsulfonic acid is also widely used in the field of pharmaceutical synthesis, such as the chiral splitting of the key intermediate of cephalexin - L-phenylglycine. And rac camphorsulfonic acid is mainly used in the field of cosmetics, as a starting material for the synthesis of terephthalylidene dicamphorsulfonic acid, which is a key ingredient in sunscreen.

[0004] Nowadays, the synthesis of camphor sulfonic acid in large-scale production mainly uses camphor powder as the starting material, and camphor sulfonic acid is obtained through sulfonation reaction. The reaction process is as follows: Figure 1 , the chemical reaction formula is as follows:

[0005]

[0006] During the sulfonation reaction, acetic anhydride is both a raw material and a reaction solvent. After the reaction is completed, the crude camphorsulfonic acid is obtained by centrifugation, and the centrifuged mother liquor is the sulfonation mother liquor. However, the sulfonation mother liquor contains a large amount of acetic acid and a small amount of acetic anhydride. Camphorsulfonic acid has good solubility in acetic acid and acetic anhydride (10-15% w / w), resulting in more camphorsulfonic acid products being dissolved in the sulfonation mother liquor. The commercial price of camphorsulfonic acid is high->100,000 yuan / ton, so the recovery of camphorsulfonic acid in actual production has considerable economic benefits.

[0007] The conventional distillation and solvent concentration method is used to recover camphor sulfonic acid by reducing the amount of solvent. However, due to the excessive amount of concentrated sulfuric acid in the system, the product is carbonized during the distillation of the sulfonated mother liquor, and the camphor sulfonic acid cannot be recovered.

[0008] Although patent-CN106496077A also discloses a method of using resin adsorption and separation to recover camphorsulfonic acid from camphorsulfonic acid synthesis mother liquor. However, the camphorsulfonic acid synthesis process described in the patent is different from the actual large-scale production and cannot be applied to large-scale production. Therefore, it is necessary to develop a feasible method to recover camphorsulfonic acid in the sulfonated mother liquor to improve the economic benefits of camphorsulfonic acid production. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides a method for recovering camphorsulfonic acid from a sulfonation mother liquor, which can recover 80-90% of the camphorsulfonic acid in the mother liquor and has considerable economic benefits.

[0010] The present invention adopts the following technical scheme: a method for recovering camphorsulfonic acid from a sulfonation mother liquor, characterized in that the steps are as follows:

[0011] (1) first adding water to dilute the sulfonation mother liquor, and then starting to distill under reduced pressure to recover acetic acid and water; water is continuously added during the distillation process until most of the acetic acid in the system is evaporated;

[0012] (2) After distillation, add 1% to 5% decolorizing agent to the mother liquor, then stir and decolorize and filter at a certain temperature;

[0013] (3) adding a resolving agent to the decolorizing solution, heating the solution to perform a salt-forming reaction, cooling the solution to crystallize, and filtering the solution to obtain a double salt of phenylglycine-camphorsulfonic acid;

[0014] (4) adding water to the double salt, and then dropping ammonia water to carry out hydrolysis reaction, cooling, filtering, and using the filter cake as a resolving agent. After drying, the filtrate is an ammonium camphorsulfonate solution;

[0015] (5) adsorbing the ammonium camphorsulfonate solution through a cation exchange resin to remove ammonia to obtain a camphorsulfonic acid solution;

[0016] (6) Finally, the camphorsulfonic acid solution is concentrated under reduced pressure until no water is evaporated, acetic acid is added for crystallization, filtered, and dried to finally obtain recovered camphorsulfonic acid.

[0017] Preferably, in step (1), water is continuously added during the distillation process, specifically, water is added at a weight ratio of (1:0.5 to 1:0.8) for the first time, and reduced pressure distillation is started to distill out a fraction with an equal weight of water; water is added at a weight ratio of (1:0.5 to 1:0.8) for the second time, and reduced pressure distillation is continued to distill out a fraction with an equal weight of water.

[0018] Preferably, the decolorizing agent in step (2) is activated carbon, macroporous resin or diatomaceous earth, and the decolorizing is carried out by stirring at a temperature of 40 to 80° C. for 1 hour.

[0019] Preferably, the decolorizing agent is activated carbon (1% w / w) 。

[0020] Preferably, different equivalents (1.0 to 1.5 equivalents) of a resolving agent are added to the decolorized mother liquor, stirred, and heated to 60 to 85° C. until the system is dissolved. If it is not dissolved, a small amount of concentrated sulfuric acid is added dropwise. The resolving agent is phenylglycine or phenylethylamine.

[0021] Preferably, in step (4), 2 times of water is added to the double salt, the mixture is stirred and heated to 50-55° C., ammonia water is slowly added dropwise to adjust the pH to 6-8, the mixture is cooled and filtered, and the filter cake is used as a resolving agent (dried and then used).

[0022] Preferably, in step (5), the ammonium camphorsulfonate solution is subjected to cationic resin adsorption deamination: the resin loading amount is 1 / 2 of the volume of the feed solution, a resin column with a height-to-diameter ratio of 5 to 10:1 is selected, and the solution flow rate is controlled to be 2BV / h for adsorption deamination.

[0023] Preferably, in the step (5), the collected camphorsulfonic acid solution is subjected to reduced pressure distillation, and after distillation until no fraction flows out, acetic acid is added, the temperature is slowly lowered to 10-15° C., filtered with suction, and dried to obtain camphorsulfonic acid solid, and the filtered mother liquor is collected in multiple batches and concentrated to half of the solvent, and then cooled to 10-15° C., filtered with suction, and dried to continue to obtain recovered camphorsulfonic acid.

[0024] Preferably, the cation exchange resin in step (5) is regenerated by hydrochloric acid (5%) to obtain a regeneration liquid - ammonium chloride solution, and the regenerated resin is reused.

[0025] Preferably, the sulfonated mother liquor is a dextrorotatory camphorsulfonic acid mother liquor or a cyclorotatory camphorsulfonic acid mother liquor.

[0026] The beneficial effect of the present invention is that a process route for recovering camphorsulfonic acid from camphorsulfonic acid sulfonation mother liquor is explored. In the existing camphorsulfonic acid production, the camphorsulfonic acid mother liquor can only be disposed as hazardous waste liquid, and it is estimated that the loss of camphorsulfonic acid in each batch accounts for about 15% of the product weight. After the implementation of the present invention, not only can 80-90% of camphorsulfonic acid be recovered from the sulfonation mother liquor, but also phenylglycine, resin and the like put into the recovery process can be reused, so the actual production cost is low and it has high economic benefits in large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the existing process flow diagram.

[0028] Figure 2 It is a process flow diagram of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with specific embodiments.

[0030] The process route of the present invention is as follows Figure 2 shown.

[0031] Step 1: taking the sulfonated mother liquor produced by production, wherein the sulfonated mother liquor can be a dextrorotatory camphorsulfonic acid mother liquor or a cyclotropic camphorsulfonic acid mother liquor, and then adding water in a weight ratio of (1:0.5 to 1:0.8) for the first time, starting reduced pressure distillation, and distilling out a fraction with the same weight of water; and then adding water in a weight ratio of (1:0.5 to 1:0.8) for the second time, continuing reduced pressure distillation, and distilling out a fraction with the same weight of water.

[0032] Step 2: After the distillation is completed, add 1% to 5% decolorizing agent to the system, maintain the temperature within the range of 40 to 80°C, stir and decolorize for 1 hour, and filter to obtain the decolorized mother liquor. The decolorizing agent can be activated carbon, macroporous resin and diatomaceous earth, preferably activated carbon (1% w / w).

[0033] Step 3: Add different equivalents (1.0 to 1.5 equivalents) of a resolving agent to the decolorized mother liquor, stir, and heat to 60 to 85°C until the system is dissolved. If it is not dissolved, add a small amount of concentrated sulfuric acid. The resolving agent can be phenylglycine or phenylethylamine; cool and filter to obtain a wet double salt product. Different resolving agents can obtain different types of double salts, including L-phenylglycine-D-camphorsulfonic acid, d-phenylglycine-d-camphorsulfonic acid, L-phenylethylamine-d-camphorsulfonic acid, and d-phenylethylamine-d-camphorsulfonic acid.

[0034] Step 4: Add 2 times of water to the double salt, stir and heat to 50-55°C. Slowly add ammonia water to adjust the pH to 6-8, cool down, filter, the filter cake is the splitting agent (dry and apply), and the filtrate is ammonium camphorsulfonate solution.

[0035] Step 5: Deamination by cationic resin adsorption of the ammonium camphorsulfonic acid solution: the resin loading amount is 1 / 2 of the volume of the feed solution, a resin column with a height-to-diameter ratio of 5 to 10:1 is selected, and the solution flow rate is controlled to be 2BV / h for adsorption deamination, and the final effluent is a camphorsulfonic acid solution.

[0036] Step 6: The collected camphorsulfonic acid solution is subjected to reduced pressure distillation, and after distillation until no fraction flows out, 50g of acetic acid is added and the temperature is slowly lowered to 10-15°C. Filter by suction and dry to obtain 40g (~75% yield) of camphorsulfonic acid solid. The mother liquor is filtered by suction and concentrated to half of the solvent after collecting multiple batches, and then cooled to 10-15°C, filtered by suction, dried, and the recovered camphorsulfonic acid ~7.5g (15%) is obtained.

[0037] Therefore, the process can eventually recover ~47.5 g of camphorsulfonic acid, that is, ~90% of camphorsulfonic acid can be recovered from the sulfonation mother liquor.

[0038] The chemical reaction formula of the present invention is as follows:

[0039]

[0040] The following table provides eight specific embodiments according to the type of sulfonation mother liquor, the weight ratio of the two water additions in step (1), and the different selections of the decolorizing agent and the resolving agent.

[0041]

[0042] The present invention mainly utilizes camphorsulfonic acid and phenylglycine to react to generate a double salt, and the double salt has low solubility in water, thereby separating the camphorsulfonic acid double salt from the mother liquor, and then undergoing post-treatment processes such as hydrolysis and resin deamination to finally obtain a qualified product-camphorsulfonic acid. In an embodiment in which phenylglycine is selected as the resolving agent, the present invention can realize the recovery of 80-90% of the camphorsulfonic acid in the mother liquor, and has considerable economic benefits.

[0043] It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the appended claims of the application.

Claims

1. A method for recovering camphorsulfonic acid from a sulfonation mother liquor, characterized in that Here are the steps: (1) first adding water to dilute the sulfonation mother liquor, and then starting to distill under reduced pressure to recover acetic acid and water; water is continuously added during the distillation process until most of the acetic acid in the system is evaporated; (2) After distillation, add 1% to 5% decolorizing agent to the mother liquor, then stir and decolorize and filter at a certain temperature; (3) adding a resolving agent to the decolorizing solution, heating the solution to perform a salt-forming reaction, cooling the solution to crystallize, and filtering the solution to obtain a double salt of phenylglycine-camphorsulfonic acid; (4) adding water to the double salt, and then dropping ammonia water to carry out hydrolysis reaction, cooling, filtering, and using the filter cake as a resolving agent. After drying, the filtrate is an ammonium camphorsulfonate solution; (5) adsorbing the ammonium camphorsulfonate solution through a cation exchange resin to remove ammonia to obtain a camphorsulfonic acid solution; (6) Finally, the camphorsulfonic acid solution is concentrated under reduced pressure until no water is evaporated, acetic acid is added for crystallization, filtered, and dried to finally obtain recovered camphorsulfonic acid.

2. A method for recovering camphorsulfonic acid from a sulfonated mother liquor according to claim 1, characterized in that In step (1), water is continuously added during the distillation process, specifically, water is added at a weight ratio of (1:0.5 to 1:0.8) for the first time, and reduced pressure distillation is started to distill out a fraction with the same weight of water; water is added at a weight ratio of (1:0.5 to 1:0.8) for the second time, and reduced pressure distillation is continued to distill out a fraction with the same weight of water.

3. A method for recovering camphorsulfonic acid from a sulfonated mother liquor according to claim 1 or 2, characterized in that The decolorizing agent in step (2) is activated carbon, macroporous resin or diatomaceous earth, and the decolorizing is carried out by stirring at a temperature of 40 to 80° C. for 1 hour.

4. A method for recovering camphorsulfonic acid from a sulfonated mother liquor according to claim 3, characterized in that The decolorizing agent is activated carbon (1% w / w) 。 5. A method for recovering camphorsulfonic acid from a sulfonated mother liquor according to claim 1, characterized in that Add different equivalents (1.0-1.5 equivalents) of a resolving agent to the decolorized mother liquor, stir, and heat to 60-85° C. until the system is dissolved. If it is not dissolved, add a small amount of concentrated sulfuric acid dropwise. The resolving agent is phenylglycine or phenylethylamine.

6. A method for recovering camphorsulfonic acid from a sulfonated mother liquor according to claim 1, characterized in that In the step (4), 2 times of water is added to the double salt, the mixture is stirred and heated to 50-55° C., ammonia water is slowly added dropwise to adjust the pH to 6-8, the mixture is cooled and filtered, and the filter cake is used as the resolving agent.

7. A method for recovering camphorsulfonic acid from a sulfonated mother liquor according to claim 1, characterized in that In the step (5), the ammonium camphorsulfonate solution is subjected to cationic resin adsorption deamination: the resin loading amount is 1 / 2 of the volume of the feed solution, a resin column with a height-to-diameter ratio of 5 to 10:1 is selected, and the solution flow rate is controlled to be 2BV / h for adsorption deamination.

8. A method for recovering camphorsulfonic acid from a sulfonated mother liquor according to claim 7, characterized in that In the step (5), the collected camphorsulfonic acid solution is subjected to reduced pressure distillation, and after distillation until no fraction flows out, acetic acid is added, the temperature is slowly lowered to 10-15° C., filtered, and dried to obtain camphorsulfonic acid solid. The filtered mother liquor is collected in multiple batches and half of the solvent is concentrated, then cooled to 10-15° C., filtered, and dried to continue to obtain recovered camphorsulfonic acid.

9. A method for recovering camphorsulfonic acid from a sulfonated mother liquor according to claim 1, characterized in that The cation exchange resin in step (5) is regenerated by hydrochloric acid (5%) to obtain a regeneration liquid - ammonium chloride solution, and the regenerated resin is reused.

10. A method for recovering camphorsulfonic acid from a sulfonation mother liquor according to claim 1, characterized in that The sulfonated mother liquor is a dextrorotatory camphorsulfonic acid mother liquor or a cyclorotatory camphorsulfonic acid mother liquor.

Images