A method for preparing caprolactam using a lysine-containing fermentation broth, lysine, or a lysine salt as a raw material

Abstract

The application discloses a method for preparing caprolactam by taking lysine-containing fermentation liquor, lysine or lysine salt as raw materials, and belongs to the technical field of caprolactam synthesis. The application solves the problems of low yield, complex and harsh operation conditions, high preparation cost and inability to be applied in large-scale industrialization in the prior art. The application takes lysine-containing fermentation liquor, lysine or lysine salt as starting raw materials, synthesizes aminocaprolactam under high temperature and high pressure with or without sodium hydroxide, then uses chloramine as a deaminating reagent to react with the amino group of aminocaprolactam, so that the amino group is converted into a hydrazine, the hydrazine is oxidized into an azo compound by chloramine, and then caprolactam is obtained by denitrogenation under alkaline conditions. The preparation method has the advantages of high product yield, short reaction path, high reaction efficiency, simple operation, low production cost and the like, and is suitable for large-scale production of caprolactam.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of caprolactam synthesis, and particularly relates to a method for preparing caprolactam from a fermentation broth containing lysine, lysine or a lysine salt as a raw material. BACKGROUND

[0002] Caprolactam is a high value-added chemical intermediate and is the main raw material for producing nylon 6. The most advanced industrial production process for caprolactam is the cyclohexanone ammonium hydroxylate liquid phase rearrangement technology, which uses cyclohexanone, hydrogen peroxide and ammonia as raw materials, titanium-silicon molecular sieve as catalyst, and tert-butyl alcohol as solvent (ammonium hydroxylate), and the cyclohexanone oxime is subjected to Beckmann rearrangement in the presence of oxalic acid to generate amide oil (liquid phase rearrangement), then ammonia water is added for neutralization and separation, and then refined to obtain caprolactam. However, this method cannot get rid of the dependence on fossil resources and the heavy pollution and corrosion of reaction vessels caused by the use of oxalic acid. The use of biomass renewable resources to prepare caprolactam can effectively alleviate the dependence of caprolactam industry on fossil resources.

[0003] Lysine (also known as 2,6-diaminohexanoic acid) is a natural renewable resource, which is mainly prepared by corn fermentation. China has abundant corn production, the largest lysine production capacity in the world (>2 million tons / year), and low prices (about 8000 yuan / ton), and there is a problem of overcapacity. Lysine has one amino group at the α and ε positions, and the amino hexanolactam obtained by condensation of the amino group at the ε position and the carboxyl group has the same seven-membered ring structure as caprolactam. The α amino group is removed to obtain caprolactam, so lysine is an ideal raw material for preparing caprolactam.

[0004] Currently, the main steps of the method for preparing caprolactam from lysine are: lysine is dehydrated and cyclized to obtain aminocaprolactam, and the aminocaprolactam is deaminated to prepare caprolactam. Chinese patent CN101006051A reports a method for synthesizing caprolactam from lysine. First, lysine is used to synthesize aminocaprolactam at high temperature and high pressure, and then caprolactam is prepared by deamination of aminocaprolactam. Although the deamination yield can reach 70%, a large amount of expensive amino-O-sulfonic acid is used in the process, increasing the cost, and the operation steps are complicated, which is not conducive to industrial production. Literature (Berger, Kathleen J., et al. Direct deamination of primary amines via isodiazene intermediates Journal of the American Chemical Society 143.42 (2021): 17366-17373.) J. Am. Chem. Soc. 2021, 143, 17366-17373. reports that lysine is heated to 200°C in ethylene glycol to obtain aminocaprolactam, and then a special amide reagent is used to realize the deamination of aminocaprolactam to synthesize caprolactam through an isodiazene intermediate. However, the amide reagent used has a cell induction effect, which has a great impact on the human body and the environment, and the synthesis cost is high, and the yield is only 58%, which is not conducive to industrial production. US2010145003A1 reports a method for directly preparing caprolactam from lysine using a Pt-S / C catalyst of transition metals. However, this method requires a high temperature and a high-pressure hydrogen and hydrogen sulfide environment, and the yield is only 15%, which is not conducive to large-scale production. Literature (Sebastian, Joby, et al. One-pot conversion of lysine to caprolactam over Ir / H-Beta catalysts Green Chemistry 21.9 (2019): 2462-2468) proposes using lysine as a raw material and loading iridium on HB-124 molecular sieve as a bifunctional metal catalyst to synthesize caprolactam from lysine in one step, but the highest yield is only 23.9%.

[0005] In summary, the methods reported for preparing caprolactam from lysine have certain limitations, such as low yield, complex operation and expensive reagents, which reduce the feasibility of industrial production. SUMMARY

[0006] The present application provides a method for preparing caprolactam from a fermentation broth containing lysine, lysine or a lysine salt as raw material, which can solve the problems of high production cost, multi-step reaction, complicated process and low product yield in the existing method.

[0007] The object of the present application is achieved by the following technical solutions:

[0008] The object of the present application is achieved by the following technical solutions:

[0009] Step one: mixing the reaction raw material with the solvent to form a solution, then performing a dehydration cyclization reaction under the condition of having or not having sodium hydroxide, purifying the reaction system after the reaction, and obtaining aminocaprolactam;

[0010] Step two: mixing the chloramine solution with aminocaprolactam, performing a reaction, purifying the reaction system after the reaction, and obtaining caprolactam.

[0011] Further limitation, the reaction raw material in step one is one or several of the fermentation broth containing lysine, lysine, lysine salt.

[0012] Further limitation, the lysine salt is one or several of lysine hydrochloride, lysine sulfate, lysine acetate, lysine phosphate.

[0013] Further limitation, when the reaction raw material in step one is lysine salt, the dehydration cyclization reaction is performed under the condition of having sodium hydroxide.

[0014] Further limitation, the solvent in step one is one or several of alcohol compound, toluene, xylene, mesitylene, tetrahydrofuran, dioxane, dichloromethane, trichloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide.

[0015] Further limitation, the solvent is alcohol compound.

[0016] Further limitation, the solvent in step one is methanol.

[0017] Further limitation, the reaction temperature in step one is 80-250 DEG C.

[0018] Further limitation, the reaction temperature is 175 DEG C.

[0019] Further limitation, the reaction pressure in step one is 0-4 MPa.

[0020] Further, the reaction time in step one is 0.5-8 hours.

[0021] Further, the reaction time is 6 hours.

[0022] Further, the concentration of the solution in step one is 0.05-2 mol / L.

[0023] Further, the concentration of the solution is 0.05 mol / L.

[0024] Further, the purification method in step one is: first, the solid material is removed by suction filtration, then the solvent is removed by distillation under reduced pressure, then the extraction solvent is added and stirred for a period of time at the extraction temperature, then hot filtration is performed, and then other solvents are removed by distillation under reduced pressure to obtain the aminocaproamide product.

[0025] Further, the extraction solvent is one or more of ethyl acetate, dichloromethane, toluene, chloroform, benzene, tetrahydrofuran, dioxolane, dioxane.

[0026] Further, the extraction temperature is 0-30°C higher or lower than the boiling point of the extraction solvent.

[0027] Further, the time is 0.5-6 hours.

[0028] Further, the chloramine solution in step two is obtained by reacting sodium hypochlorite in sodium hypochlorite solution with ammonia in ammonia water at a molar ratio of (0.5-2):1.

[0029] Further, the reaction time is 5 minutes-2 hours.

[0030] Further, the reaction time is 1 hour.

[0031] Further, the reaction temperature is -10-20°C.

[0032] Further, the reaction temperature is 0°C.

[0033] Further, the molar ratio of chloramine to aminocaproamide in the chloramine solution in step two is (2-20):1.

[0034] Further, the molar ratio of chloramine to aminocaproamide in the chloramine solution is (4-15):1.

[0035] Further, the reaction temperature in step two is 0-60°C.

[0036] Further, the reaction time in step two is 5 minutes-24 hours.

[0037] Further, the reaction time is 10 hours.

[0038] Further limited, the purification method in step two is: using acidifying reagent to adjust the reaction system to pH 4-5, then adding extraction solvent for extraction, retaining the organic phase after the extraction is completed, removing the extraction solvent to obtain caprolactam.

[0039] Still further limited, the amount of acidifying reagent is (0.1-0.5) times of the molar number of aminocaproamide.

[0040] Still further limited, the acidifying reagent is dilute sulfuric acid.

[0041] The beneficial effects of the present application are as follows:

[0042] The present application is prepared by two-step reaction of lysine-containing fermentation broth, lysine or lysine salt to prepare caprolactam. First, lysine-containing fermentation broth, lysine or lysine salt is used as the starting material, and aminocaproamide is synthesized at high temperature and high pressure, and then aminocaproamide is reacted with chloramine solution. The reaction process of aminocaproamide and chloramine solution does not need heating, and the deamination of aminocaproamide can be realized at room temperature to prepare nylon 6 monomer caprolactam. Compared with the prior art, the present application has the following advantages:

[0043] (1) The present application uses chloramine solution as the deamination reagent. The amino group of chloramine solution reacts with the amino group of aminocaproamide to convert the amino group into hydrazine. Then the hydrazine is oxidized by chloramine to generate azo, and then one molecule of nitrogen is removed under alkaline conditions to obtain caprolactam. Compared with common deamination reagents such as hydroxylamine-O-sulfonic acid, the preparation cost of chloramine is lower and the preparation method is more convenient. The alkaline solution of chloramine can be obtained by mixing ammonia and sodium hypochlorite in water. Moreover, chloramine has less impact on the environment. In addition, the use of chloramine as a deamination reagent does not require the addition of additional alkaline reagents such as sodium hydroxide or potassium hydroxide, which saves costs. Moreover, compared with the strategy of directly using metal catalysts such as Pt-S / C for deamination, this method has a great advantage in yield, which can reach 86%, much higher than the 15% yield of using metal catalysts. It also avoids the generation of high temperature and high pressure and toxic by-products, which is conducive to environmental protection and green production.

[0044] (2) Compared with the existing methods for preparing caprolactam from lysine, lysine-containing raw materials or lysine salt, the method provided by the present application has high caprolactam product yield, which can reach 86% at most. The reaction conditions are mild and the operation is simple. The reagents used in the preparation process are all bulk industrial products, which are cheap and easy to obtain, and the production cost is low. It is suitable for large-scale production of caprolactam and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The caprolactam prepared in Example 1 has a nuclear magnetic hydrogen spectrum (H-NMR). 1 H-NMR). DETAILED DESCRIPTION

[0046] In order to make the above objectives, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the embodiments of the present application. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the concept of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0047] Secondly, "one embodiment" or "an embodiment" referred to herein means that a specific feature, structure or characteristic can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is separate or alternative to other embodiments.

[0048] The experimental methods used in the following embodiments are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained by commercial channels by those skilled in the art.

[0049] Caprolactam yield = (mass of caprolactam / 113) / (mass of aminocaprolactam feed / 128) x 100%.

[0050] Example 1

[0051] The synthesis route of caprolactam in this embodiment is as follows:

[0052]

[0053] (1) In a 5L high-temperature and high-pressure reactor, 3.5L of industrial methanol with a concentration of 99.9% was added, then 639g (3.5mol) of lysine hydrochloride and 140g (3.5mol) of sodium hydroxide were added, and the reaction was stirred at 1400KPa and 150℃ for 6h. After the reaction, the solid sodium chloride and unreacted L-lysine hydrochloride were removed by filtration, then the methanol was removed by distillation under reduced pressure, and then ethyl acetate was added, and the temperature was raised to 100℃ and stirred for 3h, and then filtered while hot, followed by removing the ethyl acetate by distillation under reduced pressure to obtain solid aminocaprolactam (416g, yield 92.9%). The structure of the aminocaprolactam was characterized by nuclear magnetic hydrogen spectrum detection as follows: 1 H NMR (300 MHz, D2O) δ 3.69-3.72 (dd, 1H), 3.22-3.26 (m, 2H), 1.26-1.99 (m, 6H), according to nuclear magnetic hydrogen spectrum detection analysis, the purity of the aminocaprolactam obtained in this step is 99%;

[0054] (2) Into a 5L reactor, 0.2L ammonia water (25-28wt%, the titration concentration is 13.3mol / L, i.e. the amount of substance of ammonia in the ammonia water is 2.66mol) was added, 3L sodium hypochlorite solution (effective chlorine content 8-10%, the titration concentration is 0.75mol / L, i.e. the amount of substance of sodium hypochlorite in the solution is 2.25mol) was slowly added dropwise at 0°C, after the dropwise addition was completed, the reaction was continued to be stirred at 0°C for 20min, 3.2L of the concentration of 0.70mol / L chloramine solution was obtained (i.e. the amount of substance of chloramine in the chloramine solution is 2.24mol), then 34g (0.266mol) of aminocaprolactam was added to the chloramine solution, the temperature of the system was slowly increased to room temperature and reacted for 10h, after the reaction was completed, a small amount of the obtained substance was taken for nuclear magnetic detection, the detection results showed that the conversion rate of aminocaprolactam was 100%, then 2mol / L dilute sulfuric acid was used to acidify the reacted substance to pH 4-5, the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, the dichloromethane was rotary evaporated, and caprolactam product (24.35g, yield: 81%) was obtained, the caprolactam product was tested by nuclear magnetic resonance hydrogen spectrum, and the structure characterization was as follows: 1 HNMR (300MHz, D2O) δ 3.26-3.18 (m, 2H), 2.49-2.41 (m, 2H), 1.75 (m, 2H), 1.61 (m, 4H), according to the nuclear magnetic hydrogen spectrum detection analysis, the purity of the caprolactam product was 98%.

[0055] Example 2

[0056] The synthesis route of the caprolactam in this example was the same as that in Example 1.

[0057] (1) The aminocaprolactam was prepared according to step (1) in Example 1;

[0058] (2) Into a 5 L reactor, 0.15 L of ammonia water (25-28 wt%, the titration concentration is 13.3 mol / L, i.e. the amount of substance of ammonia in the ammonia water is 2.0 mol) was added, 3 L of sodium hypochlorite solution (effective chlorine content 8-10%, the titration concentration is 0.75 mol / L, i.e. the amount of substance of sodium hypochlorite in the solution is 2.25 mol) was slowly added dropwise at 0°C, after the dropwise addition was completed, the reaction was continued to be stirred at 0°C for 20 min, 3.15 L of chloramine solution with a concentration of 0.63 mol / L was obtained (i.e. the amount of substance of chloramine in the chloramine solution is 1.98 mol), then 25.5 g (0.2 mol) of aminocaprolactam was added to the chloramine solution, the temperature of the system was slowly increased to room temperature and reacted for 10 h, after the reaction was completed, a small amount of the obtained substance was taken for nuclear magnetic detection, the detection results showed that the conversion rate of aminocaprolactam was 100%, then 2 mol / L dilute sulfuric acid was used to acidify the obtained substance to pH 4-5, the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, the dichloromethane was rotary evaporated, and caprolactam product (19.4 g, yield: 86%) was obtained, the purity of the caprolactam product prepared in this example was 98%.

[0059] Example 3

[0060] The synthesis route of caprolactam in this example is the same as that in Example 1.

[0061] (1) Aminocaprolactam was prepared according to step (1) in Example 1;

[0062] (2) Into a 5 L reactor, 0.2 L of ammonia water (25-28 wt%, the titration concentration is 13.3 mol / L, i.e. the amount of substance of ammonia in the ammonia water is 2.66 mol) was added, 2 L of sodium hypochlorite solution (effective chlorine content 8-10%, the titration concentration is 0.75 mol / L, i.e. the amount of substance of sodium hypochlorite in the solution is 1.5 mol) was slowly added dropwise at 0°C, after the dropwise addition was completed, the reaction was continued to be stirred at 0°C for 20 min, 2.2 L of chloramine solution with a concentration of 0.68 mol / L was obtained (i.e. the amount of substance of chloramine in the chloramine solution is 1.5 mol), then 34 g (0.266 mol) of aminocaprolactam was added to the chloramine solution, the temperature of the system was slowly increased to room temperature and reacted for 10 h, after the reaction was completed, a small amount of the obtained substance was taken for nuclear magnetic detection, the detection results showed that the conversion rate of aminocaprolactam was 60%, then 2N dilute sulfuric acid was used to acidify the obtained substance to pH 4-5, the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, the dichloromethane was rotary evaporated, and caprolactam product (15.3 g, yield: 51%) was obtained, the purity of the caprolactam product prepared in this example was 98%.

[0063] Example 4

[0064] The synthetic route of caprolactam in this example is the same as that in Example 1.

[0065] (1) Amino caprolactam was prepared according to step (1) in Example 1;

[0066] (2) 0.15 L of ammonia water (25-28 wt%, the titration concentration was 13.3 mol / L, i.e. the amount of substance of ammonia in the ammonia water was 2.0 mol) was added into a 10 L reaction kettle, 5 L of sodium hypochlorite solution (the effective chlorine content was 8-10%, the titration concentration was 0.75 mol / L, i.e. the amount of substance of sodium hypochlorite in the solution was 3.75 mol) was slowly added dropwise at 0°C, after the dropwise addition was completed, the reaction was continued to be stirred at 0°C for 20 min, 5.15 L of a chloramine solution with a concentration of 0.39 mol / L was obtained (i.e. the amount of substance of chloramine in the chloramine solution was 2.0 mol), then 25.5 g (0.2 mol) of amino caprolactam was added into the chloramine solution, the temperature of the system was slowly increased to room temperature and the reaction was carried out for 10 h, after the reaction was completed, a small amount of the obtained substance was taken out for nuclear magnetic detection, the detection result showed that the conversion rate of amino caprolactam was 100%, then 2 mol / L dilute sulfuric acid was used to acidify the obtained substance to pH 4-5, the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, the dichloromethane was rotary evaporated to obtain caprolactam product (17.1 g, the yield was 76%), the purity of the caprolactam product prepared in this example was 98%.

[0067] Example 5

[0068] The synthetic route of caprolactam in this example is the same as that in Example 1.

[0069] (1) Amino caprolactam was prepared according to step (1) in Example 1;

[0070] (2) Into a 5 L reactor, 0.15 L of ammonia water (25-28 wt%, the titration concentration is 13.3 mol / L, i.e. the amount of substance of ammonia in the ammonia water is 2.0 mol) was added, 3 L of sodium hypochlorite solution (effective chlorine content 8-10%, the titration concentration is 0.75 mol / L, i.e. the amount of substance of sodium hypochlorite in the solution is 2.25 mol) was slowly added dropwise at 0°C, after the dropwise addition was completed, the reaction was continuously stirred at 0°C for 20 min, 3.15 L of chloramine solution with a concentration of 0.63 mol / L was obtained (i.e. the amount of substance of chloramine in the chloramine solution is 1.98 mol), then 64 g (0.5 mol) of aminocaprolactam was added to the chloramine solution, the temperature of the system was slowly increased to room temperature and reacted for 10 h, after the reaction was completed, a small amount of the obtained substance was taken for nuclear magnetic detection, the detection results showed that the conversion rate of aminocaprolactam was 40%, then 2 mol / L dilute sulfuric acid was used to acidify the obtained substance to pH 4-5, the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, the dichloromethane was rotary evaporated, and caprolactam product (20.34 g, yield: 36%) was obtained, the purity of the caprolactam product prepared in this example was 98%.

[0071] Example 6

[0072] The synthesis route of caprolactam in this example was the same as that in Example 1.

[0073] (1) Aminocaprolactam was prepared according to step (1) in Example 1;

[0074] (2) Into a 5 L reactor, 0.15 L of ammonia water (25-28 wt%, the titration concentration is 13.3 mol / L, i.e. the amount of substance of ammonia in the ammonia water is 2.0 mol) was added, 3 L of sodium hypochlorite solution (effective chlorine content 8-10%, the titration concentration is 0.75 mol / L, i.e. the amount of substance of sodium hypochlorite in the solution is 2.25 mol) was slowly added dropwise at 0°C, after the dropwise addition was completed, the reaction was continuously stirred at 0°C for 20 min, 3.15 L of chloramine solution with a concentration of 0.63 mol / L was obtained (i.e. the amount of substance of chloramine in the chloramine solution is 1.98 mol), then 64 g (0.5 mol) of aminocaprolactam was added to the chloramine solution, the temperature of the system was slowly increased to room temperature and reacted for 10 h, after the reaction was completed, a small amount of the obtained substance was taken for nuclear magnetic detection, the detection results showed that the conversion rate of aminocaprolactam was 40%, then 2 mol / L dilute sulfuric acid was used to acidify the obtained substance to pH 4-5, the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, the dichloromethane was rotary evaporated, and caprolactam product (20.34 g, yield: 36%) was obtained, the purity of the caprolactam product prepared in this example was 98%.

[0075] Example 7

[0076] The synthetic route of caprolactam in this example is the same as that in Example 1.

[0077] (1) Aminocaprolactam was prepared according to step (1) in Example 1;

[0078] (2) 107 g of ammonium chloride was dissolved in 0.15 L of deionized water and added to a 5 L reaction kettle, followed by the addition of 80 g of sodium hydroxide. The ammonium chloride and sodium hydroxide formed 0.15 L of ammonia water (concentration of 13.3 mol / L, i.e., 2.0 mol of ammonia in the ammonia water). Then, 3 L of sodium hypochlorite solution (effective chlorine content of 8-10%, titration concentration of 0.75 mol / L, i.e., 2.25 mol of sodium hypochlorite in the solution) was slowly added dropwise at 0°C. After the dropwise addition was completed, the reaction was continued to stir at 0°C for 20 min to obtain 3.15 L of chloramine solution (concentration of 0.63 mol / L, i.e., 1.98 mol of chloramine in the chloramine solution). Then, 25.5 g (0.2 mol) of aminocaprolactam was added to the chloramine solution, and the temperature of the system was slowly increased to room temperature for reaction for 10 h. After the reaction was completed, a small amount of the obtained substance was taken for nuclear magnetic detection, and the detection results showed that the conversion rate of aminocaprolactam was 71%. Then, 2 mol / L dilute sulfuric acid was used to acidify the obtained substance to pH 4-5, and dichloromethane was used to extract the acidified substance for 3-6 times until no product was left in the water. The dichloromethane was rotary evaporated to obtain caprolactam product (12.18 g, yield: 54%). The purity of the caprolactam product prepared in this example was 98%.

[0079] Example 8

[0080] The synthetic route of caprolactam in this example is the same as that in Example 1.

[0081] (1) Aminocaprolactam was prepared according to step (1) in Example 1;

[0082] (2) 320 g of sodium hydroxide was dissolved in 3 L of deionized water, added to a 5 L reaction kettle, and then chlorine was bubbled into the reaction kettle for 1 h. Sodium hydroxide reacted with chlorine to form a 3 L sodium hypochlorite solution (concentration of 1.33 mol / L, i.e., the amount of substance of sodium hypochlorite in the solution was 3.99 mol). Then, 0.15 L of ammonia water (25-28 wt%, titration concentration of 13.3 mol / L, i.e., the amount of substance of ammonia in the ammonia water was 2.0 mol) was added at 0°C, and after the addition was completed, the reaction was continued to be stirred at 0°C for 20 min to obtain a 3.15 L chloramine solution (concentration of 0.63 mol / L, i.e., the amount of substance of chloramine in the chloramine solution was 1.98 mol). Then, 25.5 g (0.2 mol) of aminocaprolactam was added to the chloramine solution at 0°C, and the temperature of the system was slowly increased to room temperature for reaction for 10 h. After the reaction was completed, a small amount of the obtained substance was taken for nuclear magnetic detection, and the detection results showed that the conversion rate of aminocaprolactam was 100%. Then, 2 mol / L dilute sulfuric acid was used to acidify the obtained substance to pH 4-5, and dichloromethane was used to extract the acidified substance for 3-6 times until no product was left in the water. The dichloromethane was rotary evaporated to obtain caprolactam product (19.28 g, yield: 85%). The caprolactam product prepared in this example had a purity of 98%.

[0083] Example 9

[0084] The synthesis route of caprolactam in this example was the same as that in Example 1.

[0085] (1) Aminocaprolactam was prepared according to step (1) in Example 1.

[0086] (2) 0.3 L of ammonia water (25-28 wt%, titration concentration of 13.3 mol / L, i.e., the amount of substance of ammonia in the ammonia water was 3.99 mol) was added to a 5 L reaction kettle, and 3 L of sodium hypochlorite solution (effective chlorine content of 8-10%, titration concentration of 0.75 mol / L, i.e., the amount of substance of sodium hypochlorite in the solution was 2.25 mol) was slowly added dropwise at 0°C. After the dropwise addition was completed, the reaction was continued to be stirred at 0°C for 20 min to obtain a 3.3 L chloramine solution (concentration of 0.68 mol / L, i.e., the amount of substance of chloramine in the chloramine solution was 2.24 mol). Then, 68 g (0.5 mol) of aminocaprolactam was added to the chloramine solution at 0°C, and the temperature of the system was slowly increased to room temperature for reaction for 10 h. After the reaction was completed, a small amount of the obtained substance was taken for nuclear magnetic detection, and the detection results showed that the conversion rate of aminocaprolactam was 60%. Then, 2 mol / L dilute sulfuric acid was used to acidify the obtained substance to pH 4-5, and dichloromethane was used to extract the acidified substance for 3-6 times until no product was left in the water. The dichloromethane was rotary evaporated to obtain caprolactam product (26.41 g, yield: 44%). The caprolactam product prepared in this example had a purity of 98%.

[0087] Example 10

[0088] The synthetic route of caprolactam in this example is the same as that in Example 1.

[0089] (1) Amino caprolactam was prepared according to step (1) in Example 1;

[0090] (2) 0.2 L of ammonia water (25-28 wt%, the titration concentration was 13.3 mol / L, i.e. the amount of substance of ammonia in the ammonia water was 2.66 mol) was added into a 5 L reaction kettle, 3 L of sodium hypochlorite solution (the effective chlorine content was 8-10%, the titration concentration was 0.75 mol / L, i.e. the amount of substance of sodium hypochlorite in the solution was 2.25 mol) was slowly added dropwise at 0°C, after the dropwise addition was completed, the reaction was continued to be stirred at 0°C for 20 min, 3.2 L of a chloramine solution with a concentration of 0.70 mol / L was obtained (i.e. the amount of substance of chloramine in the chloramine solution was 2.24 mol), then 45 g (0.35 mol) of amino caprolactam was added into the chloramine solution, the temperature of the system was slowly increased to room temperature and the reaction was carried out for 10 h, after the reaction was completed, a small amount of the obtained substance was taken out for nuclear magnetic detection, the detection result showed that the conversion rate of amino caprolactam was 75%, then 2 mol / L dilute sulfuric acid was used to acidify the obtained substance to pH 4-5, the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, the dichloromethane was rotary evaporated to obtain caprolactam product (27.01 g, the yield was 68%), the purity of the caprolactam product prepared in this example was 98%.

[0091] Example 11

[0092] The synthetic route of caprolactam in this example is the same as that in Example 1.

[0093] (1) Amino caprolactam was prepared according to step (1) in Example 1;

[0094] (2) Add 0.2L of ammonia water (25-28 wt%, titration concentration of 13.3 mol / L, i.e., the amount of ammonia in the ammonia water is 2.66 mol) to a 5L reactor. At 0℃, slowly add 3L of sodium hypochlorite solution (effective chlorine content 8-10%, titration concentration of 0.75 mol / L, i.e., the amount of sodium hypochlorite in the solution is 2.25 mol). After the addition is complete, continue stirring at 0℃ for 20 minutes to obtain 3.2L of chloramine solution with a concentration of 0.70 mol / L (i.e., the amount of chloramine in the chloramine solution is 2.24 mol). Then... At 0°C, 68 g (0.5 mol) of aminocaprolactam was added to a chloramine solution, and the system temperature was slowly raised to room temperature for 10 h. After the reaction, a small amount of the obtained substance was subjected to NMR detection. The detection results showed that the conversion rate of aminocaprolactam was 68%. Subsequently, the reactant was acidified to pH 4-5 with 2 mol / L dilute sulfuric acid. The acidified substance was extracted 3-6 times with dichloromethane until no product was found in water. The dichloromethane was then evaporated to obtain caprolactam product (36.02 g, yield: 60%). The purity of the caprolactam product prepared in this example was 98%.

[0095] Example 12

[0096] The synthetic route for caprolactam in this embodiment is as follows:

[0097]

[0098] (1) In a 5L high-temperature and high-pressure reactor, 3.5L of industrial methanol with a concentration of 99.9% was added, followed by 511g (3.5mol) of lysine. The mixture was stirred at 1400KPa and 150℃ for 6h. The methanol was then removed by vacuum distillation, followed by the addition of ethyl acetate. The mixture was heated to 100℃ and stirred for 3h. The mixture was filtered while hot, and the ethyl acetate was subsequently removed by vacuum distillation to obtain solid aminocaprolactam (4401g, yield 89.4%). The aminocaprolactam was characterized by 1H NMR spectroscopy, and its structure is as follows: 1 ¹H NMR (300MHz, D₂O) δ 3.69–3.72 (dd, 1H), 3.22–3.26 (m, 2H), 1.26–1.99 (m, 6H). According to the analysis of ¹H NMR, the purity of aminocaprolactam obtained in this step is 99%.

[0099] (2) Into a 5 L reactor, 0.2 L of ammonia water (25-28 wt%, the titration concentration is 13.3 mol / L, i.e. the amount of substance of ammonia in the ammonia water is 2.66 mol) was added, 3 L of sodium hypochlorite solution (effective chlorine content 8-10%, the titration concentration is 0.75 mol / L, i.e. the amount of substance of sodium hypochlorite in the solution is 2.25 mol) was slowly added dropwise at 0°C, after the dropwise addition was completed, the reaction was continued to be stirred at 0°C for 20 min, 3.2 L of chloramine solution with a concentration of 0.70 mol / L was obtained (i.e. the amount of substance of chloramine in the chloramine solution is 2.24 mol), then 34 g (0.266 mol) of aminocaprolactam was added to the chloramine solution, the temperature of the system was slowly increased to room temperature and reacted for 10 h, after the reaction was completed, a small amount of the obtained substance was taken for nuclear magnetic detection, the detection results showed that the conversion rate of aminocaprolactam was 100%, then 2 mol / L dilute sulfuric acid was used to acidify the reacted substance to pH 4-5, the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, the dichloromethane was rotary evaporated, and caprolactam product (24.35 g, yield: 81%) was obtained, the caprolactam product was tested by nuclear magnetic resonance hydrogen spectrum, and the structure characterization was as follows: 1 HNMR (300 MHz, D2O) δ 3.26-3.18 (m, 2H), 2.49-2.41 (m, 2H), 1.75 (m, 2H), 1.61 (m, 4H), according to the nuclear magnetic hydrogen spectrum detection analysis, the purity of the caprolactam product was 98%.

[0100] Comparative Example 1

[0101] (1) The aminocaprolactam was prepared according to step (1) in Example 1;

[0102] (2) Into a 5 L reactor, 0.2 L of ammonia water (25-28 wt%, the titration concentration is 13.3 mol / L, i.e. the amount of substance of ammonia in the ammonia water is 2.66 mol) was added, 3 L of sodium hypochlorite solution (effective chlorine content 8-10%, the titration concentration is 0.75 mol / L, i.e. the amount of substance of sodium hypochlorite in the solution is 2.25 mol) was slowly added dropwise at 0°C, after the dropwise addition was completed, the reaction was continued to be stirred at 0°C for 20 min, 3.2 L of chloramine solution with a concentration of 0.70 mol / L was obtained (i.e. the amount of substance of chloramine in the chloramine solution is 2.24 mol), then 34 g (0.266 mol) of aminocaprolactam was added to the chloramine solution, the temperature of the system was slowly increased to room temperature and reacted for 10 h, after the reaction was completed, a small amount of the obtained substance was taken for nuclear magnetic detection, the detection results showed that the conversion rate of aminocaprolactam was 100%, then 2 mol / L dilute sulfuric acid was used to acidify the reacted substance to pH 4-5, the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, the dichloromethane was rotary evaporated, and caprolactam product (24.35 g, yield: 81%) was obtained, the caprolactam product was tested by nuclear magnetic resonance hydrogen spectrum, and the structure characterization was as follows:

[0103] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for producing caprolactam from a lysine-containing fermentation broth, lysine or a lysine salt, characterized by, The application relates to a method for preparing caprolactam. Step one: mixing reaction raw materials with a solvent to form a solution, then performing a dehydration and cyclization reaction under the condition of having or not having sodium hydroxide, purifying the reaction system after the reaction, and obtaining aminocaprolactam; Step two: mixing a chloramine solution with aminocaprolactam, performing a reaction, purifying the reaction system after the reaction, and obtaining caprolactam. The reaction raw materials are one or more of a lysine-containing fermentation liquor, lysine and a lysine salt. The molar ratio of chloramine in the chloramine solution to aminocaprolactam in step two is 2-20:1, and the reaction temperature is 0-60 DEG C.

2. The method of claim 1, wherein, The lysine salt is one or more of lysine hydrochloride, lysine sulfate, lysine acetate and lysine phosphate.

3. The method of claim 1, wherein, When the reaction raw materials in step one are a lysine salt, the dehydration and cyclization reaction is performed under the condition of having sodium hydroxide; the solvent is one or more of an alcohol compound, toluene, dimethylbenzene, mesitylene, tetrahydrofuran, dioxane, dichloromethane, trichloromethane, N, N-dimethylformamide, N, N-dimethylacetamide and dimethyl sulfoxide.

4. The method of claim 1, wherein, The reaction temperature in step one is 80-250 DEG C, the reaction time is 0.5-8 h, the concentration of the solution is 0.05-2 mol / L, and the reaction pressure is 0-4 MPa.

5. The method of claim 4, wherein, The reaction temperature is 175 DEG C, the reaction time is 6 h, and the concentration of the solution is 0.05 mol / L.

6. The method of claim 1, wherein, The purification method in step one is: firstly, removing solid substances by suction filtration, then removing the solvent by distillation under reduced pressure, then adding an extraction solvent, stirring for a period of time at an extraction temperature, filtering while hot, then removing the extraction solvent by distillation under reduced pressure, and obtaining aminocaprolactam products.

7. The method of claim 6, wherein, The extraction solvent is one or more of ethyl acetate, dichloromethane, toluene, chloroform, benzene, tetrahydrofuran, dioxolane and dioxane, the extraction temperature is 0-30 DEG C higher or lower than the boiling point of the extraction solvent, and the time is 0.5-6 h.

8. The method of claim 1, wherein, The chloramine solution in step two is obtained by reacting sodium hypochlorite in a sodium hypochlorite solution with ammonia in ammonia water according to a molar ratio of 0.5-2:

1.

9. The method of claim 1, wherein, The reaction time in step two is 5 min-24 h.

10. The method of claim 1, wherein, The purification method in step two is: using an acidifying reagent to adjust the pH of the reaction system to 4-5, then adding an extraction solvent to perform extraction, retaining the organic phase after the extraction is completed, removing the extraction solvent, and obtaining caprolactam.

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