Method for preparing caprolactam by using lysine-containing fermentation liquor, lysine or lysine salt as raw materials

Abstract

The invention discloses a method for preparing caprolactam by using lysine-containing fermentation liquor, lysine or lysine salt as raw materials, and belongs to the technical field of caprolactam synthesis. The problems that in the prior art, caprolactam prepared from lysine is low in yield, complex and strict in operation condition, high in preparation cost, incapable of being industrially applied on a large scale and the like are solved. The method comprises the following steps: by taking lysine-containing fermentation liquor, lysine or lysine salt as initial raw materials, synthesizing aminocaprolactam at high temperature and high pressure in the presence or absence of sodium hydroxide, then reacting chloramine as a deamination reagent with amino of aminocaprolactam to convert the amino into diamine, oxidizing the diamine by chloramine to generate azo, and finally synthesizing the amino caprolactam. The preparation method provided by the invention 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 invention belongs to the technical field of caprolactam synthesis, and in particular relates to a method for preparing caprolactam by using fermentation liquid containing lysine, lysine or lysine salt as raw materials. Background Art

[0002] Caprolactam is a high value-added chemical intermediate and the main raw material for producing nylon 6. At present, the most advanced industrial production process of caprolactam is cyclohexanone ammoximation plus 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 (ammoximation). Cyclohexanone oxime undergoes Beckmann rearrangement in the presence of fuming acid to generate amide oil (liquid phase rearrangement), and then adds ammonia water for neutralization and separation, and then refines to obtain caprolactam. However, this method cannot get rid of the dependence on fossil resources and the heavy pollution caused by the use of fuming acid and the corrosion loss of the reaction container. The use of biomass renewable resources to prepare caprolactam can effectively alleviate the dependence of the caprolactam industry on fossil resources.

[0003] Lysine (also known as 2,6-diaminocaproic acid) is a natural renewable resource, which is mainly produced by corn fermentation. China has abundant corn production and the world's largest lysine production capacity (>2 million tons / year), and the price is low (about 8,000 yuan / ton), which has the problem of overcapacity. Lysine has an amino group at the α and ε positions. The aminocaprolactam obtained by condensing the amino group at the ε position with the carboxyl group has the same seven-membered ring structure as caprolactam. Caprolactam can be obtained by removing the α amino group. Therefore, lysine is an ideal raw material for preparing caprolactam.

[0004] At present, the main steps of the method for preparing caprolactam from lysine are: dehydration and cyclization of lysine to obtain aminocaprolactam, and then deamination of aminocaprolactam to prepare caprolactam. Chinese patent CN101006051A reports a method for synthesizing caprolactam from lysine, first using lysine to synthesize aminocaprolactam under high temperature and high pressure, and then deaminating aminocaprolactam to prepare caprolactam. Although the yield of deamination can reach 70%, a large amount of expensive amino-O-sulfonic acid is required in the process, which increases the cost, and the operation steps are cumbersome, which is not conducive to industrial production; the 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 reported that lysine was heated to 200°C in ethylene glycol to obtain aminocaprolactam, and then a special amide reagent was used to synthesize caprolactam by deamination of aminocaprolactam through an isodiazene intermediate. However, the amide reagent used has a cell-inducing 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; U.S. Patent US2010145003A1 reported a method for directly preparing caprolactam from lysine using a transition metal Pt-S / C catalyst, but the 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) proposed using lysine as 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 was only 23.9%.

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

[0006] In order to solve the problems of low yield, complex and harsh operating conditions, high preparation cost, and inability to be applied industrially on a large scale in a method for preparing caprolactam from lysine, the present invention provides a method for preparing caprolactam using a fermentation broth containing lysine, lysine or a lysine salt as a raw material. Caprolactam is prepared using a fermentation broth containing lysine, lysine or a lysine salt as a starting material, which can solve the problems of high production cost, need for multiple-step reactions, complicated process, low product yield, etc. in the existing method.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] The object of the present invention is to provide a method for preparing caprolactam from a lysine-containing raw material, comprising:

[0009] Step 1: mixing the reaction raw materials with a solvent to form a solution, and then carrying out a dehydration cyclization reaction in the presence or absence of sodium hydroxide, and purifying the reaction system after the reaction to obtain aminocaprolactam;

[0010] Step 2: mixing the chloramine solution with aminocaprolactam, reacting the mixture, and purifying the reaction system after the reaction to obtain caprolactam.

[0011] It is further defined that the reaction raw materials in step 1 are one or more of fermentation broth containing lysine, lysine, and lysine salt.

[0012] It is further defined that the lysine salt is one or more of lysine hydrochloride, lysine sulfate, lysine acetate, and lysine phosphate.

[0013] It is further defined that when the reaction raw material in step 1 is a lysine salt, the dehydration cyclization reaction is carried out in the presence of sodium hydroxide.

[0014] Further limited, the solvent in step 1 is one or more of alcohol compounds, toluene, xylene, mesitylene, tetrahydrofuran, dioxane, dichloromethane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

[0015] In a further embodiment, the solvent is an alcohol compound.

[0016] It is further defined that the solvent in step 1 is methanol.

[0017] It is further defined that the reaction temperature in step 1 is 80-250°C.

[0018] Further limiting the reaction temperature is 175°C.

[0019] It is further defined that the reaction pressure in step 1 is 0-4 MPa.

[0020] It is further defined that the reaction time in step 1 is 0.5 to 8 hours.

[0021] Furthermore, the reaction time is limited to 6 hours.

[0022] It is further defined that the concentration of the solution in step 1 is 0.05 to 2 mol / L.

[0023] It is further defined that the concentration of the solution is 0.05 mol / L.

[0024] It is further defined that the purification method in step one is: first, remove the solid matter by suction filtration, then remove the solvent by reduced pressure distillation, then add the extraction solvent and stir for a period of time at the extraction temperature, filter while hot, and then remove other solvents by reduced pressure distillation to obtain the aminocaprolactam product.

[0025] It is further defined that the extraction solvent is one or more of ethyl acetate, dichloromethane, toluene, chloroform, benzene, tetrahydrofuran, 1,2-dioxane and 1,2-dioxane.

[0026] It is further defined that the extraction temperature is 0 to 30° C. higher or lower than the boiling point of the extraction solvent.

[0027] It is further limited to a time period of 0.5 to 6 hours.

[0028] It is further defined that the chloramine solution in step 2 is obtained by reacting sodium hypochlorite in a sodium hypochlorite solution with ammonia in aqueous ammonia in a molar ratio of (0.5-2):1.

[0029] It is further limited that the reaction time is 5 minutes to 2 hours.

[0030] Furthermore, the reaction time is limited to 1 h.

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

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

[0033] It is further defined that the molar ratio of chloramine to aminocaprolactam in the chloramine solution in step 2 is (2-20):1.

[0034] It is further defined that the molar ratio of chloramine to aminocaprolactam in the chloramine solution is (4-15):1.

[0035] It is further defined that the reaction temperature in step 2 is 0-60°C.

[0036] It is further defined that the reaction time in step 2 is 5 min to 24 h.

[0037] Furthermore, the reaction time is limited to 10 h.

[0038] It is further defined that the purification method in step 2 is: using an acidifying agent to adjust the reaction system to a pH of 4 to 5, then adding an extraction solvent for extraction, retaining the organic phase after the extraction is completed, removing the extraction solvent, and obtaining caprolactam.

[0039] It is further defined that the amount of the acidifying agent used is (0.1 to 0.5) times the molar number of aminocaprolactam.

[0040] In a further embodiment, the acidifying agent is dilute sulfuric acid.

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

[0042] The present invention prepares caprolactam from a fermentation liquid containing lysine, lysine or a lysine salt through a two-step reaction. First, the fermentation liquid containing lysine, lysine or a lysine salt is used as a starting material to synthesize aminocaprolactam under high temperature and high pressure, and then the aminocaprolactam is reacted with a chloramine solution. The reaction process of the aminocaprolactam and the chloramine solution does not need to be heated, and the aminocaprolactam can be deaminated at room temperature to prepare nylon 6 monomer caprolactam. Compared with the prior art, the present invention has the following advantages:

[0043] (1) The present invention uses chloramine solution as a deamination reagent. The chloramine solution reacts with the amino group of aminocaprolactam to convert the amino group into hydrazine, which is then oxidized by chloramine to generate azo, and then a 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. Ammonia water and sodium hypochlorite are mixed in water to react to obtain an alkaline solution of chloramine, and chloramine has a smaller impact on the environment. In addition, when chloramine is used as a deamination reagent, no additional alkaline reagent such as sodium hydroxide or potassium hydroxide is required during the reaction process, which saves costs. Moreover, compared with the strategy of directly using a metal catalyst such as Pt-S / C for deamination, this method has a greater advantage in terms of yield, which can reach up to 86%, which is much higher than the 15% yield of using a metal catalyst. It also avoids the generation of high temperature and high pressure and toxic by-products, which is beneficial to environmental protection and green production.

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

[0045] Figure 1 The H NMR spectrum of caprolactam prepared in Example 1 ( 1 H-NMR). DETAILED DESCRIPTION

[0046] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0047] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0048] The experimental methods used in the following examples 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 through commercial channels by those skilled in the art.

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

[0050] Example 1

[0051] The synthetic route of caprolactam in the present 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, and then 639g (3.5mol) of lysine hydrochloride and 140g (3.5mol) of sodium hydroxide were added, and the mixture was stirred at 1400KPa and 150°C for 6h. After the reaction, solid sodium chloride and unreacted L-lysine hydrochloride were removed by suction filtration, and then methanol was removed by vacuum distillation. Ethyl acetate was added, the temperature was raised to 100°C and stirred for 3h, and the mixture was filtered while hot. The ethyl acetate was then removed by vacuum distillation to obtain solid aminocaprolactam (416g, yield 92.9%). The aminocaprolactam was detected by nuclear magnetic hydrogen spectrum, and its structural characterization is 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 the analysis of H NMR spectrum, the purity of aminocaprolactam obtained in this step is 99%;

[0054] (2) 0.2 L of aqueous ammonia (25-28 wt%, titration concentration of 13.3 mol / L, i.e., the amount of ammonia in the aqueous ammonia is 2.66 mol) was added to a 5 L reactor, 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 sodium hypochlorite in the solution is 2.25 mol) was slowly added dropwise at 0°C. After the addition was completed, the reaction was continued at 0°C with stirring for 20 min to obtain 3.2 L 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), and then the reaction was continued at 0°C. 34g (0.266mol) of aminocaprolactam was added to the chloramine solution, and the system temperature was slowly raised to room temperature for 10h. After the reaction, a small amount of the obtained substance was taken for nuclear magnetic resonance detection. The detection results showed that the conversion rate of aminocaprolactam was 100%. Subsequently, 2mol / L dilute sulfuric acid was used to acidify the reacted substance to a pH of 4-5, and dichloromethane was used to extract the acidified substance 3-6 times until there was no product in the water. The dichloromethane was spin-dried to obtain a caprolactam product (24.35g, yield: 81%). The caprolactam product was tested by nuclear magnetic resonance hydrogen spectrum, and its structural characterization was as follows: 1 HNMR (300 MHz, D2O) δ3.26-3.18 (m, 2H), 2.49-2.41 (m, 2H), 1.75 (m, 2H), 1.61 (m, 4H). According to hydrogen nuclear magnetic spectrum analysis, the purity of the caprolactam product is 98%.

[0055] Example 2

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

[0057] (1) Aminocaprolactam prepared according to step (1) in Example 1;

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

[0059] Example 3

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

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

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

[0063] Example 4

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

[0065] (1) Aminocaprolactam prepared according to step (1) in Example 1;

[0066] (2) 0.15 L of aqueous ammonia (25-28 wt %, titration concentration of 13.3 mol / L, i.e., the amount of ammonia in the aqueous ammonia is 2.0 mol) was added to a 10 L reactor, and 5 L of sodium hypochlorite solution (effective chlorine content of 8-10%, titration concentration of 0.75 mol / L, i.e., the amount of sodium hypochlorite in the solution is 3.75 mol) was slowly added dropwise at 0° C. After the addition was completed, stirring was continued at 0° C. for 20 min to obtain 5.15 L of chloramine solution with a concentration of 0.39 mol / L (i.e., the amount of chloramine in the chloramine solution is 2.0 mol), and then at 0° C. ℃ conditions, 25.5g (0.2mol) of aminocaprolactam was added to the chloramine solution, the system temperature was slowly raised to room temperature for reaction for 10h, and a small amount of the obtained substance was taken for nuclear magnetic resonance detection after the reaction. The detection results showed that the conversion rate of aminocaprolactam was 100%, and then 2mol / L dilute sulfuric acid was used to acidify the obtained substance to pH 4-5, and the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, and the dichloromethane was spin-dried to obtain a caprolactam product (17.1g, yield: 76%). The purity of the caprolactam product prepared in this embodiment is 98%.

[0067] Example 5

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

[0069] (1) Aminocaprolactam prepared according to step (1) in Example 1;

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

[0071] Example 6

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

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

[0074] (2) 0.15 L of ammonia water (25-28 wt %, titration concentration of 13.3 mol / L, i.e., the amount of ammonia in the ammonia water is 2.0 mol) was added to a 5 L reactor, 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 sodium hypochlorite in the solution is 2.25 mol) was slowly added dropwise at 0° C. After the addition was completed, the reaction was continued at 0° C. with stirring for 20 min to obtain 3.15 L of chloramine solution with a concentration of 0.63 mol / L (i.e., the amount of chloramine in the chloramine solution is 1.98 mol), and then heated at 0° C. Under the following conditions, 17.1 g (0.134 mol) of aminocaprolactam was added to the chloramine solution, the system temperature was slowly raised to room temperature and reacted for 10 h. After the reaction, a small amount of the obtained substance was taken for nuclear magnetic resonance detection. The detection results showed that the conversion rate of aminocaprolactam was 100%. Subsequently, 2 mol / L dilute sulfuric acid was used to acidify the obtained substance to a pH of 4 to 5, and dichloromethane was used to extract the acidified substance for 3 to 6 times until there was no product in the water. The dichloromethane was spin-dried to obtain a caprolactam product (13.0 g, yield: 86%). The purity of the caprolactam product prepared in this embodiment 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 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 reactor. Subsequently, 80 g of sodium hydroxide was added. The ammonium chloride and the sodium hydroxide produced 0.15 L of ammonia water (with a concentration of 13.3 mol / L, i.e., the amount of ammonia in the ammonia water was 2.0 mol). Then, 3 L of sodium hypochlorite solution (with an effective chlorine content of 8-10%, a titration concentration of 0.75 mol / L, i.e., the amount of sodium hypochlorite in the solution was 2.25 mol) was slowly added dropwise at 0° C. After the addition was completed, the reaction was continued at 0° C. with stirring for 20 min to obtain 3.15 L of a chloramine solution with a concentration of 0.63 mol / L (i.e., the amount of chloramine in the chloramine solution was 2.0 mol). The mass amount is 1.98mol), then under 0°C, 25.5g (0.2mol) of aminocaprolactam is added to the chloramine solution, the system temperature is slowly raised to room temperature for reaction for 10h, and a small amount of the obtained substance is taken for nuclear magnetic resonance detection after the reaction. The test results show that the conversion rate of aminocaprolactam is 71%, and then 2mol / L dilute sulfuric acid is used to acidify the reaction substance to pH 4-5, and the acidified substance is extracted with dichloromethane for 3-6 times until there is no product in the water, and the dichloromethane is spin-dried to obtain a caprolactam product (12.18g, yield: 54%). The purity of the caprolactam product prepared in this embodiment is 98%.

[0079] Example 8

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

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

[0082] (2) 320 g of sodium hydroxide was dissolved in 3 L of deionized water and added to a 5 L reactor. A sufficient amount of chlorine gas was then introduced for 1 h. The sodium hydroxide reacted with the chlorine gas to generate 3 L of sodium hypochlorite solution (with a concentration of 1.33 mol / L, i.e., the amount 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 ammonia in the ammonia water was 2.0 mol) was added at 0° C. After the addition was completed, the mixture was stirred and reacted at 0° C. for 20 min to obtain 3.15 L of chloramine solution with a concentration of 0.63 mol / L (i.e., the amount of chloramine in the chloramine solution was 2.0 mol). 1.98mol), then under 0°C, 25.5g (0.2mol) of aminocaprolactam was added to the chloramine solution, the system temperature was slowly raised to room temperature for reaction for 10h, and a small amount of the obtained substance was taken for nuclear magnetic resonance detection after the reaction. The detection result showed that the conversion rate of aminocaprolactam was 100%, and then 2mol / L dilute sulfuric acid was used to acidify the reaction substance to pH 4-5, and the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, and the dichloromethane was spin-dried to obtain a caprolactam product (19.28g, yield: 85%). The purity of the caprolactam product prepared in this embodiment is 98%.

[0083] Example 9

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

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

[0086] (2) 0.3 L of aqueous ammonia (25-28 wt%, titration concentration of 13.3 mol / L, i.e., the amount of ammonia in the aqueous ammonia is 3.99 mol) was added to a 5 L reactor, 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 sodium hypochlorite in the solution is 2.25 mol) was slowly added dropwise at 0°C. After the addition was completed, the reaction was continued at 0°C with stirring for 20 min to obtain 3.3 L of chloramine solution with a concentration of 0.68 mol / L (i.e., the amount of chloramine in the chloramine solution is 2.24 mol), and then Under 0°C conditions, 68g (0.5mol) of aminocaprolactam was added to a chloramine solution, and the system temperature was slowly raised to room temperature for reaction for 10h. After the reaction, a small amount of the obtained substance was taken for nuclear magnetic resonance detection. The detection results showed that the conversion rate of aminocaprolactam was 60%. Subsequently, 2mol / L dilute sulfuric acid was used to acidify the reaction substance to a pH of 4-5, and the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water. The dichloromethane was spin-dried to obtain a caprolactam product (26.41g, yield: 44%). The purity of the caprolactam product prepared in this embodiment was 98%.

[0087] Example 10

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

[0089] (1) Aminocaprolactam prepared according to step (1) in Example 1;

[0090] (2) 0.2 L of aqueous ammonia (25-28 wt %, titration concentration of 13.3 mol / L, i.e., the amount of ammonia in the aqueous ammonia is 2.66 mol) was added to a 5 L reactor, 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 sodium hypochlorite in the solution is 2.25 mol) was slowly added dropwise at 0° C. After the addition was completed, stirring was continued at 0° C. for 20 min to obtain 3.2 L 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), and then at 0° C. ℃ conditions, 45g (0.35mol) of aminocaprolactam was added to the chloramine solution, the system temperature was slowly raised to room temperature for reaction for 10h, and a small amount of the obtained substance was taken for nuclear magnetic resonance detection after the reaction. The detection results showed that the conversion rate of aminocaprolactam was 75%, and then 2mol / L dilute sulfuric acid was used to acidify the obtained substance to pH 4-5, and the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water, and the dichloromethane was spin-dried to obtain a caprolactam product (27.01g, yield: 68%). The purity of the caprolactam product prepared in this embodiment is 98%.

[0091] Embodiment 11

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

[0093] (1) Aminocaprolactam prepared according to step (1) in Example 1;

[0094] (2) 0.2 L of aqueous ammonia (25-28 wt%, titration concentration of 13.3 mol / L, i.e., the amount of ammonia in the aqueous ammonia is 2.66 mol) was added to a 5 L reactor, 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 sodium hypochlorite in the solution is 2.25 mol) was slowly added dropwise at 0°C. After the addition was completed, the reaction was continued at 0°C with stirring for 20 min to obtain 3.2 L 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), and then Under 0°C conditions, 68g (0.5mol) of aminocaprolactam was added to a chloramine solution, and the system temperature was slowly raised to room temperature for reaction for 10h. After the reaction, a small amount of the obtained substance was taken for nuclear magnetic resonance detection. The detection results showed that the conversion rate of aminocaprolactam was 68%. Subsequently, 2mol / L dilute sulfuric acid was used to acidify the reaction substance to a pH of 4-5, and the acidified substance was extracted with dichloromethane for 3-6 times until there was no product in the water. The dichloromethane was spin-dried to obtain a caprolactam product (36.02g, yield: 60%). The purity of the caprolactam product prepared in this embodiment was 98%.

[0095] Example 12

[0096] The synthetic route of caprolactam in the present 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, and then 511g (3.5mol) of lysine was added. The mixture was stirred at 1400KPa and 150°C for 6h, and then the methanol was removed by vacuum distillation. Ethyl acetate was added, and the mixture was heated to 100°C and stirred for 3h. The mixture was filtered while hot, and then the ethyl acetate was removed by vacuum distillation to obtain solid aminocaprolactam (4401g, yield 89.4%). The aminocaprolactam was detected by nuclear magnetic hydrogen spectrum, and its structural characterization is 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 the analysis of H NMR spectrum, the purity of aminocaprolactam obtained in this step is 99%;

[0099] (2) 0.2 L of aqueous ammonia (25-28 wt%, titration concentration of 13.3 mol / L, i.e., the amount of ammonia in the aqueous ammonia is 2.66 mol) was added to a 5 L reactor, 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 sodium hypochlorite in the solution is 2.25 mol) was slowly added dropwise at 0°C. After the addition was completed, the reaction was continued at 0°C with stirring for 20 min to obtain 3.2 L 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), and then the reaction was continued at 0°C. 34g (0.266mol) of aminocaprolactam was added to the chloramine solution, and the system temperature was slowly raised to room temperature for 10h. After the reaction, a small amount of the obtained substance was taken for nuclear magnetic resonance detection. The detection results showed that the conversion rate of aminocaprolactam was 100%. Subsequently, 2mol / L dilute sulfuric acid was used to acidify the reacted substance to a pH of 4-5, and dichloromethane was used to extract the acidified substance 3-6 times until there was no product in the water. The dichloromethane was spin-dried to obtain a caprolactam product (24.35g, yield: 81%). The caprolactam product was tested by nuclear magnetic resonance hydrogen spectrum, and its structural characterization was as follows: 1 HNMR (300 MHz, D2O) δ3.26-3.18 (m, 2H), 2.49-2.41 (m, 2H), 1.75 (m, 2H), 1.61 (m, 4H). According to hydrogen nuclear magnetic spectrum analysis, the purity of the caprolactam product is 98%.

[0100] Comparative Example 1

[0101] (1) Aminocaprolactam prepared according to step (1) in Example 1;

[0102] (2) Add 0.2L of ammonia water (25-28wt%, titration concentration of 13.3mol / L, i.e., the amount of ammonia in the ammonia water is 2.66mol) to a 5L reactor, and slowly add 3L of sodium hypochlorite solution (effective chlorine content of 8-10%, titration concentration of 0.75mol / L, i.e., the amount of sodium hypochlorite in the solution is 2.25mol) at 0°C. After the addition is completed, continue to stir and react at 0°C for 20min to obtain a solution with a concentration of 0.70mol 1 / L chloramine solution 3.2L (i.e., the amount of chloramine in the chloramine solution is 2.24mol), then under 0°C, 340g (2.66mol) of aminocaprolactam is added to the chloramine solution, the system temperature is slowly raised to room temperature for reaction for 10h, and then 2mol / L dilute sulfuric acid is used to acidify the reacted substance to a pH of 4-5, and the acidified substance is extracted with dichloromethane, and the dichloromethane is spin-dried to obtain no caprolactam product (0g, yield: 0%).

[0103] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing caprolactam using a fermentation broth containing lysine, lysine or a lysine salt as a raw material, characterized in that: include: Step 1: mixing the reaction raw materials with a solvent to form a solution, and then carrying out a dehydration cyclization reaction in the presence or absence of sodium hydroxide, and purifying the reaction system after the reaction to obtain aminocaprolactam; Step 2: mixing the chloramine solution with aminocaprolactam, reacting the mixture, and purifying the reaction system after the reaction to obtain caprolactam; The reaction raw materials are one or more of fermentation liquid containing lysine, lysine and lysine salt.

2. The method according to claim 1, characterized in that The lysine salt is one or more of lysine hydrochloride, lysine sulfate, lysine acetate and lysine phosphate.

3. The method according to claim 1, characterized in that: When the reaction raw material in step 1 is lysine salt, a dehydration cyclization reaction is carried out in the presence of sodium hydroxide; the solvent is one or more of an alcohol compound, toluene, xylene, mesitylene, tetrahydrofuran, dioxane, dichloromethane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

4. The method according to claim 1, characterized in that: In step 1, the reaction temperature is 80-250° 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 according to claim 4, characterized in that The reaction temperature is 175°C; the reaction time is 6h; and the concentration of the solution is 0.05mol / L.

6. The method according to claim 1, characterized in that The purification method in step 1 is: first, remove the solid matter by suction filtration, then remove the solvent by reduced pressure distillation, then add the extraction solvent and stir at the extraction temperature for a period of time, filter while hot, and then remove the extraction solvent by reduced pressure distillation to obtain the aminocaprolactam product.

7. The method according to claim 6, characterized in that The extraction solvent is one or more of ethyl acetate, dichloromethane, toluene, chloroform, benzene, tetrahydrofuran, dioxolane and dioxane; the extraction temperature is 0°C to 30°C higher or lower than the boiling point of the extraction solvent; and the time is 0.5 to 6 hours.

8. The method according to claim 1, characterized in that In step 2, the chloramine solution is obtained by reacting sodium hypochlorite in the sodium hypochlorite solution with ammonia in the ammonia water in a molar ratio of (0.5-2):

1.

9. The method according to claim 1, characterized in that: In step 2, the molar ratio of chloramine to aminocaprolactam in the chloramine solution is (2-20):1; the reaction temperature is 0-60° C., and the reaction time is 5 min-24 h.

10. The method according to claim 1, characterized in that The purification method in step 2 is: using an acidifying agent to adjust the reaction system to a pH of 4 to 5, then adding an extraction solvent for extraction, retaining the organic phase after the extraction is completed, removing the extraction solvent, and obtaining caprolactam.

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