A process for the preparation of nylon 11

Abstract

The present application relates to the technical field of high polymer material, and more particularly to a preparation method of nylon 11, comprising the following steps: methyl esterification: dodecanedioic acid is dissolved in methanol, and dodecanedioic acid dimethyl ester is synthesized by dehydration under the action of a first catalyst; ester exchange: dodecanedioic acid dimethyl ester, dodecanedioic acid and methanol are dissolved in an organic solvent, a second catalyst is added, and dodecanedioic acid monomethyl ester is prepared by refluxing reaction in the organic solvent; ammonia addition: 11-amino-undecanoic acid is prepared by taking dodecanedioic acid monomethyl ester as a raw material and through amide reaction and Hoffmann rearrangement; and polymerization: PA11 is obtained by high-temperature polymerization of 11-amino-undecanoic acid under nitrogen protection. The preparation method has the characteristics of short process route and stable intermediates, and can be suitable for batch production and continuous production.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a method for preparing nylon 11. Background Technology

[0002] Polyundecyl lactam (Nylon 11, abbreviated as PA11) is a long-chain, soft nylon synthesized from castor oil. Compared with other nylons, Nylon 11 has advantages such as low density, high strength, good dimensional stability, stable chemical properties, excellent electrical insulation properties, excellent mechanical properties, low temperature sensitivity, low water absorption, melting point of 186℃~190℃, resistance to high temperatures of 200℃ and low temperatures of -60℃, plasticity, corrosion resistance, oil resistance, chemical resistance, and biochemical resistance. It is widely used in the automotive, electronics, and military industries.

[0003] In related technologies, the preparation process of nylon 11 uses castor oil as raw material, which is cracked to obtain 10-undecenoic acid, then subjected to addition, ammonolysis, and polymerization to form nylon 11 resin, followed by modification and molding to obtain the product. The main steps are: castor oil to 10-undecenoic acid (castor → pressing → castor oil → esterification → methyl ricinoleate → cracking → methyl 10-undecenoate → hydrolysis → 10-undecenoic acid) → bromination (11-bromoundecanoic acid) → ammonolysis (11-aminoundecanoic acid) → polymerization → nylon 11 → molding → product. The production process of nylon 11 using castor oil as raw material is complex and has a long production line. Although renewable castor oil is used as raw material, it suffers from problems such as low yield, high energy consumption, high cost, and many by-products. Summary of the Invention

[0004] This invention provides a method for preparing nylon 11, which solves the problems of existing nylon 11 production processes, such as complex processes, long production lines, low yield, high energy consumption, high cost and many by-products.

[0005] According to a first aspect of the present invention, the present invention provides a method for preparing nylon 11, comprising the following steps:

[0006] Step 1, Methyl Esterification: Dodecanoic acid is dissolved in methanol and dehydrated under the action of a first catalyst to synthesize dimethyl dodecanoic acid.

[0007] Step 2, transesterification: The synthesized dimethyl dodecanoic acid, dodecanoic acid and methanol are dissolved in an organic solvent, a second catalyst is added, and the mixture is refluxed in an organic solvent to prepare monomethyl dodecanoic acid.

[0008] Step 3, Ammonia addition: Using the prepared dodecanoic acid monomethyl ester as raw material, 11-amino-undecanoic acid is prepared through amidation reaction and Hoffmann rearrangement reaction;

[0009] Step 4, Polymerization: The prepared 11-amino-undecanic acid is polymerized at high temperature to obtain Nylon 11.

[0010] This invention discloses a method for preparing nylon 11 using dodecanoic acid as an initial raw material, which undergoes sequential methylation, transesterification, ammonia addition, and polymerization reactions to obtain nylon 11. The key point of this invention lies in the preparation of dodecanoic acid monomethyl ester during the transesterification process. Generally, in long-chain diacid molecules, the two carboxyl groups are far apart, and their mutual influence should be minimal, seemingly indicating a stronger selective monoesterification ability. However, this is not actually the case. Due to the free rotation of the carbon-carbon single bond, the two carboxyl groups become very close during the actual reaction due to carbon chain torsion, thus influencing each other. Therefore, the synthesis of long-chain diacid monoesters is relatively difficult. Currently, the synthesis of long-chain diacid monoesters suffers from problems such as uncontrollable reactions, numerous side reactions, low yield of the target product, cumbersome post-processing of enzymes and carriers, and high process costs. Through experimental practice, in order to improve the purity and yield of the target product, this invention selects dodecanoic acid, dimethyl dodecanoic acid, and methanol as raw materials, dissolves them in an organic solvent at a certain molar ratio, and performs transesterification under the action of a second catalyst. The resulting monomethyl dodecanoic acid ester has high purity and high yield, which is beneficial to the subsequent reaction. Compared with the process of preparing nylon 11 from castor oil through up to 11 steps, the method for preparing nylon 11 provided by this invention has the characteristics of short process route and well-defined and stable intermediates, and can be applied to both batch and continuous production.

[0011] Furthermore, in step 2, n(dodecanoic acid):n(dimethyl dodecanoic acid):n(methanol) = 1:0.5:1 to 1:1:2;

[0012] And / or, the amount of the second catalyst is 0.5%-5% of the sum of the amounts of dodecanoic acid and dimethyl dodecanoic acid ester;

[0013] And / or, the weight-to-volume ratio of the total transesterification reactants to the organic solvent is 1:0.5 to 1:3.

[0014] In the above scheme, by rationally selecting the molar ratio of raw materials dodecanoic acid, dimethyl dodecanoic acid, and methanol, the amount of the second catalyst, and the amount of organic solvent in the transesterification process of step 2, the purity and yield of intermediate dodecanoic acid monomethyl ester can be effectively improved. The purity of dodecanoic acid monomethyl ester is ≥95%, and the yield is 70%-95%.

[0015] Further, in step 2, the organic solvent includes cyclohexane, chloroform, benzene, toluene, or xylene; preferably, the organic solvent is xylene.

[0016] In the above scheme, during the transesterification process, in order to remove the water generated in the reaction from the reaction system in a timely manner, an organic solvent is used as a dehydrating agent. The dehydrating agent can form a binary or ternary azeotrope with water or one of the reactants, thereby removing the water from the reaction system in a timely manner, thus shifting the equilibrium towards the direction favorable to the formation of ester. In the transesterification of this invention, the melting point of the dodecanoic acid is 128℃-130℃. In order to achieve a more effective removal of water during the reaction process, the above scheme makes reasonable selection of the type of organic solvent used in step 2, thereby further improving the purity and yield of the intermediate dodecanoic acid monomethyl ester.

[0017] Further, in step 2, the second catalyst comprises concentrated hydrochloric acid, concentrated sulfuric acid, p-toluenesulfonic acid, a strong acidic cation exchange resin, supported phosphotungstic acid, and a solid superacid; wherein the supported phosphotungstic acid comprises silica-supported phosphotungstic acid and / or activated carbon-supported phosphotungstic acid; and the solid superacid comprises TiO2-ZrO2 / SO4. 2- Preferably, the second catalyst is concentrated sulfuric acid, p-toluenesulfonic acid, or a strong acid cation exchange resin.

[0018] And / or, the reflux reaction temperature is the reflux temperature of the organic solvent.

[0019] In the above scheme, by effectively selecting and controlling the type of the second catalyst and the reflux reaction temperature in step 2, the efficiency of the transesterification reaction can be improved, and the purity and yield of the intermediate dodecanoic acid monomethyl ester can be further improved.

[0020] Furthermore, step 3 includes the following steps:

[0021] Step 31, amidation reaction: Monomethyl dodecanoic acid and urea are reacted sequentially at 80℃~200℃ for 5h~24h; after the reaction is completed, an amide compound of monomethyl dodecanoic acid is prepared.

[0022] Step 32, Hoffmann rearrangement reaction: The amide compound of the prepared dodecanoic acid monomethyl ester and sodium hypohalate are added to the reaction system, the pH is adjusted to 10-14 with alkaline solution, and the reaction is carried out at -4℃ to 80℃ for 0.5h-24h. After the reaction is completed, molecular distillation is performed to separate the 11-amino-undecanoic acid.

[0023] In the above scheme, by rationally designing the amidation reaction and Hoffmann rearrangement reaction in step 3, the yield of the intermediate 11-amino-undecanoic acid can be improved.

[0024] It should be noted that deprotection also occurred during the Hoffmann rearrangement reaction. The amide compound of the dodecanoic acid monomethyl ester reacts with sodium hypohalate to first generate 11-amino-undecanoic acid monomethyl ester. Under stirring conditions in an alkaline solution of 11-amino-undecanoic acid monomethyl ester, the methanol protection is removed by heating, and 11-amino-undecanoic acid is obtained. The alkaline solution is one or a mixture of sodium hydroxide and potassium hydroxide, with a concentration of 1-10 M.

[0025] Furthermore, the reaction system for the Hoffmann rearrangement reaction is a reaction system formed by a mixture of one or two of methanol and ethanol with water.

[0026] Another challenge of this invention lies in the preparation process of 11-aminoundecanoic acid from dodecanoic acid monomethyl ester monoamide. Typically, the Hoffmann rearrangement reaction is a homogeneous reaction in an aqueous phase. Dodecanoic acid monomethyl ester monoamide is almost insoluble in water, thus the usual aqueous phase reaction results in a low yield of the target product. To achieve the research objective of a homogeneous reaction, this invention uses water-miscible organic solvents such as methanol, ethanol, acetonitrile, and DMF as dispersants to achieve a homogeneous reaction. Experiments have shown that acetonitrile is unsuitable for this reaction system due to its alkaline environment. Therefore, the preferred raw material dispersant is one or a mixture of methanol and ethanol.

[0027] Furthermore, in step 31, n(dodecanoic acid monomethyl ester):n(urea) = 1:0.5 to 1:5;

[0028] And / or, in step 32, n (amide compound of dodecanoic acid monomethyl ester): n (sodium hypohalite) = 1:1 to 1:3.

[0029] In the above scheme, by rationally selecting the molar ratio of dodecanoic acid monomethyl ester to urea in step 31, the amidation reaction efficiency can be effectively improved, increasing the yield of the amide compound of the product dodecanoic acid monomethyl ester, thus facilitating the subsequent reaction. Similarly, by rationally selecting the molar ratio of the amide compound of dodecanoic acid monomethyl ester to sodium oxide in step 32, the Hofmann rearrangement reaction efficiency can be effectively improved, increasing the yield of the product 11-amino-undecanoic acid, thus facilitating the subsequent reaction.

[0030] Furthermore, in step 1, the mass-to-volume ratio of the dodecanoic acid to the methanol is between 1:1 and 1:50.

[0031] And / or, the first catalyst comprises one or more of inorganic acids, organic acids, and strongly acidic ion exchange resins; the inorganic acid comprises concentrated hydrochloric acid, concentrated sulfuric acid, or concentrated phosphoric acid; the organic acid comprises p-toluenesulfonic acid;

[0032] And / or, the amount of the first catalyst is 0.1%-20% of the mass of the dodecanoic acid;

[0033] And / or, the dehydration synthesis temperature is the reflux temperature of methanol.

[0034] In the above scheme, by rationally designing the mass-volume ratio of raw material dodecanoic acid to methanol, the type and amount of the first catalyst, and the dehydration synthesis temperature in step 1, the efficiency of the methyl esterification reaction can be improved, thereby increasing the yield of dimethyl dodecanoic acid.

[0035] Furthermore, step 4 specifically includes the following steps:

[0036] Dry 11-amino-undecanoic acid and water were placed in a reactor, and then a third catalyst, an antioxidant, and a molecular weight regulator were added in sequence. Nitrogen gas was introduced into the reactor to create a nitrogen atmosphere. The temperature was raised from 100°C to 200°C over 3 hours to melt the material, and then maintained at 200°C for 2 hours. The temperature was then raised to 250°C and held at 250°C for 3 hours. After the reaction was completed, the reactant was removed, which was Nylon 11.

[0037] In the above scheme, by rationally designing the polymerization reaction process in step 4, the efficiency of the polymerization reaction can be improved, thereby increasing the yield of nylon 11.

[0038] Furthermore, in step 4, the mass ratio of 11-amino-undecanoic acid to water is 1:0.5-1:4;

[0039] And / or, based on the mass of the total reactants from the polymerization reaction in step 4, the mass fraction of the third catalyst is 0.01%-1%, the mass fraction of the antioxidant is 0.05%-1%, and the mass fraction of the molecular weight regulator is 0.001%-5%.

[0040] In the above scheme, by rationally selecting the mass ratio of 11-amino-undecanoic acid and water, the raw materials for polymerization reaction in step 4, and the amount of each auxiliary raw material, the efficiency of the polymerization reaction can be improved, thereby increasing the yield of nylon 11.

[0041] The effective effects of this invention are as follows:

[0042] This invention discloses a method for preparing nylon 11 using dodecanoic acid as an initial raw material, which involves sequential methylation, transesterification, ammonia addition, and polymerization to obtain nylon 11. This method features a short process route and well-defined, stable intermediates, making it suitable for both batch and continuous production. This invention also provides new ideas for the production of other long-chain nylon N. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is the HPLC chromatogram of dimethyl dodecanoate, the intermediate obtained in Example 1 of the present invention;

[0045] Figure 2 This is the HPLC chromatogram of the intermediate dodecanoic acid monomethyl ester obtained in Example 1 of the present invention;

[0046] Figure 3 The 1H-NMR spectrum of the intermediate dodecanoic acid monomethyl ester obtained in Example 1 of this invention;

[0047] Figure 4 The 13C-NMR spectrum of the intermediate dodecanoic acid monomethyl ester obtained in Example 1 of this invention;

[0048] Figure 5 The LC-MS spectrum of the intermediate 11-aminoundecanoic acid obtained in Example 1 of this invention in positive ion mode;

[0049] Figure 6 This is a spectrum of nylon 11 obtained in Example 1 of the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0051] Example 1

[0052] This embodiment provides a method for preparing nylon 11, the specific reaction route of which is as follows:

[0053]

[0054] Specifically, the steps include the following:

[0055] Step 1, Methyl Esterification: 230g of dodecanoic acid, 700ml of methanol, and 30ml of concentrated sulfuric acid were placed in a 2L three-necked reaction flask and refluxed at 66℃ for 6 hours. After reflux, the mixture was neutralized to pH neutral with sodium hydroxide, and methanol was removed by rotary evaporation to obtain a solid. The solid was washed with 500ml of water (3 times the volume) and then dried to obtain dimethyl dodecanoic acid, with a yield of 95%. The product was analyzed by high-performance liquid chromatography (HPLC), and the chromatogram is shown below. Figure 1 As shown, the purity of the obtained dimethyl dodecanoate product is >98%.

[0056] Step 2, transesterification: 23g of dodecanoic acid, 20g of dimethyl dodecanoic acid, 3.2g of methanol, 0.3g of p-toluenesulfonic acid, and 50ml of xylene were placed in a three-necked flask. A water separator was added, and the mixture was refluxed at 140℃ for 5 hours. After the reaction, the mixture was cooled to room temperature and washed twice with 100ml of saturated sodium carbonate solution each time. Then, the organic phase was washed with 100ml of deionized water. After washing, the aqueous phases were combined. The aqueous phase was neutralized with 3M HCl to approximately pH 3.5, yielding a solid precipitate. The precipitate was collected by filtration and washed with water until neutral to obtain monomethyl dodecanoic acid, with a yield of 70%. The product was analyzed by high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR). The HPLC chromatogram is shown below. Figure 2 As shown, the chromatographic purity of the obtained dodecanoic acid monomethyl ester product is 95%, and the 1H-NMR spectrum is as follows. Figure 3 As shown, the 13C-NMR spectrum is as follows Figure 4 As shown.

[0057] Step 3, adding ammonia, specifically includes:

[0058] Step 31, amidation reaction: Take 24.4g of dimethyl dodecanoate, add 40ml of water, then add about 7ml of concentrated ammonia (25%-28%), heat to 80℃ to dissolve, then add 6g of urea and dissolve. Increase the reaction temperature to 120℃ and react for 1h, increase the temperature to 140℃ and heat for 1h, increase the temperature to 160℃ and heat for 2h, increase the temperature to 180℃ and heat for 1h, increase the temperature to 200℃ and heat for 30min. Cool to room temperature to obtain a white solid, pulverize in a mortar, wash the solid powder twice with water, collect the white solid, dry it to obtain about 20g of the amide compound of monomethyl dodecanoate, with a yield of about 80%.

[0059] Step 32, Hoffmann rearrangement reaction: Approximately 2.4 g of the amide compound of dodecanoic acid monomethyl ester was dissolved in 15 ml of anhydrous ethanol. 13 ml of 8% sodium hypochlorite solution was added, and the pH was adjusted to approximately 13 with sodium hydroxide solution. The reaction was carried out at 25°C and 210 rpm for 0.5 h, followed by a reaction at 70°C for 1 h. After the reaction was complete, 100 ml of water was added, and the pH was adjusted to 6-7 with hydrochloric acid solution. The mixture was filtered, and the solid was collected. The solid was washed three times with water to obtain a mixture containing 11-amino-undecanoic acid. Molecular distillation was performed to obtain pure 11-amino-undecanoic acid, with a yield of approximately 60%. The obtained 11-amino-undecanoic acid was detected by positive ion mode LC-MS, and the LC-MS spectrum is shown below. Figure 5 As shown, where,

[0060] Step 4, Polymerization: Place 5g of 11-amino-undecanoic acid, 5g of water, 0.0005g of lauric acid, and 0.003g of antioxidant 1098 into a nylon synthesis bottle. Connect nitrogen gas and evacuate to a vacuum level of 0.08MPa using a vacuum pump, then continue purging with nitrogen. Repeat this process 5 times, ensuring the reaction is under a nitrogen atmosphere. Within three hours, raise the temperature from 100℃ to 200℃ to melt the materials, and maintain this temperature for 2 hours. Then, raise the temperature to 250℃ at a rate of 10℃ / h and maintain this temperature for 3 hours. After the reaction is complete, break the reaction bottle, remove the reactants, and perform chromatographic analysis on the resulting reactants. Figure 6 The spectrum shows that the reactant obtained is Nylon 11.

[0061] Example 2

[0062] The difference from Example 1 is that the ratio of n(dodecanoic acid):n(dimethyl dodecanoic acid):n(methanol) is different, as shown in Table 1 below. The chromatographic purity and yield of the obtained monomethyl dodecanoic acid are shown in Table 1 below.

[0063] Table 1

[0064]

[0065] Example 3

[0066] The difference from Example 1 is that the type of organic solvent used in step 2, the transesterification is different, and the specific differences and the chromatographic purity and yield of the obtained dodecanoic acid monomethyl ester product are shown in Table 2 below.

[0067] Table 2

[0068] organic solvents chromatographic purity of product yield benzene 50～65％ 15～30％ Toluene 70～80％ 40～65％

[0069] Example 4

[0070] The difference from Example 1 is as follows:

[0071] Step 32, Hoffmann rearrangement reaction: Take about 2.4 g of the amide compound of dodecanoic acid monomethyl ester, add 13 ml of 8% sodium hypochlorite solution, and then adjust the pH to about 13 with sodium hydroxide solution. React at 35℃ and 210 r / min for 0.5 h, then at 70℃ for 2 h. After the reaction is complete, adjust the pH to 6-7 with hydrochloric acid solution. Filter and collect the solid. Wash the solid three times with water to obtain a mixture containing 11-amino-undecanoic acid, with a product yield of about 10%.

[0072] Example 5

[0073] The difference from Example 1 is that acetonitrile is used in step 32, the Hoffmann rearrangement reaction. Specifically, approximately 2.4 g of the amide compound of dodecanoic acid monomethyl ester is dissolved in 20 ml of anhydrous acetonitrile, followed by 13 ml of 8% sodium hypochlorite solution. The pH is then adjusted to approximately 13 with sodium hydroxide solution. The reaction is carried out at 25°C and 210 rpm for 0.5 hours, followed by a reaction at 70°C for 1 hour. The product is almost undetectable. This is because acetonitrile undergoes hydrolysis and oxidation under these reaction conditions, consuming sodium hypochlorite and preventing the target reaction from being achieved.

[0074] Example 6

[0075] The difference from Example 1 is that the ratio of n(dodecanoic acid monomethyl ester):n(urea) is different in step 31. The specific differences and the yield of the amide compound of dodecanoic acid monomethyl ester are shown in Table 3 below.

[0076] Table 3

[0077] n(monomethyl dodecanoate): n(urea) yield 1:0.5 55～60％ 1:5 88～92％ 1:2 85％

[0078] Example 7

[0079] The difference from Example 1 is that the ratio of n (amide compound of dodecanoic acid monomethyl ester) to n (sodium hypohalite) is different in step 32. The specific differences and the yield of 11-amino-undecanoic acid are shown in Table 4 below.

[0080] Table 4

[0081] n(amide compound of dodecanoic acid monomethyl ester): n(sodium hypohalite) yield 1:1 45％ 1:3 80～85％

[0082] Example 8

[0083] The difference from Example 1 is that the mass-to-volume ratio of dodecanoic acid to methanol is different in step 1. The specific differences and the yield of dimethyl dodecanoic acid are shown in Table 5 below.

[0084] Table 5

[0085] Mass-volume ratio of dodecanoic acid to methanol yield 1:1 ～80％ 1:50 65～75％ 1:5 ＞95％

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for the preparation of nylon 11, characterized in that, The method comprises the following steps: Step 1, methyl esterification: dodecanedioic acid is dissolved in methanol, and dodecanedioic acid dimethyl ester is synthesized by dehydration under the action of a first catalyst; Step 2, ester exchange: the synthesized dodecanedioic acid dimethyl ester, dodecanedioic acid and methanol are dissolved in an organic solvent, a second catalyst is added, and reflux reaction is carried out in the organic solvent to prepare dodecanedioic acid monomethyl ester; Step 3, ammonia addition: the prepared dodecanedioic acid monomethyl ester is used as a raw material, and 11-amino-undecanoic acid is prepared through amidation reaction and Hofmann rearrangement reaction; Step 4, polymerization: the prepared 11-amino-undecanoic acid is polymerized at high temperature to obtain nylon 11; In the step 2, n (dodecanedioic acid) : n (dodecanedioic acid dimethyl ester) : n (methanol) = 1:0.5:1-1:1:2; The amount of the second catalyst is 0.5%-5% of the sum of the amounts of dodecanedioic acid and dodecanedioic acid dimethyl ester; the second catalyst is p-toluenesulfonic acid; The weight-to-volume ratio of the total ester exchange reactants to the organic solvent is 1:0.5-1:3; The organic solvent is xylene; In the step 1, the mass-to-volume ratio of the dodecanedioic acid to the methanol is 1:1-1:50; The step 3 comprises the following steps: Step 31, amidation reaction: dodecanedioic acid monomethyl ester and urea are sequentially reacted at 80-200 DEG C for 5-24 hours to prepare an amide compound of dodecanedioic acid monomethyl ester; Step 32, Hofmann rearrangement reaction: the prepared amide compound of dodecanedioic acid monomethyl ester and sodium hypohalite are put into a reaction system, a basic solution is used to adjust the pH to 10-14, the reaction is carried out at 25 DEG C for 0.5 hours, and then at 70 DEG C for 1 hour, the reaction is completed, and molecular distillation separation is carried out to prepare 11-amino-undecanoic acid; the reaction system of the Hofmann rearrangement reaction is a reaction system formed by one or a mixture of two of methanol and ethanol and water; In the step 31, n (dodecanedioic acid monomethyl ester) : n (urea) = 1:0.5-1:5; In the step 32, n (amide compound of dodecanedioic acid monomethyl ester) : n (sodium hypohalite) = 1:1-1:

3.

2. The production method according to claim 1, characterized by, In the step 2, the temperature of the reflux reaction is the reflux temperature of the organic solvent.

3. The preparation method according to claim 1, characterized in that, In the step 1, the first catalyst comprises one or more of inorganic acid, organic acid and strong acid ion exchange resin; the inorganic acid comprises concentrated hydrochloric acid, concentrated sulfuric acid or concentrated phosphoric acid; the organic acid comprises p-toluenesulfonic acid; And / or, the amount of the first catalyst is 0.1%-20% of the mass of the dodecanedioic acid; And / or, the dehydration synthesis temperature is the reflux temperature of methanol.

4. The preparation method according to claim 1, characterized in that, The step 4 specifically comprises the following steps: The dried 11-amino-undecanoic acid and water are placed in a reactor, then the third catalyst, antioxidant and molecular weight regulator are added in sequence; nitrogen is introduced into the reactor to make the reactor in a nitrogen atmosphere; the temperature is raised from 100℃ to 200℃ in 3h to melt the material, then maintained at 200℃ for 2h, then raised to 250℃, and maintained at 250℃ for 3h; after the reaction is completed, the reaction material is taken out, which is nylon 11.

5. The production method according to claim 4, characterized by, In the step 4, the mass ratio of 11-amino-undecanoic acid to water is 1:0.5-1:4; And / or, based on the total reactants of the polymerization reaction in the step 4, the mass fraction of the third catalyst is 0.01%-1%, the mass fraction of the antioxidant is 0.05%-1%, and the mass fraction of the molecular weight regulator is 0.001%-5%.

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