Process for the preparation of piperazine adipate and nylon 56

Abstract

The present application provides a method for preparing a pentanediamine dicarboxylate salt (e.g., pentanediamine adipate), comprising the step of reacting a pentanediamine derivative with a dicarboxylic acid (e.g., adipic acid), wherein the pentanediamine derivative has the chemical formula H2N(CH2)5NH2CO2, and the N atom is connected to the C atom by a covalent bond. The present application also provides a method for preparing nylon 56 using the pentanediamine adipate prepared by the method described herein.

Description

Technical Field

[0001] This application belongs to the field of chemical engineering, and specifically relates to a method for preparing pentanediamine adipate and nylon 56 using sublimated purified pentanediamine derivatives. Background Technology

[0002] Pentylene diamine adipate is an intermediate in the synthesis of nylon 56 (also known as polyamide 56, PA56). It is generally synthesized through a high-temperature dehydration condensation reaction in aqueous solution. Nylons such as PA6 and PA66 possess high mechanical strength, good toughness, high tensile and compressive strength, outstanding fatigue resistance, and excellent dyeing properties, and have a huge market potential. PA56 has similar physical and thermal properties to PA66, making it an ideal substitute. Although the monomer hexamethylenediamine for PA66 has overcome technical bottlenecks and is gradually achieving large-scale production, its price remains relatively high. Pentylene diamine (PDA) can be synthesized via bio-methods, at a cost 20-30% lower than petroleum-based hexamethylenediamine. PA56, synthesized from bio-based PDA and adipic acid, is a bio-based plastic (45% bio-based content). Given the increasingly stringent global carbon emission regulations, PA56 has a bright future.

[0003] Currently, publicly available methods for synthesizing pentamethylenediamine adipate aqueous solutions include, for example, the direct reaction of PDA with water and adipic acid, where the PDA is derived from bio-based pentamethylenediamine hydrochloride. The pentamethylenediamine hydrochloride solution is first desalted with sodium hydroxide to obtain free PDA, which is then purified through extraction, distillation, and other steps to finally obtain PDA with a purity higher than 99%. However, this process requires the use of the organic solvent n-butanol, which is a hazardous solvent. Recovering the solvent requires increased equipment investment, raising production costs and being environmentally unfriendly.

[0004] Currently disclosed methods for synthesizing pentamethylenediamine adipate aqueous solutions include, for example, adding hexamethylenediamine to a pentamethylenediamine carbonate aqueous solution. For instance, WO2006123778A1 describes a biological method for obtaining a pentamethylenediamine carbonate aqueous solution, adding an equimolar amount of adipic acid to PDA for a salt displacement reaction, resulting in a pentamethylenediamine adipate aqueous solution containing impurities. This solution is then centrifuged to remove impurities and bacteria, and activated carbon is added to further remove impurities and colored components, ultimately yielding a clear pentamethylenediamine adipate aqueous solution. While this process is simple, skipping the intermediate PDA generation process, activated carbon decolorization and purification primarily removes colored impurities and large particles. Furthermore, in actual large-scale production, the filters used generally have a precision of at least 5 μm, which cannot adsorb or filter out some ionic impurities and small particles. Therefore, the pentamethylenediamine adipate aqueous solution obtained by this process has relatively low purity due to the lack of true purification, which may negatively impact downstream polymerization.

[0005] Therefore, new methods for preparing pentanediamine adipate and nylon 56 still need to be developed. Summary of the Invention

[0006] In one aspect, this application provides a method for preparing pentamethylenediamine dicarboxylate, comprising the step of reacting a pentamethylenediamine derivative with a dicarboxylic acid, wherein the chemical formula of the pentamethylenediamine derivative is H2N(CH2)5NH2CO2, and wherein the N atom and the C atom are connected by a covalent bond.

[0007] In some embodiments, the method for preparing pentanediamine dicarboxylate provided in this application includes dissolving the pentanediamine derivative in a solvent, and then adding the dicarboxylic acid to perform a salt displacement reaction to obtain a pentanediamine dicarboxylate solution. In some embodiments, the solvent is pure water. In some embodiments, the dicarboxylic acid is added in excess of pentanediamine in the pentanediamine derivative, making the pentanediamine dicarboxylate solution acidic. In some embodiments, the pH of the pentanediamine dicarboxylate solution is 6.0-7.0. In some embodiments, after the reaction between the pentanediamine derivative and the dicarboxylic acid is completed, the pH of the pentanediamine dicarboxylate solution is adjusted to alkaline. In some embodiments, the pH of the pentanediamine dicarboxylate solution is adjusted to 7.5-8.5. In some embodiments, the pH of the pentanediamine dicarboxylate solution is adjusted to alkaline using fresh pentanediamine.

[0008] In some embodiments, the method for preparing pentamethylenediamine dicarboxylate provided in this application further includes a decolorization step. In some embodiments, the method for preparing pentamethylenediamine dicarboxylate provided in this application further includes a step of adding activated carbon and filtering for decolorization.

[0009] In some embodiments, the pentanediamine derivative has an amide ester. Structure. In some embodiments, the pentanediamine derivative has the following chemical structure: In some embodiments, the pentanediamine derivative exists in the form of a mixture. In some embodiments, the pentanediamine derivative comprises the following structure: In some implementations, Total moles and The molar amounts are basically the same.

[0010] In some embodiments, the pentanediamine derivative does not release carbon dioxide at temperatures between 70 and 140°C. In some embodiments, the sublimation temperature of the pentanediamine derivative is between 70 and 140°C. In some embodiments, the chemical bond configuration of the pentanediamine derivative differs in deuterated aqueous solvents and other deuterated solvents. In some embodiments, the NMR spectrum of the pentanediamine derivative after dissolution in the deuterated solvent CD3OD is as follows... Figure 1 As shown. In some embodiments, the pentanediamine derivative is dissolved in a deuterated aqueous solvent (D2O). 1 H-NMR spectrum and 13 The C-NMR spectra are as follows: Figure 2 and Figure 3 As shown. In some embodiments, the pentanediamine derivative... 1 H- 1 H COSY spectrum and 1 H- 13 The C COSY spectra are as follows: Figure 4 and Figure 5 As shown. In some embodiments, the pentanediamine derivative does not contain carbonate ions (CO3). 2- ) or bicarbonate ions (HCO3) - ).

[0011] In some embodiments, the pentanediamine derivative is obtained by sublimation purification. In some embodiments, the sublimation purification includes heating a mixture containing the pentanediamine derivative to the sublimation temperature of the pentanediamine derivative to obtain a gaseous pentanediamine derivative. The sublimation temperature is 70–140°C. In some embodiments, the purification method does not include the step of alkalizing the mixture containing the pentanediamine derivative with an alkaline substance. In some embodiments, the alkaline substance is selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, and any combination thereof.

[0012] In some embodiments, the purification method further includes sublimation treatment of the obtained gaseous pentanediamine derivative. In some embodiments, the sublimation treatment is performed at 30–50°C.

[0013] In some embodiments, the mixture containing the pentanediamine derivative is prepared by passing carbon dioxide into lysine to form lysine carbonate (bicarbonate), and then reacting the lysine carbonate (bicarbonate) with lysine decarboxylase to generate the pentanediamine derivative.

[0014] In some embodiments, the dicarboxylic acid described in this application is adipic acid, and the pentanediamine dicarboxylic acid salt is pentanediamine adipate.

[0015] In another aspect, this application provides a method for preparing pentanediamine adipate, comprising reacting a pentanediamine derivative obtained by sublimation purification with adipic acid, wherein the chemical formula of the pentanediamine derivative is H2N(CH2)5NH2CO2, wherein the N atom and the C atom are connected by a covalent bond.

[0016] In another aspect, this application provides a method for preparing nylon 56, comprising adding an auxiliary agent to a pentanediamine adipate solution prepared according to the method of this application, stirring and heating to concentrate, prepolymerizing at a pressure of 1-2 MPa and a temperature of 200-300°C, then reducing pressure for polymerization, and finally polycondensing under normal pressure or vacuum. Attached Figure Description

[0017] The above and other features of this application will become more fully clear from the following description and appended claims, taken in conjunction with the accompanying drawings. It is understood that these drawings depict only a few embodiments of this application and should not be considered as limiting the scope of the application. The application will be described more clearly and in more detail with reference to the accompanying drawings.

[0018] Figure 1 The NMR spectrum of the PDA·CO2 covalent compound described in this application after dissolution in deuterated methanol (CD3OD) is shown.

[0019] Figure 2 The image shows the PDA·CO2 covalent compound described in this application dissolved in a deuterated aqueous solvent (D2O). 1 H-NMR spectrum.

[0020] Figure 3 The image shows the PDA·CO2 covalent compound described in this application dissolved in a deuterated aqueous solvent (D2O). 13 C-NMR spectrum.

[0021] Figure 4 The PDA·CO2 covalent compound described in this application is shown. 1 H- 1 H COSY spectrum.

[0022] Figure 5 The PDA·CO2 covalent compound described in this application is shown. 1 H- 13 C COSY spectrum. Detailed Implementation

[0023] The illustrative embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments and variations may be employed without departing from the spirit or scope of the subject matter of this application. It is understood that various different configurations, substitutions, combinations, and designs can be made to the various aspects of the general description and illustrated in the drawings of this application, all of which explicitly constitute part of the content of this application.

[0024] Method for preparing pentanediamine dicarboxylate

[0025] In one aspect, this application provides a method for preparing pentamethylenediamine dicarboxylate, comprising the step of reacting a pentamethylenediamine derivative with a dicarboxylic acid, wherein the chemical formula of the pentamethylenediamine derivative is H2N(CH2)5NH2CO2, and wherein the N atom and the C atom are connected by a covalent bond.

[0026] In some embodiments, the method for preparing pentanediamine dicarboxylate according to this application includes dissolving the pentanediamine derivative in a solvent, and then adding the dicarboxylic acid to perform a salt displacement reaction to obtain a pentanediamine dicarboxylate solution. In some embodiments, the solvent is water. In some embodiments, the solvent is pure water. In some embodiments, the method for preparing pentanediamine dicarboxylate according to this application includes dissolving the pentanediamine derivative in pure water, and then adding the dicarboxylic acid to perform a salt displacement reaction to obtain an aqueous solution of pentanediamine dicarboxylate.

[0027] In some embodiments, the pentanediamine derivative is dissolved in pure water under a high-purity nitrogen atmosphere. In some embodiments, the pure water is deoxygenated before dissolving the pentanediamine derivative, for example, by vacuum deoxygenation or purging with high-purity nitrogen. After deoxygenation, the pentanediamine derivative is added and stirred to dissolve under a high-purity nitrogen atmosphere. In some embodiments, an antifoaming agent is used during the dissolution of the pentanediamine derivative. Commonly used antifoaming agents include, for example, silicone-based antifoaming agents (e.g., polydimethylsiloxane), polyether-based antifoaming agents (e.g., copolymers of ethylene oxide and propylene oxide), and higher alcohol-based antifoaming agents (e.g., alcohols containing 7 to 9 carbon atoms). In some embodiments, a silicone-based antifoaming agent is used during the dissolution of the pentanediamine derivative.

[0028] In some embodiments, the dicarboxylic acid is added in excess of the pentanediamine in the pentanediamine derivative, making the pentanediamine dicarboxylate solution acidic. In some embodiments, the dicarboxylic acid is added in excess of the pentanediamine in the pentanediamine derivative, making the pentanediamine dicarboxylate solution weakly acidic. While not bound by any particular theory, it is considered particularly advantageous to make the pentanediamine dicarboxylate solution weakly acidic because the excess dicarboxylic acid accelerates the reaction process and ensures a complete salt displacement reaction.

[0029] In some embodiments, the dicarboxylic acid is added in an amount (by molar) not exceeding 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% excess of pentanediamine in the pentanediamine derivative.

[0030] In some embodiments, the dicarboxylic acid is added in excess of the pentanediamine in the pentanediamine derivative, such that the pH of the pentanediamine dicarboxylic acid solution is 6.0-7.0 (e.g., any value within the range of about 6.1, about 6.2, about 6.3, about 6.4, about 6.5, about 6.6, about 6.7, about 6.8, about 6.9, or any two of the above values). In some embodiments, after the dicarboxylic acid reacts with the pentanediamine derivative for 20-40 minutes, the pH is measured, and the pH is required to be between 6.0 and 7.0. If the pH is ≥7.0, dicarboxylic acid can be added until this range is reached. The pH is measured again after another 5-20 minutes. If the difference between the two pH readings is less than 0.05, the pH is considered essentially stable, and the reaction is essentially complete.

[0031] In some embodiments, after the reaction between the pentanediamine derivative and the dicarboxylic acid is completed, the pH of the pentanediamine dicarboxylic acid solution is adjusted to alkaline. In some embodiments, after the reaction between the pentanediamine derivative and the dicarboxylic acid is completed, the pH of the pentanediamine dicarboxylic acid solution is adjusted to 7.5-8.5 (e.g., about 7.5, about 7.6, about 7.7, about 7.8, about 7.9, about 8.0, about 8.1, about 8.2, about 8.3, about 8.4, about 8.5, or any value within the range of any two of these values). In some embodiments, after the reaction between the pentanediamine derivative and the dicarboxylic acid is completed, the pH of the pentanediamine dicarboxylic acid solution is adjusted to 7.88, 8.07, 7.94, 8.12, 7.87, or 8.18.

[0032] In some embodiments, the pH of the pentanediamine dicarboxylate solution is adjusted to alkaline using fresh pentanediamine. While not bound by any theoretical framework, it is considered particularly advantageous to adjust the pH of the pentanediamine dicarboxylate solution to a slightly alkaline state using fresh pentanediamine, as this allows for fine-tuning of the pH to meet downstream requirements, and the method is simple and convenient.

[0033] In some embodiments, the method for preparing pentamethylenediamine dicarboxylate further includes a step of adding activated carbon and filtering to remove color. In some embodiments, 0.5-5% (e.g., any value within the range of any two values ​​between 1%, 2%, 3%, 4%, 5%, or more) of activated carbon is added to the total weight of the reaction solution, and the temperature is raised to 50-100°C (e.g., any temperature between any two temperature ranges between 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or more) while stirring. After reaching the set temperature, the temperature is maintained and stirred for 30-60 minutes (e.g., any value within the range of any two values ​​between 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, or more). After completion, the solution is cooled to room temperature (20-35°C), filtered, and colored substances and impurities are removed to obtain a pure, colorless pentamethylenediamine dicarboxylate solution. In some embodiments, the activated carbon is a powdered activated carbon for decolorization, with a particle size of 100 mesh or more, preferably 200 mesh, and an iodine value of 800 mg / g or more.

[0034] (1) Pentylene diamine derivatives

[0035] In this application, the term "derivative" refers to any compound having the same or similar core structure as a given compound (also known as the parent compound) but having at least one structural difference (including substitution, deletion, and / or addition of one or more atoms or functional groups). For example, "pentanediamine derivative" refers to any compound having the same or similar core structure as pentanediamine but having at least one structural difference (including substitution, deletion, and / or addition of one or more atoms or functional groups). "Derivative" may include deuterated, oxidized, dehydrated, unsaturated, polymerically conjugated, or glycosylated forms of the parent compound, or may include its ester, amide, lactone, homologue, ether, thioether, cyano, amino, alkylamino, thiohydrogen, heterocyclic, fused heterocyclic, polymerized, PEGylated, benzylidene, triazolyl, piperazine, or deuterated forms.

[0036] In some embodiments, the pentanediamine derivative described in this application has the same core structure as 1,5-pentanediamine (also known as "cadaverine" or PDA). (where * is connected to other atoms), but has additional carbon and oxygen atoms.

[0037] In some embodiments, the pentanediamine derivative described in this application is a covalent compound formed by pentanediamine and carbon and oxygen atoms, wherein the molar ratio of pentanediamine to other carbon and oxygen atoms (excluding the carbon atom in pentanediamine) in each molecule of the pentanediamine derivative is 1:1:2. The molar ratio of each atom in the pentanediamine derivative can be determined by methods known in the art, such as elemental analysis and mass spectrometry.

[0038] In some embodiments, the pentanediamine derivative described in this application is a derivative of 1,5-pentanediamine. In some embodiments, the chemical formula of the pentanediamine derivative described in this application is H2N(CH2)5NH2CO2 (also referred to as "PDA·CO2" in this application).

[0039] In some embodiments, the pentanediamine derivative described in this application has the chemical formula H2N(CH2)5NH2CO2, wherein the nitrogen atom (N atom) and the carbon atom (C atom) are connected by a covalent bond. In this application, "covalent bond" refers to a chemical bond in which electron pairs are shared between atoms, and in particular, to a stable balance of attractive and repulsive forces between atoms when they share electrons.

[0040] In some embodiments, the pentanediamine derivatives described in this application have an amide ester. Structure. In some embodiments, the pentanediamine derivatives described in this application comprise a zwitterionic structure with an amide ester structure. In some embodiments, the pentanediamine derivatives described in this application have the following chemical structures: In some embodiments, the pentanediamine derivative described in this application comprises (5-pentane)carbamate (i.e., (5-azaniumylpentyl)carbamate).

[0041] In some embodiments, the pentanediamine derivative described in this application has the following chemical structure: In some embodiments, the pentanediamine derivative described in this application comprises...

[0042] In some embodiments, the pentamethylenediamine derivatives described in this application are present in the form of a mixture. In some embodiments, the pentamethylenediamine derivatives described in this application are present in the form of a mixture and contain... In some embodiments, the pentanediamine derivative described in this application exists in the form of a mixture and contains... In some embodiments, the pentanediamine derivative described in this application exists in the form of a mixture and contains... In some embodiments, the pentanediamine derivatives described in this application exist in the form of a mixture, comprising... and The molar amounts are basically the same.

[0043] "Substantially the same" means that the difference between two or more values ​​does not exceed ±5% (e.g., not exceeding ±4%, ±3%, ±2%, ±1%, ±0.5%, ±0.1%, etc.). For example, when referring to "substantially the same molar quantity," it means that the difference between molar quantities does not exceed ±5% (e.g., not exceeding ±4%, ±3%, ±2%, ±1%, ±0.5%, ±0.1%, etc.).

[0044] In some embodiments, the pentanediamine derivatives described in this application exist in the form of a mixture, comprising... and The molar amounts are the same.

[0045] In some embodiments, the pentanediamine derivative described in this application comprises the following structure:

[0046] In some embodiments, the pentanediamine derivative described in this application is made from...

[0047] composition.

[0048] In some embodiments, the pentanediamine derivative described in this application comprises

[0049] in Total moles and The molar amounts are substantially the same. In some embodiments, the pentanediamine derivative described in this application comprises...

[0050] in Total moles and The molar amounts are the same.

[0051] In some embodiments, the pentanediamine derivative described in this application comprises

[0052] in Their molar quantities are basically the same, and their total molar amount is similar to that of the others. The molar amounts are basically the same.

[0053] In some embodiments, the pentanediamine derivative described in this application comprises...

[0054] in The molar amounts are the same, and their total molar amount is the same as... The molar amounts are the same. In some embodiments, the pentanediamine derivative described in this application comprises... Furthermore, the molar ratio of the three components is 2:1:1.

[0055] In some embodiments, the pentanediamine derivative described in this application is made from...

[0056] Composition, in which The molar amounts are the same, and their total molar amount is the same as... The molar amounts are the same. In some embodiments, the pentanediamine derivative described in this application is made from... The composition consists of three components, and the molar ratio of the three components is 2:1:1.

[0057] In some embodiments, the pentamethylenediamine derivative described in this application does not release carbon dioxide at temperatures above 70°C. In some embodiments, the pentamethylenediamine derivative described in this application sublimates at temperatures above 70°C (e.g., 70–200°C) to form a gaseous pentamethylenediamine derivative, but does not decompose. In some embodiments, the pentamethylenediamine derivative described in this application does not release carbon dioxide at temperatures between 70 and 200°C (e.g., 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, or any value between any two of these ranges). In some embodiments, the pentamethylenediamine derivative described in this application does not release carbon dioxide at temperatures between 70 and 140°C. In some embodiments, the sublimation temperature of the pentamethylenediamine derivative described in this application is 70–140°C (e.g., 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, or any specific temperature between any two of the above ranges). In some embodiments, the density and / or hardness of the pentamethylenediamine derivative described in this application increases after sublimation.

[0058] In some embodiments, the pentanediamine derivatives described in this application exhibit different chemical bond configurations in deuterated aqueous solvents and other deuterated solvents (e.g., deuterated chloroform, deuterated methanol, etc.). The chemical bond configurations of the pentanediamine derivatives described in this application in deuterated solvents can be determined using methods commonly used in the art (e.g., NMR analysis). The inventors of this application have discovered that when NMR analysis is performed on the same sample of the pentanediamine derivatives provided in this application using different deuterated solvents, their NMR characterization information is not identical; that is, the solvent affects the structural changes of the sample.

[0059] In some embodiments, the NMR spectrum of the pentanediamine derivative described in this application after dissolving in deuterated methanol (CD3OD) is as follows: Figure 1 As shown. In some embodiments, the pentanediamine derivative described in this application is dissolved in a deuterated aqueous solvent (D2O). 1 H-NMR analysis spectrum as follows Figure 2 As shown. In some embodiments, the pentanediamine derivative described in this application is dissolved in a deuterated aqueous solvent (D2O). 13 C-NMR spectrum as follows Figure 3 As shown. In some embodiments, the pentanediamine derivative described in this application... 1 H- 1 H chemical shift correlation spectrum ( 1 H- 1 H COSY spectrum (as shown) Figure 4 As shown. In some embodiments, the pentanediamine derivative described in this application... 1 H- 13 C chemical shift correlation spectrum ( 1 H- 13 C COSY spectrum) as Figure 5 As shown.

[0060] In some embodiments, the pentanediamine derivative described in this application does not contain carbonate ions (CO3-). 2- In some embodiments, the pentanediamine derivative described in this application does not contain bicarbonate ions (HCO3-). - In some embodiments, the pentanediamine derivative described in this application does not contain carbonate ions (CO3). 2- ) and bicarbonate ions (HCO3) - In some embodiments, the pentanediamine derivative described in this application is a PDA·CO2 covalent compound.

[0061] (2) Sublimation purification of pentanediamine derivatives

[0062] In some embodiments, the pentanediamine derivative described in this application is obtained through sublimation purification.

[0063] In some embodiments, the sublimation purification includes heating a mixture containing the pentanediamine derivative as described in this application to the sublimation temperature of the pentanediamine derivative to obtain a gaseous pentanediamine derivative. All content described in the "(1) Pentanediamine Derivatives" section of this application also applies to the description of the purification methods for pentanediamine derivatives in this section, and therefore will not be repeated here.

[0064] In this application, the "mixture containing pentamethylenediamine derivatives" contains impurities in addition to pentamethylenediamine derivatives, such as other salts, sugars, bacterial cells, etc.

[0065] In some embodiments, the purity of the pentanediamine derivative in the mixture containing the pentanediamine derivative is 80% or higher (e.g., 85% or higher, 86% or higher, 87% or higher, 88% or higher, 89% or higher, 90% or higher, 91% or higher, 92% or higher, 93% or higher, 94% or higher, 95% or higher, or 96% or higher). The inventors of this application unexpectedly discovered that a higher purity gaseous pentanediamine derivative can be obtained by heating the mixture containing the pentanediamine derivative described in this application to a certain temperature, causing the pentanediamine derivative to sublimate. Furthermore, the obtained higher purity pentanediamine derivative can react with a dicarboxylic acid (e.g., adipic acid) to prepare a pentanediamine dicarboxylate (e.g., pentanediamine adipate). The purity of the gaseous pentanediamine derivative obtained by this method can reach 98% or higher, thus meeting the needs of large-scale industrial production.

[0066] The mixture containing the pentanediamine derivative can be sublimated using methods common in the art. For example, the mixture can be heated by controlling parameters such as temperature and pressure, causing the pentanediamine derivative to be converted into a gaseous state while impurities remain in the mixture. Alternatively, the mixture can be heated using a commercially available purification device (e.g., a flash evaporator) to convert the pentanediamine derivative into a gaseous state while impurities remain in the mixture. In some embodiments, the heating temperature is controlled at a temperature at which the pentanediamine derivative sublimates but does not decompose. While not limited by any theory, controlling the heating temperature at a temperature at which the pentanediamine derivative sublimates but does not decompose is preferred because this setting ensures both sufficiently high purity of the obtained gaseous pentanediamine derivative and a sufficiently high yield of the purified pentanediamine derivative.

[0067] In some embodiments, the sublimation temperature of the pentanediamine derivative is 70–140°C (e.g., 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, or any specific temperature between any two of the above numerical ranges). In some embodiments, the mixture containing the pentanediamine derivative is heated to 70–140°C (e.g., 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, or any specific temperature between any two of the above numerical ranges).

[0068] In some embodiments, the heating of the mixture containing the pentanediamine derivative is carried out in a heater having a heating medium. The heating medium can be any heating medium known in the art. In some embodiments, the heating medium is selected from the group consisting of: inorganic superconducting heat transfer media, composite thermally conductive fiber media, graphite thermally conductive media, carbon fiber thermally conductive media, thermally conductive oil, high-pressure steam, or molten salt. In some embodiments, the heating medium is thermally conductive oil. In some embodiments, the thermally conductive oil is selected from one or more of the group consisting of: alkylnaphthalene, alkylbenzene, dibenzyltoluene, and hydrogenated terphenyl. In some embodiments, the thermally conductive oil causes the heating temperature to reach or exceed the sublimation temperature of the pentanediamine derivative. For example, the heat-conducting oil causes the heating temperature to reach or exceed 70–140°C (e.g., 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, or any specific temperature between any two of the above ranges).

[0069] In some embodiments, the outer surface of the heater's inner tube is coated with a thermally conductive metal, such as aluminum, copper, silver, aluminum alloy, copper alloy, or silver alloy. Coating the outer surface of the heater's inner tube with a thermally conductive metal can further save energy, thereby reducing energy consumption and saving costs.

[0070] While not limited by any theory, it is considered particularly preferred to perform a preheating step before the sublimation of the pentanediamine derivative in the purification steps of this application. For example, before the sublimation of the pentanediamine derivative, the mixture containing the pentanediamine derivative is preheated to, for example, 100–140°C (e.g., 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, or any specific temperature between any two of the above ranges).

[0071] In some embodiments, the step of purifying the pentanediamine derivative described in this application includes flash sublimation of the preheated pentanediamine derivative in a separator to form a gaseous pentanediamine derivative.

[0072] In some embodiments, the step of purifying the pentanediamine derivative described in this application further includes sublimation treatment of the obtained gaseous pentanediamine derivative. While not limited by any theory, it is generally believed that lower sublimation temperatures are more favorable for the sublimation of the gaseous pentanediamine derivative. In some embodiments, the obtained gaseous pentanediamine derivative is sublimated at 30–50°C (e.g., 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, or any specific temperature between any two of these ranges).

[0073] In some embodiments, the method for preparing pentamethylenediamine dicarboxylate provided in this application includes a step of purifying the PDA·CO2 covalent compound before reacting it with the dicarboxylic acid. This purification step includes: preheating the mixture containing the PDA·CO2 covalent compound to a temperature close to or equal to the sublimation temperature of the PDA·CO2 covalent compound; and separating the preheated PDA·CO2 covalent compound at its sublimation temperature. In some embodiments, the sublimation temperature of the PDA·CO2 covalent compound is 70–140°C (e.g., 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, or any specific temperature between any two of these ranges). In some embodiments, the obtained gaseous PDA·CO2 covalent compound is subjected to a deposition treatment. In some embodiments, the obtained gaseous PDA·CO2 covalent compound is subjected to sublimation treatment at 30–50°C (e.g., 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, or any specific temperature between any two of the above numerical ranges).

[0074] In some embodiments, the purification steps of the pentanediamine derivatives provided in this application do not include the step of alkalizing the mixture containing the pentanediamine derivatives with an alkaline substance (e.g., sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, or any combination thereof). In conventional methods for preparing pentanediamine dicarboxylate (e.g., pentanediamine adipate), the mixture of pentanediamine derivatives is desalted and converted into free pentanediamine through the alkalization treatment, and then a subsequent salt substitution reaction with a dicarboxylic acid is performed to generate pentanediamine dicarboxylate (e.g., pentanediamine adipate). However, in the method of this application, it is not necessary to convert the pentanediamine derivatives into free amines through alkalization treatment. Instead, the pentanediamine derivatives are directly purified, and the purified pentanediamine derivatives are then directly subjected to a salt substitution reaction with a dicarboxylic acid to generate pentanediamine dicarboxylate (e.g., pentanediamine adipate). The direct purification method of the pentanediamine derivatives of this invention not only avoids the desalting step, reducing equipment corrosion and investment costs, but also avoids the operation steps of separating free amines and water, greatly simplifying the process and reducing energy consumption.

[0075] In addition, the pentamethylenediamine derivative purified by the method provided in this application contains virtually no volatile organic compounds (VOCs), and the pentamethylenediamine dicarboxylate prepared by reacting the purified pentamethylenediamine derivative with a dicarboxylic acid also contains virtually no VOCs.

[0076] Mixtures containing pentamethylenediamine derivatives can be prepared using any method known in the art. In some embodiments, mixtures containing pentamethylenediamine derivatives are prepared by a bio-enzymatic catalysis. In some embodiments, mixtures containing pentamethylenediamine derivatives are prepared by passing carbon dioxide into a lysine solution to form lysine carbonate (bicarbonate), and then reacting the lysine carbonate (bicarbonate) with a lysine decarboxylase to generate pentamethylenediamine derivatives.

[0077] In some embodiments, carbon dioxide is bubbled into the lysine solution until the pH reaches 7-8 (e.g., any specific pH value within the range of any two of 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, or above), at which point the carbon dioxide supply is stopped.

[0078] In some embodiments, the concentration of the formed lysine bicarbonate solution is from 200 g / L to 650 g / L, for example, 210 g / L, 220 g / L, 230 g / L, 240 g / L, 250 g / L, 260 g / L, 270 g / L, 280 g / L, 285 g / L, 290 g / L, 300 g / L, 350 g / L, 400 g / L, 4... Any specific concentration within the range of 50 g / L, 500 g / L, 510 g / L, 520 g / L, 530 g / L, 540 g / L, 550 g / L, 560 g / L, 570 g / L, 580 g / L, 590 g / L, 600 g / L, 610 g / L, 620 g / L, 630 g / L, 640 g / L, 650 g / L, or any two of the above values.

[0079] In some embodiments, the lysine decarboxylase is a purified lysine decarboxylase. In some embodiments, the lysine decarboxylase is derived from bacterial cells expressing lysine decarboxylase. In some embodiments, the bacterial cells include wet bacterial cells, bacterial cell lysate, or immobilized bacterial cells. In some embodiments, the bacterial cells are derived from recombinant engineered bacteria. In some embodiments, the lysine decarboxylase is derived from recombinant engineered *E. coli* bacteria expressing lysine decarboxylase. In some embodiments, the lysine decarboxylase is derived from wet bacterial cells of recombinant engineered *E. coli* bacteria expressing lysine decarboxylase. In some embodiments, the lysine decarboxylase is derived from bacterial cell lysate of recombinant engineered *E. coli* bacteria expressing lysine decarboxylase. In some embodiments, the lysine decarboxylase is derived from immobilized bacterial cells of recombinant engineered *E. coli* bacteria expressing lysine decarboxylase.

[0080] In some embodiments, the lysine carbonate (bicarbonate) reacts with lysine decarboxylase at a temperature of 20–40°C (e.g., any specific temperature within the range of 20°C, 25°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, or any two of the above values) to generate a pentamethylenediamine derivative.

[0081] In some embodiments, the reaction time of the lysine carbonate (bicarbonate) with lysine decarboxylase is 5 to 15 hours (e.g., any specific time within the range of 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, or any two of the above values).

[0082] In some embodiments, when the lysine content is <0.5% (w / v), for example 0.4%, 0.3%, 0.2%, 0.1% or even lower, it indicates that the catalytic reaction of lysine carbonate (bicarbonate) with lysine decarboxylase has ended. Those skilled in the art can determine the lysine content using conventional methods in the art, such as HPLC.

[0083] In some embodiments, after the catalytic reaction of lysine carbonate (bicarbonate) with lysine decarboxylase has completed, the process further includes removing residues from the reaction solution. In some embodiments, the residues include large particulate impurities, such as cells, bacterial debris, aggregates, flocs, etc., as well as small molecule impurities, such as nucleic acids and nucleic acid fragments, proteins, and culture medium components in bacterial culture media. Those skilled in the art can use conventional separation methods to remove the catalyst residues from the mixture according to their actual needs, such as one or more of the following methods: filtration, centrifugation, microfiltration, ultrafiltration, etc.

[0084] In some embodiments, the filtration is achieved using filter paper or filter cloth. The filter paper or filter cloth described in this invention can be commercially available, such as filter paper or filter cloth manufactured by companies like GE Healthcare Life Sciences, Spice, and Asahi Kasei. In some embodiments, the pore size of the filter paper or filter cloth is 10–150 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, or any value between any two of these ranges. Those skilled in the art can select an appropriate pore size for the filter paper or filter cloth to remove impurities based on their size.

[0085] In some embodiments, microfiltration is achieved by passing the reaction solution through a microfiltration membrane. The microfiltration membrane described in this invention can be a commercially available microfiltration membrane, such as the hollow fiber microfiltration membrane series manufactured by GE Healthcare Life Sciences, Spice, Asahi Kasei, etc. In some embodiments, the pore size of the microfiltration membrane is 0.1 μm to 0.6 μm, for example, 0.1 μm, 0.15 μm, 0.2 μm, 0.22 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, or any value between any two of the above ranges. Those skilled in the art can select an appropriate microfiltration membrane pore size to remove impurities based on their size.

[0086] In some embodiments, ultrafiltration is achieved by passing the reaction solution through an ultrafiltration membrane. The ultrafiltration membrane described in this invention can be a commercially available ultrafiltration membrane, such as the ultrafiltration hollow fiber membrane series manufactured by companies like GE Healthcare Life Sciences, Spice, and Asahi Kasei. In some embodiments, the ultrafiltration membrane is a hollow fiber ultrafiltration membrane with a pore size of 5kD to 500kD, for example, a hollow fiber ultrafiltration membrane with a pore size of 5kD, 6kD, 7kD, 8kD, 9kD, 10kD, 20kD, 30kD, 40kD, 50kD, 60kD, 70kD, 80kD, 90kD, 100kD, 150kD, 200kD, 250kD, 300kD, 350kD, 400kD, 450kD, 500kD, or any value between any two of these ranges. Those skilled in the art can select an appropriate ultrafiltration membrane pore size to remove impurities based on their size.

[0087] In some embodiments, the preparation of the pentanediamine derivative is further included in concentration. In some embodiments, the concentration is achieved by depressurization, for example, by pumping the filtered, microfiltered, or ultrafiltered reaction solution into a concentration device for depressurization concentration to 1 / 3, 1 / 4, 1 / 5, 1 / 6, 1 / 7, 1 / 8, 1 / 9, 1 / 10 of the original volume, or any value between any two of the above ranges.

[0088] In some embodiments, the preparation of the pentanediamine derivative further includes crystallization. In some embodiments, crystallization is achieved by lowering the temperature and adding an organic solvent (e.g., methanol, ethanol, isopropanol, etc.), for example, by adding 1, 2, 3, or 4 times the volume of organic solvent dropwise to a concentrated reaction solution, and crystallizing at low temperatures (e.g., 10°C, 5°C, or lower). In some embodiments, crystallization is performed by vacuum drying. For example, the prepared pentanediamine derivative is dried in a vacuum oven at 50–70°C (e.g., any specific temperature between any two specific ranges of 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, or above) to obtain the pentanediamine derivative.

[0089] In some embodiments, a lysine bicarbonate solution with a concentration of 500 g / L to 650 g / L (e.g., any specific concentration within the range of 500 g / L, 510 g / L, 520 g / L, 530 g / L, 540 g / L, 550 g / L, 560 g / L, 570 g / L, 580 g / L, 590 g / L, 600 g / L, 610 g / L, 620 g / L, 630 g / L, 640 g / L, 650 g / L, or any two of the above values) is prepared, and then added to the prepared solution... Wet cells of engineered *E. coli* containing lysine decarboxylase were added to a lysine carbonate (bicarbonate) solution for an enzymatic reaction catalyzed for 8–12 hours (e.g., any specific time within the range of 8, 9, 10, 11, 12 hours, or more), with the reaction temperature controlled at 35–40°C (e.g., any specific temperature within the range of 35, 36, 37, 38, 39, 40°C, or more). The reaction was terminated when the lysine content determined by HPLC was <0.5% (w / v). Residues in the reaction solution were then removed, and the product was dried in a vacuum oven at 50–70°C to obtain the crude pentanediamine derivative.

[0090] In some embodiments, a 600 g / L lysine carbonate (bicarbonate) solution is prepared. Then, wet cells of engineered *E. coli* containing lysine decarboxylase are added to the prepared lysine carbonate (bicarbonate) solution to initiate an enzymatic reaction for 10 hours, with the reaction temperature controlled at 37°C. The reaction is terminated when the lysine content, as determined by HPLC, is <0.5% (w / v). Residues in the reaction solution are then removed, and the solution is dried in a vacuum oven at 50–70°C to obtain the crude pentanediamine derivative.

[0091] The mixture containing the pentamethylenediamine derivative can exist in any suitable state. In some embodiments, the mixture containing the pentamethylenediamine derivative is in a solid state. In some embodiments, the mixture containing the pentamethylenediamine derivative is in powder form. Without being limited by any theory, it is considered that a powdered mixture is more conducive to the purification of the pentamethylenediamine derivative.

[0092] In some embodiments, the dicarboxylic acid is a dicarboxylic acid having 2 to 15 carbon atoms (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, etc.). Exemplary dicarboxylic acids include, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, terephthalic acid, isophthalic acid, etc. In some embodiments, the dicarboxylic acid is adipic acid. In some embodiments, the dicarboxylic acid is adipic acid, and the pentanediamine dicarboxylic acid salt is pentanediamine adipate. "Pentanediamine adipate" is also referred to as "PDA·AA salt" in this application.

[0093] In some embodiments, the pentanediamine derivative is a PDA·CO2 covalent compound, the dicarboxylic acid is adipic acid, and the PDA·CO2 covalent compound contains the following three components:

[0094] (principal component 1),

[0095]

[0096] (subcomponent 2) and (Sub-component 3).

[0097] The reaction equation for the salt formation of main component 1 with adipic acid in water is shown below. The reaction is a salt displacement reaction, and the product is PDA·AA salt + CO2.

[0098]

[0099] Secondary component 2 releases protons H in water. The secondary component PDA further reacts with adipic acid in a neutralization salt formation reaction, and the product is PDA·AA salt (see reaction equation below).

[0100]

[0101] The reaction equation of secondary component 3 in water is similar to that of principal component 1, which is a salt displacement reaction, and the product is PDA·AA salt + 2CO2.

[0102] On the other hand, this application provides a method for preparing pentanediamine adipate, comprising reacting a pentanediamine derivative obtained by sublimation purification with adipic acid, wherein the chemical formula of the pentanediamine derivative is H2N(CH2)5NH2CO2, wherein the N atom and the C atom are connected by a covalent bond.

[0103] In some embodiments, the method for preparing pentanediamine adipate provided in this application includes reacting a PDA·CO2 covalent compound obtained through sublimation purification with adipic acid, wherein the chemical formula of the PDA·CO2 covalent compound is H2N(CH2)5NH2CO2, and the N atom and the C atom are connected by a covalent bond.

[0104] On the other hand, this application provides a method for preparing pentanediamine adipate, wherein the method includes:

[0105] (i) Place pure water in a container and remove the internal gas by applying a vacuum of -0.090 MPa or higher at room temperature. Replace the internal atmosphere with high-purity nitrogen at 0.005-0.02 MPa at intervals. Then, bubble high-purity nitrogen into the container below the surface of the pure water for 30-60 minutes and stir magnetically at 100-500 rpm to remove oxygen from the water.

[0106] (ii). The sublimated and purified PDA·CO2 covalent compound was added to the deoxygenated pure water from step (i), dissolved at room temperature, and stirred until fully dissolved to obtain the first solution;

[0107] (iii) Add a slight excess of adipic acid to the first solution obtained in step (ii) to carry out a salt displacement reaction until the reaction is basically completed. Then adjust the pH of the solution to weakly alkaline (e.g., 7.5-8.5) to end the reaction. (iv) Add 0.5-5% of the total weight of the reaction solution of decolorizing wood powder activated carbon to the solution obtained in step (iii). Heat the solution to 50-100°C with stirring. After reaching the set temperature, keep it warm and stir for 30-60 minutes. After completion, cool to room temperature (20-35°C), filter to remove colored substances and impurities, and obtain a pure and colorless PDA·AA salt aqueous solution.

[0108] On the other hand, this application provides a method for preparing pentanediamine adipate, wherein the method includes:

[0109] (i) Carbon dioxide is bubbled into a lysine solution to form lysine bicarbonate, and then the lysine is...

[0110] Carbonate (bicarbonate) reacts with lysine decarboxylase to produce a mixture containing PDA·CO2 covalent compounds.

[0111] Compounds;

[0112] (ii) Heating the mixture containing the PDA·CO2 covalent compound obtained in step (i) to the point where

[0113] The sublimation temperature of PDA·CO2 covalent compound is determined to obtain gaseous PDA·CO2 covalent compound;

[0114] (iii) The gaseous PDA·CO2 covalent compound obtained in step (ii) is subjected to sublimation treatment to obtain a solid.

[0115] PDA·CO2 covalent compounds in various forms;

[0116] (iv) Place pure water in the container and evacuate the internal gas at a vacuum of -0.090 MPa or higher at room temperature. Replace the internal atmosphere with high-purity nitrogen gas at 0.005-0.02 MPa intermittently. Then, fill the container with pure water.

[0117] High-purity nitrogen gas is bubbled through the bottom for 30-60 minutes, and magnetic stirring is performed at a speed of 100-500 rpm to remove oxygen from the water;

[0118] (v) Add the solid-state PDA·CO2 covalent compound obtained in step (iii) to step (iv).

[0119] Dissolve the substance in deoxygenated pure water at room temperature, add the substance and stir until fully dissolved to obtain the first solution;

[0120] (vi) Add a slight excess of adipic acid to the first solution obtained in step (v) to carry out a salt displacement reaction until the reaction proceeds.

[0121] Once the reaction is essentially complete, adjust the pH of the solution to a slightly alkaline level (e.g., 7.5–8.5) to end the reaction.

[0122] (vii) Add 0.5-5% (by weight of total weight of the reaction solution) of decolorizing wood powder active agent to the solution obtained in step (vi).

[0123] The charcoal is heated to 50-100℃ with stirring. After reaching the set temperature, it is kept at that temperature and stirred for 30-60 minutes to complete the process.

[0124] After cooling to room temperature (20-35℃), filter to remove colored substances and impurities, and obtain a pure, colorless PDA·AA salt aqueous solution.

[0125] In some embodiments, the lysine decarboxylase described in step (i) is a purified lysine decarboxylase or derived from bacterial cells expressing lysine decarboxylase.

[0126] Methods for preparing nylon 56

[0127] On the other hand, this application also provides a method for preparing nylon 56, comprising adding an auxiliary agent to a pentanediamine adipate solution prepared according to the method of this application, stirring and heating to concentrate, prepolymerizing at a pressure of 1-2 MPa and a temperature of 200-300°C, then reducing pressure to polymerize, and finally polycondensing under normal pressure or vacuum.

[0128] Nylon 56, also known as polyamide 56 or PA56, is a polyamide polymerized from pentanediamine and adipic acid. Pentanediamine adipate is an intermediate product in the production of nylon 56. The method for preparing nylon 56 provided in this application involves using pentanediamine adipate prepared by the method described in this application, followed by concentration, prepolymerization, and polycondensation steps to obtain nylon 56.

[0129] In some embodiments, the auxiliary includes a catalyst, such as one or more of boric acid, sodium hypophosphite, sodium hypophosphite, potassium hypophosphite, sodium hypophosphite, magnesium hypophosphite, calcium hypophosphite, and zinc hypophosphite. In some embodiments, the catalyst is sodium hypophosphite.

[0130] In some embodiments, the additives include defoamers, such as silicone defoamers (e.g., polydimethylsiloxane), polyether defoamers (e.g., copolymers of ethylene oxide and propylene oxide), and higher alcohol defoamers (e.g., alcohols containing 7 to 9 carbon atoms). In some embodiments, silicone defoamers are used in the process of dissolving the pentanediamine derivative.

[0131] In some embodiments, prepolymerization is performed at a pressure of 1–2 MPa (e.g., any pressure within the range of 1 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2 MPa, or any higher). In some embodiments, prepolymerization is performed at a pressure of 1.75 MPa. In some embodiments, prepolymerization is performed at a temperature of 200–300°C (e.g., any temperature within the range of 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, or any higher). In some embodiments, prepolymerization is performed at a temperature of 275°C. In some embodiments, prepolymerization is performed at a pressure of 1.75 MPa and a temperature of 275°C.

[0132] In some embodiments, prepolymerization is carried out at a pressure of 1.75 MPa and a temperature of 275°C for 60 to 120 minutes (e.g., 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes), followed by decompression polymerization, and finally atmospheric pressure or vacuum polycondensation.

[0133] In some embodiments, the nylon 56 chips prepared by the method provided in this application have a relative viscosity of 2.4 or higher, for example, a viscosity in the range of any value between 2.45, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2 or higher.

[0134] In some embodiments, the extractable content of nylon 56 prepared by the method provided in this application is less than 1.2%, for example, within the range of any value above 1.2%, 1.1%, 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%. In some embodiments, the extractable content of nylon 56 prepared by the method provided in this application is between 0.2% and 1.2%.

[0135] The method for preparing pentanediamine adipate or nylon 56 provided in this application has at least the following advantages:

[0136] (1) This method directly uses sublimated purified PDA·CO2 covalent compound powder as raw material, which solves the problem that the purity of PDA·AA salt obtained by adding adipic acid to the fermented and filtered PDA carbonate aqueous solution does not meet the requirements in the prior art. This method improves the purity of the product PDA·AA salt aqueous solution and can be applied to downstream polymerization.

[0137] (2) The process is simple. The synthesis of PDA·AA salt solution skips the method of synthesizing PDA first in the existing technology. The whole process does not require the participation of organic solvents, reduces equipment investment, and is environmentally friendly.

[0138] (3) This method first uses an excess of adipic acid to participate in the reaction, which accelerates the reaction process and ensures that the salt replacement reaction is complete; after the reaction, the pH value is adjusted to weak alkalinity with fresh PDA. The pH value can be finely adjusted according to the downstream requirements. This method can improve the purity of PDA·AA salt solution and is simple and convenient.

[0139] (4) PDA·CO2 covalent compound powder is relatively stable to store and convenient for industrial transportation. It can be prepared into PDA·AA salt water solution at any time according to the downstream needs for the next reaction, thus shortening the turnaround time.

[0140] (5) This technical solution further decolorizes and removes impurities by using activated carbon, and the UV index of the finished product is also significantly reduced, avoiding the problem of excessively high UV index when directly synthesizing PDA·AA salt solution.

[0141] The above is an overview of this application, and there may be simplifications, generalizations, and omissions of details. Therefore, those skilled in the art should recognize that this section is merely illustrative and not intended to limit the scope of this application in any way. This overview section is neither intended to identify the key or essential features of the claimed subject matter nor to serve as an aid in determining the scope of the claimed subject matter.

[0142] Example

[0143] To provide a fuller understanding of the invention, the following embodiments are shown. It should be understood that these embodiments are for illustrative purposes only and are not to be construed as limiting in any way.

[0144] Example 1: Preparation of crude pentandiamine derivative

[0145] Engineered Escherichia coli containing lysine decarboxylase was cultured in a 15L fermenter for 30 hours, and then centrifuged at 8000 rpm for 10 minutes to obtain wet engineered Escherichia coli, which was collected for later use.

[0146] To prepare a 600 g / L lysine carbonate (bicarbonate) solution, the specific procedure is as follows: First, add 420 g of lysine (99% purity) to 680 ml of water, stir to dissolve, and then bubble carbon dioxide into the solution until the pH reaches 7.1-7.6, at which point the carbon dioxide supply is stopped. Next, add 9 g of the wetted E. coli culture containing lysine decarboxylase prepared above, and 0.05 g of pyridoxal phosphate. The reaction begins at 37°C. The pH is not controlled during the reaction. The reaction is terminated after 10 hours when the lysine content, as determined by HPLC, is <0.5% (w / v).

[0147] The reaction solution was passed through a 0.2 μm ceramic membrane to remove large particulate impurities, such as bacterial cells and bacterial fragments, and through a 10 KD ultrafiltration membrane to remove small molecule impurities, such as nucleic acids and nucleic acid fragments, amino acids, and proteins in the fermentation broth. The solution was concentrated under reduced pressure to 680 g and then dried directly in a vacuum oven at 50–70 °C to obtain 467.3 g of white solid with a pentanediamine carbonate content of 98.1% and a yield of 94.7%.

[0148] Example 2: Purification and structural confirmation of the compound

[0149] purification

[0150] First, the inventors purified the pentanediamine derivative prepared in Example 1. Specifically, the white solid prepared in Example 1 was heated and stirred in a sealed container at 70–140°C, gradually undergoing sublimation. The sublimated gaseous substance was transported in a heated pipeline, and the obtained gaseous substance was subjected to condensation treatment in a pipeline at a temperature below 80°C to obtain a pure white and dense solid.

[0151] During the above experiments, the inventors discovered that, unlike other amines that decompose upon heating after absorbing CO2 and release the absorbed CO2, the pentanediamine derivative prepared in Example 1 of this application can form a stable compound that does not release CO2 during heating, but instead sublimates in a 1:1 ratio. The elemental analysis of the sublimated substance is consistent with that of the unsublimated substance, but the density (compactness) / hardness of the sublimated substance increases.

[0152] Structural confirmation

[0153] (1) Elemental analysis

[0154] Elemental analysis was performed on the substance before and after sublimation to study its composition. Its approximate elemental composition is known to be C. a H b N2O c The elemental composition analysis is as follows:

[0155]

[0156] By analyzing the nitrogen content from the fixed composition of two nitrogen atoms in the sample and the elemental analysis, the molecular weight of the sample can be deduced. By combining the sample molecular weight with the carbon / hydrogen content, the number of carbon / hydrogen atoms can be inferred. The oxygen content was not determined, but the number of oxygen atoms can be inferred by combining the proportions of each element.

[0157] As shown above, the elemental composition of the sample is C6H. 14 N2O2 is expressed as H2N(CH2)5NH2·CO2 or PDA·CO2.

[0158] (2) Nuclear magnetic resonance analysis

[0159] Nuclear magnetic resonance (NMR) analysis of the same PDA·CO2 sample using different deuterated solvents revealed different NMR characterizations. The NMR spectra after dissolution in deuterated methanol are shown below. Figure 1 As shown. The pentanediamine derivatives prepared in Example 1 were subjected to one-dimensional nuclear magnetic resonance analysis using deuterated aqueous solvent. 1 H-NMR analysis, 13 C-NMR analysis) and two-dimensional NMR analysis ( 1 H- 1 H COSY and 1 H- 13 The obtained NMR spectra are as follows (C COSY). Figure 2 , Figure 3 , Figure 4 and Figure 5 .

[0160] Based on preliminary analysis, the inventors believe that the pentanediamine derivative prepared in Example 1 is not carbonate (CO3). 2- ) or bicarbonate (HCO3) - The pentanediamine derivative solution obtained in Example 1, after undergoing a concentration and drying process, does not yield a traditional PDA carbonate containing ionic bonds, but rather a PDA·CO2 covalent compound existing in the form of a mixture.

[0161] According to existing reports (Ciftja, AF; Hartono, A.; Svendsen, F. "Carbamate Formation in Aqueous-Diamine-CO2 Systems" Energy Procedia, 2013, 37, 1605) and Figure 2 , Figure 3 , Figure 4 and Figure 5 The spectra show that the pentanediamine derivative prepared in Example 1 is a mixture mainly comprising the following three structures:

[0162] The molar ratio of the three is 2:1:1.

[0163] Example 3: Preparation of pentanediamine adipate aqueous solution (using sublimated purified PDA·CO2 covalent compound aqueous solution)

[0164] Example 3.1

[0165] First, add 102g of pure water (Watson's 105℃ distilled water) to a deoxygenated 500ml four-necked flask. Vacuum deoxygenation (-0.090MPa) and purging of the internal atmosphere with high-purity nitrogen (0.01MPa) three times intermittently are performed. The oil bath temperature is controlled at 25℃, the magnetic stirring speed at 200rpm, and 0.01MPa of high-purity nitrogen is introduced to bubble below the water surface for 30min at a nitrogen flow rate of 100ml / min. After deoxygenation, under high-purity nitrogen protection, add 60g of the PDA·CO2 covalent compound powder purified by sublimation and deposition as described in Example 2 and 0.005g of high-temperature resistant organosilicon defoamer, and stir to dissolve for 15min.

[0166] After dissolution, add 60g of adipic acid under nitrogen protection. Observe the temperature rise and foam production. If the temperature rise is too rapid or there is too much foam, slow down the addition rate. After adding adipic acid, remove the generated CO2 under vacuum of -0.040MPa and purge the internal atmosphere with high-purity nitrogen several times. Then, set the oil bath temperature to 55℃ under nitrogen protection. After reacting for 30 minutes, take 1g of the reaction solution and dilute it with pure water to 5g. The pH value measured by a pH meter is 6.86. After 15 minutes, take another sample and measure the pH value again. If it is 6.89, the reaction is considered to be fully completed.

[0167] Then, under nitrogen protection, 1.1g of fresh PDA was added to the reaction solution. After reacting for 15 minutes, the pH value was measured to be 7.88, which was basically constant and within the required range. Cooling was then initiated. After cooling to 35℃, the weight of the CO2-removed reaction solution was measured to be 202g. Under nitrogen protection, 4.04g of decolorizing powdered activated carbon (200 mesh particle size, 800mg / g iodine value) was added (accounting for 2% of the reaction solution weight). The temperature was raised to 50℃ and stirred for another 30 minutes.

[0168] After 30 minutes, cooling was initiated and the solution was cooled to 30°C. Filtering was then performed using slow-speed filter paper (2-3 μm pore size) to obtain approximately 196.2 g of pentanediamine adipate aqueous solution. The filtrate was analyzed for quality parameters, and the color (platinum-cobalt color number) of the 35% diluted solution was measured to be 13.8, and the UV index (absorbance at 279 nm) was 0.46 × 10⁻⁶. -3 The solution purity is 99.4% (liquid chromatography).

[0169] Example 3.2

[0170] Based on Example 3.1, the formulation and process parameters of the added materials remain unchanged. Finally, the pH value of the pentanediamine adipate aqueous solution is adjusted to 8.07, cooled to 35°C, and 8.08g of powdered activated carbon for decolorization (particle size 200 mesh, iodine value 800mg / g) (accounting for 4% of the weight of the reaction solution) is added under nitrogen protection. The temperature is raised to 50°C and stirred for another 30 minutes.

[0171] After 30 minutes, cooling was initiated and the solution was cooled to 30°C. Filtering was then performed using slow-speed filter paper (2-3 μm pore size) to obtain approximately 195.4 g of pentanediamine adipate aqueous solution. The filtrate was analyzed for quality parameters, and the color (platinum-cobalt color number) of the 35% diluted solution was measured to be 8.8, and the UV index (absorbance at 279 nm) was 0.29 × 10⁻⁶. -3 The solution purity is 99.5% (liquid chromatography).

[0172] Comparing the results of Examples 3.1 and 3.2, it can be seen that in Example 3.1, the main mass parameters of the pentanediamine adipate aqueous solution synthesized from the sublimated purified PDA·CO2 covalent compound powder are as follows: 35% solution color 13.8 (≤15), UV index 0.46*10⁻⁶. -3 (≤0.50*10 -3 The solution purity of 99.4% is close to 99.5%, which basically meets the quality requirements. When the activated carbon for decolorization is increased by 1 time in Example 3.2, the color of the solution (8.8) and UV index (0.29*10) are significantly improved. -3 Both the purity (99.5%) and the purity were significantly improved.

[0173] Example 4: Preparation of pentanediamine adipate aqueous solution (using unsublimed purified PDA·CO2 salt aqueous solution)

[0174] Example 4.1

[0175] Based on Example 3.1, the PDA·CO2 reaction solution obtained by the biological method in Example 1 was cooled to 4°C and then centrifuged (12000 rpm, 10 min) to remove cells and residues, and a 37% concentration solution was prepared. A total of 162 g of the solution was added to a 500 ml four-necked flask that had been deoxygenated. Deoxygenation, defoaming agent and adipic acid were added in sequence, and the amount added and the process were the same as in Example 3.1.

[0176] The final pentanediamine adipate aqueous solution had a pH of 7.94 and a reaction solution weight of 202 g. Activated carbon was added at a rate of 4.04 g (2% of the reaction solution weight). The decolorization process was the same as in Example 3.1. After filtration, 196 g of pentanediamine adipate aqueous solution was obtained. Analysis of the filtrate quality indicators revealed that the color (platinum-cobalt color number) of the 35% diluted solution was 16.7, and the UV index (absorbance at 279 nm) was 0.61*10⁻⁶. -3 The solution purity was 98.5% (liquid chromatography).

[0177] Comparing the results of Examples 3.1 and 4.1, it can be seen that the color, UV index and purity of the pentanediamine adipate aqueous solution obtained in Example 4.1 are different from those in Example 3.1, even with the same proportion of activated carbon added.

[0178] Example 4.2

[0179] Based on Example 3.1, the PDA·CO2 reaction solution obtained by the biological method in Example 1 was cooled to 4°C and then centrifuged (12000 rpm, 10 min) to remove cells and residues, and a 37% concentration solution was prepared. A total of 162 g of the solution was added to a 500 ml four-necked flask that had been deoxygenated. Deoxygenation, defoaming agent and adipic acid were added in sequence, and the amount added and the process were the same as in Example 3.1.

[0180] The final obtained pentanediamine adipate aqueous solution had a pH of 8.12 and a reaction solution weight of 202 g. Activated carbon was added at a rate of 8.08 g (4% of the reaction solution weight). The decolorization process was the same as in Example 3.1. After filtration, 195.1 g of pentanediamine adipate aqueous solution was obtained. Analysis of the filtrate quality indicators showed that the color (platinum-cobalt color number) of the 35% diluted solution was 11.7, and the UV index (absorbance at 279 nm) was 0.45*10. -3 The solution purity was 98.8% (liquid chromatography).

[0181] Comparing the results of Example 4.2 and Example 4.1, it can be seen that when the activated carbon for decolorization is increased by 1 time based on Example 4.1, the color, UV index and purity of the obtained pentamethylenediamine adipate aqueous solution are all improved, but the purity does not reach the requirement of 99.5%.

[0182] Comparing the results of Example 4.2 and Example 3.2, it can be seen that, under the same activated carbon addition ratio, the color, UV index and purity of the pentanediamine adipate aqueous solution obtained in Example 3.2 are significantly better than those in Example 4.2. The color and UV index of the pentanediamine adipate aqueous solution obtained in Example 4.2 basically meet the quality requirements, but the purity is only 98.8%, which is still far from the purity of 99.5% that can be achieved in Example 3.2.

[0183] Example 5: Direct synthesis of pentamethylenediamine adipate aqueous solution from pentamethylenediamine

[0184] Example 5.1

[0185] Based on Example 3.1, 42g of fresh pentanediamine was used to replace 60g of PDA·CO2 covalent compound powder, and other formulations and processes were the same as in Example 3.1.

[0186] The final obtained pentanediamine adipate aqueous solution had a pH of 7.87, and 202g of the reaction solution was weighed (Example 5.1 did not require the addition of defoamer for defoaming or activated carbon for decolorization). The quality indicators of the reaction solution were analyzed, and the color (platinum-cobalt color number) of the 35% diluted solution was measured to be 4.78, and the UV index (absorbance of the solution at 279nm) was 0.63*10. -3 The solution purity is 99.5% (liquid chromatography).

[0187] Example 5.2

[0188] Based on Example 3.1, 42g of fresh pentanediamine was used to replace 60g of PDA·CO2 covalent compound powder, and other formulations and processes were the same as in Example 3.1.

[0189] The final obtained pentanediamine adipate aqueous solution had a pH of 8.18, and 202g of the reaction solution was weighed (Example 5.2 did not require the addition of defoamer for defoaming or activated carbon for decolorization). The quality indicators of the reaction solution were analyzed, and the color (platinum-cobalt color number) of the 35% diluted solution was measured to be 4.64, and the UV index (absorbance of the solution at 279nm) was 0.59*10. -3 The solution purity is 99.6% (liquid chromatography).

[0190] Comparing the results of Example 5.2 and Example 3.2, it can be seen that the color of the pentanediamine adipate aqueous solution obtained in Example 5.2 is ≤5, and generally no activated carbon decolorization is required. Compared with Example 3.2, the color is better and the yield is higher, but the UV value is higher and the purity is similar.

[0191] Comparing the results of Example 5.2 and Example 5.1, it can be seen that the pH value of the obtained pentamethylenediamine adipate aqueous solution is slightly different, but the color, UV value and purity are not significantly different.

[0192] The characterization data and effect data of Examples 3.1, 3.2, 4.1, 4.2, 5.1 and 5.2 are compared in the table below.

[0193]

[0194] Example 6: Exploration of Salt Replacement Reaction Conditions

[0195] The PDA·CO2 covalent compound powder purified by sublimation and deposition in Example 2 was used to conduct a salt displacement reaction with adipic acid to prepare pentanediamine adipate. Examples 6.1, 6.2, and 6.3 were set up to explore the effects of the amount of adipic acid added and the pH value on the salt displacement reaction. The reaction conditions and the measured PDA·AA salt solution content are shown in the table below.

[0196]

[0197] As shown in the table above, the theoretical PDA·AA salt aqueous solution obtained by reacting equimolar amounts of PDA·CO2 with adipic acid should contain 50% PDA·AA salt. However, in reality, this 50% concentration can only be achieved when there is a slight excess of adipic acid, i.e., when the pH is weakly acidic. This demonstrates that the covalent compound PDA·CO2 and adipic acid can only fully complete the salt displacement reaction under weakly acidic conditions, thus yielding PDA·AA salt with better color.

[0198] Example 7: Synthesis of Polymer Nylon 56 from Pentylene Diamine Adipate

[0199] Example 7.1

[0200] 270g of PDA·AA salt solution (50% purity, pH 8.10) was synthesized using the method in Example 3.2. This salt solution was added to a 500ml high-pressure polymerization reactor, along with 0.005g of sodium hypophosphite (National Pharmaceutical AR grade) and 0.005g of high-temperature defoamer (J-502). The stirring speed was 100rpm / min. The reactor was evacuated and the internal atmosphere was replaced with high-purity nitrogen four times intermittently. The heating temperature was set to 150℃. After reaching a pressure of 0.14MPa, some water vapor was released for concentration. The temperature and pressure were then increased further. When the pressure reached 1.75MPa, the pressure was slightly released to maintain stability until the temperature reached 275℃. Prepolymerization was carried out under pressure for 90min. Then, the pressure was reduced for polycondensation, with a pressure reduction of 0.25-0.3MPa every 10 minutes, while maintaining the reaction temperature. After reaching atmospheric pressure, the vacuum pump was started, and the vacuum level inside the reactor was adjusted to -0.070 MPa. The torque display on the reactor slowly increased from 1.0 N*cm to 2.0 N*cm. The vacuum was then stopped, and high-purity nitrogen was added to the reactor to pressurize it to 0.1 MPa. The material was then discharged, stretched and granulated underwater, and dried in a vacuum oven at 80℃ for 6 hours to obtain Nylon 56 dry chips. The relative viscosity of the dry chips was measured to be 2.67 using an Ubbelohde viscometer; the extract content was 0.91% as determined by high-temperature water extraction.

[0201] Example 7.2

[0202] The formulation and polymerization process were the same as in Example 7.1. After depressurizing the reactor, the vacuum pump was started to evacuate the reactor to a vacuum level of -0.070 MPa. The reactor torque was gradually increased from 1.0 N*cm to 2.3 N*cm. Other post-processing was the same as in Example 7.1. The relative viscosity of the dry slices was measured to be 2.77 using an Ubbelohde viscometer; the extract content was 0.90% as determined by high-temperature water extraction.

[0203] The parameters and experimental results of Examples 7.1 and 7.2 are summarized in the table below.

[0204]

Claims

1. A method for preparing pentamethylenediamine dicarboxylate, comprising the step of reacting a pentamethylenediamine derivative with a dicarboxylic acid, wherein, The chemical formula of the pentanediamine derivative is H2N(CH2)5NH2CO2, wherein the N atom and the C atom are connected by a covalent bond.

2. The method according to claim 1, comprising dissolving the pentanediamine derivative in a solvent, and then adding the dicarboxylic acid to perform a salt substitution reaction to obtain a pentanediamine dicarboxylic acid solution.

3. The method according to claim 2, wherein the solvent is pure water.

4. The method according to any one of the preceding claims, wherein the dicarboxylic acid is added in an excess amount relative to the pentanediamine in the pentanediamine derivative, such that the pentanediamine dicarboxylic acid solution is acidic.

5. The method according to claim 4, wherein the pH value of the pentanediamine dicarboxylate solution is 6.0-7.

0.

6. The method according to claim 5, wherein after the reaction between the pentanediamine derivative and the dicarboxylic acid is completed, the pH of the pentanediamine dicarboxylic acid solution is adjusted to alkaline.

7. The method according to claim 6, wherein the pH of the pentanediamine dicarboxylate solution is adjusted to 7.5-8.

5.

8. The method of claim 7, wherein the pH of the pentanediamine dicarboxylate solution is adjusted to alkaline using fresh pentanediamine.

9. The method according to any one of the preceding claims, further comprising the step of adding activated carbon for filtration and decolorization.

10. The method according to any one of the preceding claims, wherein the pentanediamine derivative has an amide ester. structure.

11. The method according to any one of the preceding claims, wherein the pentanediamine derivative has the following chemical structure: and / or 12. The method according to any one of the preceding claims, wherein the pentanediamine derivative is present in the form of a mixture.

13. The method according to any one of the preceding claims, wherein the pentanediamine derivative comprises the following structure:

14. The method of claim 13, wherein Total moles and The molar amounts are basically the same.

15. The method according to any one of the preceding claims, wherein the pentanediamine derivative does not release carbon dioxide at a temperature of 70–140°C.

16. The method according to any one of the preceding claims, wherein the sublimation temperature of the pentanediamine derivative is 70–140°C.

17. The method according to any one of the preceding claims, wherein the pentanediamine derivative is obtained by sublimation purification.

18. The method of claim 17, wherein the sublimation purification comprises heating a mixture containing the pentanediamine derivative to the sublimation temperature of the pentanediamine derivative to obtain a gaseous pentanediamine derivative.

19. The method according to claim 18, wherein the sublimation temperature is 70–140°C.

20. The method of claim 18, wherein the purification method does not include the step of alkalizing the mixture containing the pentanediamine derivative with an alkaline substance.

21. The method according to claim 20, wherein the alkaline substance is selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide, and any combination thereof.

22. The method of claim 18, wherein the purification method further comprises sublimation treatment of the obtained gaseous pentanediamine derivative.

23. The method of claim 22, wherein the sublimation treatment is performed at 30–50°C.

24. The method according to claim 18, wherein the mixture containing the pentanediamine derivative is prepared by passing carbon dioxide into lysine to form lysine carbonate (bicarbonate), and then reacting the lysine carbonate (bicarbonate) with lysine decarboxylase to generate the pentanediamine derivative.

25. The method according to any one of the preceding claims, wherein the dicarboxylic acid is adipic acid, and the pentanediamine dicarboxylic acid salt is pentanediamine adipate.

26. A method for preparing pentanediamine adipate, comprising reacting a pentanediamine derivative obtained through sublimation purification with adipic acid, wherein, The chemical formula of the pentanediamine derivative is H2N(CH2)5NH2CO2, wherein the N atom and the C atom are connected by a covalent bond.

27. A method for preparing nylon 56, comprising adding an auxiliary agent to a pentanediamine adipate solution prepared according to any one of the preceding claims, stirring and heating to concentrate, prepolymerizing at a pressure of 1-2 MPa and a temperature of 200-300°C, then reducing pressure to polymerize, and finally polycondensing under normal pressure or vacuum.

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