N, N, N-triacyl-2, 4, 6-triaminotoluene nucleating agent, preparation method, device and application

Abstract

This invention discloses an N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent, its preparation method, apparatus, and applications. The method is based on an acylation mechanism, using 2,4,6-triaminotoluene as a raw material, and undergoing a directed acylation reaction with an acylation reagent under low-temperature conditions in a system containing a haloalkanes solvent and an organic base. This invention utilizes highly reactive acyl chlorides or anhydrides as reaction substrates, combined with specific solvents and systems, effectively overcoming the significant steric hindrance effect of the para-amino group of the methyl group in the TAT molecule. In particular, it achieves the efficient synthesis of N,N,N-tripentanoyl-2,4,6-triaminotoluene. The process features mild reaction conditions (starting at 0-10℃), requires no high temperature or high pressure, and post-processing only requires simple water washing and separation to obtain the target product with high purity (HPLC>98%) and high yield (>87%). The solvent is easily recoverable and environmentally friendly. When applied to polypropylene, the nucleating agent prepared by this invention significantly increases the crystallization temperature and reduces haze, exhibiting excellent overall performance.

Description

Technical Field

[0001] This invention belongs to the field of polymer material additives synthesis technology, specifically relating to an N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent, its preparation method, apparatus, and application. Background Technology

[0002] 2,4,6-Triaminotoluene (TAT) is the main reduction product of decommissioned energetic material 2,4,6-trinitrotoluene (TNT). Converting TAT into high-value-added fine chemicals can not only solve the problem of safe disposal and resource utilization of waste explosives, but also turn waste into treasure. Studies have shown that N,N,N-triacyl-2,4,6-triaminotoluene compounds have a unique rigid planar structure and can be used as highly efficient nucleating agents in the modification of polymer materials such as polypropylene (PP), significantly improving the crystallization temperature, transparency, and mechanical properties of the materials.

[0003] Currently, there are two main technical routes for the synthesis of such triamide-based nucleating agents, but both have significant drawbacks in industrial applications:

[0004] (1) Transesterification reaction route (as disclosed in patent CN113861058B) This route uses carboxylic acid esters as acylation reagents, and the transesterification reaction is carried out with TAT under high temperature or reflux conditions catalyzed by strongly basic metal alkoxides (such as sodium tert-butoxide). Defect 1: Harsh reaction conditions. Metal alkoxide catalysts are extremely sensitive to moisture and oxygen. The production process requires strict control of anhydrous and oxygen-free environments, placing extremely high demands on equipment sealing and operation, making stable production difficult under conventional industrial conditions. Defect 2: Poor adaptability to sterically hindered groups. When introducing sterically hindered groups with excellent nucleation properties (such as tert-valeryl), the high kinetic resistance of the transesterification reaction often leads to incomplete reactions, easily generating mono- or di-substituted byproducts, severely affecting product purity and nucleation efficiency. Defect 3: High energy consumption and pollution in post-processing. This process typically uses "alcohol precipitation" (i.e., adding a large amount of ethanol to the reaction solution to precipitate the product) for post-processing. Producing one ton of product requires tens of tons of alcohol solvents, resulting in huge energy consumption for solvent recovery, difficult mother liquor treatment, and high emissions of waste.

[0005] (2) Conventional acyl chloride / acid anhydride high temperature route Some literature reports acylation using acyl chlorides or anhydrides under reflux conditions in solvents such as tetrahydrofuran (THF) and toluene. However, there are two main drawbacks: 1. The raw materials are easily oxidized and deteriorate. The amino groups in TAT molecules are not only easily acylated but also readily oxidized. In high-temperature and conventional solvent systems, TAT readily undergoes oxidative coupling, causing the reaction solution to darken. This not only reduces the yield but also results in a poor color (yellowish or grayish) of the final nucleating agent product, making it unsuitable for use in polypropylene products requiring high transparency. 2. Reaction selectivity is difficult to control. Under high-temperature and vigorous reaction conditions, it is difficult to achieve stepwise complete substitution of the three amino groups through kinetic control, especially when synthesizing asymmetric or sterically hindered structures, leading to numerous side reactions and significant purification difficulties. Current technologies cannot simultaneously meet the industrial requirements of mild reaction conditions, complete substitution of sterically hindered groups, and green post-processing. Therefore, developing a novel preparation process with mild reaction conditions (avoiding oxidation), effectively overcoming steric hindrance (achieving efficient introduction of large sterically hindered groups such as pivaloyl groups), and simple and environmentally friendly post-processing (avoiding alcohol precipitation) is the key to achieving low-cost, high-quality industrial production of this type of nucleating agent, and is also a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the technical problems of existing synthesis processes for N,N,N-triacyl-2,4,6-triaminotoluene nucleating agents, such as demanding reaction conditions (requiring a strictly anhydrous environment), limited reactivity to sterically hindered acyl groups, and cumbersome post-processing (requiring alcohol precipitation and high energy consumption for solvent recovery), this invention provides a method for preparing three N,N,N-triacyl-2,4,6-triaminotoluene nucleating agents with mild reaction conditions, simple operation, high yield, and excellent purity. Furthermore, this invention also provides the application of the above-mentioned nucleating agents in polymer modification, and a rapid screening method for nucleating agents based on thermodynamic and optical performance evaluation. Specifically, it includes an N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent, its preparation method, apparatus, and applications.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing an N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent includes the following steps: Step S1: Dissolve 2,4,6-triaminotoluene in a haloalkanes solvent, and add an organic base as an activator under low temperature conditions to obtain an activated system; Step S2: Under low temperature and stirring conditions, add an acylation reagent dropwise to the activation system. The acylation reagent is selected from acid anhydrides or acyl chlorides. After the addition is complete, continue the reaction at room temperature until the reaction endpoint is reached. Step S3: After the reaction is completed, the reaction mixture is washed with water, separated, dried and the solvent is recovered to obtain the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent.

[0008] Optionally, the halocarbon solvent is at least one of dichloromethane, chloroform, and 1,2-dichloroethane.

[0009] Optionally, the organic base is at least one selected from triethylamine, pyridine, and potassium tert-butoxide; The molar ratio of the acylation reagent to 2,4,6-triaminotoluene is (3.2-4.2):1.

[0010] Optionally, in steps S1 and S2, the low-temperature condition is to control the temperature of the reaction system at 0 to 10°C; in step S2, the temperature of the reaction after the addition is completed is 20 to 30°C.

[0011] Optionally, depending on the target product, the acylation reaction may employ one of the following reaction systems: When preparing N,N,N-triacetyl-2,4,6-triaminotoluene, the acylation reagent is acetyl chloride, and the organic base is triethylamine; When preparing N,N,N-tribenzoyl-2,4,6-triaminotoluene, the acylation reagent is benzoic anhydride, and the organic base is triethylamine; When preparing N,N,N-terpentanoyl-2,4,6-triaminotoluene, the acylation reagent is terpentanoic anhydride, and the organic base is triethylamine.

[0012] A low-temperature amidation reaction apparatus for implementing the preparation method of N,N,N-triacyl-2,4,6-triaminotoluene nucleating agents according to any one of the present invention, characterized in that it comprises: Reactor: It is equipped with an inner liner and a jacket covering the outer layer, and a sealed reactor lid on top; the reactor lid has multiple connection ports for material input and connection to other functional components; the bottom of the reactor is equipped with a discharge valve; The dropper assembly, stirring assembly, and condensing assembly are installed on the reactor lid at the top of the reactor. The dropper assembly is used to precisely control the drop rate of the liquid acylation reagent at low temperature. The stirring assembly is used to ensure uniform contact of the materials in the reaction. The condensing assembly is used to condense and reflux the volatile halogenated hydrocarbon solvent. The reactor lid is evenly equipped with condenser assembly connection ports, liquid feed ports, solid feed ports, temperature measuring ports, stirring assembly connection ports, and dripping assembly connection ports. The condenser assembly connection ports are used to install and connect the condenser assembly, the liquid feed ports are used to add liquid materials, the solid feed ports are used to add solid raw materials, the stirring assembly connection ports are used to install and connect the stirring assembly, and the dripping assembly connection ports are used to install and connect the dripping assembly.

[0013] An N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent, characterized in that it is prepared by any of the preparation methods of the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agents described in this invention.

[0014] The application of the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent described in this invention in the modification of polypropylene.

[0015] Optionally, the nucleating agent is added to polypropylene at an amount of 0.05% to 0.5% of the mass of polypropylene; the nucleating agent is used to increase the crystallization temperature and tensile strength of polypropylene and reduce the haze of polypropylene.

[0016] The beneficial effects of this invention are: The reaction conditions are mild. This invention adopts an acylation route of "acyl chloride / acid anhydride + organic base" with a reaction temperature not exceeding 30°C. It does not require high-temperature reflux and has low sensitivity to moisture in the system, which significantly reduces energy consumption and equipment requirements, and the process has good stability. Overcoming steric hindrance, achieving both high yield and purity: By selecting dichloromethane as a good solvent and triethylamine as an organic base, this invention effectively solves the problem of the difficulty in reacting large sterically hindered groups (especially pentanoyl groups) on the para-amino group of TAT. Experimental data show that the yields of the three nucleating agents prepared by this invention all reach over 87% (up to 90%), and the purity (HPLC) is all greater than 98%, demonstrating excellent product quality. The post-processing is simplified and environmentally friendly: This invention utilizes the difference in solubility between the product and the by-product in the aqueous phase. Only simple water washing, filtration and drying are required to obtain a high-purity product. The solvent dichloromethane is easy to recover and reuse, avoiding the process of precipitation by using large amounts of solvents such as ethanol, which significantly reduces the discharge of "three wastes" and production costs. Excellent application performance: The nucleating agent prepared by the method of this invention, especially N,N,N-tert-pentanoyl-2,4,6-triaminotoluene, exhibits excellent nucleation effects in polypropylene. At an addition level of 0.2%, the light transmittance of the polypropylene sheet reaches 94.5%, the haze is reduced to 13.9%, and the tensile strength and flexural strength are significantly improved, demonstrating outstanding performance. The performance of N,N,N-tert-pentanoyl-2,4,6-triaminotoluene reaches the level of commercially available XT386. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1The 1H NMR spectrum of N,N,N-triacetyl-2,4,6-triaminotoluene prepared in Example 1 of the present invention is shown. Figure 2 The carbon NMR spectrum of N,N,N-triacetyl-2,4,6-triaminotoluene prepared in Example 1 of the present invention is shown. Figure 3 The Fourier transform infrared spectrum of N,N,N-triacetyl-2,4,6-triaminotoluene prepared in Example 1 of the present invention is shown. Figure 4 The high-performance liquid chromatogram of N,N,N-triacetyl-2,4,6-triaminotoluene prepared in Example 1 of the present invention is shown. Figure 5 The 1H NMR spectrum of N,N,N-tribenzoyl-2,4,6-triaminotoluene prepared in Example 2 of the present invention is shown. Figure 6 The carbon NMR spectrum of N,N,N-triacetyl-2,4,6-triaminotoluene prepared in Example 2 of the present invention is shown. Figure 7 The Fourier transform infrared spectrum of N,N,N-triacetyl-2,4,6-triaminotoluene prepared in Example 2 of the present invention is shown. Figure 8 The high-performance liquid chromatogram of N,N,N-triacetyl-2,4,6-triaminotoluene prepared in Example 2 of the present invention is shown. Figure 9 The 1H NMR spectrum of N,N,N-triacetyl-2,4,6-triaminotoluene prepared in Example 3 of the present invention is shown. Figure 10 The carbon NMR spectrum of N,N,N-triacetyl-2,4,6-triaminotoluene prepared in Example 3 of the present invention is shown. Figure 11 The Fourier transform infrared spectrum of N,N,N-triacetyl-2,4,6-triaminotoluene prepared in Example 3 of the present invention is shown. Figure 12 The high-performance liquid chromatogram of N,N,N-triacetyl-2,4,6-triaminotoluene prepared in Example 3 of the present invention is shown. Figure 13 This is a schematic diagram of the low-temperature amidation reaction apparatus of the present invention; Figure 14 for Figure 13 A schematic diagram of the structure of the reactor lid; The labels in the diagram represent: 1-Reaction vessel, 11-Reaction vessel cover, 12-Inner liner, 13-Jacket, 14-Discharge valve, 2-Condensation assembly, 3-Stirring assembly, 4-Drip assembly, 5-Pressure gauge, 6-Support; 111-Condensation component connection port, 112-Liquid inlet port, 113-Solid feed port, 114-Temperature measuring port, 115-Stirring component connection port, 116-Drip component connection port. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0019] This invention provides a method for preparing three N,N,N-triacyl-2,4,6-triaminotoluene nucleating agents (Formula I) with mild reaction conditions, simple operation, high yield and excellent purity.

[0020] Ⅰ; The present invention discloses a method for preparing N,N,N-triacyl-2,4,6-triaminotoluene nucleating agents, wherein the method uses 2,4,6-triaminotoluene (TAT) as a raw material and reacts it with an acylation reagent in the presence of an organic solvent and an organic base; the acylation reagent is selected from acid anhydrides or acyl chlorides.

[0021] The specific preparation steps include: Step S1 (Dissolution and Activation): Dissolve 2,4,6-triaminotoluene in an organic solvent, cool to 0-10°C, add an organic base as a dehydrogenating agent, and stir to mix; the ratio of 2,4,6-triaminotoluene to organic base should be at least 1:3 (based on its stoichiometric ratio in chemical reaction), and the ratio of organic base used in each addition should preferably be consistent with the molar ratio of amide or acid anhydride. Step S2 (low-temperature acylation): Under low-temperature conditions, slowly add the acylation reagent to the system of step S1, controlling the system temperature to not exceed 10°C during the addition process; after the addition is complete, continue the reaction at room temperature until the reaction is complete. Step S3 (Post-processing): After the reaction is complete, the generated salt byproducts are removed by washing with water, the organic phase is collected by separation, and after drying, solvent recovery and drying treatment, N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent solid is obtained.

[0022] In this invention, the organic solvent is preferably a halogenated hydrocarbon solvent, more preferably dichloromethane. Dichloromethane has excellent solubility for the raw material TAT, is chemically stable, does not participate in the acylation competition reaction, has a moderate boiling point, and is easy to recover.

[0023] In this invention, the organic base is preferably triethylamine. Triethylamine can effectively neutralize the acid (such as acetic acid or hydrogen chloride) generated in the reaction, promote the acylation reaction to proceed in the forward direction, and the solvent system formed by it and dichloromethane has good stability.

[0024] In this invention, the molar ratio of the acylation reagent to 2,4,6-triaminotoluene is 3.0 to 4.5:1, preferably 3.5 to 4.0:1, to ensure that the acylation reaction of all three amino sites is complete.

[0025] In this invention, the specific implementation of the acylation reaction varies depending on the structure of the target product: When preparing N,N,N-triacetyl-2,4,6-triaminotoluene, acetyl chloride is used as the acylation reagent; when preparing N,N,N-tribenzoyl-2,4,6-triaminotoluene, benzoic anhydride is used as the acylation reagent; and when preparing N,N,N-terpentylyl-2,4,6-triaminotoluene, terpentyl anhydride is used as the acylation reagent. To address the significant steric hindrance of the terpentylyl group, this invention uses anhydride as the acylation reagent in conjunction with triethylamine, effectively overcoming the low reactivity of the para-amino group of the methyl group in the TAT molecule, and achieving efficient synthesis of the fully substituted product.

[0026] In this invention, the post-treatment operation in step S3 specifically involves filtering the reaction mixture, washing the filter cake (or organic phase) multiple times with distilled water until the washing liquid is neutral, and then vacuum drying or rotary evaporation drying. This post-treatment process utilizes the characteristic that the product is insoluble in water while the byproduct (triethylamine salt) is readily soluble in water, avoiding complex alcohol precipitation and recrystallization steps.

[0027] This invention also protects the application of the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent obtained by the above preparation method in the modification of polypropylene (PP).

[0028] In this invention, the nucleating agent is added to polypropylene at a concentration of 0.05% to 0.5% (mass fraction). Application tests show that adding this type of nucleating agent can significantly increase the crystallization temperature of polypropylene, greatly reduce material haze, and improve light transmittance and mechanical properties.

[0029] Furthermore, this invention also provides a rapid screening method for 2,4,6-triaminotoluene-derived nucleating agents, the method comprising the following steps: Melting point screening: Determine the melting point of the synthesized product and screen compounds with melting points higher than 250℃ and higher than the processing temperature of polypropylene; Crystallization thermodynamic screening: Prepare a sample by mixing the nucleating agent to be tested with polypropylene, and determine the crystallization peak temperature by differential scanning calorimetry (DSC), and select nucleating agents that can increase the crystallization temperature of polypropylene by more than 10℃; Optical performance verification: Prepare the above samples into standard plates and test the haze and transmittance, and select nucleating agents that can significantly reduce haze.

[0030] Combination Figure 13 and 14 The low-temperature amidation reaction apparatus of the present invention is configured as follows: Reactor body: It adopts a double-layer glass structure with an inner liner and an outer jacket; the inlet and outlet of the jacket are connected to a low-temperature cooling liquid circulation system to maintain the reaction system in a low-temperature environment of 0-10℃; Precision feeding system: including a constant pressure dropping funnel and a solid feeding port located at the top of the reactor; the constant pressure dropping funnel is used to precisely control the dropping rate of liquid acylation reagent at low temperature to match the rate of heat release of the reaction; Stirring and reflux assembly: including an explosion-proof variable frequency stirring motor and a vertical condenser reflux pipe connected to the vessel lid; the condenser reflux pipe is used to condense and reflux the volatile dichloromethane solvent; The bottom of the reactor body is equipped with a large-diameter discharge valve. The outlet end of the discharge valve is directly connected to the solid-liquid separation equipment through a connecting pipeline for the rapid discharge of high solid content reaction slurry.

[0031] The specific plan is as follows: Reactor 1: It adopts a double-layer glass structure, with an inner liner 12 and a jacket 13 wrapped around the outer layer, and a sealed reactor cover 11 on the top; the reactor cover 11 is provided with multiple connection ports for material input and connection to other functional components; the inlet and outlet of the jacket 13 are connected to a low-temperature cooling liquid circulation system to maintain the reaction system in a low-temperature environment of 0-10℃; the bottom of the reactor 1 is provided with a large-diameter discharge valve 14, and the outlet end of the discharge valve 14 is directly connected to the solid-liquid separation equipment through a connecting pipeline for rapid discharge of high solid content reaction slurry; Precision feeding system: including a dropping component 4 and a solid feeding port 113 installed on the reactor lid 11 at the top of the reactor 1; the dropping component 4 is specifically implemented as a constant pressure dropping funnel, which is used to precisely control the dropping rate of liquid acylation reagent at low temperature to match the release rate of reaction heat; The stirring and reflux assembly includes a stirring assembly 3 and a condensing assembly 2 mounted on the reactor lid 11. The stirring assembly 3 is equipped with an explosion-proof variable frequency stirring motor and a stirring paddle. The condensing assembly 2 is specifically a vertical condensing reflux pipe connected to the reactor lid 11, used to condense and reflux the volatile halogenated hydrocarbon solvent. The entire reaction device is mounted on a support 6, and a pressure gauge 5 is mounted on the support 6 to detect the overall reaction pressure inside the reactor 1.

[0032] Specifically, the reactor lid 11 is evenly provided with a condenser assembly connection port 111, a liquid feed port 112, a solid feed port 113, a temperature measuring port 114, a stirring assembly connection port 115, and a dropping assembly connection port 116. The condenser assembly connection port 111 is used to install and connect the condenser assembly 2. The liquid feed port 112 is used to add liquid materials. The solid feed port 113 is used to add solid raw materials. The temperature measuring port 114 is used to install and connect temperature measuring equipment, such as a thermometer or temperature sensor. The stirring assembly connection port 115 is used to install and connect the stirring assembly 3. The dropping assembly connection port 116 is used to install and connect the dropping assembly 4.

[0033] General instructions: (I) Principles and reaction mechanisms for selecting process parameters 1. Solvent-specific selection: This invention identifies dichloromethane (DCM) as the optimal reaction solvent. TAT, a polar molecule, exhibits poor solubility in conventional nonpolar solvents. While it dissolves in strongly polar solvents such as tetrahydrofuran (THF), THF is miscible with water, leading to difficulties in post-processing. DCM not only possesses excellent solubility for TAT (solventization effect), allowing TAT molecules to fully extend and expose amino sites, but it is also immiscible with water. This enables the direct removal of byproducts after the reaction via simple water washing and separation, achieving a unique and highly efficient process of "heterogeneous reaction - homogeneous transformation - two-phase separation."

[0034] 2. Low-temperature activation overcomes steric hindrance mechanism: To address the challenge of reacting sterically hindered groups such as pivaloyl groups, this invention employs a low-temperature activation strategy of 0-10°C. Studies have shown that at low temperatures, triethylamine can form an active intermediate with the acylation reagent. Encapsulated in a dichloromethane solvent cage, this intermediate is relatively stable and can attack the third sterically hindered amino group on TAT with a lower activation energy. Compared to high-temperature reflux processes, this "low-temperature kinetic control" strategy effectively suppresses side reactions and achieves quantitative conversion of sterically hindered groups.

[0035] (II) Main Raw Materials and Reagents In the embodiments of this invention, unless otherwise stated, all chemical reagents used are commercially available analytical grade or industrial grade products. The specific specifications of the core raw materials are as follows: 2,4,6-Triaminotoluene (TAT): Prepared in-house. It is produced by catalytic hydrogenation reduction of 2,4,6-trinitrotoluene (TNT). It is a light brown solid with a purity of 98.0% as determined by high performance liquid chromatography (HPLC).

[0036] Acylating reagent: Acetyl chloride: Analytical grade (AR), purity 99.0%.

[0037] Benzoic anhydride: Analytical grade (AR), purity 99.0%.

[0038] Pteropenic anhydride: Analytical grade (AR), purity 99.0%.

[0039] Solvents and additives: Dichloromethane (DCM): Industrial grade, dried with 4A molecular sieve before use, with a water content of <0.05%.

[0040] Triethylamine (TEA): Analytical grade (AR), used as an organic base.

[0041] Polymer matrix: Polypropylene (PP): Grade HN7330B, purchased from China Petroleum & Chemical Corporation, used as the matrix resin for nucleating agent application testing.

[0042] (III) Instruments and Equipment The main instruments and equipment used in the embodiments of this invention are as follows: Reaction apparatus: 5L explosion-proof double-layer glass reactor system (model: YASC-5HL, self-made), equipped with a precision temperature control jacket (connected to a low-temperature coolant circulation pump), a mechanical stirrer (explosion-proof motor), a constant-pressure dropping funnel, and a reflux condensation system. The apparatus structure is as follows: Figure 14 As shown.

[0043] Nuclear magnetic resonance spectrometer: Bruker Avance III 400MHz, used for proton NMR spectroscopy of product structure ( 1 HNMR and carbon spectroscopy (HNMR) 13 Confirmed by CNMR.

[0044] Fourier transform infrared spectrometer: Nicolet 6700, used for product functional group analysis.

[0045] High-performance liquid chromatography (HPLC): used for product purity analysis. The chromatographic column is XDB-C18, the mobile phase is methanol / water (80:20 v / v), and the detection wavelength is 254 nm.

[0046] (iv) Testing Standards and Methods Yield calculation: Yield (%) = (actual dried product mass / theoretical product mass) × 100%.

[0047] To ensure complete reaction at all three amino sites, especially to overcome the steric hindrance of the pivaloyl group, the acylation reagent needs to be maintained in a moderate excess. The preferred molar ratio in this invention is 3.2–4.2:1. Experiments show that when the molar ratio is below 3.2, the yield of the sterically hindered product decreases significantly; when it is above 4.2, although the conversion rate can be guaranteed, the load on subsequent neutralization and washing will increase significantly.

[0048] Purity determination: Calculated using the area normalization method of high performance liquid chromatography (HPLC).

[0049] Optical performance testing: According to GB / T2410-2008 "Determination of transmittance and haze of transparent plastics", the injection-molded polypropylene sheet (1.5mm thick) was tested and the transmittance and haze values ​​were recorded.

[0050] Mechanical property testing: Tensile strength is tested according to GB / T1040.2-2006 standard, and flexural strength is tested according to GB / T9341-2008 standard.

[0051] Crystallization temperature (Tc) determination: DSC was performed under a nitrogen atmosphere. After eliminating the thermal history, the temperature was lowered at a rate of 10 °C / min, and the peak temperature of the exothermic peak was taken as the crystallization temperature Tc.

[0052] Example 1: Small-scale preparation of N,N,N-triacetyl-2,4,6-triaminotoluene This embodiment aims to verify the feasibility of using acetyl chloride as an acylation reagent to prepare the target product.

[0053] Addition and Dissolution: In a 250 mL three-necked flask equipped with a magnetic stirrer, thermometer, and constant-pressure dropping funnel, add 5.00 g (approximately 36.5 mmol) of 2,4,6-triaminotoluene (TAT) and 50.00 mL of dichloromethane. Start stirring and cool in an ice-water bath, controlling the system temperature at 0–5 °C, until the TAT is completely dissolved to obtain a homogeneous solution.

[0054] Activation: While maintaining a low temperature (0–10°C) with stirring, slowly add 14.75 g of triethylamine dropwise through a constant-pressure dropping funnel. Control the dropping rate during the process to prevent localized overheating. After the addition is complete, continue stirring in an ice bath for 30 minutes to initiate proton transfer and activate the pre-reaction.

[0055] Acylation reaction: 11.46 g of acetyl chloride was slowly added dropwise under continuous stirring and low temperature conditions of 0–10 °C. During the addition, a violent exothermic reaction was observed, producing a large amount of white fumes and the solution color changed from brown to light brown. The dropping rate needed to be strictly controlled to maintain the system temperature within acceptable limits. After the addition was complete, the reaction was continued in an ice bath for 30 minutes, then the ice bath was removed, and the mixture was allowed to warm naturally to room temperature, followed by stirring for another 3.5 hours. TLC monitoring showed the disappearance of the starting material spot.

[0056] Post-processing: After the reaction was complete, the reaction mixture was filtered. The filter cake was washed repeatedly with distilled water (to remove triethylamine salt and unreacted substances) until the filtrate was neutral. The resulting solid was dried in a vacuum drying oven to obtain a powdery white solid product.

[0057] Results: A total of 8.41g of dried product was obtained, with a calculated yield of 87.6%.

[0058] Example 2: Small-scale preparation of N,N,N-tribenzoyl-2,4,6-triaminotoluene In this embodiment, benzoic anhydride is used as the acylation reagent to verify the applicability of the system to aromatic acylation reagents.

[0059] Feeding and dissolving: Accurately weigh 5.00g of TAT raw material, add it to 50.00mL of dichloromethane, and stir until completely dissolved under ice bath conditions (0~10℃).

[0060] Activation: Slowly add 14.75g of triethylamine dropwise at low temperature. After the addition is complete, keep warm and stir for 30 minutes to ensure that the TAT amino group is fully activated.

[0061] Acylation reaction: 33.02 g of benzoic anhydride was slowly added. During the addition, the system exhibited significant exothermic reaction and the solution became viscous. The dropping rate was controlled to maintain a low temperature. After the addition was complete, the mixture was stabilized in an ice bath for 30 minutes, then heated to room temperature and stirred for another 3 hours.

[0062] Post-processing: Stop stirring and filter to separate the resulting solid product. Wash the obtained solid repeatedly with distilled water to remove water-soluble impurities, filter under vacuum, and dry under vacuum.

[0063] Results: 14.41 g of a pinkish-white solid was obtained, with a calculated yield of 88%.

[0064] Example 3: Small-scale preparation of N,N,N-tert-pentanoyl-2,4,6-triaminotoluene This embodiment targets the tervaline group, which has significant steric hindrance, and uses tervaline anhydride for reaction to verify the ability of the process of the present invention to overcome steric hindrance effects.

[0065] Feeding and dissolving: Accurately weigh 5.00g of TAT raw material, dissolve it in 50.00mL of dichloromethane, and cool it to 0~10℃ in an ice bath.

[0066] Activation: Slowly add 14.75g of triethylamine, controlling the addition rate to prevent overheating, and stir at low temperature for 30 minutes after the addition is complete.

[0067] Acylation reaction: 27.19 g of pivalic anhydride was slowly added dropwise. Due to the steric hindrance of the pivalic acyl group, the reaction rate was relatively slow, requiring precise control of the dropping rate. After the addition was complete, the mixture was stirred in an ice bath for 30 minutes, then heated to room temperature, and the reaction time was extended to 5 hours to ensure complete reaction of the sterically hindered amino group at the para-methyl position.

[0068] Post-processing: After the reaction is complete, the mixture is filtered, and the filter cake is thoroughly washed with a large amount of distilled water and then dried under vacuum.

[0069] Results: 12.35 g of white solid was obtained, with a calculated yield of 87%. Using the DCM water washing process of this invention, the loss of organic solvent is less than 0.05 kg per kg of nucleating agent produced; while using the existing ethanol precipitation method (alcohol precipitation method), the loss of organic solvent (ethanol) is typically 0.5-1.0 kg. This process significantly reduces waste emissions and production costs.

[0070] Note: This result shows that even when faced with large sterically hindered groups, the acylation reagent + organic base system of the present invention can still maintain a very high reaction conversion rate, which is superior to the traditional transesterification method.

[0071] Process Comparison Analysis: Compared with the prior art (Example CN 113861058 B), the prior art uses methyl pivalate for transesterification, reacting at 80°C for 10 hours, with a product yield of only about 75%, and requires large-scale recrystallization with ethanol for purification. In contrast, this example uses pivalic anhydride at 0-10°C, shortening the reaction time to 5 hours, increasing the yield to 87%, and achieving a direct HPLC purity of 98.6%, without the need for recrystallization. This strongly demonstrates the significant advantages of the low-temperature process of this invention in constructing sterically hindered structures.

[0072] Example 4: Pilot-scale preparation of N,N,N-triacetyl-2,4,6-triaminotoluene To verify the industrialization potential of the process, a kilogram-scale scale-up experiment was conducted in a 5L reactor.

[0073] Feeding: Add 658.00g of TAT raw material and 6.50L of dichloromethane to a 5L double-walled glass reactor. Turn on the jacket cooling circulation and control the temperature inside the reactor to drop to 0~10℃. Stir until the TAT is completely dissolved.

[0074] Activation: 1941.47g of triethylamine was slowly added dropwise through a constant pressure feeding tank while closely monitoring the temperature inside the tank. After the addition was completed, the mixture was kept warm and stirred for 30 minutes.

[0075] Acylation reaction: Slowly add 1508.0g of acetyl chloride dropwise. Due to the large amount of material and high total heat release, the dropping rate must be strictly controlled and a cooling medium must be circulated to ensure that the reaction temperature remains below 10℃. After the addition is complete, raise the temperature to room temperature and react for 3.5 hours.

[0076] Post-processing: The reaction solution is discharged through the discharge valve, filtered, and the filter cake is rinsed with dichloromethane and washed with water, and then dried.

[0077] Results: A total of 1123.98g of dried product was obtained, with a single-batch yield of 89%. The scale-up effect did not negatively impact the yield, demonstrating good process stability.

[0078] Example 5: Pilot-scale preparation of N,N,N-tert-pentanoyl-2,4,6-triaminotoluene Feeding: Add 658.00g of TAT raw material and 6.50L of dichloromethane to a 5L reactor and cool to dissolve.

[0079] Activation: Slowly add 1941.47g of triethylamine and activate at low temperature for 30 minutes.

[0080] Acylation reaction: Slowly add 3578.0 g of pentaponic anhydride. Control the dropping rate and maintain the temperature inside the reactor at 0-10°C. After the addition is complete, raise the temperature to room temperature and react for 5 hours.

[0081] Post-processing: filtration, washing, drying.

[0082] Results: A total of 1662.27g of dried product was obtained, with a single-batch yield of 89%.

[0083] Note: This embodiment strongly demonstrates the industrial feasibility of the method of the present invention in preparing high-value, sterically hindered nucleating agents, with single-batch yields exceeding kilogram levels and maintaining high yield.

[0084] Structural characterization and quality control: To confirm the chemical structure and purity of the products prepared in the above embodiments, the present invention used nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT-IR) and high performance liquid chromatography (HPLC) for systematic characterization and analysis.

[0085] (I) Characterization of N,N,N-triacetyl-2,4,6-triaminotoluene The dried powder sample prepared in Example 1 was tested.

[0086] 1H NMR spectrum ( 1 HNMR analysis: such as Figure 1 As shown, the solvent is DMSO-d6. In the spectrum, a broad peak appears at δ 9.94 ppm, attributed to the active hydrogen (-NH-) on the amide group; a signal at δ 7.50 ppm is attributed to the proton (Ar-H) on the benzene ring; and a sharp single peak at δ 2.07 ppm is attributed to the methyl proton (-CH3) on the acetyl group. The integral ratio of each peak is approximately 3:2:9, consistent with the target molecular formula C. 13 H 17 The theoretical number of hydrogen atoms in N3O3 is completely consistent. No amino oxidation impurity peaks were observed, proving that no oxidation side reactions occurred during the reaction process.

[0087] Carbon nuclear magnetic resonance spectroscopy (NMR) 13 CNMR analysis: such as Figure 2 As shown, the characteristic peak at δ168.0 ppm is assigned to the carbonyl carbon (C=O) in the amide bond; the signals at δ136-137 ppm, 122 ppm, and 113 ppm are assigned to the carbons in the benzene ring framework; and the signal at δ23.8 ppm is assigned to the methyl carbon of the acetyl group. The spectrum showed no impurity peaks, confirming the skeletal structure of the target product.

[0088] FT-IR spectroscopy analysis: such as Figure 3 As shown, in the range of 3100-3500cm -1 The characteristic peak of NH stretching vibration appears in the range of 1630-1680 cm⁻¹. -1 A strong characteristic peak of C=O stretching vibration appears in the interval; at 2970 cm⁻¹ -1 The presence of CH characteristic peaks nearby further corroborates the formation of amide bonds.

[0089] Purity analysis (HPLC): Separation and detection were performed using a methanol / water mobile phase system on a C18 column. For example... Figure 4 As shown, the retention time of the main peak is approximately 1.5 min, and the peak shape is sharp and symmetrical. The purity of N,N,N-triacetyl-2,4,6-triaminotoluene was calculated to be 98.8% using the area normalization method.

[0090] (II) Characterization of N,N,N-tribenzoyl-2,4,6-triaminotoluene The sample prepared in Example 2 was used for testing.

[0091] 1H NMR spectrum ( 1 HNMR analysis: such as Figure 5 As shown, the signals at δ 10.40 ppm and 10.13 ppm are attributed to the imino protons (-NH-) of the three amide groups, and their significant low field shifts are due to the strong electron-withdrawing effect and conjugation effect of the benzoyl group; the multiplets in the range of δ 7.57-8.07 ppm are attributed to the protons on the benzene ring.

[0092] Carbon nuclear magnetic resonance spectroscopy (NMR) 13 CNMR analysis: such as Figure 6 As shown, the signal near δ166ppm is attributed to the carbonyl carbon of the benzoyl group (C=O); the multiple signals in the range of δ128-137ppm are attributed to carbon atoms of the benzene ring.

[0093] FT-IR spectroscopy analysis: such as Figure 7 As shown, NH (3100-3500 cm⁻¹) is clearly visible in the spectrum. -1 ) and C=O (1630-1680cm) -1 The characteristic absorption peaks confirmed the complete benzoylation reaction.

[0094] Purity analysis (HPLC): such as Figure 8 The retention time of the main peak shown is approximately 2.0 min. The purity of N,N,N-tribenzoyl-2,4,6-triaminotoluene was calculated to be 98.5%.

[0095] (III) Characterization of N,N,N-tert-pentanoyl-2,4,6-triaminotoluene The sample prepared in Example 3 was used for testing. The successful synthesis and high purity of this compound, due to the steric hindrance effect of the pivaloyl group, are the core manifestations of the advanced technology of this invention.

[0096] 1H NMR spectrum ( 1 HNMR analysis: such as Figure 9 As shown, the broad peaks at δ 9.26 ppm and 9.05 ppm correspond to the active hydrogens (-NH-) of the three amide groups; the peak at δ 7.45 ppm corresponds to the skeletal hydrogen of the benzene ring; and the multiplet at δ 1.11-1.27 ppm is attributed to the methyl protons (-C(CH3)3) on the pivaloyl group. The accurate integration ratio of the methyl protons proves that all three amino sites have been successfully substituted by the sterically hindered pivaloyl group.

[0097] Carbon nuclear magnetic resonance spectroscopy (NMR) 13 CNMR analysis: such as Figure 10 As shown, a characteristic peak for the pivaloyl carbonyl carbon (C=O) appears at δ175-180 ppm; the signal for the tertiary carbon atom is at δ38-40 ppm; and the signal for the methyl carbon is at δ25-30 ppm. The chemical shifts of each carbon atom perfectly match the theoretical structure.

[0098] FT-IR spectroscopy analysis: such as Figure 11 As shown, at 2970cm -1 (CH), 3100-3500cm -1 (NH) and 1630-1680cm- 1Strong characteristic peaks appeared at (C=O), confirming the generation of the target structure.

[0099] Purity analysis (HPLC): such as Figure 12 As shown, the retention time of the main peak is approximately 2.4 min. Calculations show that the purity of N,N,N-tert-pentanoyl-2,4,6-triaminotoluene is as high as 98.6%. This indicates that the low-temperature activation process of "acyl chloride + organic base" used in this invention effectively suppresses the formation of monosubstituted or disubstituted byproducts.

[0100] Application examples and performance tests: To verify the actual effect of the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent prepared in this invention in polymer modification, it was applied to the processing and molding of polypropylene (PP), and the optical properties, mechanical properties and crystallization thermodynamic properties of the material were tested.

[0101] Example 6: Preparation of polypropylene / nucleating agent composite material 1. Raw material pretreatment: The nucleating agent powder prepared in Examples 1-3 and polypropylene matrix (PP, grade HN7330B) were placed in a forced-air drying oven and dried at 120°C for 2 hours to remove moisture.

[0102] 2. Mixing: Weigh the nucleating agent and PP separately according to their mass fractions, so that the addition amounts of nucleating agent are 0.1%, 0.2%, and 0.5%, respectively. Put the materials into a high-speed mixer (550 r / min) and mix them evenly.

[0103] 3. Melt extrusion: The mixture is added to a twin-screw extruder for melt blending and granulation.

[0104] Extruder temperature zone settings: Zone 1 160℃, Zone 2 180℃, Zone 3 200℃, Zones 4 to 9 230℃, Zone 10 200℃, Die head 160℃.

[0105] Process parameters: main machine speed 150 r / min, discharge speed 30 kg / h. The extruded sample is cooled by air and then pelletized.

[0106] Injection Molding and Annealing: The granulated masterbatch is used in an injection molding machine to prepare standard test specimens (1.5 mm thick) and mechanical test strips. To eliminate internal stress and promote perfect crystallization, the prepared specimens are annealed at 160℃ for 2 hours.

[0107] Example 7: Optical Performance Testing (Haze and Transmittance) Optical properties of PP sheets with different amounts of nucleating agent were tested according to GB / T2410-2008 standard. For comparison, blank PP samples without nucleating agent were tested, and the results are shown in Table 1.

[0108] Table 1 Optical property data of PP modified with different nucleating agents

[0109] Results analysis: 1. Compared with blank PP, after adding the three nucleating agents prepared in this invention, the light transmittance of PP sheets increased from 79.5% to over 93%, and the haze decreased from 28.0% to below 15%, a reduction of nearly 50%, with an extremely significant effect on enhancing light transmittance.

[0110] 2. At the same addition level, the pivaloyl group exhibits the best optical modification effect. With an addition of only 0.2%, the transmittance reaches 94.5%, and the haze decreases to 13.9%. This is attributed to the larger steric hindrance and unique spatial configuration of the pivaloyl group, which enables the formation of a more stable supramolecular network in the PP melt, inducing the generation of smaller, more uniformly distributed grains, thereby minimizing light scattering.

[0111] Performance comparison with mainstream products on the market: To further verify the practical application value of the nucleating agent prepared in this invention, N,N,N-tert-pentanoyl-2,4,6-triaminotoluene prepared in Example 3 of this invention was injection molded and its performance was tested under the same process conditions (addition amount 0.2%, matrix resin PP HN7330B). The comparison results are shown in Table 2.

[0112] Table 2 shows the data for competing products on the market, based on measured values ​​under identical experimental conditions.

[0113] Example 8: Mechanical Property Testing The tensile and flexural strengths of the modified PP material were tested according to GB / T1040.2 and GB / T9341 standards. The test results are shown in Table 2.

[0114] Table 3 Mechanical property data of PP modified with different nucleating agents

[0115] Results Analysis: The nucleating agent prepared in this invention significantly improves the optical properties of PP while also endowing the material with excellent mechanical properties. Specifically, the pivaloyl nucleating agent, at an addition of 0.5%, exhibits a tensile strength of 26.1 MPa and a flexural strength of 47.8 MPa, demonstrating the best balance between stiffness and toughness. This indicates that the microcrystalline structure induced by the nucleating agent enhances the intermolecular forces.

[0116] Example 9: Crystallization Thermodynamic Screening (DSC Test) The crystallization peak temperature (Tc) of PP at different addition levels was determined using differential scanning calorimetry (DSC) to serve as a basis for rapid evaluation of nucleating agent activity. The test conditions were: nitrogen atmosphere, heating to eliminate thermal history, followed by cooling at a rate of 10℃ / min. The test results are shown in Table 3.

[0117] Table 4. Effect of different nucleating agents on the crystallization temperature (Tc) of PP

[0118] Results analysis: After adding the nucleating agent prepared in this invention, the crystallization temperature of PP increased to above 130℃, which is more than 10℃ higher than that of blank PP. Among them, the Tc of pivaloyl group reached as high as 133.2℃ at an addition amount of 1.0%, indicating that it has extremely high nucleating activity and can significantly shorten the molding cycle of PP.

[0119] V. Conclusion This invention successfully solves the technical problems of difficult synthesis, low purity, and complex post-processing of N,N,N-triacyl-2,4,6-triaminotoluene nucleating agents through a unique low-temperature acylation process of "acyl chloride / acid anhydride + organic base".

[0120] The process operates under mild reaction conditions (0-10℃), the solvent (dichloromethane) is easily recoverable, and post-treatment requires only water washing, making it environmentally friendly. The product yield is consistently between 87% and 90%, with a purity exceeding 98%, fully meeting the requirements for industrial production. The prepared nucleating agents (especially the pivaloyl nucleating agent) exhibit significant effects, increasing the transmittance of polypropylene to 94.5%, reducing haze to 13.9%, and raising the crystallization temperature to 133.2℃. Its excellent overall performance indicates broad market application prospects.

[0121] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing an N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent, characterized in that, Includes the following steps: Step S1: Dissolve 2,4,6-triaminotoluene in a haloalkanes solvent, and add an organic base as an activator under low temperature conditions to obtain an activated system; Step S2: Under low temperature and stirring conditions, add an acylation reagent dropwise to the activation system. The acylation reagent is selected from acid anhydrides or acyl chlorides. After the addition is complete, continue the reaction at room temperature until the reaction endpoint is reached. Step S3: After the reaction is completed, the reaction mixture is washed with water, separated, dried and the solvent is recovered to obtain the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent.

2. The method for preparing the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent according to claim 1, characterized in that, The halocarbon solvent is at least one of dichloromethane, chloroform, and 1,2-dichloroethane.

3. The method for preparing the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent according to claim 1 or 2, characterized in that, The organic base is at least one of triethylamine, pyridine, and potassium tert-butoxide; The molar ratio of the acylation reagent to 2,4,6-triaminotoluene is (3.2-4.2):

1.

4. The method for preparing the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent according to claim 1 or 2, characterized in that, In steps S1 and S2, the low-temperature condition is to control the temperature of the reaction system at 0 to 10°C; in step S2, the temperature of the reaction after the addition is completed is 20 to 30°C.

5. The method for preparing the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent according to any one of claims 1 to 4, characterized in that, Depending on the target product, the acylation reaction employs one of the following reaction systems: When preparing N,N,N-triacetyl-2,4,6-triaminotoluene, the acylation reagent is acetyl chloride, and the organic base is triethylamine; When preparing N,N,N-tribenzoyl-2,4,6-triaminotoluene, the acylation reagent is benzoic anhydride, and the organic base is triethylamine; When preparing N,N,N-terpentanoyl-2,4,6-triaminotoluene, the acylation reagent is terpentanoic anhydride, and the organic base is triethylamine.

6. A low-temperature amidation reaction apparatus for implementing the preparation method of the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent according to any one of claims 1-5, characterized in that, include: Reactor (1): It is equipped with an inner liner (12) and a jacket (13) wrapped around the outer layer, and a sealed reactor cover (11) is provided on the top; the reactor cover (11) is provided with multiple connection ports for material input and connection to other functional components; the bottom of the reactor (1) is provided with a discharge valve (14). The dropper assembly (4), stirring assembly (3) and condensing assembly (2) are set on the top reactor lid (11) of the reactor (1). The dropper assembly (4) is used to precisely control the dropper speed of the liquid acylation reagent at low temperature. The stirring assembly (3) is used to ensure uniform reaction contact of the materials. The condensing assembly (2) is used to condense and reflux the volatile halogenated hydrocarbon solvent. The reactor lid (11) is uniformly provided with a condenser assembly connection port (111), a liquid feed port (112), a solid feed port (113), a temperature measuring port (114), a stirring assembly connection port (115), and a dripping assembly connection port (116). The condenser assembly connection port (111) is used to install and connect the condenser assembly (2), the liquid feed port (112) is used to add liquid materials, the solid feed port (113) is used to add solid raw materials, the stirring assembly connection port (115) is used to install and connect the stirring assembly (3), and the dripping assembly connection port (116) is used to install and connect the dripping assembly (4).

7. An N,N,N-triacyl-2,4,6-triaminotoluene-based nucleating agent, characterized in that, It was prepared using the preparation method of the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent according to any one of claims 1-5.

8. The application of the N,N,N-triacyl-2,4,6-triaminotoluene nucleating agent according to claim 7 in the modification of polypropylene.

9. The application according to claim 8, characterized in that, The nucleating agent is added to polypropylene at a rate of 0.05% to 0.5% of the mass of polypropylene; the nucleating agent is used to increase the crystallization temperature and tensile strength of polypropylene and reduce the haze of polypropylene.

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