Preparation method of N, N '-bis (2, 2, 6, 6-tetramethyl-4-piperidyl)-1, 3-benzenedicarboxamide

Abstract

The invention discloses a preparation method of N, N '-bis (2, 2, 6, 6-tetramethyl-4-piperidyl)-1, 3-benzene dicarboxamide, which comprises the following steps: mixing isophthalonitrile, 2, 2, 6, 6-tetramethylpiperidinol and water, adding a catalyst, filling inert gas, and heating and stirring for reaction to obtain N, N'-bis (2, 2, 6, 6-tetramethyl-4-piperidyl)-1, 3-benzene dicarboxamide; the molar ratio of the isophthalonitrile to the 2, 2, 6, 6-tetramethyl piperidinol is 1: (2.0-2.3), and the molar ratio of the isophthalonitrile to the 2, 2, 6, 6-tetramethyl The mass ratio of the isophthalonitrile to the catalyst is 1: (0.005-0.05); the catalyst is an acidic catalyst; the heating temperature is 80-150 DEG C, and the reaction time is 4-8 hours. The N, N '-bis (2, 2, 6, 6-tetramethyl-4-piperidinyl)-1, 3-benzene dicarboxamide is prepared by taking isophthalonitrile and 2, 2, 6, 6-tetramethylpiperidinol as raw materials, the synthesis method is carried out under the condition of an aqueous solution, the generation of organic three wastes is remarkably reduced, the operation is simple, the requirement on reaction conditions is low, and the method is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of amide light stabilizer synthesis, and specifically relates to a method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide. Background Art

[0002] N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarboxylate is a light stabilizer suitable for polymer materials such as polyethylene, polypropylene, polyvinyl chloride, polyurethane, polyamide, etc. It can be used alone or in combination with benzophenone ultraviolet absorbers or phosphite antioxidants, and has a good synergistic effect. Therefore, N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarboxylate is widely used as an important light stabilizer.

[0003] In the prior art, N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide is usually prepared using 2,2,6,6-tetramethyl-4-aminopiperidine and isophthaloyl chloride or isophthalic acid diester as reaction raw materials, such as CN105481759, CN103508938, US20060199963, WO2004016591 and US2018194727.

[0004] However, when isophthalic acid chloride is used as a raw material, the acyl chloride is highly active and easy to react, but the disadvantage is that the acyl chloride is easily hydrolyzed, and the reaction needs to be carried out under anhydrous conditions, the reaction conditions are harsh, and sodium hydroxide is needed for neutralization, which produces a large amount of wastewater and solid waste sodium chloride, which is very polluting to the environment. When isophthalic acid diester is used as a raw material, two equivalents of alcohol compounds are produced, which are very soluble in water, resulting in a high VOC in the wastewater during the post-treatment washing process.

[0005] Therefore, the present invention provides a method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide in view of the deficiencies in the prior art, which can reduce the generation of three organic wastes, reduce environmental pollution, and has the advantages of simple operation, green process, high product yield, high purity and high atom economy.

[0007] The present invention adopts the following technical solutions: The invention provides a preparation method of N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide. The preparation method comprises the following steps: mixing isophthalonitrile, 2,2,6,6-tetramethylpiperidinol and a certain amount of water, adding a catalyst, charging an inert gas, heating and stirring to react, adding deionized water after the reaction is completed, and cooling to room temperature to obtain N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0008]

[0009] As a further preferred embodiment of the present invention, the molar ratio of isophthalonitrile to 2,2,6,6-tetramethylpiperidinol is 1:(2.0-2.3).

[0010] As a further preferred embodiment of the present invention, the molar ratio of isophthalonitrile to 2,2,6,6-tetramethylpiperidinol is 1:(2.0-2.1).

[0011] As a further preferred embodiment of the present invention, the mass ratio of isophthalonitrile to catalyst is 1:(0.005-0.05).

[0012] As a further preferred embodiment of the present invention, the mass ratio of isophthalonitrile to the catalyst is 1:(0.018-0.023).

[0013] As a further preferred embodiment of the present invention, the mass ratio of isophthalonitrile to water is 1:(0.1-2.0).

[0014] As a further preferred embodiment of the present invention, the catalyst is an acidic catalyst, specifically at least one of sulfuric acid, formic acid and acetic acid.

[0015] As a further preferred embodiment of the present invention, the heating temperature is 80-150° C. and the reaction time is 4-8 hours.

[0016] As a further preferred embodiment of the present invention, the heating temperature is 85-150° C. and the reaction time is 5-6 hours.

[0017] As a further preferred embodiment of the present invention, the inert gas is nitrogen.

[0018] As a further preferred embodiment of the present invention, after the reaction is completed, water is added to the reaction system and the mixture is stirred and cooled to room temperature, solid-liquid separation is performed, and the obtained solid is washed with water to obtain N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

[0019] As a further preferred embodiment of the present invention, the mass ratio of the water added again to isophthalonitrile is (0.5-1.5):1.

[0020] Beneficial effects of the present invention: (1) The present invention uses isophthalonitrile and 2,2,6,6-tetramethylpiperidinol as raw materials, adds a catalyst and heats the reaction to prepare N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide, does not require an organic solvent, significantly reduces the generation of organic waste gas, organic solid waste and organic wastewater, and greatly reduces the generation of three organic wastes; (2) The present invention has reasonable design, simple operation, low requirements on reaction conditions, and is suitable for industrial production. The target product HLPC content can reach more than 99.8% and the yield can reach 95%. It has high atom economy and uses green and environmentally friendly solvents.

[0021] (2) The present invention has reasonable design, simple operation, low requirements on reaction conditions, and is suitable for industrial production. The target product HLPC content can reach more than 99.8% and the yield can reach 95%. It has high atom economy and uses green and environmentally friendly solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The gas chromatography analysis spectrum of the product prepared in Example 1 of the present invention; Figure 2 This is the hydrogen NMR spectrum of the product prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] Example 1 The embodiment of the present invention provides a method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide, the preparation method comprising: Step 1, take 50.0 g (0.39 mol) of isophthalonitrile and 122.7 g (0.78 mol) of 2,2,6,6-tetramethylpiperidinol, add them into a 1 L reactor, add 1.0 g of sulfuric acid as a catalyst and 50 g of pure water, fill with nitrogen, then stir and heat, keep the temperature at 85°C for 4 h; Step 2: After the reaction is completed, add 50 g of water to the reaction system and stir and cool to room temperature, separate the solid and liquid, rinse the solid with water, and dry to obtain 164 g of the target compound N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide. The gas chromatography analysis of the product prepared in this example is shown in Figure 1 , H NMR spectrum analysis see Figure 2 The yield calculated based on isophthalonitrile is 89%, and the content detected by HPLC is greater than 99%.

[0025] Example 2 The embodiment of the present invention provides a method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide, the preparation method comprising: Step 1, take 60.0 g (0.468 mol) of isophthalonitrile and 151 g (0.960 mol) of 2,2,6,6-tetramethylpiperidinol, add them into a 1 L reactor, add 1.1 g of sulfuric acid as a catalyst and 90 g of pure water, fill with nitrogen, then stir and heat, keep the temperature at 85°C for 4 h; Step 2: After the reaction is completed, add 50 g of water to the reaction system and stir and cool to room temperature, separate the solid and liquid, rinse the solid with water, and dry to obtain 197 g of the target compound N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide. The yield is 95.2% based on isophthalonitrile, and the content is greater than 99% when detected by HPLC.

[0026] Example 3 The embodiment of the present invention provides a method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide, the preparation method comprising: Step 1, take 65.0 g (0.507 mol) of isophthalonitrile and 161 g (1.02 mol) of 2,2,6,6-tetramethylpiperidinol, add them into a 1 L reactor, add 1.5 g of acetic acid as a catalyst and 120 g of pure water, fill with nitrogen, then stir and heat, keep the temperature at 150°C for 5 h; Step 2: After the reaction is completed, add 50 g of water to the reaction system and stir and cool to room temperature, separate the solid and liquid, rinse the solid with water, and dry to obtain 213 g of the target compound N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide. The yield is 95.1% based on isophthalonitrile, and the content is greater than 99% when detected by HPLC.

[0027] Example 4 The embodiment of the present invention provides a method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide, the preparation method comprising: Step 1, take 85.0 g (0.663 mol) of isophthalonitrile and 161 g (1.39 mol) of 2,2,6,6-tetramethylpiperidinol, add them into a 1 L reactor, add 1.8 g of acetic acid as a catalyst and 170 g of pure water, fill with nitrogen, then stir and heat, and keep the temperature at 100°C for 5.5 h; Step 2: After the reaction is completed, 50 g of water is added to the reaction system and stirred and cooled to room temperature, solid-liquid separation is performed, and the obtained solid is washed with water and dried to obtain 279.8 g of N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide. The yield is 95.3% calculated based on isophthalonitrile, and the content detected by HPLC is greater than 99%.

[0028] Example 5 The embodiment of the present invention provides a method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide, the preparation method comprising: Step 1, take 100.0 g (0.780 mol) of isophthalonitrile and 252 g (1.60 mol) of 2,2,6,6-tetramethylpiperidinol, add them into a 1 L reactor, add 1.8 g of formic acid as a catalyst and 150 g of pure water, fill with nitrogen, then stir and heat, keep the temperature at 100°C for 5 h; Step 2: After the reaction is completed, 50 g of water is added to the reaction system and stirred and cooled to room temperature, solid-liquid separation is performed, and the obtained solid is washed with water and dried to obtain 329.8 g of the target compound N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide. The yield is 95.3% calculated based on isophthalonitrile, and the content detected by HPLC is greater than 99%.

[0029] Example 6 The embodiment of the present invention provides a method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide, the preparation method comprising: Step 1: Take 100.0 g (0.780 mol) of isophthalonitrile and 252 g (1.60 mol) of 2,2,6,6-tetramethylpiperidinol, add them into a 1 L reactor, add a catalyst, add 100 g of 1M formic acid, fill with nitrogen, then stir and heat, and keep the temperature at 100°C for 5.5 hours; Step 2: After the reaction is completed, add 50 g of water to the reaction system and stir and cool to room temperature, separate the solid and liquid, rinse the solid with water, and dry to obtain 330.1 g of the target compound N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide. The yield is 95.6% based on isophthalonitrile, and the content is greater than 99% by HPLC.

[0030] The invention uses isophthalonitrile and 2,2,6,6-tetramethylpiperidinol as raw materials, adds a catalyst for heating reaction to prepare N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide, does not require an organic solvent, significantly reduces the generation of organic waste gas and waste water, and can greatly reduce the generation of three wastes; the operation is simple, the requirements for reaction conditions are low, and it is suitable for industrial production. The method can be used to obtain a target product with an HLPC content of more than 99%, a yield of up to 95%, and high atom economy.

[0031] The above are only preferred implementations of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide, characterized in that: The preparation method is: Mix isophthalonitrile, 2,2,6,6-tetramethylpiperidinol and water, add a catalyst, fill with inert gas, heat and stir to react, add deionized water after the reaction is completed, and cool to room temperature to obtain N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

2. The method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide according to claim 1, characterized in that: The molar ratio of isophthalonitrile to 2,2,6,6-tetramethylpiperidinol is 1:(2.0-2.3).

3. The method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide according to claim 1, characterized in that: The mass ratio of the isophthalonitrile to the catalyst is 1:(0.005-0.05).

4. The method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide according to claim 1, characterized in that: The mass ratio of isophthalonitrile to water is 1:(0.1-2.0).

5. The method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide according to claim 1, characterized in that: The catalyst is an acidic catalyst, specifically at least one of sulfuric acid, formic acid and acetic acid.

6. The method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide according to claim 1, characterized in that: The heating temperature is 80-150° C., and the reaction time is 4-8 hours.

7. The method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide according to claim 1, characterized in that: The inert gas is nitrogen.

8. The method for preparing N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide according to claim 1, characterized in that: After the reaction is completed, deionized water is added to the reaction system and the mixture is stirred and cooled to room temperature, followed by solid-liquid separation, and the obtained solid is washed with water to obtain N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarbamide.

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