CN116903472A - Synthesis method of 2,3,5,6-tetramethyl-p-phenylenediamine - Google Patents

Abstract

The invention discloses a method for synthesizing 2,3,5,6-tetramethyl-p-phenylenediamine, which has the following steps: ① Using tetramethylbenzene as the starting material, first perform a halogenation reaction with a halogenating reagent to obtain 1, 4-dihalo-2,3,5,6-tetramethylbenzene; ②The 1,4-dihalo-2,3,5,6-tetramethylbenzene obtained in step ① is reacted with an ammonolysis reagent to obtain The target product is 2,3,5,6-tetramethyl-p-phenylenediamine. The synthesis method of the present invention not only avoids the three waste pollution problems existing in the existing methods, is more environmentally friendly and safer, but also avoids the problem of using expensive precious metal catalysts in the existing methods. The production cost is low, and the synthesis method is more environmentally friendly and safer. The invented synthesis method is simple to operate, has a high yield, and is suitable for industrial large-scale production.

Description

Synthesis method of 2,3,5,6-tetramethyl-p-phenylenediamine

Technical field

The invention belongs to the technical field of material intermediate synthesis, and specifically relates to a synthesis method of 2,3,5,6-tetramethyl-p-phenylenediamine.

Background technique

In the 1960s, various countries were researching, developing and utilizing polyimide, and listed it as one of the most promising engineering plastics in the 21st century. Because of its outstanding characteristics in performance and synthesis, whether as a structural material or As a functional material, its huge application prospects have been fully reflected.

The gas separation membrane is a selective membrane with large permeation flux and its mechanical strength can withstand a certain pressure difference. Asymmetric membranes and composite membranes are mostly used in industry. Gas separation membrane technology is a new technology that has developed rapidly in recent years. Different polymer membranes have different permeability and selectivity for different types of gas molecules. Therefore, certain gases can be selectively separated from a gas mixture, such as from It has wide application prospects in the fields of collecting oxygen from the air, recovering hydrogen from ammonia synthesis tail gas, and separating hydrogen and carbon monoxide from the mixed gas of petroleum cracking.

2,3,5,6-Tetramethyl-p-phenylenediamine, off-white solid, CAS number: 3102-87-2, molecular formula: C ₁₀ H ₁₆ N ₂ , molecular weight: 164.25, melting range: 150~155℃, Its structural formula is as follows:

.

2,3,5,6-tetramethyl-p-phenylenediamine is an important polyimide monomer. p-phenylenediamine type monomer is copolymerized with 6FDA. The more methyl groups introduced ortho to the amino group, the better the polymer. The greater the increase in free volume, the greater the reduction in gas permeability coefficient and selectivity. 2,3,5,6-Tetramethyl-p-phenylenediamine introduces four methyl groups into the amino group and uses it as a raw material to synthesize The permeability and selectivity of polyimide gas separation membranes have been greatly improved. As a special engineering material, polyimide polymer materials have been widely used in aviation, aerospace, microelectronics, nanometers, liquid crystals, Separation membrane, laser and other fields.

There are very few literature reports on the synthesis of 2,3,5,6-tetramethyl-p-phenylenediamine in the prior art. Only Document 1 discloses a catalytic hydrogenation reaction using dinitro-pyromylene as the starting material. Preparation of diaminotetramethylbenzene (i.e. 2,3,5,6-tetramethyl-p-phenylenediamine).

Regarding the above-mentioned starting material dinitro-pyromylene, Document 2 and Document 3 both disclose using pyromylene as the starting material and preparing dinitro-pyromylene through nitration reaction.

The shortcomings of the above-mentioned synthetic route of the prior art are: (1) the nitration reaction is not only less safe, but also produces a large amount of three wastes, which is extremely unfriendly to the environment and causes great corrosion to the equipment; (2) the catalytic hydrogenation reaction requires an expensive method precious metal catalysts, resulting in higher production costs.

Document 1: "Restricted Rotation in Aryl Amines. IX. Diaminodurene Derivatives", Roger Adams and Nils K. Nelson, Journal of the American Chemical Society, Volume 72, Issue 1, Pages 132-135, January 1950.

Document 2: United States patent document US2864871A, published on December 16, 1958.

Document 3: United States patent document US3153099A, published on October 13, 1964.

Contents of the invention

The purpose of the present invention is to solve the above problems and provide a 2,3,5,6-tetramethyl which is safer, more environmentally friendly, has lower production cost, and especially has higher reaction yield and product purity. Synthesis method of p-phenylenediamine.

The technical solution to achieve the object of the present invention is: a synthesis method of 2,3,5,6-tetramethyl-p-phenylenediamine, which has the following steps: ① Using pyromethylene tetramethylbenzene as the starting raw material, first perform halogenation with a halogenating reagent Reaction to obtain 1,4-dihalo-2,3,5,6-tetramethylbenzene; ②The 1,4-dihalo-2,3,5,6-tetramethylbenzene obtained in step ① is reacted with the ammonolysis reagent Aminolysis reaction gives the target product 2,3,5,6-tetramethyl-p-phenylenediamine.

The halogenating reagent described in the above step ① is chlorine gas, liquid bromine or elemental iodine; accordingly, 1,4-dichloro-2,3,5,6-tetramethylbenzene and 1,4-dibromo-2 are obtained respectively. 3,5,6-tetramethylbenzene and 1,4-diiodo-2,3,5,6-tetramethylbenzene.

The halogenation reaction temperature described in the above step ① is -10~-5°C, and the time is 4~6h.

The halogenation reaction described in the above step ① is carried out in a first solvent; the first solvent is one of dichloromethane, dichloroethane, chloroform, and carbon tetrachloride.

The halogenation reaction described in the above step ① is carried out in the presence of the first catalyst; the first catalyst is anhydrous aluminum chloride, and the dosage of the first catalyst is the 1,2,4,5- 0.5~1.5wt% of the weight of tetramethylbenzene.

The ammonolysis reagent described in the above step ② is ammonia water or liquid ammonia.

The ammonolysis reaction temperature described in the above step ② is 190 to 210°C, the ammonolysis reaction pressure is 4.0 to 5.0 MPa, and the ammonolysis reaction time is 14 to 16 hours.

The ammonolysis reaction described in the above step ② is carried out in the presence of a second catalyst; the second catalyst is a cuprous chloride + copper powder combined catalyst; the amount of cuprous chloride is 1, 2 to 3 wt% of the weight of 4-dihalo-2,3,5,6-tetramethylbenzene, and the amount of copper powder used is the 1,4-dihalo-2,3,5,6-tetramethylbenzene 0.3~1wt% of weight.

The aminolysis reaction described in the above step ② is carried out in the presence of N,N'-bis(2,4,6-trimethoxyphenyl)oxamide; the N,N'-bis(2, The amount of 4,6-trimethoxyphenyl)oxamide is 2 to 3 wt% of the weight of the 1,4-dihalo-2,3,5,6-tetramethylbenzene.

The invention has positive effects: the synthesis method of the invention not only avoids the three waste pollution problems existing in the existing methods, is more environmentally friendly and safer, but also avoids the problem of using expensive precious metal catalysts in the existing methods. The production cost is low, the synthesis method of the invention is simple to operate, has a high yield, and is suitable for industrial large-scale production.

Description of the drawings

Figure 1 is the DSC spectrum of the intermediate product prepared in step ① of Example 1:

Figure 2 is the LC-MS spectrum of the intermediate product prepared in step ① of Example 1:

Figure 3 is the DSC spectrum of the target product prepared in step ② of Example 1:

Figure 4 is the LC-MS spectrum of the target product prepared in step ② of Example 1:

Detailed ways

(Example 1)

The specific route of the synthesis method of 2,3,5,6-tetramethyl-p-phenylenediamine in this embodiment is as follows:

.

The specific method for synthesizing 2,3,5,6-tetramethyl-p-phenylenediamine in this embodiment is as follows:

①Add 33.56g (0.25mol) tetramethylbenzene and 369.16mL dichloroethane into a 500mL four-necked flask (hereinafter referred to as R1) connected to the thermowell, condenser tube and air tube (the air tube is connected to the absorption device) , then place R1 in a low-temperature tank, stir to dissolve and cool to -10~-5°C (colorless to light yellow transparent solution), then add 0.336g anhydrous aluminum chloride, and then control the temperature to -10~-5 ℃, chlorine gas is introduced (control one bubble every 1 to 2 seconds). At first, the solution changes from colorless to pink. As the reaction proceeds, the color gradually deepens, and then the color gradually becomes lighter and a large amount of white precipitate is produced. It stops after about 4 hours. Pour in chlorine gas and continue to stir for 1 hour. The reaction of monochloropylene tetramethylbenzene in the HPLC control is completed, and a suspended liquid is obtained.

Add 120mL of saturated NaHCO ₃ solution dropwise to R1 (more bubbles will be generated, control the dropping speed), stir for 0.5h after the dripping, let stand for 0.5h, separate the aqueous phase, and return the organic phase to R1; then add 90mL of purified solution to R1 water, stir for 0.5h, let stand for 0.5h, separate the water phase to obtain the organic phase, and return the organic phase to R1; then add 90mL of purified water to R1, stir and raise the temperature to 90°C, and evaporate the solvent dichloroethane under normal pressure ( As the amount of dichloroethane gradually decreases, a large amount of white solid precipitates from the system). The resulting suspension is stirred and cooled to 5-10°C, stirred for 0.5h, and filtered to obtain a wet product. The wet product is vacuum dried in an oven at 80°C for 14h. 47.95g of white intermediate product was obtained, the yield was 94.69%, and the HPLC purity was 98.37%.

The DSC spectrum of the intermediate product is shown in Figure 1. It can be seen from Figure 1 that the melting point of the intermediate product is 187.9~190.8°C. The LC-MS spectrum of the intermediate product is shown in Figure 2. It can be seen from Figure 2 that the intermediate product The molecular weight is 203.6, which is basically the same as 3,6-dichloro-1,2,4,5-tetramethylbenzene.

②Add 20.3g (0.1mol) of the intermediate product obtained in step ①, 121.8mL ammonia water (21%, 6V), and 0.55g of N,N'-bis(2,4,6-trimethoxy) into a 500mL pressurized reaction kettle. phenyl)oxamide, 0.51g cuprous chloride and 0.1g copper powder, replace with nitrogen three times, raise the temperature to 190℃, the pressure is 4.1~4.3MPa, stir and react for 16h, release the pressure and cool to 0~5℃, pump Filter to obtain a light yellow crude product.

Under nitrogen protection, add the above crude product to a 100mL four-necked flask containing 50.75mL n-butanol. Stir and heat it to 80~90°C. After dissolving, add 0.61g activated carbon, keep it warm for 1 hour, filter while it is hot, and transfer the mother liquor to another room. In a 500 mL four-necked flask, add 152.25 mL of anhydrous methanol dropwise under nitrogen protection, keep it at 0 to 5°C for 2 hours, filter with suction, rinse the filter cake with 10 mL of anhydrous methanol, and drain to obtain a wet product. The wet product is placed at 70°C. After vacuum drying in an oven for 14 hours, 13.80 g of the off-white target product was obtained, with a yield of 84.02% and an HPLC purity of 99.51%.

The DSC spectrum of the target product is shown in Figure 3. It can be seen from Figure 3 that the melting point of the target product is 155.0~156.5°C, which is basically consistent with 2,3,5,6-tetramethyl-p-phenylenediamine; the target product The LC-MS spectrum is shown in Figure 4. It can be seen from Figure 4 that the molecular weight of the target product is 164.2, which is basically consistent with 2,3,5,6-tetramethyl-p-phenylenediamine.

(Comparative Example 1)

The rest of this comparative example is the same as Example 1, except that N,N'-bis(2,4,6-trimethoxyphenyl)oxamide was not added in step ②, and 8.76g of the off-white target product was obtained. , the yield is 53.32%, and the HPLC purity is 97.85%.

(Example 2)

The specific route of the synthesis method of 2,3,5,6-tetramethyl-p-phenylenediamine in this embodiment is as follows:

.

The specific method for synthesizing 2,3,5,6-tetramethyl-p-phenylenediamine in this embodiment is as follows:

①Add 33.56g (0.25mol) tetramethylbenzene and 369.16mL dichloroethane into a 500mL four-necked flask (hereinafter referred to as R2) connected with a thermowell, condenser tube and air tube (the air tube is connected to the absorption device) , then place R2 in a low-temperature tank, stir to dissolve and cool to -10~-5°C (colorless to light yellow transparent solution), then add 0.336g (2.5mmol) anhydrous aluminum chloride, and then control the temperature - Pour in chlorine gas at 10~-5°C (control one bubble every 2 seconds). At first, the solution changes from colorless to pink. As the reaction proceeds, the color gradually deepens, and then the color gradually becomes lighter and a large amount of white precipitate is produced for about 6 hours. Afterwards, the flow of chlorine gas was stopped, and stirring was continued for 1 hour. The HPLC control medium-controlled reaction of monochloropylene tetramethylbenzene was completed, and a suspended liquid was obtained.

Add 120mL of saturated NaHCO ₃ solution dropwise to R2 (more bubbles will be generated, control the dropping speed), stir for 0.5h after the dripping, let stand for 0.5h, separate the aqueous phase, and return the organic phase to R2; then add 90mL of purified solution to R2 water, stir for 0.5h, let stand for 0.5h, separate the water phase to obtain the organic phase, and return the organic phase to R2; then add 90mL of purified water to R2, stir and raise the temperature to 90°C, and evaporate the solvent dichloroethane under normal pressure ( As the amount of dichloroethane gradually decreases, a large amount of white solid precipitates from the system). The resulting suspension is stirred and cooled to 5-10°C, stirred for 0.5h, and filtered to obtain a wet product. The wet product is vacuum dried in an oven at 80°C for 14h. 47.26g of white intermediate product was obtained, the yield was 93.33%, and the HPLC purity was 98.29%.

②Add 20.3g (0.1mol) of the intermediate product obtained in step ①, 121.8mL ammonia water (21%, 6V), and 0.55g of N,N'-bis(2,4,6-trimethoxy) into a 500mL pressurized reaction kettle. phenyl)oxamide, 0.51g cuprous chloride and 0.1g copper powder, replace with nitrogen three times, raise the temperature to 210℃, the pressure is 4.7~4.8MPa, stir and react for 14h, release the pressure and cool to 0~5℃, pump Filter to obtain a light yellow crude product.

Under nitrogen protection, add the above crude product to a 100mL four-necked flask containing 50.75mL n-butanol. Stir and heat to 80-90°C to dissolve. Add 0.61g activated carbon, keep it warm for 1 hour, filter while hot, and transfer the mother liquor to 500mL four-necked flask. In a flask, add 152.25mL of anhydrous methanol dropwise under nitrogen protection, keep it at 0-5°C for 2 hours, filter with suction, rinse the filter cake with 10mL of anhydrous methanol, and dry it to obtain a wet product. The wet product is placed in a 70°C oven under vacuum After drying for 14 hours, 13.84g of the off-white target product was obtained, with a yield of 84.26% and an HPLC purity of 99.67%.

(Example 3)

The specific route of the synthesis method of 2,3,5,6-tetramethyl-p-phenylenediamine in this embodiment is as follows:

.

The specific method for synthesizing 2,3,5,6-tetramethyl-p-phenylenediamine in this embodiment is as follows:

①Add 33.56g (0.25mol) tetramethylbenzene and 369.16mL dichloroethane into a 500mL four-necked flask (hereinafter referred to as R3) connected with a thermometer tube, a condenser tube and a constant pressure dropping funnel, and then place R3 In a low-temperature tank, stir to dissolve and cool to -10~-5℃ (colorless to light yellow transparent solution), then add 0.336g anhydrous aluminum chloride, then add 84.0g dropwise at -10~-5℃ (0.525mol) liquid bromine (control one drop every 2 to 3 seconds). At first, the solution changed from colorless to reddish brown. As the reaction progressed, the color gradually deepened, and then the color gradually became lighter and a large amount of loose precipitate was produced. After about 5 hours After the dripping is completed, stirring is continued for 1 hour. The reaction of monobrominated tetramethylbenzene in the HPLC control is completed, and a suspended liquid is obtained.

Add 120mL of saturated NaHCO ₃ solution dropwise to R3 (more bubbles will be generated, control the dropping speed), stir for 0.5h after the dripping, let stand for 0.5h, separate the aqueous phase, and return the organic phase to R3; then add 90mL of purified solution to R3 water, stir for 0.5h, let stand for 0.5h, separate the water phase to obtain the organic phase, and return the organic phase to R3; then add 90mL of purified water to R3, stir and raise the temperature to 90°C, and evaporate the solvent dichloroethane under normal pressure ( As the amount of dichloroethane gradually decreases, a large amount of solid precipitation precipitates from the system). The resulting suspension is stirred and cooled to 5-10°C, stirred for 0.5h, and filtered to obtain a wet product. The wet product is vacuum dried in an oven at 80°C for 14h. 68.13g of crystalline powdery intermediate product was obtained, with a yield of 93.54% and a purity of 98.03%.

②Add 29.2g (0.1mol) of the intermediate product obtained in step ①, 175.2mL ammonia water (21%, 6V), and 0.55g of N,N'-bis(2,4,6-trimethoxy) into a 500mL pressurized reaction kettle. phenyl)oxamide, 0.74g cuprous chloride and 0.15g copper powder, replace with nitrogen three times, raise the temperature to 210℃, the pressure is 4.7~4.8MPa, stir for 16h, release the pressure and cool to 0~5℃, pump Filter to obtain a light yellow crude product.

Under nitrogen protection, add the above crude product to a 100mL four-necked flask containing 50.75mL n-butanol. Stir and heat to 80-90°C to dissolve. Add 0.61g activated carbon, keep it warm for 1 hour, filter while hot, and transfer the mother liquor to 500mL four-necked flask. In a flask, add 152.25mL of anhydrous methanol dropwise under nitrogen protection, keep it at 0-5°C for 2 hours, filter with suction, rinse the filter cake with 10mL of anhydrous methanol, and dry it to obtain a wet product. The wet product is placed in a 70°C oven under vacuum After drying for 14 hours, 13.78g of the off-white target product was obtained, with a yield of 83.90% and an HPLC purity of 99.64%.

Claims (10)

1. The synthesis method of the 2,3,5, 6-tetramethyl-p-phenylenediamine is characterized by comprising the following steps of:

(1) taking durene as a starting material, and carrying out halogenation reaction with a halogenating reagent to obtain 1, 4-dihalogenated-2, 3,5, 6-durene;

(2) carrying out ammonolysis reaction on the 1, 4-dihalogenated-2, 3,5, 6-tetramethylene obtained in the step (1) and an ammonolysis reagent to obtain a target product 2,3,5, 6-tetramethylp-phenylenediamine.

2. The method for synthesizing 2,3,5, 6-tetramethyl-p-phenylenediamine according to claim 1, wherein: the halogenating agent in the step (1) is chlorine, liquid bromine or elemental iodine.

3. The method for synthesizing 2,3,5, 6-tetramethyl-p-phenylenediamine according to claim 1, wherein: the halogenation reaction temperature in the step (1) is-10 to-5 ℃ and the time is 4 to 6 hours.

4. The method for synthesizing 2,3,5, 6-tetramethyl-p-phenylenediamine according to claim 1, wherein: the halogenation reaction described in the above step (1) is carried out in a first solvent; the first solvent is one of dichloromethane, dichloroethane, chloroform and carbon tetrachloride.

5. The method for synthesizing 2,3,5, 6-tetramethyl-p-phenylenediamine according to claim 1, wherein: the halogenation reaction described in step (1) above is carried out in the presence of a first catalyst; the first catalyst is anhydrous aluminum chloride, and the dosage of the first catalyst is 0.5-1.5 wt% of the weight of the 1,2,4, 5-tetramethylbenzene.

6. The method for synthesizing 2,3,5, 6-tetramethyl-p-phenylenediamine according to claim 1, wherein: the ammonolysis reagent in the step (2) is ammonia water or liquid ammonia.

7. The method for synthesizing 2,3,5, 6-tetramethyl-p-phenylenediamine according to claim 1, wherein: the ammonolysis reaction temperature in the step (2) is 190-210 ℃, the ammonolysis reaction pressure is 4.0-5.0 MPa, and the ammonolysis reaction time is 14-16 h.

8. The method for synthesizing 2,3,5, 6-tetramethyl-p-phenylenediamine according to claim 1, wherein: the ammonolysis reaction in the step (2) is carried out in the presence of a second catalyst; the second catalyst is a cuprous chloride+copper powder combined catalyst.

9. The method for synthesizing 2,3,5, 6-tetramethyl-p-phenylenediamine according to claim 8, wherein: the cuprous chloride is used in an amount of 2-3 wt% of the 1, 4-dihalogenated-2, 3,5, 6-tetramethylbenzene, and the copper powder is used in an amount of 0.3-1 wt% of the 1, 4-dihalogenated-2, 3,5, 6-tetramethylbenzene.

10. The process for the synthesis of 2,3,5, 6-tetramethyl-p-phenylenediamine according to any of claims 1 to 9, characterized in that: the ammonolysis reaction in the step (2) is carried out in the presence of N, N' -bis (2, 4, 6-trimethoxyphenyl) oxamide; the amount of the N, N' -bis (2, 4, 6-trimethoxyphenyl) oxamide is 2 to 3wt% of the weight of the 1, 4-dihalo-2, 3,5, 6-tetramethylbenzene.