Novel preparation method of dimethyl diethyl ammonium chloride

Abstract

The invention discloses a novel preparation method of dimethyl diethyl ammonium chloride. The method comprises the following specific steps: adding diethylamine hydrochloride, dimethyl carbonate and a reaction solvent into a pressure reaction kettle, reacting at 90-180 DEG C for 8-24 hours, cooling to release gas produced by the reaction when the pressure of the reaction kettle reaches a certain value during the reaction, and concentrating, crystallizing, filtering and drying the reaction liquid after the reaction is finished, thereby obtaining the methylation and quaternization of amines. The high-purity dimethyl diethyl ammonium chloride is obtained. According to the method, expensive reagents N, N-dimethylethylamine and N, N-diethyl methylamine are not used, meanwhile, reagents chloroethane and chloromethane which are high in harm and toxicity are also not used, the problem that the pressure of a reaction kettle is too high in the methylation process of the reaction is solved by releasing gas generated in the reaction process, the obtained product is high in purity, the yield is high, and the method is suitable for industrial production. And the halogen ion and metal ion residues are very low. The novel method for preparing dimethyl diethyl ammonium chloride is green, safe, low in cost and high in product quality.

Description

Technical Field

[0001] The present invention relates to a novel method for preparing a quaternary ammonium salt phase transfer catalyst, and more particularly to a novel method for preparing dimethyldiethylammonium chloride. Background Art

[0002] With the rapid development of science and technology, researchers have discovered that the advantages of quaternary ammonium phase transfer catalysts in organic synthesis, petrochemicals, environmental protection, sewage treatment, papermaking and textiles are becoming increasingly apparent. Long-chain quaternary ammonium salts, as non-oxidizing fungicides, have advantages over traditional fungicides, such as low toxicity, broad spectrum and high efficiency. Short-chain quaternary ammonium salts have played a significant role in chemical synthesis, electronic chemistry, materials chemistry, petrochemicals, papermaking and textiles. In recent years, some researchers have also converted quaternary ammonium halide anions into HCOO-, OAc-, NO3-, OTF-, BF4-, PF6-, isobutyrate, maleate, succinate, etc. through chemical reactions, thereby obtaining a large number of quaternary ammonium ionic liquids. These ionic liquids have found great applications in cellulose extraction, textile processing, plastic degradation, and other fields, promoting the rapid development of green chemistry. Dimethyldiethylammonium chloride (DMDAC) is a widely used product with distinct advantages in various fields. High-purity, low-halogen, and low-metal ion residual products are particularly used in the production of high-end electronic chemicals. However, most commercially available products do not meet these requirements, resulting in high-quality DMDAC being very expensive. Therefore, it would be valuable to develop a new technology for producing high-quality DMDAC that is simple, safe, and adaptable to large-scale production using low-cost, low-toxic raw materials.

[0003] At present, there are two most commonly used methods for synthesizing dimethyldiethylammonium chloride: The first method is to first methylate diethylamine to produce N,N-diethylmethylamine, or directly purchase N,N-diethylmethylamine and then react it with methyl chloride to obtain dimethyldiethylammonium chloride. However, the problem with this method is that diethylamine is highly toxic, corrosive, and has an amine odor, making it unsuitable as a direct raw material for quaternary ammonium salt production. N,N-diethylmethylamine is expensive, which will lead to excessively high final production costs.

[0004] The second method is to use N,N-dimethylethylamine to react with ethyl chloride to obtain dimethyldiethylammonium chloride. However, N,N-dimethylethylamine has a low boiling point, is flammable, volatile, highly toxic, has a strong ammonia smell, and is expensive. From the perspective of chemical experiments and economics, it is very unsuitable to use N,N-dimethylethylamine to produce dimethyldiethylammonium chloride.

[0005] Reference Zheng, Zhuo Qun, Jie Wang, Ting Hua Wu, and Xiao Ping Zhou. 2007. “Alkylation of Ammonium Salts Catalyzed by Imidazolium‐Based Ionic Liquid Catalysts.” Advanced Synthesis&Catalysis 349 (7): 1095–1101 discloses a method for producing different types of quaternary ammonium salts using dimethyl carbonate and ammonium salt as raw materials and the ionic liquid 1-ethyl-3-methylimidazolium bromide [Emim]Br as the optimal catalyst. However, because [Emim]Br itself is also an ionic liquid quaternary ammonium salt catalyst, it is difficult to completely separate it from the product, which inevitably reduces the purity of the product.

[0006] Patent CN101245019B uses dimethyl carbonate and ammonium salt to react and synthesize different kinds of quaternary ammonium salts without using any catalyst and solvent. However, the dimethyl carbonate and ammonium salt molar ratio used in this patent is too low, which can cause the product to not react completely. The product purity is insufficient, and not using solvent can also cause the reaction product to stick in the reactor, which cannot be collected, and the product yield reduces. In addition, this patent reaction temperature is higher, which can make the dimethyl carbonate part pyrolysis, and the reactor pressure is too high, which can threaten the safety of the experimenter. Moreover, too high a reaction temperature and pressure can cause this method to have too high a requirement on reaction equipment when industrial amplification is carried out, and it is impossible to move from the laboratory to large-scale production, thus creating economic value.

[0007] In summary, the commonly used methods for preparing dimethyldiethylammonium chloride have the following problems: (1) the unavoidable use of the toxic and corrosive raw material diethylamine, and (2) the use of expensive raw materials N,N-diethylmethylamine and N,N-dimethylethylamine. The preparation method described in the literature using dimethyl carbonate and an ammonium salt in the presence of a catalyst has the following problems: (1) low product quality, (2) low product yield, and (3) inability to scale up industrial production. Summary of the Invention

[0008] The invention overcomes various problems existing in common methods for synthesizing dimethyldiethylammonium chloride, and develops a new method for preparing dimethyldiethylammonium chloride that can be industrially produced, is green and safe, has low cost, and has high product quality.

[0009] In order to achieve the above object, the method of the present invention is conceived as follows: using dimethyl carbonate as a methylating agent, connecting two methyl groups at the amino position of diethylamine hydrochloride, using an appropriate amount of solvent methanol to lower the reaction temperature, and using a cooling and venting method to reduce the pressure of the reactor.

[0010] The technical solution of the present invention comprises the following steps: A new method for efficiently preparing high-purity dimethyldiethylammonium chloride comprises the following steps: (1) Add a certain amount of diethylamine hydrochloride and dimethyl carbonate to the pressure reactor, then add an appropriate amount of solvent, close the pressure reactor, purge with nitrogen to remove the air, start stirring and heat, when the pressure in the reactor reaches a certain value, cool it with cold water, release carbon dioxide gas when the temperature drops to room temperature, and then continue stirring and heating to react.

[0011] (2) After the reaction is completed, the reaction liquid is concentrated, crystallized, filtered, and dried to obtain high-purity dimethyldiethylammonium chloride.

[0012] The reaction solvent in step (1) is methanol, dimethyl carbonate, ethanol, isopropanol, ethylene glycol, propylene glycol, tert-butanol, n-pentanol, acetonitrile, acetone, toluene, etc., preferably methanol.

[0013] The reaction temperature in step (1) is 90-180°C, preferably 120-140°C.

[0014] The reaction pressure in step (1) is 0.1-4 MPa, preferably 0.1-2.5 MPa.

[0015] The reaction time of step (1) is 8-24 hours, preferably 10-16 hours.

[0016] In step (1), the molar ratio of diethylamine hydrochloride to dimethyl carbonate as the reaction raw materials is 1:(2.0-4.0), preferably 1:(2.1-3.0).

[0017] The reaction in step (1) may or may not use a small amount of quaternary ammonium salt ionic liquid as a catalyst, and preferably does not use any co-catalyst.

[0018] The reaction in step (1) releases gas 1-3 times, and the specific number is determined by the size of the reaction vessel, the amount of reactants added, the ratio of reactants, and the set gas release pressure.

[0019] After the reaction in step (2) is completed, high-purity, low-halogen ion and metal ion dimethyldiethylammonium chloride product can be obtained without special treatment such as recrystallization, ion adsorption and the like. The dimethyldiethylammonium chloride prepared by the above steps (1) and (2) has the following advantages: (1) The product purity is greater than 99%, the product molar yield is greater than 97%, the halogen content is less than 20ppm, and the metal ion content is less than 30ppm. The produced products can be used in the field of high-end electronic chemistry.

[0020] (2) The solvent methanol can be reused, and the excess molar amount of dimethyl carbonate required for the reaction can be used in the next batch with almost no loss.

[0021] (3) It avoids the use of toxic, harmful or expensive reagents, and the products produced have greater price advantages.

[0022] (4) The process is simple, the requirements for production equipment are not high, and the product is easier to put into large-scale production. DETAILED DESCRIPTION

[0023] The present invention will be described in more detail below with reference to the examples, but the examples do not limit the scope of protection of the present invention. Example 1

[0024] Weigh 64g of diethylamine hydrochloride, 135g of dimethyl carbonate, and 60g of methanol, and add them sequentially into a 1000ml pressure reactor. Close the pressure reactor, purge with nitrogen for 5-10min, and heat to 130°C with stirring. Keep the reaction for about 4h. When the pressure in the pressure reactor reaches about 2.5mpa, pass cold water to reduce the temperature of the reactor to room temperature and release carbon dioxide gas. Then close the pressure reactor, heat to 130°C with stirring, and keep the reaction for 10h, during which the maximum pressure of the reactor is 1.5mpa. After the reaction, concentrate the reaction solution, crystallize, filter, and dry to obtain 81.0g of dimethyldiethylammonium chloride, with a product yield of 98.1%. Quantitative analysis shows a product content of 99.7%, 0.05% ammonium salt, 0.2% water, 10ppm residual bromide ions, 12ppm residual sodium ions, 8ppm residual potassium ions, and 16ppm residual iron ions. Example 2

[0025] Weigh 64g of diethylamine hydrochloride, 135g of dimethyl carbonate, and 30g of methanol, and add them sequentially into a 1000ml pressure reactor. Close the pressure reactor, purge with nitrogen for 5-10min, and heat to 130°C with stirring. Keep the reaction for about 4h. When the pressure in the pressure reactor reaches about 2.5mpa, pass cold water to reduce the reactor temperature to room temperature and release carbon dioxide gas. Then close the pressure reactor, heat to 130°C with stirring, and keep the reaction for 10h, during which the maximum pressure of the reactor is 1.45mpa. After the reaction, concentrate the reaction solution, crystallize, filter, and dry to obtain 80.4g of dimethyldiethylammonium chloride, with a product yield of 97.4%. Quantitative analysis shows a product content of 99.4%, ammonium salt of 0.15%, water of 0.4%, residual bromide ions of 14ppm, residual sodium ions of 15ppm, residual potassium ions of 10ppm, and residual iron ions of 21ppm. Example 3

[0026] Weigh 64g of diethylamine hydrochloride, 135g of dimethyl carbonate, and 10g of methanol, and add them sequentially into a 1000ml pressure reactor. Close the pressure reactor, purge with nitrogen for 5-10min, and heat to 130°C with stirring. Keep the reaction for about 4h. When the pressure in the pressure reactor reaches about 2.5mpa, pass cold water to reduce the temperature of the reactor to room temperature and release carbon dioxide gas. Then close the pressure reactor, heat to 130°C with stirring, and keep the reaction for 10h, during which the maximum pressure of the reactor is 1.4mpa. After the reaction, concentrate the reaction solution, crystallize, filter, and dry to obtain 75.2g of dimethyldiethylammonium chloride, with a product yield of 91.1%. Quantitative analysis shows a product content of 98.7%, 0.8% ammonium salt, 0.4% water, 28ppm residual bromide ions, 35ppm residual sodium ions, 32ppm residual potassium ions, and 55ppm residual iron ions. Example 4

[0027] Weigh 64g of diethylamine hydrochloride, 135g of dimethyl carbonate, and 100g of methanol, and add them sequentially into a 1000ml pressure reactor. Close the pressure reactor, purge with nitrogen for 5-10min, and heat to 130°C with stirring. Keep the reaction for about 4h. When the pressure in the pressure reactor reaches about 2.5mpa, pass cold water to reduce the reactor temperature to room temperature and release carbon dioxide gas. Then close the pressure reactor, heat to 130°C with stirring, and keep the reaction for 10h, during which the maximum pressure of the reactor is 1.55mpa. After the reaction, concentrate the reaction solution, crystallize, filter, and dry to obtain 80.65g of dimethyldiethylammonium chloride, with a product yield of 97.7%. Quantitative analysis shows a product content of 99.5%, 0.1% ammonium salt, 0.3% water, 7ppm residual bromide ions, 10ppm residual sodium ions, 7ppm residual potassium ions, and 23ppm residual iron ions. Example 5

[0028] Weigh 64g of diethylamine hydrochloride, 135g of dimethyl carbonate, and 60g of methanol, and add them sequentially into a 2000ml pressure reactor. Close the pressure reactor, purge with nitrogen for 5-10min, heat to 130°C with stirring, and keep the reaction for 14h. During this period, the maximum pressure of the reactor is 2.0 MPa. After the reaction, concentrate the reaction solution, crystallize, filter, and dry to obtain 81.2g of dimethyldiethylammonium chloride. The product yield is 98.3%. Quantitative analysis shows that the product content is 99.8%, ammonium salt is 0.05%, water is 0.1%, bromide ion residue is 7ppm, sodium ion residue is 9ppm, potassium ion residue is 5ppm, and iron ion residue is 13ppm. Example 6

[0029] Weigh 64g diethylamine hydrochloride, 135g dimethyl carbonate, and 60g methanol, add them sequentially into a 500ml pressure reactor, close the pressure reactor, purge with nitrogen for 5-10min, heat to 130°C with stirring, and keep the reaction for about 4h. When the pressure in the pressure reactor reaches about 2.5mpa, pass cold water to reduce the reactor temperature to room temperature and release carbon dioxide gas. Then close the pressure reactor and heat to 130°C with stirring. Release the gas a total of 3 times. After the last release of gas, keep the reaction for 10h, during which the maximum pressure of the reactor is 0.5mpa. After the reaction is completed, the reaction solution is concentrated, crystallized, filtered, and dried to obtain 80.8g dimethyldiethylammonium chloride, with a product yield of 97.8%, a quantitative analysis product content of 99.5%, an ammonium salt of 0.1%, a moisture content of 0.35%, a bromide ion residue of 15ppm, a sodium ion residue of 18ppm, a potassium ion residue of 15ppm, and an iron ion residue of 22ppm.

[0030] Comparative Example 1 Weigh 64g of diethylamine hydrochloride and 135g of dimethyl carbonate and add them sequentially into a 1000ml pressure reactor. Close the pressure reactor, purge with nitrogen for 5-10min, and heat to 130°C with stirring. Keep the reaction for about 3h. When the pressure in the pressure reactor reaches about 2.5mpa, pass cold water to reduce the reactor temperature to room temperature and release carbon dioxide gas. Then close the pressure reactor and heat to 130°C with stirring. Keep the reaction for 10h, during which the maximum pressure of the reactor is 1.38mpa. After the reaction, concentrate the reaction solution, crystallize, filter, and dry to obtain 70.2g of dimethyldiethylammonium chloride. The product yield is 85.0%. Quantitative analysis shows that the product content is 98.3%, ammonium salt is 1.1%, water is 0.5%, bromide ion residues are 30ppm, sodium ion residues are 44ppm, potassium ion residues are 38ppm, and iron ion residues are 72ppm.

[0031] Comparative Example 2 Weigh 64g of diethylamine hydrochloride, 135g of dimethyl carbonate, and 60g of methanol, and add them sequentially into a 500ml pressure reactor. Close the pressure reactor, purge with nitrogen for 5-10min, heat to 130°C with stirring, and keep the reaction for about 14h. During this period, the maximum pressure of the reactor is 8.0 MPa. After the reaction, concentrate the reaction solution, crystallize, filter, and dry to obtain 67.5g of dimethyldiethylammonium chloride. The product yield is 81.7%. Quantitative analysis shows that the product content is 97.8%, ammonium salt is 1.5%, water is 0.6%, bromide ion residue is 25ppm, sodium ion residue is 33ppm, potassium ion residue is 30ppm, and iron ion residue is 60ppm.

[0032] The above embodiments are merely further elaborations of the present invention to help understand the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, replacements, and changes to the technical solutions of the present invention based on the technical concept of the present invention fall within the technical protection scope of the present invention.

Claims

1. A novel method for preparing dimethyldiethylammonium chloride, characterized in that: Add diethylamine hydrochloride, dimethyl carbonate and reaction solvent in a certain molar ratio into an autoclave, react at a temperature of 90-180°C, a pressure of 0.1-4 MPa and a time of 8-24 hours, during which reaction gas is released 1-3 times. After the reaction is completed, the reaction liquid is concentrated, crystallized, filtered and dried to obtain high-purity dimethyldiethylammonium chloride.

2. According to claim 1, it is characterized in that The reaction solvent is methanol, dimethyl carbonate, ethanol, isopropanol, ethylene glycol, propylene glycol, tert-butanol, n-pentanol, acetonitrile, acetone, toluene, etc.

3. According to claim 1, it is characterized in that The reaction temperature is 90-180°C.

4. According to claim 1, it is characterized in that The reaction pressure is 0.1-3 MPa.

5. According to claim 1, it is characterized in that The reaction time is 8-24h.

6. According to claim 1, it is characterized in that The molar ratio of the reaction raw materials diethylamine hydrochloride to dimethyl carbonate is 1:(2.0-4.0).

7. According to claim 1, it is characterized in that The reaction does not use any reaction co-catalyst.

8. According to claim 1, it is characterized in that The reaction releases gas 1-3 times, and the specific number is determined by conditions such as the size of the reaction container, the amount of reaction materials added, the ratio of reactants, and the set gas release pressure.

9. According to claim 1, it is characterized in that After the reaction is completed, a high-purity dimethyldiethylammonium chloride product with low halogen ion and metal ion content can be obtained without special treatment such as recrystallization, ion adsorption and the like.