WO2021088222A1 - Method for synthesizing imidazole additive - Google Patents

Abstract

Disclosed is a method for synthesizing an imidazole additive, belonging to the technical field of battery electrolyte additives. The method comprises: providing allyl alcohol or propargyl alcohol as a raw material; feeding phosgene to the raw material at a rate of 40-50 mL/min at 0°C or below; feeding phosgene to proceed with a reaction process and controlling the reaction temperature to be less than 5°C; after the reaction is complete, incubating the reaction for 20-30 min; feeding nitrogen gas to the reaction vessel at room temperature for 1-1.5 h; performing distillation at reduced pressure and collecting fractions for later use; adding dichloromethane and imidazole to the reaction vessel, and adding triethylene amine to the reaction vessel at a rate of 90-100 mL/min; after addition is complete, feeding nitrogen gas to replace the gas in the reaction vessel; raising the temperature to reflux temperature, and adding the collected fractions dropwise to the reaction vessel; after addition is complete, stirring for 3-5 h; performing suction filtration, and washing the separated mother solution with an alkali solution until pH 7.2-7.3; then performing drying and reduced-pressure distillation to obtain the product. The method has a simple synthesis route, is easy to implement, low in energy consumption, and generates fewer by-products.

Description

Synthesis method of imidazole additives Technical field

The invention belongs to the technical field of battery electrolyte additives, relates to imidazole carboxylic acid esters used in battery electrolytes, and specifically relates to a method for synthesizing imidazole carboxylic acid esters.

Background technique

With the continuous expansion of the use range of lithium-ion batteries, functional additives for lithium-ion batteries have become a new technological development direction, and certain performances of the batteries can be changed in a targeted manner with a smaller dose. The imidazole carboxylic acid ester is used as an additive in the battery electrolyte, which can improve the battery cathode interface and the existence of the cathode material, and improve the battery's high and low temperature cycle and safety performance. However, the existing imidazole carboxylic acid ester synthesis method has three wastes, High energy consumption, long working hours, and large equipment investment are not conducive to industrialized mass production and the concept of green environmental protection.

Summary of the invention

In order to solve the above problems, the present invention provides a method for synthesizing imidazole additives. The preparation method of the invention is simple, has high atomic utilization rate, less three wastes, and high yield, which is beneficial to industrialized mass production and the concept of green environmental protection.

The technical scheme adopted by the present invention to achieve its purpose is: the method for synthesizing imidazole additives, the key lies in including the following steps:

I. It is carried out in a reactor equipped with a thermometer, a gas duct and an exhaust gas absorption device, using allyl alcohol or propargyl alcohol as raw materials, cooling to below 0°C, and feeding into the reactor at a rate of 40-50mL/min Phosgene, control the temperature of the reactor to be less than 5°C during the reaction by introducing phosgene, and monitor the progress of the reaction by TLC. After the reaction is completed, heat preservation for 20-30min, and then purge the reactor with nitrogen at room temperature for 1-1.5h , Vacuum distillation, collecting fractions for later use, specifically: the reaction raw material is allyl alcohol, and the 108-110°C fraction is collected; the reaction raw material is propargyl alcohol, and the 118-122°C fraction is collected;

II. Add dichloromethane and imidazole to the reaction kettle, add triethylamine to the reaction kettle at a rate of 90-100mL/min, after the addition, replace the gas in the reaction kettle with nitrogen, heat up to the reflux temperature, and add triethylamine to the reaction kettle. Add the fractions collected in step I dropwise, dropwise time 0.5-1h, after the dripping, stir for 3-5h, suction filtration, the filter cake is washed with dichloromethane, the separated mother liquor is washed with lye to pH 7.2-7.3, Dry and distill under reduced pressure to obtain the product shown in formula i or formula ii;

Further, in the step II, the molar ratio of imidazole to triethylamine is 1: (1-1.2).

Further, in the step II, the amount of dichloromethane used is: 3-4 ml of dichloromethane for 1 g of imidazole.

Further, in the step II, the molar ratio of imidazole to the fraction collected in step I is 1: (0.8-1.5).

Further, in the step II, the lye is an aqueous sodium bicarbonate solution with a concentration of 10 g/L.

Further, in the step II, anhydrous sodium sulfate or anhydrous magnesium sulfate is used for drying.

The beneficial effects of the present invention are:

The synthetic route of the invention is simple and easy to operate, the reaction process is strictly controlled, the energy consumption is low, the by-products are few, and the total yield is 88-91%.

2. In the first step of the reaction, by controlling the addition rate of phosgene to 40-50 mL/min and the combined reaction temperature less than 5°C, the effect is to reduce the generation of by-products, make the reaction proceed fully and quickly, and shorten the reaction time.

3. In the step II reaction, by controlling the rate of triethylamine, the dropping time of the distillate, and the stirring reaction time, the function is to obtain a product with a high yield and improve the conversion efficiency and the conversion rate.

After the 2-propyn-1-yl 1H-imidazole-1-carboxylate or 2-propyn-1-yl 1H-imidazole-1-carboxylate prepared by the invention is added to the electrolyte, there are no side effects and can reduce The battery swells after being placed at high temperature to improve the charge and discharge performance and cycle times of the battery, and form an overcharge protection film on the surface of the battery positive electrode to improve the overcharge resistance performance.

Description of the drawings

Figure 1 is a mass spectrum of the product of Example 1 of the present invention.

Figure 2 is a 1H NMR spectrum of the product of Example 1 of the present invention.

Figure 3 is a 13C NMR spectrum of the product of Example 1 of the present invention.

Figure 4 is a mass spectrum of the product of Example 4 of the present invention.

Figure 5 is a 1H NMR spectrum of the product of Example 4 of the present invention.

Figure 6 is a 13C NMR spectrum of the product of Example 4 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

1. Synthesis of 2-propen-1-yl 1H-imidazole-1-carboxylate

Example 1

I. Taking 58.08g of allyl alcohol as raw material, cooling to -5°C, and injecting phosgene into the reactor at a rate of 40mL/min, and controlling the temperature of the reactor to be less than 5°C during the process of introducing phosgene to carry out the reaction. TLC thin layer chromatography scanner monitors the progress of the reaction. After the reaction is over, keep it warm for 20 minutes, then pour nitrogen into the reactor at room temperature for 1 hour, distill under reduced pressure, and collect the 108°C fraction to obtain 114.5g fraction for use, with a yield of 95%;

II. Add 242.52ml of dichloromethane and 80.84g of imidazole to the reaction kettle, add 164.6ml of triethylamine to the reaction kettle at a rate of 90mL/min, after the addition, replace the gas in the reaction kettle with nitrogen, and heat to reflux temperature , Add the fraction collected in step I dropwise to the reaction kettle for 0.5h, after dripping, stirring for 3h, suction filtration, the filter cake is washed with dichloromethane, the separated mother liquor is washed with lye to pH 7.2, with Dry with anhydrous sodium sulfate and distill under reduced pressure to obtain 135.87g of product with a yield of 94%; the lye is an aqueous solution of sodium bicarbonate with a concentration of 10g/L, as shown in Figure 1-3, which is identified by mass spectrum, H spectrum and C spectrum. The resulting product is 2-propen-1-yl 1H-imidazole-1-carboxylate, and the structural formula of 2-propen-1-yl 1H-imidazole-1-carboxylate is:

Example 2

I. Taking 58.08g of allyl alcohol as raw material, cooling to -10°C, and injecting phosgene into the reactor at a rate of 50mL/min, and controlling the temperature of the reactor to be less than 5°C during the process of introducing phosgene to carry out the reaction. TLC monitors the progress of the reaction. After the reaction is completed, heat preservation for 30 minutes, and then pour nitrogen into the reactor at room temperature for 1.5 hours, distill under reduced pressure, and collect the fraction at 110°C to obtain 115.71 g fraction for use, with a yield of 96%;

II. Add 174.28ml of dichloromethane and 43.57g of imidazole to the reactor, add 106.46ml of triethylamine to the reactor at a rate of 100mL/min, after the addition, replace the gas in the reactor with nitrogen, and heat to reflux temperature , Add the fractions collected in step I dropwise to the reaction kettle, dripping for 1h, after dripping, stirring for 5h, suction filtration, the filter cake is washed with dichloromethane, the separated mother liquor is washed with lye to pH 7.3, with no The hydrous magnesium sulfate was dried and distilled under reduced pressure to obtain 135.84 g of product with a yield of 93%; the lye was an aqueous sodium bicarbonate solution with a concentration of 10 g/L. The mass spectrum, H spectrum and C spectrum were used to identify the resulting product as 2-propylene- 1-yl 1H-imidazole-1-carboxylate.

Example 3

I. Take 58.08g of allyl alcohol as raw material, cool to -6°C, and pass phosgene into the reactor at a rate of 45mL/min. During the process of passing phosgene to the reaction, control the temperature of the reactor to be less than 5°C. TLC monitors the progress of the reaction. After the reaction is over, keep it warm for 25 minutes, then pour nitrogen into the reactor for 1.2 hours at room temperature, distill under reduced pressure, and collect the fraction at 110°C to obtain 115.50 g fraction for use, with a yield of 95.83%;

II. Add 260.96ml of dichloromethane and 65.24g of imidazole to the reactor, and add 146.12ml of triethylamine to the reactor at a rate of 95mL/min. The molar ratio of imidazole to triethylamine is 1:1.1. After the addition, replace the gas in the reactor with nitrogen, heat up to reflux temperature, add the fraction collected in step I dropwise to the reactor, drip for 40min, after dripping, stir for 4h, filter with suction, and wash the filter cake with dichloromethane , The separated mother liquor was washed with lye to pH 7.3, dried with anhydrous magnesium sulfate, and distilled under reduced pressure to obtain 136.87g product with a yield of 93.87%; lye was an aqueous solution of sodium bicarbonate with a concentration of 10g/L. The mass spectrum, H spectrum and C spectrum identified the obtained product as 2-propen-1-yl 1H-imidazole-1-carboxylate. 2. Synthesis of 2-propyn-1-yl 1H-imidazole-1-carboxylate

Example 4

I. Using 56g propynol as raw material, cooling to -8°C, phosgene was introduced into the reactor at a rate of 50mL/min, and the temperature of the reactor was controlled to be less than 5°C during the process of introducing phosgene to carry out the reaction. TLC Monitor the progress of the reaction. After the reaction, heat preservation for 30 minutes, then pour nitrogen into the reactor at room temperature for 1.5 hours, distill under reduced pressure, and collect 118°C fractions to obtain 113.79g fractions for use, with a yield of 96%;

II. Add 174.28ml of dichloromethane and 43.57g of imidazole to the reactor, add 106.46ml of triethylamine to the reactor at a rate of 100mL/min, after the addition, replace the gas in the reactor with nitrogen, and heat to reflux temperature , Add the fractions collected in step I dropwise to the reaction kettle, dripping for 1h, after dripping, stirring for 5h, suction filtration, the filter cake is washed with dichloromethane, the separated mother liquor is washed with lye to pH 7.3, with no The hydrous magnesium sulfate was dried and distilled under reduced pressure to obtain 135.50g of product with a yield of 94%; the lye was an aqueous solution of sodium bicarbonate with a concentration of 10g/L, as shown in Figure 4-6, using mass spectrum, H spectrum and C spectrum to identify the obtained product The product is 2-propyn-1-yl 1H-imidazole-1-carboxylate. The structural formula of 2-propyn-1-yl 1H-imidazole-1-carboxylate is:

Example 5

I. Using 56g propargyl alcohol as the raw material, the temperature is lowered to -5°C, phosgene is introduced into the reactor at a rate of 40 mL/min, and the temperature of the reactor is controlled to be less than 5°C during the process of introducing phosgene to carry out the reaction. TLC Monitor the progress of the reaction. After the reaction, heat preservation for 20 minutes, and then pour nitrogen into the reactor at room temperature for 1 hour, distill under reduced pressure, and collect the 122°C distillate to obtain 112.60g distillate for use, with a yield of 95%;

II. Add 242.52ml of dichloromethane and 80.84g of imidazole to the reactor, add 164.60ml of triethylamine to the reactor at a rate of 90mL/min, after the addition, replace the gas in the reactor with nitrogen, and heat to reflux temperature , Add the fraction collected in step I dropwise to the reaction kettle for 0.5h, after dripping, stirring for 3h, suction filtration, the filter cake is washed with dichloromethane, the separated mother liquor is washed with lye to pH 7.2, with Dry with anhydrous sodium sulfate and distill under reduced pressure to obtain 132.66g of product with a yield of 93%; the lye is an aqueous sodium bicarbonate solution with a concentration of 10g/L. The mass spectrum, H spectrum and C spectrum are used to identify the resulting product as 2-propane Alkyn-1-yl 1H-imidazole-1-carboxylate.

Example 6

I. Using 56g propargyl alcohol as raw material, cooling to -4°C, inject phosgene into the reaction kettle at a rate of 45 mL/min, and control the temperature of the reaction kettle to be less than 5°C during the process of introducing phosgene to carry out the reaction, TLC Monitor the progress of the reaction. After the reaction is completed, heat preservation for 25 minutes, and then pour nitrogen into the reactor for 1.2 hours at room temperature, distill under reduced pressure, and collect the distillate at 120°C to obtain 113.44g distillate for use, with a yield of 95.71%;

II. Add 260.64ml of dichloromethane and 65.16g of imidazole to the reactor, add 145.94ml of triethylamine to the reactor at a rate of 95mL/min, after the addition, replace the gas in the reactor with nitrogen, and heat to reflux temperature , Add the fractions collected in step I dropwise to the reaction kettle for 40 min, after dripping, stirring for 4 hours, suction filtration, washing the filter cake with dichloromethane, and washing the separated mother liquor with lye to pH 7.3. The hydrous magnesium sulfate was dried and distilled under reduced pressure to obtain 134.02g of product with a yield of 93.26%; the lye was an aqueous sodium bicarbonate solution with a concentration of 10g/L. The resulting product was identified as 2-propyne by mass spectrum, H spectrum and C spectrum. -1-yl 1H-imidazole-1-carboxylate.

Claims (6)

The method for synthesizing imidazole additives is characterized in that it comprises the following steps: I. It is carried out in a reactor equipped with a thermometer, a gas duct and an exhaust gas absorption device, using allyl alcohol or propargyl alcohol as the raw material, cooling to below 0°C, and feeding into the reactor at a rate of 40-50mL/min Phosgene, control the temperature of the reactor to be less than 5°C during the reaction by introducing phosgene, and monitor the progress of the reaction by TLC. After the reaction is completed, heat preservation for 20-30min, and then purge the reactor with nitrogen at room temperature for 1-1.5h , Vacuum distillation, collect fractions for later use, specifically: the reaction raw material is allyl alcohol, collect the 108-110°C fraction; the reaction raw material is propargyl alcohol, and the 118-122°C fraction is collected; II. Add dichloromethane and imidazole to the reaction kettle, add triethylamine to the reaction kettle at a rate of 90-100mL/min, after the addition, replace the gas in the reaction kettle with nitrogen, heat up to the reflux temperature, and add triethylamine to the reaction kettle. Add the fractions collected in step I dropwise, dropwise time 0.5-1h, after the dripping, stir for 3-5h, suction filtration, the filter cake is washed with dichloromethane, the separated mother liquor is washed with lye to pH 7.2-7.3, Dry and distill under reduced pressure to obtain the product shown in formula i or formula ii;

The method for synthesizing imidazole additives according to claim 1, wherein in the step II, the molar ratio of imidazole to triethylamine is 1: (1-1.2). The method for synthesizing imidazole additives according to claim 1, characterized in that, in the step II, the amount of dichloromethane used is: 1 g of imidazole with 3-4 ml of dichloromethane. The method for synthesizing imidazole additives according to claim 1, wherein in said step II, the molar ratio of imidazole to the fraction collected in step I is 1: (0.8-1.5). The method for synthesizing imidazole additives according to claim 1, wherein in the step II, the lye is an aqueous sodium bicarbonate solution with a concentration of 10 g/L. The method for synthesizing imidazole additives according to claim 1, characterized in that, in the step II, the drying adopts anhydrous sodium sulfate or anhydrous magnesium sulfate.

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