High-yield ethyl chrysanthemate preparation method

A high-yield technology of ethyl chrysanthemum acid, applied in the field of chemical technology, can solve the problem of low chemical yield, and achieve the effects of reducing poisoning and excellent environmental protection performance

Active Publication Date: 2020-11-24

湖北中灏科技有限公司

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AI-Extracted Technical Summary

Problems solved by technology

Use ethyl diazoacetate and 2,5-dimethyl-2,4-hexadiene as raw materials to prepare ethyl chrysanthemum acid, usually using...

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Method used

As can be seen from table 1, adopt dimethyl carbonate to make solvent, cuprous chloride can substantially improve ethyl chrysanthemum acid content and ethyl chrysanthemum acid yield (in hexadiene) as catalyzer in cycliz...

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Abstract

The invention belongs to the technical field of chemical processes, and specifically relates to a high-yield ethyl chrysanthemate preparation method. The high-yield ethyl chrysanthemate preparation method comprises the following steps: (1) diazotization: a step of adding water, glycine ethyl ester acid salt, glacial acetic acid and dimethyl carbonate as solvents into a diazotization kettle, dropwisely adding a sodium nitrite aqueous solution into the diazotization kettle, and carrying out a reaction so as to a diazo liquid; (2) cyclization: a step of putting 2,5-dimethyl-2,4-hexadiene into a cyclization kettle, and carrying out a reaction with cuprous chloride as a catalyst so as to obtain a cyclized solution; (3) desolventizing: a step of sending the cyclized solution into a high-yield desolventizing tower to remove the solvents so as to obtain a crude ethyl chrysanthemate product; and (4) distillation: a step of putting the crude ethyl chrysanthemate product into a distillation kettle, and carrying out vacuum distillation so as to obtain the high-purity ethyl chrysanthemate. The high-yield ethyl chrysanthemate preparation method provided by the invention has the following beneficial effects: when the dimethyl carbonate is used as a solvent, a diazotization reaction can be carried out more completely, so the loss of raw materials is reduced; and meanwhile, the yield of ethyl chrysanthemate in the subsequent cyclization reaction can be improved.

Application Domain

Physical/chemical process catalystsOrganic compound preparation +1

Technology Topic

DiazoChrysanthemic acid ethyl ester +14

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Examples

Experimental program(6)
Effect test(1)

Example Embodiment

[0037] Example 1

[0038] A method for preparing ethyl chrysanthenate with high yield, comprising the following steps:

[0039] (1) diazotization: put in 600 parts of water, 490 parts of glycine ethyl acetate and 35 parts of glacial acetic acid in the diazotization kettle, stir to dissolve the solid, and adopt glacial acetic acid to keep the pH value of the diazotization reaction at 3.5~ Between 4.5, then put 800 parts of dimethyl carbonate into the diazotization kettle as a solvent, open the freezing, make the temperature of the material in the diazotization kettle drop to 20~25 ℃, and then drop the sodium nitrite aqueous solution in the diazotization kettle. , the dropwise addition time of sodium nitrite is controlled at 4~5h, after the dropwise addition, the temperature is kept for 60min, after the reaction is completed, static layering is performed, and the lower water layer is discharged to the waste liquid collection tank, that is, the diazo liquid is obtained;

[0040](2) Cyclization: put 1100 parts of 2,5-dimethyl-2,4-hexadiene into the cyclization kettle, use 2 parts of cuprous chloride as a catalyst, turn on stirring, and heat up to 90~95℃ Start dropping the whole batch of diazo liquid in step (1), the diazo dropping time is 10-12 h, the dropping rate is ≤ 100 L/h, after the diazo liquid is added dropwise, the temperature is kept for 90 min, and the cyclization kettle is open after the reaction is complete. The water is cooled to 45~60℃ to obtain the cyclization solution;

[0041] (3) Precipitation: S1. Open the cyclization liquid feed valve and the vacuum tube valve of the high-efficiency precipitation tower to vacuum a certain amount of cyclized liquid into the high-efficiency precipitation tower, and open the manual venting tube venting valve to make the high-efficiency precipitation tower. After returning to normal pressure, turn on the high-efficiency precipitation tower agitator, the jacketed steam feed pipe and the condensed water discharge pipe, and begin to heat up and reflux;

[0042] S2, after refluxing for 20min, open the dimethyl carbonate receiving tank, the dimethyl carbonate feed valve and its upper vacuum valve for vacuum distillation, and observe the temperature trend balance, adjust the reflux ratio, and maintain the temperature at the top of the tower below 90 ° C, let Dimethyl carbonate continues to evaporate;

[0043] S3, when dimethyl carbonate was recovered to 80%, close the dimethyl carbonate receiving tank toluene feed valve and its upper vacuum valve, stop receiving dimethyl carbonate, open 2,5-dimethyl-2,4- The 2,5-dimethyl-2,4-hexadiene feed valve of the hexadiene receiving tank starts to remove 2,5-dimethyl-2,4-hexadiene;

[0044] S4, the first stage is the removal stage of the former 2,5-dimethyl-2,4-hexadiene, this stage is atmospheric distillation, the top temperature of this stage is 60-135 ℃; the second stage is 2 ,5-dimethyl-2,4-hexadiene removal stage, this stage is atmospheric distillation, the top temperature of this stage is 135-138 ℃; the third stage is vacuum removal of 2,5-dimethylene In the stage of base-2,4-hexadiene, the pressure in the tower is ≥0.07Mpa, the temperature is 115-120℃; the removal of S5 and 2,5-dimethyl-2,4-hexadiene is completed Then close the steam feed valve, condensate discharge valve and 2,5-dimethyl-2,4-hexadiene receiving tank vacuum valve of the high-efficiency precipitation tower, and open the circulating water of the high-efficiency precipitation tower to start cooling, When the temperature of the material in the high-efficiency precipitation tower drops to 50-70 °C, open the discharge valve at the lower part of the high-efficiency precipitation tower and start barreling and weighing to obtain crude ethyl chrysanthemate;

[0045] (4) distillation: S1, open the crude product ethyl chrysanthenate feed valve and the still vacuum tube valve to vacuum in the still kettle and pump the crude product ethyl chrysanthenate, close the crude product ethyl chrysanthenate feed valve and the vacuum tube valve, open and manually put Empty pipe vent valve to return the distillation kettle to normal pressure;

[0046] S2. Open the gas phase feed valve, liquid phase discharge valve, inlet and outlet valve of circulating water, front distillate receiving tank feed valve and its upper vacuum valve of the distillation kettle condenser, when the pressure in the distillation kettle reaches the vacuum degree ≥ 0.08MPa When above, turn on the high vacuum system;

[0047] S3, control the vacuum degree to be stable, and open the still agitator, open the still jacket steam feed valve and the condensed water discharge valve, start to heat up and distill out the front fraction, and the distillation temperature is about 105 ° C at this time;

[0048] S4, when the temperature in the distillation kettle rises significantly, the fore-cut distillation process ends, close the fore-cut receiving tank feed valve and its upper vacuum valve, open the main-cut receiving tank feed valve and its upper vacuum valve, and open a large distillation The steam feed valve of the kettle jacket makes the temperature in the distillation kettle reach about 113 °C, and the main distillate starts to be distilled;

[0049] S5, when the temperature in the still still drops significantly, the main fraction distillation process ends;

[0050] The preparation process of ethyl chrysanthenate was controlled by DCS chain control system.

Example Embodiment

[0051] Example 2

[0052] The difference between embodiment 2 and embodiment 1 is:

[0053] (1) diazotization: put in 500 parts of water, 480 parts of glycine ethyl acetate and 36 parts of glacial acetic acid in the diazotization kettle, stir to dissolve the solid, and adopt glacial acetic acid to keep the pH value of the diazotization reaction at 3.5~ Between 4.5, then put 800 parts of dimethyl carbonate into the diazotization kettle as a solvent, open the freezing, make the temperature of the material in the diazotization kettle drop to 20~25 ℃, and then drop the sodium nitrite aqueous solution in the diazotization kettle. , the dropwise addition time of sodium nitrite is controlled at 4~5h, after the dropwise addition, the temperature is kept for 45min, after the reaction is completed, static layering is performed, and the lower water layer is discharged to the waste liquid collection tank, that is, the diazo liquid is obtained;

[0054] (2) Cyclization: put 1,100 parts of 2,5-dimethyl-2,4-hexadiene into the cyclization kettle, use 3.5 parts of cuprous chloride as a catalyst, turn on stirring, and heat up to 90-95° C. Start dropping the whole batch of diazo liquid in step (1), the diazo dropping time is 10-12 h, the dropping rate is ≤ 100 L/h, after the diazo liquid is added dropwise, the temperature is kept for 70 min, and the cyclization kettle is open after the reaction is complete. The water is cooled to 45-60°C to obtain the cyclization solution.

Example Embodiment

[0055] Example 3

[0056] The difference between Example 3 and Example 1 is:

[0057] (1) diazotization: put 700 parts of water, 470 parts of glycine ethyl acetate and 37 parts of glacial acetic acid in the diazotization kettle, stir to dissolve the solid, and adopt glacial acetic acid to keep the pH value of the diazotization reaction at 3.5~ Between 4.5, then put 800 parts of dimethyl carbonate into the diazotization kettle as a solvent, open the freezing, make the temperature of the material in the diazotization kettle drop to 20~25 ℃, and then drop the sodium nitrite aqueous solution in the diazotization kettle. , the dropwise addition time of sodium nitrite is controlled at 4~5h, after the dropwise addition, the temperature is kept for 60min, after the reaction is completed, static layering is performed, and the lower water layer is discharged to the waste liquid collection tank, that is, the diazo liquid is obtained;

[0058] (2) Cyclization: put 1100 parts of 2,5-dimethyl-2,4-hexadiene into the cyclization kettle, use 2 to 5 parts of cuprous chloride as a catalyst, turn on stirring, and heat up to 90 to 90 After ℃, the whole batch of diazo liquid in step (1) was added dropwise. The diazo liquid was added dropwise for 10 to 12 hours, and the dropping rate was ≤ 100 L/h. After the diazo liquid was added dropwise, the temperature was kept for 60 min, and the cyclization was completed after the reaction was completed. The kettle is cooled to 45-60 ℃ with water to obtain the cyclized liquid.

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High-yield ethyl chrysanthemate preparation method

A high-yield technology of ethyl chrysanthemum acid, applied in the field of chemical technology, can solve the problem of low chemical yield, and achieve the effects of reducing poisoning and excellent environmental protection performance

AI-Extracted Technical Summary

Problems solved by technology

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Abstract

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Example Embodiment

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