阅读说明：本技术 一种乳化催化合成3,4-亚甲二氧基苯乙醇酸的方法及装置 (Method and device for synthesizing 3, 4-methylenedioxymandelic acid through emulsification catalysis ) 是由 陈学成 那平 王淳 于 2018-07-04 设计创作，主要内容包括：本发明公开了一种采用乳化催化过程进行合成3,4-亚甲二氧基苯乙醇酸的方法,该方法在制备混酸及乳化合成过程中都向反应体系中通入气体,使反应体系中产生大量气泡,从而使反应物表面积增大,增加反应物之间的接触面积,可以提高反应的转化率及产率。利用乳化过程的均质作用,使胡椒环以极小的液滴均匀的分散在乙醛酸中,可以提高反应物之间接触效率,提高产物纯度及产率。在反应过程中用添加相转移催化剂的办法,提高水相与油相的亲和性,进一步提高乳化的效果,从而提高的反应的选择性及产率。本发明还公开了一种乳化催化合成3,4-亚甲二氧基苯乙醇酸的装置,可以实现采用乳化催化过程进行合成3,4-亚甲二氧基苯乙醇酸的方法。(The invention discloses a method for synthesizing 3, 4-methylenedioxymandelic acid by adopting an emulsification catalysis process, which is characterized in that gas is introduced into a reaction system in the processes of preparing mixed acid and emulsification synthesis, so that a large amount of bubbles are generated in the reaction system, the surface area of reactants is increased, the contact area among the reactants is increased, and the conversion rate and the yield of the reaction can be improved. The homogeneity of the emulsification process is utilized to ensure that the pepper rings are uniformly dispersed in the glyoxylic acid in the form of tiny droplets, so that the contact efficiency between reactants can be improved, and the purity and the yield of the product can be improved. In the reaction process, a method of adding a phase transfer catalyst is used to improve the affinity of the water phase and the oil phase and further improve the emulsification effect, thereby improving the selectivity and the yield of the reaction. The invention also discloses a device for synthesizing 3, 4-methylenedioxymandelic acid by emulsification catalysis, which can realize a method for synthesizing 3, 4-methylenedioxymandelic acid by adopting an emulsification catalysis process.)

1. A method for synthesizing 3, 4-methylenedioxymandelic acid by emulsification catalysis is characterized by comprising the following steps:

step 1, mixing water in a mass ratio: 50 wt% glyoxylic acid aqueous solution ═ 1: stirring the mixture of 15-20 at constant temperature, wherein the constant temperature stirring temperature is-30 ℃ to-20 ℃, and the stirring speed is 350rpm to 450 rpm;

step 2, after stirring, dripping 98 wt% of concentrated sulfuric acid into the mixture, wherein the dripping amount per minute is 0.03-0.1 time of the mass of the mixture, and the ratio of the total mass of the 98 wt% of concentrated sulfuric acid to the mass of the water in the step 1 is 98 wt% of concentrated sulfuric acid: 12-15% of water: 1, stirring at-30 to-20 ℃;

step 3, after all the 98 wt% concentrated sulfuric acid is dripped, continuously stirring for 20-40 min at the stirring temperature of minus 30-minus 20 ℃;

step 4, adding 3, 4-methylenedioxymandelic acid and benzyltriethylammonium chloride into the solution after the step 3 is completed, wherein the ratio of the added 3, 4-methylenedioxymandelic acid to the water mass in the step 1 is 3, 4-methylenedioxymandelic acid: water is 0.1-1: 1, adding benzyltriethylammonium chloride in a mass ratio of benzyltriethylammonium chloride to the water in the step 1: 0.5-1.5% of water: 1;

step 5, emulsifying the solution obtained in the step 4 at an emulsifying speed of 10-15 Kr/min, dripping pepper rings at the same time during emulsification, wherein the dripping amount per minute is 0.1-1 time of the mass of the water obtained in the step 1, and the emulsifying time is 3-10 min;

step 6, repeating the step 5 for multiple times, wherein the interval between every two times is 3-10 min, and the ratio of the total amount of added piperonyl butoxide to the mass of the water in the step 1 is piperonyl butoxide: water is 10-15: 1;

step 7, stirring the solution obtained after the step 6 at a constant temperature of 0-10 ℃, at a stirring speed of 400-600 rpm for 20-40 min;

step 8, adding a stop solution into the solution after the step 7 is finished, wherein the ratio of the total amount of the stop solution to the water mass in the step 1 is the stop solution: 15-30% of water: 1, terminating the reaction to obtain a product;

and the processes of the step 1 to the step 7 also comprise a process of blowing gas into the solution, wherein the gas blowing amount per minute is 7-20 times of the volume of the mixture.

2. The method for emulsion catalytic synthesis of 3, 4-methylenedioxymandelic acid according to claim 1, wherein in step 1, the ratio of water: 50 wt% glyoxylic acid aqueous solution ═ 1: 15-17, stirring at a constant temperature of-28 to-23 ℃ and at a stirring speed of 380 to 420 rpm.

3. The emulsion-catalyzed synthesis method of 3, 4-methylenedioxymandelic acid according to claim 1, wherein in step 4, the ratio of the amount of 3, 4-methylenedioxymandelic acid added to the mass of water is 3, 4-methylenedioxymandelic acid: water is 0.1-0.4: 1.

4. the method for emulsion catalytic synthesis of 3, 4-methylenedioxymandelic acid according to claim 1, wherein the ratio of the amount of benzyltriethylammonium chloride added in step 4 to the mass of water in step 1 is benzyltriethylammonium chloride: water is 0.8-1.2: 1.

5. the method for the emulsion catalytic synthesis of 3, 4-methylenedioxymandelic acid according to claim 1, wherein in step 5, the emulsion speed is 10-12 Kr/min, pepper rings are added dropwise during the emulsion, the amount of the added pepper rings is 0.5-0.8 times of the mass of the water per minute, and the emulsion time is 5-10 min.

6. The method for synthesizing 3, 4-methylenedioxymandelic acid by emulsion catalysis as claimed in claim 1, wherein in step 6, step 5 is repeated 3-8 times, each time with an interval of 3-10 min, and the ratio of the total amount of piperonyl to the mass of water is piperonyl: water is 10-12: 1.

7. the method for synthesizing 3, 4-methylenedioxymandelic acid by emulsion catalysis according to claim 1, wherein in step 8, the stop solution is added as water, and the ratio of the total amount of the stop solution added to the mass of the water in step 1 is stop solution: 15-25% of water: 1.

8. the emulsion-catalyzed synthesis of 3, 4-methylenedioxymandelic acid according to claim 1, comprising the steps of:

step 1, mixing water in a mass ratio: 50 wt% glyoxylic acid aqueous solution ═ 1: stirring the mixture of 14-16 at constant temperature, wherein the constant temperature stirring temperature is-30 ℃ to-25 ℃, and the stirring speed is 400 rpm;

step 2, after stirring, dripping 98 wt% of concentrated sulfuric acid into the mixture, wherein the dripping amount per minute is 0.03-0.07 time of the mass of the mixture, and the mass ratio of the total mass of the 98 wt% of concentrated sulfuric acid to the water in the step 1 is 98 wt% of concentrated sulfuric acid: 12-14% of water: 1, stirring at-30 to-20 ℃;

step 3, after all the 98 wt% concentrated sulfuric acid is dripped, continuously stirring for 20-30 min at the stirring temperature of minus 30-minus 25 ℃;

and 4, adding 3, 4-methylenedioxybenzene glycolic acid and benzyltriethylammonium chloride into the solution after the step 3 is completed, wherein the mass ratio of the added 3, 4-methylenedioxybenzene glycolic acid to the water in the step 1 is 3, 4-methylenedioxybenzene glycolic acid: water is 0.3-0.4: 1, adding benzyltriethylammonium chloride in a mass ratio of benzyltriethylammonium chloride to water in the step 1: water is 0.8-1: 1;

step 5, emulsifying the solution obtained in the step 4 at an emulsifying speed of 11-12 Kr/min, and simultaneously dripping pepper rings at a dripping amount of 0.5-0.6 time of the mass of the water obtained in the step 1 per minute for 3-5 min;

step 6, repeating the step 5 for multiple times, wherein the interval between every two times is 3-10 min, and the mass ratio of the total amount of the added piperonyl butoxide to the water in the step 1 is: water is 10-11: 1;

step 7, stirring the solution obtained after the step 6 at a constant temperature of 0-10 ℃, at a stirring speed of 400-600 rpm for 20-40 min;

step 8, adding a stop solution into the solution after the step 7 is finished, wherein the ratio of the total amount of the stop solution to the water mass in the step 1 is the stop solution: 15-20% of water: 1, terminating the reaction to obtain a product;

the processes of the step 1 to the step 7 also comprise a process of blowing gas into the solution, wherein the gas blowing amount per minute is 12-20 times of the volume of the mixture.

9. The method for synthesizing 3, 4-methylenedioxymandelic acid by emulsion catalysis according to any one of claims 1 to 8, wherein the air-blowing medium used in the air-blowing process is nitrogen.

10. A device for synthesizing 3, 4-methylenedioxymandelic acid by emulsification and catalysis is characterized by comprising a jacketed distributor stirred tank, a sulfuric acid metering tank, a jacketed distributor emulsified tank, a jacketed distributor product stirred tank, a pepper ring metering tank, a thermostatic tank, a filtering device, a feeding pump, an air storage tank and a filtrate tank, wherein an outlet of the sulfuric acid metering tank is connected with a jacketed distributor stirred tank pipeline, a circulating liquid outlet of the thermostatic tank is respectively connected with a jacket inlet of the jacketed distributor stirred tank, a jacket inlet of the jacketed distributor emulsified tank and a jacket inlet of the jacketed distributor product stirred tank by pipelines, a circulating liquid inlet of the thermostatic tank is respectively connected with a jacket outlet of the jacketed distributor stirred tank, a jacket outlet of the jacketed distributor emulsified tank and a jacket outlet of the jacketed distributor product stirred tank by pipelines, the export of jacketed distributor stirred tank links to each other with the inlet pipeline of charge pump, the export of pepper ring metering tank links to each other with jacketed distributor emulsification cauldron pipeline, jacketed distributor emulsification cauldron export with jacketed distributor product stirring cauldron inlet pipeline links to each other, jacketed distributor product stirring cauldron export with filtration equipment's feed inlet pipe connection, the export of gas holder adopts the pipe connection respectively jacketed distributor stirred tank's gas distribution pipe entry the gas distribution pipe entry and the jacketed distributor product stirring cauldron gas distribution pipe entry of jacketed distributor emulsification cauldron, filtration equipment liquid phase exit linkage the filter tank entry.

Technical Field

The invention belongs to the technical field of chemical engineering, and particularly relates to a method and a device for synthesizing 3, 4-methylenedioxymandelic acid through emulsification catalysis.

Background

3, 4-methylenedioxymandelic acid is an intermediate in the synthesis of piperonal. Piperonal is widely used in perfumes, spices, cherry and vanilla flavors. The perfume has long fragrance retention time, is used as a blending agent and a fixing agent, is a safe perfume accepted by American Association for the manufacture of spice extracts, and is widely applied to indoor fragrances, soap essences, food essences and tobacco essences. It can also be used in chemical and biological pharmacy. Is one of special commodities for which the country enforces export licenses.

The traditional synthesis method of 3, 4-methylenedioxymandelic acid is a method of synthesizing piperonyl-acetal and glyoxylic acid under acidic conditions, and the influence of reaction factors such as reaction temperature, reaction time, molar ratio of glyoxylic acid to piperonyl-acetal is studied by Shaoxing army and the like (the study on synthesis of 3, 4-methylenedioxymandelic acid by Shaoxing army, Doismen chemical industry, 2007, 2; 46-47.). Wangshuai et al (Wangshuai, Li dazao, Wangsheng. King Hengchang. air catalytic oxidation synthesis heliotropin [ J ]. applied chemical industry, 2009, 4: 491 + 493.) and Zhang Kun water (Zhang Kun water, Huanghan, Chenyi. pharmaceutical jasmal synthesis) when researching the synthesis method of heliotropin, similar preparation of 3, 4-methylenedioxymandelic acid is adopted. Ximidago considers the influence of factors such as reaction temperature, catalyst concentration, raw material ratio and reaction time, and discusses the mechanism of action and possible reaction process of sulfuric acid catalyst (ximidago, wuxian, king england. helional intermediate 3, 4-methylenedioxymandelic acid synthesis and characterization [ J ] chemical research and application, 2009, 21: 396-400 ].

The above prior art has the following disadvantages;

the product 3, 4-methylenedioxymandelic acid has high viscosity, poor fluidity and low mass transfer efficiency in the synthesis process, and the piperonyl and glyoxylic acid are not mutually soluble and the contact area between the two phases is small, so that the reaction is insufficient, the yield is low, the heat transfer effect is not uniform, and the phenomena of poor selectivity and more byproducts of the reaction are easy to occur

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method and a device for synthesizing 3, 4-methylenedioxymandelic acid by emulsification and catalysis.

The invention is realized by the following technical scheme:

a method for synthesizing 3, 4-methylenedioxymandelic acid by emulsification catalysis is characterized by comprising the following steps:

step 1, mixing water in a mass ratio: 50 wt% glyoxylic acid aqueous solution ═ 1: stirring the mixture of 15-20 at constant temperature, wherein the constant temperature stirring temperature is-30 ℃ to-20 ℃, and the stirring speed is 350rpm to 450 rpm;

step 2, after stirring, dripping 98 wt% of concentrated sulfuric acid into the mixture, wherein the dripping amount per minute is 0.03-0.1 time of the mass of the mixture, and the ratio of the total mass of the 98 wt% of concentrated sulfuric acid to the mass of the water in the step 1 is 98 wt% of concentrated sulfuric acid: 12-15% of water: 1, stirring at-30 to-20 ℃;

step 3, after all the 98 wt% concentrated sulfuric acid is dripped, continuously stirring for 20-40 min at the stirring temperature of minus 30-minus 20 ℃;

step 4, adding 3, 4-methylenedioxymandelic acid and benzyltriethylammonium chloride into the solution after the step 3 is completed, wherein the ratio of the added 3, 4-methylenedioxymandelic acid to the water mass in the step 1 is 3, 4-methylenedioxymandelic acid: water is 0.1-1: 1, adding benzyltriethylammonium chloride in a mass ratio of benzyltriethylammonium chloride to the water in the step 1: 0.5-1.5% of water: 1;

step 5, emulsifying the solution obtained in the step 4 at an emulsifying speed of 10-15 Kr/min, dripping pepper rings at the same time during emulsification, wherein the dripping amount per minute is 0.1-1 time of the mass of the water obtained in the step 1, and the emulsifying time is 3-10 min;

step 6, repeating the step 5 for multiple times, wherein the interval between every two times is 3-10 min, and the ratio of the total amount of added piperonyl butoxide to the mass of the water in the step 1 is piperonyl butoxide: water is 10-15: 1;

step 7, stirring the solution obtained after the step 6 at a constant temperature of 0-10 ℃, at a stirring speed of 400-600 rpm for 20-40 min;

step 8, adding a stop solution into the solution after the step 7 is finished, wherein the ratio of the total amount of the stop solution to the water mass in the step 1 is the stop solution: 15-30% of water: 1, terminating the reaction to obtain a product;

and the processes of the step 1 to the step 7 also comprise a process of blowing gas into the solution, wherein the gas blowing amount per minute is 7-20 times of the volume of the mixture.

In the above technical scheme, in the step 1, the mass ratio of water: 50 wt% glyoxylic acid aqueous solution ═ 1: 15-17, stirring at a constant temperature of-28 to-23 ℃ and at a stirring speed of 380 to 420 rpm.

In the above technical scheme, in the step 4, the ratio of the amount of the 3, 4-methylenedioxymandelic acid added to the mass of the water is 3, 4-methylenedioxymandelic acid: water is 0.1-0.4: 1.

in the above technical scheme, in the step 4, the ratio of the amount of the added benzyltriethylammonium chloride to the mass of the water in the step 1 is benzyltriethylammonium chloride: water is 0.8-1.2: 1.

in the technical scheme, in the step 5, the emulsifying speed is 10-12 Kr/min, pepper rings are added dropwise simultaneously during emulsification, the adding amount per minute is 0.5-0.8 times of the mass of the water, and the emulsifying time is 5-10 min.

In the above technical scheme, in the step 6, the step 5 is repeated for 3-8 times, the interval between every two times is 3-10 min, and the ratio of the total amount of added piperonyl butoxide to the mass of water is piperonyl butoxide: water is 10-12: 1.

in the above technical solution, in the step 8, the added stop solution is water, and the ratio of the total amount of the stop solution added to the water in the step 1 is the stop solution: 15-25% of water: 1.

in the technical scheme, the method comprises the following steps:

step 1, mixing water in a mass ratio: 50 wt% glyoxylic acid aqueous solution ═ 1: stirring the mixture of 14-16 at constant temperature, wherein the constant temperature stirring temperature is-30 ℃ to-25 ℃, and the stirring speed is 400 rpm;

step 2, after stirring, dripping 98 wt% of concentrated sulfuric acid into the mixture, wherein the dripping amount per minute is 0.03-0.07 time of the mass of the mixture, and the mass ratio of the total mass of the 98 wt% of concentrated sulfuric acid to the water in the step 1 is 98 wt% of concentrated sulfuric acid: 12-14% of water: 1, stirring at-30 to-20 ℃;

step 3, after all the 98 wt% concentrated sulfuric acid is dripped, continuously stirring for 20-30 min at the stirring temperature of minus 30-minus 25 ℃;

and 4, adding 3, 4-methylenedioxybenzene glycolic acid and benzyltriethylammonium chloride into the solution after the step 3 is completed, wherein the mass ratio of the added 3, 4-methylenedioxybenzene glycolic acid to the water in the step 1 is 3, 4-methylenedioxybenzene glycolic acid: water is 0.3-0.4: 1, adding benzyltriethylammonium chloride in a mass ratio of benzyltriethylammonium chloride to water in the step 1: water is 0.8-1: 1;

step 5, emulsifying the solution obtained in the step 4 at an emulsifying speed of 11-12 Kr/min, and simultaneously dripping pepper rings at a dripping amount of 0.5-0.6 time of the mass of the water obtained in the step 1 per minute for 3-5 min;

step 6, repeating the step 5 for multiple times, wherein the interval between every two times is 3-10 min, and the mass ratio of the total amount of the added piperonyl butoxide to the water in the step 1 is: water is 10-11: 1;

step 7, stirring the solution obtained after the step 6 at a constant temperature of 0-10 ℃, at a stirring speed of 400-600 rpm for 20-40 min;

step 8, adding a stop solution into the solution after the step 7 is finished, wherein the ratio of the total amount of the stop solution to the water mass in the step 1 is the stop solution: 15-20% of water: 1, terminating the reaction to obtain a product;

the processes of the step 1 to the step 7 also comprise a process of blowing gas into the solution, wherein the gas blowing amount per minute is 12-20 times of the volume of the mixture.

In the technical scheme, the air blowing medium adopted in the air blowing process is nitrogen.

A device for synthesizing 3, 4-methylenedioxymandelic acid by emulsification and catalysis comprises a jacketed distributor stirring kettle, a sulfuric acid metering tank, a jacketed distributor emulsifying kettle, a jacketed distributor product stirring kettle, a pepper ring metering tank, a thermostatic tank, a filtering device, a feeding pump, a gas storage tank and a filtrate tank, wherein an outlet of the sulfuric acid metering tank is connected with a jacketed distributor stirring kettle pipeline, a circulating liquid outlet of the thermostatic tank is respectively connected with a jacket inlet of the jacketed distributor stirring kettle, a jacket inlet of the jacketed distributor emulsifying kettle and a jacket inlet of the jacketed distributor product stirring kettle by pipelines, a circulating liquid inlet of the thermostatic tank is respectively connected with a jacket outlet of the jacketed distributor stirring kettle, a jacket outlet of the jacketed distributor emulsifying kettle and a jacket outlet of the jacketed distributor product stirring kettle by pipelines, an outlet of the jacketed distributor stirring kettle is connected with an inlet pipeline of the feeding pump, the export of pepper ring metering tank links to each other with jacket formula distributor emulsification cauldron pipeline, jacket formula distributor emulsification cauldron export with jacket formula distributor product stirred tank inlet pipeline links to each other, jacket formula distributor product stirred tank export with filtration equipment's feed inlet pipe connects, the export of gas holder adopts the pipe connection respectively jacket formula distributor stirred tank's gas distribution pipe entry jacket formula distributor emulsification cauldron's gas distribution pipe entry and jacket formula distributor product stirred tank gas distribution pipe entry, filtration equipment liquid phase exit linkage the filtrate groove entry.

In the technical scheme, flow meters are arranged at outlet pipes of the sulfuric acid metering tank and the pepper ring metering tank.

In the technical scheme, the sulfuric acid metering tank is arranged above the jacketed distributor stirring kettle, and the pepper ring metering tank is arranged above the jacketed distributor emulsifying kettle.

In the technical scheme, the jacket inlet pipe of the jacketed distributor stirring kettle, the jacket inlet pipe of the jacketed distributor emulsifying kettle and the jacket inlet pipe of the jacketed distributor product stirring kettle are all provided with liquid flow meters.

Among the above-mentioned technical scheme, all be provided with gas flowmeter on the gas distribution pipe inlet tube of jacketed distributor stirred tank, the gas distribution pipe inlet tube of jacketed distributor emulsification cauldron and the jacketed distributor product stirred tank gas distribution pipe inlet tube.

In the technical scheme, the emulsifying device and the wall scraping stirring device are arranged on the jacket type distributor emulsifying kettle.

In the technical scheme, 2 sets of emulsifying devices and wall scraping stirring devices are arranged on the jacketed distributor emulsifying kettle.

In the above technical solution, the filtering device may be a multi-stage filtering device.

In the above technical solution, the filtering device may be a 2-stage filtering device.

In the technical scheme, the jacketed distributor stirring kettle and the jacketed distributor emulsifying kettle are both provided with temperature detecting instruments.

The invention has the advantages and beneficial effects that:

1. the method for synthesizing the 3, 4-methylenedioxymandelic acid adopts the emulsification catalysis process, and the method introduces gas into the reaction system in the processes of preparing the mixed acid and the emulsification synthesis, so that a large amount of bubbles are generated in the reaction system, the surface area of reactants is increased, the contact area between the reactants is increased, and the conversion rate and the yield of the reaction can be improved.

2. The invention adopts an emulsification method to synthesize the 3, 4-methylenedioxymandelic acid, and utilizes the homogenization effect of the emulsification process in the synthesis process to uniformly disperse the piperonyl in the glyoxylic acid by tiny droplets, thereby improving the contact efficiency between reactants and improving the purity and the yield of the product.

3. The emulsifier adopted by the invention is 3, 4-methylenedioxymandelic acid, and the method takes the product as the emulsifier according to the principle that the 3, 4-methylenedioxymandelic acid has both lipophilic group and hydrophilic group, so that a stable emulsion system can be formed, and substances outside a reaction system are not introduced, so that the product separation process is simpler and easier.

4. The invention uses a method of adding phase transfer catalyst in the reaction process to improve the affinity of the water phase and the oil phase and further improve the emulsification effect, thereby improving the selectivity and the yield of the reaction.

Drawings

FIG. 1 is a schematic diagram of a process for the emulsion-catalyzed synthesis of 3, 4-methylenedioxymandelic acid.

Fig. 2 is a schematic diagram of embodiment 3 of the present invention.

Fig. 3 is a schematic diagram of embodiment 4 of the present invention.

Wherein:

1: jacketed distributor stirred tank, 2: sulfuric acid metering tank, 3: jacketed distributor emulsifying kettle, 4: pepper ring metering tank, 5: thermostatic bath, 6: filtration apparatus, 7: charge pump, 8: gas storage tank, 9: a filtrate tank; 12: a jacketed distributor product stirred tank;

6-1: primary filtering equipment, 6-2: secondary filtration device, 10-1: first gas flow meter, 10-2: second gas flowmeter, 10-3: third gas flow meter, 11-1: first liquid flow meter, 11-2: second liquid flow meter, 11-3: and a third liquid flow meter.

For a person skilled in the art, other relevant figures can be obtained from the above figures without inventive effort.

Detailed Description

In order to make the technical solution of the present invention better understood, the technical solution of the present invention is further described below with reference to specific examples.

Comparative example

1. 100g of piperonyl butoxide, 10g of water, 160g of 50% glyoxylic acid aqueous solution and 140g of 98% concentrated sulfuric acid are weighed.

2. To a jacketed reactor were added 10g of water and 160g of 50% aqueous glyoxylic acid.

3. Connecting the jacket reactor with a constant temperature bath, setting the temperature of the constant temperature bath to be 5 ℃, operating the constant temperature bath to cool for more than half an hour until the temperature of liquid in the jacket reaches 5 ℃.

4. Connecting an electric stirrer, and stirring the liquid in the jacket reactor by using a plastic stirring blade at the rotating speed of 400r/min

5. Dropwise adding 140g of concentrated sulfuric acid at a constant speed of 7g/min by using a constant-pressure funnel, and continuously stirring for 30min after dropwise adding. Obtaining the mixed acid.

6. And (3) removing the mixed acid accounting for 70 percent of the total mass of the mixed acid out of the jacketed reactor, and refrigerating the mixed acid in an environment at 5 ℃.

7. 30g of piperonyl butoxide is dropwise added into the jacketed reactor at a constant speed of 3g/min by using a constant-pressure funnel. After the dropwise addition, stirring was continued for 30 min.

8. Dropwise adding 70% of the mixed acid removed in the step 6 (the adding time is 1h) and 70g of piperonyl (the adding time is 0.5h) into a jacketed reactor at a constant speed by using a constant-pressure funnel.

9. After the dropwise addition, the speed of the stirring equipment is adjusted to 500r/min, and the stirring reaction is continued for 35min

10. The reaction was terminated by adding 200mL of water to the jacketed reactor.

11. Suction filtration was performed using a 1L suction flask to obtain a solid, which was weighed, dried and checked by liquid chromatography.

12. The detection result shows that the yield is 71.42%, the purity is 68.54%, and the total yield is 44.64%.