Method for synthesizing malathion in laboratory
By using commonly used laboratories in the laboratory and controlling process flow, malathion was synthesized in three steps, which solved the safety and purity of synthesis of malathion in the laboratory, and achieved convenient and safe preparation of high-purity malathion.
Patent Information
- Application Number
- CN202411805364.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-10
- Publication Date
- 2025-03-21
AI Technical Summary
The prior art is difficult to synthesize a small amount of malathion in a laboratory safely and conveniently, and it is easy to decompose, store and transport.
Using commonly used glassware and instruments in the laboratory, by controlling the process flow and reaction temperature, using raw materials such as diphosphorus pentasulfide, methanol, ethanol, maleic anhydride, etc., malathion is synthesized in three steps: vulcanization reaction, esterification reaction and synthesis reaction.
It has achieved the safe preparation of high-purity malathion in a small amount and multiple times in the laboratory, solving the problems of easy decomposition, storage and transportation, and is suitable for chemical defense military training and protective performance tests.
Abstract
Description
Technical Field
[0001] The invention relates to the field of chemical warfare agent simulation synthesis, and in particular to a method for synthesizing malathion in a laboratory. Background Art
[0002] Malathion, also known as marathion or insecticide 4049, is scientifically known as O,O-dimethyl-S-(1,2-dihydroxyethoxyethyl) dithiophosphate. It is an organic compound with the chemical formula C 10 H 19 O6PS2, molecular weight 330.3, boiling point 385.1℃, density 1.23g / cm 3 It is an insecticide with a wide range of insecticides, a long residual effect and very low toxicity to humans and animals. It is available for commercial and household use on the market. The pure product is a yellow oily liquid, which is difficult to dissolve in water but soluble in organic solvents or vegetable oils.
[0003] Malathion is used as a simulant of Class V nerve agents because of its low toxicity and sulfur-containing leaving groups, which can simulate Class V nerve agents to a certain extent. It is widely used in chemical defense military training, exercises and protective performance tests.
[0004] The existing synthesis methods have the following disadvantages: ① Malathion is widely used in chemical plants as a low-toxic and widely used insecticide. In the field of chemical technology, reaction pots / reactors / reactors are often used to design and build reaction devices. The pressure in the synthesis device is unstable, which poses certain safety hazards and is suitable for the synthesis of malathion with large-scale preparation and low purity.
[0005] ② Malathion is a chemotherapeutic drug, commonly used for skin treatment and cleaning. It is also synthesized in small quantities in pharmaceutical laboratories, but its pH value is tested. In the pharmaceutical field, it is often used internally in medicine, and the preparation method and products are not disclosed.
[0006] In summary, none of them meet the needs of chemical laboratories. Summary of the invention
[0007] The present invention overcomes the deficiencies of the prior art and provides a method for synthesizing malathion in a laboratory. The present invention uses commonly used laboratory glassware and instruments and equipment to synthesize malathion by controlling the process flow and reaction temperature, thereby achieving small-scale and multiple preparation of malathion and solving the problems of malathion's packaging, easy decomposition, difficult storage, and difficult transportation.
[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for synthesizing malathion in the laboratory, firstly, methanol and phosphorus pentasulfide are reacted in a toluene medium to generate dimethoxy dithiophosphate, then maleic anhydride and ethanol are reacted in a benzene and sulfuric acid medium to generate diethyl maleate, and finally malathion is synthesized from dimethoxy dithiophosphate and diethyl maleate.
[0009] As a further limitation of the technical solution of the present invention, the method specifically comprises the following steps: (1) Toluene and phosphorus pentasulfide are fully mixed, vacuum treated, and then methanol is added dropwise at a temperature of 50°C to 70°C for 1 h to 2 h. The reaction is maintained at a temperature of 40°C to 80°C for 2 h to 3 h to terminate the reaction. After cooling, a crude dimethoxy dithiophosphate is obtained. (2) Ethanol, maleic anhydride, benzene and sulfuric acid are fully mixed, heated to a slight boil, and waited for about 1.5 hours. After the material temperature rises to 70°C to 90°C, the temperature is maintained for more than 8 hours. The reaction is terminated and the material is cooled and discharged to obtain crude diethyl maleate; (3) Dimethoxy dithiophosphate is slowly added dropwise into diethyl maleate, and the temperature is maintained at 50°C to 60°C for about 1 hour. The temperature is then raised to 70°C to 80°C and maintained for at least 8 hours to terminate the reaction and obtain crude malathion.
[0010] As a further limitation of the technical solution of the present invention, in step (1), the mass ratio of toluene to phosphorus pentasulfide is 1:2-3, and the mass of the methanol added is 0.4-0.7 times that of the phosphorus pentasulfide.
[0011] As a further limitation of the technical solution of the present invention, in step (2), the mass ratio of ethanol, maleic anhydride, benzene and sulfuric acid is 1:0.7-1.0:1-1.3:0.2-0.4, and the concentration of the sulfuric acid is ≥95%.
[0012] As a further limitation of the technical solution of the present invention, in step (3), the mass ratio of dimethoxy dithiophosphate to diethyl maleate is about 1:1.
[0013] As a further limitation of the technical solution of the present invention, the purity of the dimethoxy dithiophosphate obtained in step (1) is improved by alkali washing or the like.
[0014] As a further limitation of the technical solution of the present invention, the purity of diethyl maleate obtained in step (2) is improved by alkali washing, water washing, distillation and the like.
[0015] Compared with the prior art, the present invention has the following beneficial effects: At present, both abroad and at home, reaction pots / reactors / reactors are generally used as reaction devices, and malathion is synthesized into a crude product through at least two steps. There are few convenient preparation processes suitable for synthesizing a small amount of malathion in the laboratory. The present invention uses commonly used laboratory instruments / equipment as a synthesis device, and uses phosphorus pentasulfide, methanol, and ethanol as raw materials to prepare malathion products with high yield, high purity, and high safety. The method determines the route and process parameters suitable for preparing malathion in the laboratory by determining the synthesis process and optimizing the preparation process parameters. It solves the problem of preparing malathion in small quantities and safely in the laboratory.
[0016] The invention uses commonly used glassware and instruments in laboratories to realize the synthesis of malathion, is convenient for preparing malathion in small quantities and multiple times, and solves the problems that malathion is easy to decompose, difficult to store and difficult to transport.
[0017] The malathion synthesis process of the present invention is stable. According to the preparation process specification, 50 mL of malathion with a purity of ≥90% can be prepared at a time through process flow control and parameter setting adjustment in each link, thereby solving the problem of preparing and synthesizing malathion with a small amount and high purity safely in the laboratory; and convenient and safe storage is achieved.
[0018] The method of the invention is suitable for synthesizing malathion in a chemical laboratory and is used in chemical defense military training, exercises and protective performance tests. DETAILED DESCRIPTION
[0019] The present invention is further described below in conjunction with specific embodiments.
[0020] Raw materials and synthesis instruments / equipment The main raw materials for the synthesis of malathion are: phosphorus pentasulfide, methanol, ethanol, maleic anhydride, deionized water, soda ash, toluene, benzene, sulfuric acid, etc.
[0021] The synthesis apparatus / equipment of malathion include: constant temperature heating magnetic stirrer, constant pressure dropping funnel, four-necked round-bottom flask, vacuum pump, resistance thermometer, wide-mouth glass bottle, separatory funnel, condenser, collecting bottle, electronic balance, etc.
[0022] Synthesis Overview The laboratory synthesis of malathion is divided into three steps: sulfidation reaction - methanol reacts with phosphorus pentasulfide in a toluene medium to produce dimethoxy dithiophosphate; esterification reaction - maleic anhydride reacts with ethanol in a benzene and sulfuric acid medium to produce diethyl ester; synthesis reaction - dimethoxy dithiophosphate and diethyl maleate are used to synthesize crude malathion. Example 1
[0023] A method for synthesizing malathion in a laboratory comprises the following steps: Toluene and phosphorus pentasulfide in a mass ratio of 1:2 were fully mixed, and after vacuum treatment, methanol with a mass 0.6 times that of phosphorus pentasulfide was added dropwise at a temperature of 55°C for about 2 hours, and the reaction was maintained at 60°C for 3 hours to terminate the reaction. After cooling, a crude dimethoxy dithiophosphate was obtained; Then, ethanol, maleic anhydride, benzene and sulfuric acid in a mass ratio of 1:0.85:1:0.3 were fully mixed, heated to a slight boil, and waited for about 1.5 hours. After the material temperature rose to 77°C, the temperature was maintained for more than about 8 hours. When the amount of water discharged was very small, the reaction was terminated and cooled to obtain crude diethyl maleate; Dimethoxy dithiophosphate and diethyl ester in a mass ratio of about 1:1 are reacted, and dimethoxy dithiophosphate is slowly dripped into diethyl ester, the temperature is maintained at 55°C for 1 hour, and then the temperature is raised to 76°C and maintained for more than 8 hours to terminate the reaction, thereby obtaining crude malathion.
[0024] The preparation process adopts chemical purification method - alkali washing and evaporation to improve the quality of intermediate dimethoxy dithiophosphate, and adopts alkali washing, water washing and steam distillation to improve the quality of diethyl maleate. The purity of the prepared product can reach more than 90%.
[0025] The purity of malathion prepared in this example is 92%. Example 2
[0026] A method for synthesizing malathion in a laboratory comprises the following steps: Toluene and phosphorus pentasulfide in a mass ratio of 1:3 were fully mixed, and after vacuum treatment, methanol with a mass 0.4 times that of phosphorus pentasulfide was added dropwise at 60°C for about 1 hour, and the reaction was maintained at 80°C for 2 hours to terminate the reaction. After cooling, a crude dimethoxy dithiophosphate was obtained; Then, ethanol, maleic anhydride, benzene and sulfuric acid in a mass ratio of 1:0.7:1.3:0.2 are fully mixed, heated to a slight boil, and waited for about 1 hour. After the material temperature rises to 80°C, the temperature is maintained for more than about 8 hours. When the amount of water discharged is very small, the reaction is terminated and cooled to obtain crude diethyl maleate; Dimethoxy dithiophosphate and diethyl ester in a mass ratio of about 1:1 are reacted, and dimethoxy dithiophosphate is slowly dripped into diethyl ester, the temperature is maintained at 50°C for 50 minutes, and then the temperature is raised to 70°C and maintained for more than 8 hours to terminate the reaction, thereby obtaining crude malathion.
[0027] The preparation process adopts chemical purification methods such as alkali washing to improve the quality of the intermediate dimethoxy dithiophosphate, and adopts alkali washing, water washing, distillation and other methods to improve the quality of diethyl maleate. The purity of the prepared product can reach more than 90%.
[0028] The purity of malathion prepared in this example is 91%. Example 3
[0029] A method for synthesizing malathion in a laboratory comprises the following steps: Toluene and phosphorus pentasulfide in a mass ratio of 1:2 were fully mixed, and after vacuum treatment, methanol with a mass 0.4 times that of phosphorus pentasulfide was added dropwise at a temperature of 50°C for about 1.5 hours, and the reaction was maintained at 40°C for 2.5 hours to terminate the reaction. After cooling, a crude dimethoxy dithiophosphate was obtained; Then, ethanol, maleic anhydride, benzene and sulfuric acid in a mass ratio of 1:1:1.1:0.4 were fully mixed, heated to a slight boil, and waited for about 2 hours. After the material temperature rose to 90°C, the temperature was maintained for about 8 hours or more. When the amount of water discharged was very small, the reaction was terminated and cooled to obtain crude diethyl maleate; Dimethoxy dithiophosphate and diethyl ester in a mass ratio of about 1:1 are reacted, and dimethoxy dithiophosphate is slowly dripped into diethyl ester. The temperature is maintained at 60°C for 50 minutes, and then the temperature is raised to 80°C and maintained for more than 8 hours to terminate the reaction, thereby obtaining a crude malathion.
[0030] The preparation process adopts chemical purification method - alkali washing and evaporation to improve the quality of intermediate dimethoxy dithiophosphate, and adopts alkali washing, water washing and steam distillation to improve the quality of diethyl maleate. The purity of the prepared product can reach more than 90%.
[0031] The purity of malathion prepared in this example is 90.5%.
Claims
1. A method for synthesizing malathion in a laboratory, characterized in that: First, methanol reacts with phosphorus pentasulfide in a toluene medium to produce dimethoxy dithiophosphate, then maleic anhydride reacts with ethanol in a benzene and sulfuric acid medium to produce diethyl maleate, and finally malathion is synthesized from dimethoxy dithiophosphate and diethyl maleate.
2. The method for laboratory synthesis of malathion according to claim 1, characterized in that: The specific steps include: (1) Toluene and phosphorus pentasulfide are fully mixed, vacuum treated, and then methanol is added dropwise at a temperature of 50°C to 70°C for 1 h to 2 h. The reaction is maintained at a temperature of 40°C to 80°C for 2 h to 3 h to terminate the reaction. After cooling, a crude dimethoxy dithiophosphate is obtained. (2) Fully mix ethanol, maleic anhydride, benzene and sulfuric acid, heat to a slight boil, wait for 1.5 hours, and after the material temperature rises to 70°C to 90°C, maintain the temperature for more than 8 hours, terminate the reaction, cool and discharge the material to obtain crude diethyl maleate; (3) Dimethoxy dithiophosphate is slowly added dropwise into diethyl maleate, and the temperature is maintained at 50°C to 60°C for 1 hour. The temperature is then raised to 70°C to 80°C and maintained for at least 8 hours to terminate the reaction and obtain crude malathion.
3. The method for laboratory synthesis of malathion according to claim 2, characterized in that: In step (1), the mass ratio of toluene to phosphorus pentasulfide is 1:2-3, and the mass of methanol added is 0.4-0.7 times of phosphorus pentasulfide.
4. The method for laboratory synthesis of malathion according to claim 2, characterized in that: In step (2), the mass ratio of ethanol, maleic anhydride, benzene and sulfuric acid is 1:0.7-1.0:1-1.3:0.2-0.4, and the concentration of the sulfuric acid is ≥95%.
5. The method for laboratory synthesis of malathion according to claim 2, characterized in that: In step (3), the mass ratio of dimethoxy dithiophosphate to diethyl maleate is 1:
1.
6. The method for laboratory synthesis of malathion according to claim 2, characterized in that: The purity of the dimethoxy dithiophosphate obtained in step (1) is improved by alkali washing.
7. The method for laboratory synthesis of malathion according to claim 2, characterized in that: The purity of diethyl maleate obtained in step (2) is improved by alkali washing, water washing and distillation.