Process for the preparation of diethyl methyl phosphite and apparatus therefor

Abstract

The application discloses a preparation method and equipment of diethyl methyl phosphite, and belongs to the technical field of chemistry and chemical industry. The preparation method of diethyl methyl phosphite comprises the following steps: (1) reacting aluminum powder and chloromethane to obtain a sesqui-reaction solution; (2) mixing phosphorus trichloride, a solid acid catalyst and the sesqui-reaction solution and reacting; (3) removing the phosphorus trichloride, adding sodium chloride and performing a dissociation reaction to obtain methyl phosphorus dichloride and sodium tetrachloroaluminate; and (4) putting the methyl phosphorus dichloride, ethanol, liquid nitrogen and isohexane into an esterification reaction kettle, performing an esterification reaction, purifying and obtaining pure diethyl methyl phosphite. The application further discloses an esterification reaction kettle which comprises a barrel, a feeding pipe, a stirring main shaft and a special-shaped umbrella body, and the surface of the special-shaped umbrella body is provided with grooves. The preparation method has high product purity and high yield, and the equipment is uniformly stirred, so that the reaction can be completely performed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of chemical engineering, and particularly relates to a preparation method and equipment of diethyl methyl phosphite. BACKGROUND

[0002] Diethyl methyl phosphite is an important organic chemical intermediate of pesticides, medicines and synthetic materials, and is widely used in the synthesis of organophosphorus pesticides, such as the herbicide amicarbazone, the alkylthiophosphonate insecticide methyl parathion, and the like. In addition, it can also be used as a raw material or additive for the synthesis of flame retardants, building materials, and the like. There are two traditional routes for synthesizing diethyl methyl phosphite; the first route is to synthesize diethyl methyl phosphite from methyl phosphinic dichloride and anhydrous ethanol, which has harsh reaction conditions in the synthesis process, a low product yield, and the use of noble metal as a catalyst, resulting in high production cost; the second route is to synthesize diethyl methyl phosphite from chloro-diethyl phosphite and methyl magnesium chloride through a Grignard reaction, which has many side reactions in the synthesis process of the intermediate chloro-diethyl phosphite, the main product is easily oxidized or hydrolyzed, and the total reaction yield is not high.

[0003] The production of diethyl methyl phosphite has low purity and low total yield. In the production process of diethyl methyl phosphite, a plurality of equipment is needed, and the mixing part is the most important mixing component in the stirring related equipment. During stirring, whether the material mixing is uniform will directly affect the reaction rate of diethyl methyl phosphite. In the prior art, the material mixing is often performed by the shearing force of the blade, and such mixing mode is not uniform. After all the materials are added to the mixing box, stirring is performed, which can not mix uniformly in local areas, thereby causing waste of reactants and reducing the conversion rate of the reactants. SUMMARY

[0004] Therefore, the present application provides a preparation method and equipment of diethyl methyl phosphite to overcome the technical problems of low purity, low yield, uneven material mixing, and low conversion rate of reactants in the preparation of diethyl methyl phosphite in the prior art.

[0005] The application discloses a preparation method of diethyl methyl phosphite, which comprises the following steps: (1) adding aluminum powder into a double half reaction kettle, starting stirring, and feeding liquid chloromethane with a concentration of 100% into a chloromethane gasification measuring tank through a chloromethane feeding pump, weighing and measuring, starting steam of a gasification measuring tank jacket (gasification conditions are as follows: temperature 30 DEG C, saturated steam pressure 0.5-0.6 MPa), continuously feeding chloromethane gas in the measuring tank into the reaction kettle for double half reaction to generate methyl aluminum dichloride and dimethyl aluminum chloride, the molar ratio of aluminum powder and chloromethane is 1:1.55, the reaction temperature of the double half reaction is 120-130 DEG C, the reaction pressure is 0.2-0.3 MPa, and the reaction is completed when the pressure reaches 0.4 MPa, and the double half reaction liquid is obtained;

[0006] (2) adding phosphorus trichloride into a phosphorization reaction kettle after measuring, starting stirring, adding a solid acid catalyst into the double half reaction liquid, controlling the reaction temperature to be 50-60 DEG C, not more than 80 DEG C, and adding 5h to generate a complex, and obtaining the complex mixed liquid after the reaction is completed;

[0007] (3) distilling the complex mixed liquid, removing phosphorus trichloride, adding sodium chloride, and carrying out dissociation reaction, and obtaining methyl phosphorus dichloride and sodium tetrachloroaluminate (by-product is reserved for other use) after the reaction is completed;

[0008] (4) putting the methyl phosphorus dichloride, ethanol, liquid ammonia and isohexane into an esterification reaction kettle, adding the liquid ammonia into the reaction liquid in the form of drop, carrying out esterification reaction, and obtaining crude diethyl methyl phosphite at a reaction temperature of 25-35 DEG C;

[0009] (5) taking the crude diethyl methyl phosphite to carry out pressure filtration and crude ester rectification, and obtaining pure diethyl methyl phosphite.

[0010] The preparation process of diethyl methyl phosphite in the application is as follows:

[0011]

[0012] A device based on the diethyl methyl phosphite is disclosed in the preceding description, and the esterification reaction kettle comprises a barrel, a plurality of feeding pipes arranged on the top of the barrel and communicated with the barrel, a stirring main shaft arranged at the bottom of the barrel and connected with a rotating electrode, and a special-shaped umbrella body fixedly connected with the stirring main shaft, and the surface of the special-shaped umbrella body is provided with grooves.

[0013] As preferred, the surface of the special-shaped umbrella body is provided with helical grooves.

[0014] As preferred, the surface of the special-shaped umbrella body is provided with a plurality of linear recesses which are not communicated with each other.

[0015] As preferred, a plurality of stirring supports are fixed on the stirring spindle, and the stirring support comprises a first stirring rod which is inclined downward and a second stirring rod which is extended upward.

[0016] As preferred, the surface of the inner wall of the barrel body is uneven.

[0017] As preferred, the inner diameter of the barrel body is greater than the maximum diameter of the special-shaped umbrella body.

[0018] The preparation method of the methyl phosphite diethyl ester comprises the following steps: firstly, complexation reaction is carried out by using aluminum powder, phosphorus trichloride and methyl chloride to generate a complex; then, the complex is aged (the complexation reaction is enhanced) and the phosphorus trichloride is distilled under reduced pressure; then, methyl phosphonodichloridate is prepared by using the concentrated complex and sodium chloride through a decomplexation reaction; then, the methyl phosphonodichloridate, ammonia gas and ethanol are subjected to esterification reaction to generate a crude methyl phosphite diethyl ester; then, the crude methyl phosphite diethyl ester is centrifuged and washed to obtain by-product ammonium chloride; and then, the centrifuged crude methyl phosphite diethyl ester is refined by rectification to obtain the finished product of the methyl phosphite diethyl ester. The prepared methyl phosphite diethyl ester has high purity and high yield. The device for preparing the methyl phosphite diethyl ester is also provided, wherein the design of the special-shaped umbrella body can effectively improve the uniformity of material mixing in the reaction process, so that the reaction can be fully carried out to achieve the purpose of improving the yield, and the device has simple structure and is easy to operate and maintain. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The device structure schematic diagram of the methyl phosphite diethyl ester provided in the specific embodiment of the present application is shown in the figure;

[0020] Figure 2 The device structure schematic diagram of the methyl phosphite diethyl ester provided in the specific embodiment of the present application is shown in the figure;

[0021] Figure 3 The device structure schematic diagram of the methyl phosphite diethyl ester provided in the specific embodiment of the present application is shown in the figure;

[0022] Figure 4 The device structure schematic diagram of the methyl phosphite diethyl ester provided in the specific embodiment of the present application is shown in the figure;

[0023] Figure 5 The device structure schematic diagram of the methyl phosphite diethyl ester provided in the specific embodiment of the present application is shown in the figure.

[0024] The device structure schematic diagram of the methyl phosphite diethyl ester provided in the specific embodiment of the present application is shown in the figure; Detailed Implementation

[0025] The present invention will now be described in detail with reference to specific embodiments.

[0026] Example 1

[0027] A method for preparing diethyl methyl phosphite includes the following steps;

[0028] (1) Add aluminum powder to the sesqui-half reaction vessel, start stirring, and pump 100% chloromethane liquid into the chloromethane vaporization metering tank through the chloromethane feed pump. Weigh and measure the liquid. Turn on the steam jacket of the vaporization metering tank (vaporization conditions: temperature 30℃, saturated vapor pressure 0.5-0.6MPa). After being metered by the vaporization metering tank, the chloromethane gas in the metering tank is continuously fed into the reaction vessel to carry out the sesqui-half reaction, generating methyl aluminum dichloride and dimethyl aluminum chloride. The molar ratio of aluminum powder to chloromethane is 1:1.55. The reaction temperature of the sesqui-half reaction is 120℃ and the reaction pressure is 0.2MPa. When a certain pressure of 0.4MPa is reached, the reaction ends and the sesqui-half reaction liquid is obtained.

[0029] (2) Phosphorus trichloride was metered and added to the phosphating reactor. The molar ratio of sesqui-part reaction solution to 2600L of 99% liquid phosphorus trichloride was 1:3.33. Stirring was started, and solid acid catalyst and sesqui-part reaction solution were added. The reaction temperature was controlled at 50 degrees Celsius and not more than 80 degrees Celsius. After 5 hours of dropwise addition, a complex was generated. After the reaction was completed, a complex mixture was obtained.

[0030] (3) Distill the complex mixture to remove phosphorus trichloride, add sodium chloride to carry out the dissociation reaction, and after the reaction is completed, methyl phosphorus dichloride and sodium tetrachloroaluminate are obtained (byproducts are reserved for other uses);

[0031] (4) The methyl phosphorus dichloride, ethanol, liquid nitrogen and isohexane are placed in the esterification reaction vessel 1. Liquid ammonia is added dropwise to the reaction solution to carry out the esterification reaction. The reaction temperature of the esterification reaction is 25°C to obtain crude methyl diethyl phosphite.

[0032] (5) Crude diethyl methyl phosphite was subjected to pressure filtration and crude ester distillation to obtain pure diethyl methyl phosphite.

[0033] Please see Figures 1 to 4 An apparatus based on the aforementioned diethyl methyl phosphite, wherein the esterification reactor 1 includes a cylindrical body 2, multiple feed pipes 3 disposed at the top of the cylindrical body and communicating with the cylindrical body 2, a stirring spindle 4 disposed at the bottom of the cylindrical body 2 and connected to a rotating electrode, and an irregularly shaped umbrella body 5 fixedly connected to the stirring spindle 4. A discharge port is provided at a corresponding position of the cylindrical body 2, and a groove 6 is provided on the surface of the irregularly shaped umbrella body 5.

[0034] The surface of the special-shaped umbrella body 5 is provided with a spiral groove 6. Figure 4 The figure is a top view of the special-shaped umbrella body 5 in this embodiment. When various materials to be mixed fall on the surface of the special-shaped umbrella body 5, the materials to be mixed will rotate under the action of shearing force as the special-shaped umbrella body 5 rotates, and the various materials will collide with each other on the surface of the special-shaped umbrella body 5 to mix, and then slide downward along the special-shaped umbrella body 5 under the action of gravity to fall into the barrel 2 for further mixing. The spiral groove 6 can guide the flow of liquid materials into the barrel 2 as a flow guide.

[0035] A plurality of stirring supports 41 are fixed on the stirring main shaft 4, and the stirring support 41 includes a first stirring rod 411 inclined downward and a second stirring rod 412 extended upward. The stirring supports arranged in this way can mix the materials more uniformly, avoid local accumulation of materials during the stirring and mixing process, and ensure that the reaction proceeds fully.

[0036] The surface of the inner wall of the barrel 2 is uneven. The inner diameter of the barrel 2 is greater than the maximum diameter of the special-shaped umbrella body 5. The uneven structure of the inner wall of the barrel 2 has two effects. First, when the mixed liquid droplets carried by the surface of the special-shaped umbrella body 5 during rotation are separated from the special-shaped umbrella body 5 due to excessive centrifugal force, they will collide with the uneven inner wall of the barrel 2, which can realize the mixing of the liquid droplets again. Second, during the stirring process of the stirring supports 41, the liquid in the barrel 2 is rotated, and the liquid contacts the uneven inner wall of the barrel 2, which changes the direction of rotation and increases the uniformity of stirring.

[0037] Embodiment 2

[0038] A preparation method of methyl phosphite diethyl ester, comprising the following steps:

[0039] (1) aluminum powder is added into a half-reaction kettle, stirring is started, 600L (850kg) of liquid of chloromethane with a concentration of 100% is pumped into a chloromethane gasification metering tank through a chloromethane material pumping pump, is weighed and metered, a steam jacket of the gasification metering tank is started (the gasification conditions are: temperature 30℃, saturated steam pressure 0.5-0.6MPa), the chloromethane gas in the metering tank is continuously fed into the reaction kettle for half-reaction, methyl aluminum dichloride and dimethyl aluminum chloride are generated, the molar ratio of aluminum powder to chloromethane is 1:1.55, the reaction temperature of the half-reaction is 130℃, the reaction pressure is 0.3MPa, when a certain pressure 0.4Mpa is reached, the reaction is ended, and a half-reaction liquid is obtained;

[0040] (2) phosphorus trichloride is metered and added to the phosphorization reactor, the molar ratio of the half reaction liquid to 99% liquid phosphorus trichloride 2600L is 1:3.33, stirring is started, the solid acid catalyst is added to the half reaction liquid, the reaction temperature is controlled at 60 degrees Celsius, not more than 80 degrees Celsius, the complex is generated after 5 hours of dropwise addition, and the complex mixture liquid is obtained after the reaction is completed;

[0041] (3) the complex mixture liquid is distilled to remove phosphorus trichloride, sodium chloride is added to perform dissociation reaction, and methyl phosphorus dichloride and sodium tetrachloroaluminate (by-product to be used separately) are obtained after the reaction is completed;

[0042] (4) the methyl phosphorus dichloride, ethanol, liquid ammonia, and isohexane are put into an esterification reactor 1, the liquid ammonia is in the form of dropwise addition and is gradually added to the reaction liquid to perform esterification reaction, the reaction temperature of the esterification reaction is 35 degrees Celsius, and the crude methyl phosphite is obtained;

[0043] (5) the crude methyl phosphite is subjected to pressure filtration and crude ester rectification to obtain pure methyl phosphite.

[0044] Please refer to Figure 1 、 Figure 2 、 Figure 5 , a methyl phosphite device based on the foregoing, the esterification reactor 1 comprises a barrel 2, a plurality of feeding pipes 3 arranged on the top of the barrel and in communication with the barrel 2, a stirring main shaft 4 arranged at the bottom of the barrel 2 and connected with a rotating electrode, and a special-shaped umbrella body 5 fixedly connected with the stirring main shaft 4, wherein the surface of the special-shaped umbrella body 5 is provided with grooves 6.

[0045] Preferably, the surface of the special-shaped umbrella body 5 is provided with a plurality of linear grooves 6 that are not in communication with each other.

[0046] Preferably, a plurality of stirring supports 41 are fixedly connected to the stirring main shaft 4, and the stirring support 41 comprises a first stirring rod 411 inclined downward and a second stirring rod 412 extended upward.

[0047] Preferably, the surface of the inner wall of the barrel 2 is uneven.

[0048] Preferably, the inner diameter of the barrel 2 is greater than the maximum diameter of the special-shaped umbrella body 5.

[0049] Example 3

[0050] A preparation method of methyl phosphite, comprising the following steps:

[0051] (1) aluminum powder is added into the semi-reaction kettle, stirring is started, 600L (850kg) of liquid methyl chloride with a concentration of 100% is pumped into the methyl chloride gasification metering tank by a methyl chloride pump, the weight is measured, the jacket steam of the gasification metering tank is started (the gasification conditions are: temperature 30℃, saturated steam pressure 0.5-0.6MPa), the methyl chloride gas in the metering tank is continuously fed into the reaction kettle for semi-reaction, the molar ratio of aluminum powder to methyl chloride is 1:1.55, the reaction temperature of the semi-reaction is 125℃, the reaction pressure is 0.25MPa, when the pressure reaches 0.4MPa, the reaction is completed, and the semi-reaction liquid is obtained;

[0052] (2) phosphorus trichloride is measured and then added into the phosphorization reaction kettle, the molar ratio of the semi-reaction liquid to 2600L of liquid phosphorus trichloride with a concentration of 99% is 1:3.33, stirring is started, the solid acid catalyst is added into the semi-reaction liquid, the reaction temperature is controlled to be less than 80℃, the complex is generated after 5h of dropwise addition, and the complex mixture liquid is obtained after the reaction is completed;

[0053] (3) the complex mixture liquid is distilled to remove phosphorus trichloride, sodium chloride is added, and dissociation reaction is carried out, and methyl phosphorus dichloride and sodium tetrachloroaluminate (by-product to be used separately) are obtained after the reaction is completed;

[0054] (4) the methyl phosphorus dichloride, ethanol, liquid ammonia, and isohexane are put into the esterification reaction kettle 1, the liquid ammonia is in the form of dropwise addition and is gradually added into the reaction liquid, esterification reaction is carried out, the reaction temperature of the esterification reaction is 30℃, and the crude methyl phosphite diethyl ester is obtained;

[0055] (5) the crude methyl phosphite diethyl ester is taken out, pressure filtration and crude ester rectification are carried out, and pure methyl phosphite diethyl ester is obtained.

[0056] The esterification reaction kettle 1 used in this embodiment is the same as that in embodiment 1.

[0057] The purity and total yield of the methyl phosphite diethyl ester in embodiments 1 to 3 are measured after the reaction is completed, and the results are as follows:

[0058] Group Example 1 Example 2 Example 3 Purity % 98.6 98.3 97.2 Overall reaction yield % 82.4 81.6 79.7

[0059] The specific embodiments of the application described above do not constitute a limitation on the protection scope of the application. Any various other corresponding changes and modifications made according to the technical concept of the application should be included in the protection scope of the claims of the application.

Claims

1. A method for preparing diethyl methyl phosphite, characterized in that, Includes the following steps; (1) Add aluminum powder to a sesqui-half reaction vessel, and purge chloromethane gas into the vessel while stirring to carry out a sesqui-half reaction and obtain a sesqui-half reaction solution. (2) Add phosphorus trichloride to the phosphating reactor, add solid acid catalyst and sesqui-reaction solution, and after the reaction is completed, a complex mixture is obtained; (3) Distill the complex mixture to remove phosphorus trichloride, add sodium chloride to carry out a dissociation reaction, and after the reaction is completed, methyl phosphorus dichloride and sodium tetrachloroaluminate are obtained. (4) The methyl phosphorus dichloride, ethanol, liquid nitrogen and isohexane are placed in an esterification reactor to carry out an esterification reaction to obtain crude methyl diethyl phosphite; (5) Crude diethyl methyl phosphite was subjected to pressure filtration and crude ester distillation to obtain pure diethyl methyl phosphite. The esterification reactor includes a cylinder, multiple feed pipes disposed at the top of the cylinder and communicating with the cylinder, a stirring shaft disposed at the bottom of the cylinder and connected to a rotating electrode, and an irregularly shaped umbrella body fixedly connected to the stirring shaft. The surface of the irregularly shaped umbrella body is provided with a spiral groove or multiple non-communicating straight grooves, and the surface of the inner wall of the cylinder is uneven.

2. The method for preparing diethyl methyl phosphite according to claim 1, characterized in that, The reaction temperature of the sesqui-half reaction is 120-130℃, and the reaction pressure is 0.2-0.3MPa.

3. The method for preparing diethyl methyl phosphite according to claim 2, characterized in that, The molar ratio of aluminum powder to chloromethane in step (1) is 1:1.

55.

4. The method for preparing diethyl methyl phosphite according to claim 1, characterized in that, The reaction temperature for the esterification reaction in step (4) is 25-35℃.

5. The method for preparing diethyl methyl phosphite according to claim 1, characterized in that, Multiple stirring supports are fixedly connected to the stirring spindle. Each stirring support includes a first stirring rod that tilts downward and a second stirring rod that extends upward.

6. The method for preparing diethyl methyl phosphite according to claim 1, characterized in that, The inner diameter of the cylinder is greater than the maximum diameter of the irregularly shaped umbrella.

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