Novel method for synthesizing bifenthrin

Abstract

The invention belongs to the field of preparation of pesticide raw materials, and particularly relates to a preparation method of bifenthrin, which comprises the following steps: (1) mixing and reacting kung-fu acid, an inert organic solvent and a catalyst to generate a kung-fu acid anhydride solution; and (2) mixing biphenyl benzyl alcohol, an organic solvent and a phase transfer catalyst, then dropwise adding an acid-binding agent aqueous solution and the kung-fu anhydride solution obtained in the step (1), and after the reaction is finished, carrying out phase separation and reduced-pressure solvent recovery to obtain bifenthrin with the purity of more than 98%. The method is simple in operation process, bifenthrin with the purity larger than 98% can be obtained after phase separation and solvent recovery under reduced pressure, the recrystallization step of a traditional process is omitted, the yield reaches 98% or above, and the method is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of pesticide raw material preparation, and particularly relates to a method for preparing bifenthrin. Background Art

[0002] Bifenthrin is a pyrethroid insecticide and acaricide. It has the characteristics of strong knockdown, broad spectrum, high efficiency, rapidity and long residual effect. It mainly acts as a contact and stomach poison, and has no systemic effect. It can be used to control cotton bollworm, pink bollworm, tea geometrid, tea caterpillar, apple or hawthorn red spider, peach borer, aphid, cabbage worm, cabbage moth, citrus leafminer, etc. Compared with other pyrethroids, it also has repellent and antifeedant effects under the contact and stomach poison effects, and has a certain egg-killing ability. It has a good control effect on chewing pests and piercing-sucking pests. Due to the high risk of bifenthrin to the environment, this product is highly toxic to fish, shrimp, bees and silkworms. When using it, stay away from beekeeping areas and do not pour the residual liquid into rivers, ponds and fish ponds. It has gradually become a mainstream termite control agent in the field of sanitary medicine: Bifenthrin has a strong repellent effect on termite control, good stability in the soil, a long lasting effect, low toxicity to mammals and other advantages. It is currently the most widely used type of termite control agent in China.

[0003] The current biphenyl preparation process is to react gongfu acid and thionyl chloride to obtain gongfu acid chloride, which is then reacted with biphenyl benzyl alcohol to obtain bifenthrin. The bifenthrin obtained by this method has a low purity and needs to be recrystallized and purified to obtain bifenthrin with a purity of more than 98%, and the yield is low. The overall yield of the synthesis and recrystallization steps is only about 90%. Summary of the invention

[0004] In view of the problems that the synthesis process of bifenthrin in the prior art has many steps, complicated operation and low yield, the present invention provides a method for preparing bifenthrin with simple production process, low cost and high yield.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for preparing bifenthrin comprises the following steps:

[0007] (1) mixing caustic soda, an inert organic solvent and a catalyst to generate a caustic soda anhydride solution;

[0008] (2) mixing biphenyl benzyl alcohol, an organic solvent and a phase transfer catalyst, then dropwise adding an acid binding agent aqueous solution and the acid anhydride solution of step (1); after the reaction is completed, phase separation and solvent recovery under reduced pressure are performed to obtain bifenthrin with a purity greater than 98%.

[0009] Step (1) The reaction temperature is 150-200° C., the reaction time is 2-4 h, and the pressure is 0.4-0.8 MPa;

[0010] The reaction temperature of step (2) is -5 to 30°C, and the acid binding agent aqueous solution and the acid anhydride solution are added dropwise and reacted for 2 to 4 hours.

[0011] The catalyst in step (1) is one or more of 98% sulfuric acid, 98% nitric acid, and super acid resin; preferably 98% sulfuric acid;

[0012] In step (1), the mass ratio of the caustic soda to the catalyst is 1:0.001 to 0.1. Preferably, the mass ratio of the caustic soda to the catalyst is 1:0.001;

[0013] In step (2), the molar ratio of biphenyl benzyl alcohol to chlorinated acid is 1:1 to 1.5; preferably, the molar ratio of biphenyl benzyl alcohol to chlorinated acid is 1:1;

[0014] In step (2), the molar ratio of biphenyl benzyl alcohol to the acid binding agent is 1:1-2; preferably, the molar ratio of biphenyl benzyl alcohol to the acid binding agent is 1:1.1.

[0015] In step (2), the mass ratio of biphenyl benzyl alcohol to the phase catalyst is 1:0.001-0.1; preferably, the mass ratio of biphenyl benzyl alcohol to the catalyst is 1:0.001;

[0016] In step (2), the mass ratio of biphenyl benzyl alcohol to the organic solvent is 1:1 to 50. Preferably, the mass ratio of biphenyl benzyl alcohol to the organic solvent is 1:3.

[0017] The organic solvent in step (2) is one or more of toluene, xylene, and ethylbenzene; preferably, the organic solvent is toluene;

[0018] The acid-binding agent in step (2) is one or more of sodium hydroxide, sodium carbonate, and potassium carbonate; preferably, the acid-binding agent is sodium hydroxide;

[0019] The phase catalyst in step (2) is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and triethylamine; preferably, the phase catalyst is N,N-dimethylformamide.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] The method of the invention has a simple operation process, and after phase separation and reduced pressure solvent recovery, bifenthrin with a purity greater than 98% can be obtained, the recrystallization step of the traditional process is omitted, and the yield reaches more than 98%, and is suitable for industrial production.

[0022] The method of the invention can obtain bifenthrin with a purity greater than 98% after phase separation and reduced pressure solvent recovery, and the yield is greater than 98%. The process is simple to operate, has fewer steps, and can directly obtain bifenthrin with higher purity. DETAILED DESCRIPTION

[0023] Example 1

[0024] (1) 100 g of tadalafil, 100 g of toluene and 0.1 g of 98% sulfuric acid were placed in an autoclave and heated to 165° C. and a pressure of 0.5 MPa, and reacted for 2 hours to generate a tadalafil anhydride solution;

[0025] (2) In another reaction kettle, 81.6 g of benzyl alcohol, 191.2 g of toluene, and 0.1 g of N,N-dimethylformamide were added, and at 0° C., an aqueous sodium hydroxide solution (18.2 g of sodium hydroxide, 42.5 g of water, and a molar ratio of sodium hydroxide to benzyl alcohol of 1:1.1) and the anhydride solution of gong gong acid prepared in the above step were added dropwise, and the molar ratio of benzyl alcohol to gong gong acid was 1:1. After 2 hours of the completion of the reaction, 171.1 g of bifenthrin with a purity greater than 98% was obtained after phase separation and solvent recovery under reduced pressure, with a yield of 98.23%.

[0026] Example 2

[0027] (1) 100 g of tadalafil, 100 g of toluene and 0.1 g of 98% sulfuric acid were placed in an autoclave and heated to 165° C. and a pressure of 0.5 MPa, and reacted for 2 hours to generate a tadalafil anhydride solution;

[0028] (2) In another reaction kettle, 74.2 g of benzyl alcohol, 191.2 g of toluene, and 0.1 g of N,N-dimethylformamide were added, and at 0° C., an aqueous sodium hydroxide solution (18.2 g of sodium hydroxide, 42.5 g of water, and a molar ratio of sodium hydroxide to benzyl alcohol of 1:1.1) and the anhydride solution of gong gong acid prepared in the above step were added dropwise, and the molar ratio of benzyl alcohol to gong gong acid was 1:1.1. After 2 hours of the completion of the dropwise addition, the reaction was completed, and the solvent was recovered by phase separation and reduced pressure to obtain 150.3 g of bifenthrin with a purity greater than 98%, with a yield of 98.04%.

[0029] Example 3

[0030] (1) 100 g of tadalafil, 100 g of toluene and 0.1 g of 98% sulfuric acid were placed in an autoclave and heated to 165° C. and a pressure of 0.5 MPa, and reacted for 2 hours to generate a tadalafil anhydride solution;

[0031] (2) In another reaction kettle, 81.6 g of benzyl alcohol, 191.2 g of toluene, and 0.1 g of N,N-dimethylacetamide were added, and at 0° C., an aqueous sodium hydroxide solution (18.2 g of sodium hydroxide, 42.5 g of water, and a molar ratio of sodium hydroxide to benzyl alcohol of 1:1.1) and the anhydride solution of gong gong acid prepared in the above step were added dropwise, and the molar ratio of benzyl alcohol to gong gong acid was 1:1. After 2 hours of the completion of the dropwise addition, 171.0 g of bifenthrin with a purity greater than 98% was obtained after phase separation and reduced pressure solvent recovery, with a yield of 98.16%.

[0032] Example 4

[0033] (1) 100 g of tadalafil, 100 g of toluene and 0.1 g of 98% sulfuric acid were placed in an autoclave and heated to 175° C. and a pressure of 0.5 MPa, and reacted for 2 hours to generate a tadalafil anhydride solution;

[0034] (2) In another reaction kettle, 81.6 g of benzyl alcohol, 191.2 g of toluene, and 0.1 g of N,N-dimethylformamide were added, and at 0° C., an aqueous sodium hydroxide solution (24.8 g of sodium hydroxide, 57.9 g of water, and a molar ratio of sodium hydroxide to benzyl alcohol of 1:1.5) and the anhydride solution of gong gong acid prepared in the above step were added dropwise, and the molar ratio of benzyl alcohol to gong gong acid was 1:1. After 2 hours of the completion of the reaction, 170.7 g of bifenthrin with a purity greater than 98% was obtained after phase separation and reduced pressure solvent recovery, with a yield of 98.01%.

[0035] Example 5

[0036] (1) 100 g of tadalafil, 100 g of toluene and 0.1 g of 98% sulfuric acid were placed in an autoclave and heated to 165° C. and a pressure of 0.5 MPa, and reacted for 2 hours to generate a tadalafil anhydride solution;

[0037] (2) In another reaction kettle, 81.6 g of benzyl alcohol, 191.2 g of toluene, and 0.1 g of N,N-dimethylacetamide were added, and at 0° C., an aqueous sodium carbonate solution (43.7 g of sodium carbonate, 131.1 g of water, and a molar ratio of sodium hydroxide to benzyl alcohol of 1:1.1) and the anhydride solution of kung fu acid prepared in the above step were added dropwise, and the molar ratio of benzyl alcohol to kung fu acid was 1:1. After 2 hours of the completion of the reaction, 171.0 g of bifenthrin with a purity greater than 98% was obtained after phase separation and solvent recovery under reduced pressure, with a yield of 98.16%.

[0038] Comparative Example 1

[0039] (1) 100 g of gongfu acid, 200 g of toluene, and 0.1 g of N,N-dimethylacetamide were placed in a reaction kettle, the temperature was lowered to 15° C., 52 g of thionyl chloride was added dropwise, and after the addition was completed, the temperature was kept for 5 hours, and then the toluene was recovered under reduced pressure to obtain gongfu acid chloride;

[0040] (2) In another reaction kettle, 81.6 g of benzyl alcohol, 326.4 g of toluene, and 0.1 g of N,N-dimethylacetamide were added, and at 0° C., an aqueous sodium hydroxide solution (18.2 g of sodium hydroxide, 42.5 g of water, and a molar ratio of sodium hydroxide to benzyl alcohol of 1:1.1) and the acyl chloride prepared in the above step were added dropwise at the same time, and the molar ratio of benzyl alcohol to acyl chloride was 1:1. After 2 hours of the completion of the reaction, the crude bifenthrin was obtained after phase separation and solvent recovery under reduced pressure. The crude bifenthrin was recrystallized by adding 300 g of isopropanol. After recrystallization, the solvent of the bifenthrin was removed under reduced pressure to obtain 154.8 g of bifenthrin, with a yield of 88.86%.

[0041] It can be seen from the above examples and comparative examples that comparative example 1 changes and adopts the current preparation process of bifenthrin, which is cumbersome to operate, needs to be recrystallized to obtain bifenthrin, and the yield is only 88.86%, which is much lower than the yield of more than 98% in the embodiment of the present invention. Therefore, the embodiment of the present invention controls specific reaction conditions to prepare bifenthrin with a purity of more than 98%, omits the recrystallization step of the traditional process, and the yield reaches more than 98%, which is suitable for industrial production.

Claims

1. A method for preparing bifenthrin, characterized in that: The steps include: (1) mixing caustic soda, an inert organic solvent and a catalyst to generate a caustic soda anhydride solution; (2) mixing biphenyl benzyl alcohol, an organic solvent and a phase transfer catalyst, then dropwise adding an acid binding agent aqueous solution and the acid anhydride solution of step (1); after the reaction is completed, phase separation and solvent recovery under reduced pressure are performed to obtain bifenthrin with a purity greater than 98%.

2. The method for preparing bifenthrin according to claim 1, wherein: The reaction temperature of step (1) is 150-200° C., the reaction time is 2-4 hours, and the pressure is 0.4-0.8 MPa.

3. The preparation method of bifenthrin according to claim 1, characterized in that: The reaction temperature of step (2) is -5 to 30°C, and the acid binding agent aqueous solution and the acid anhydride solution are added dropwise and reacted for 2 to 4 hours.

4. The method for preparing bifenthrin according to claim 1, wherein: The catalyst in step (1) is one or more of 98% sulfuric acid, 98% nitric acid, and super acid resin; In step (1), the mass ratio of the acid to the catalyst is 1:0.001-0.

1.

5. The method for preparing bifenthrin according to claim 1, wherein: The molar ratio of biphenyl benzyl alcohol to the acid in step (2) is 1:1 to 1.5; the molar ratio of biphenyl benzyl alcohol to the acid binding agent in step (2) is 1:1 to 2.

6. The method for preparing bifenthrin according to claim 1, wherein: The mass ratio of biphenyl benzyl alcohol to the phase catalyst in step (2) is 1:0.001-0.1; the mass ratio of biphenyl benzyl alcohol to the organic solvent in step (2) is 1:1-50.

7. The method for preparing bifenthrin according to claim 1, wherein: The organic solvent in step (2) is one or more of toluene, xylene and ethylbenzene; The acid binding agent in step (2) is one or more of sodium hydroxide, sodium carbonate and potassium carbonate; The phase catalyst in step (2) is one or more of N,N-dimethylformamide, N,N-dimethylacetamide and triethylamine.