A safe preparation method for bromofen technical

Abstract

The present invention discloses a safe and clean preparation method for a bromofen technical, belonging to the field of chemical synthesis technology. 4,4′-dibromodiphenylacetic acid isopropyl ester is first dissolved in a DMF solvent, the flow rate is controlled, and the product is simultaneously pumped into a microreactor with hydrogen peroxide to obtain the bromofen technical. The preparation method of the present invention uses hydrogen peroxide as an oxidant to react with the liquid-liquid flow stream, which is a single-phase reaction and can greatly reduce the amount of oxidant used. The present invention also adopts a continuous feeding and discharging method in the microreactor to reduce the contact time between the excess oxidant and the product bromofen, thereby controlling the generation of peroxide and avoiding the occurrence of safety accidents.

Description

Technical Field

[0001] The present invention relates to a synthesis process of bromofen technical, in particular to a safe and clean synthesis process of bromofen. Background Art

[0002] Bromoxifen is also known as alpha,alpha-bis(p-bromophenyl)glycolic acid isopropyl ester; 4,4'-dibromobenzilic acid isopropyl ester; Acarol; Bromoxifen; Bromoxifen; 4,4'-dibromobenzilic acid isopropyl ester; and Mite Control. Bromoxifen has a broad spectrum of activity, a long residual effect, and low toxicity, making it a relatively safe acaricide for natural enemies, bees, and crops. It has a strong contact effect and is non-systemic, showing some killing effects on adult mites, nymphs, and eggs. Temperature fluctuations have little effect on its efficacy.

[0003] The current synthesis method for bromofen is to oxidize 4,4'-dibromodiphenylacetic acid isopropyl with an oxidant. For example, Chinese patent CN200710070384, a method for synthesizing bromofen, discloses using oxygen or air as the oxidant to produce the technical bromofen in a four-necked flask or reactor. According to Example 7 of the specification, the resulting bromofen content is greater than 95%, with a yield of 90.2%. This synthesis method yields a high product purity and yield. However, due to the use of oxygen as the oxidant, the oxidation reaction is a gas-liquid two-phase reaction, requiring a large amount of catalyst. The bromofen produced by the reaction will continue to react with excess oxygen in the reactor, producing peroxides. Oxygen is colorless and odorless. If it leaks, prolonged exposure to oxygen-rich concentrations can cause significant damage to the body. Therefore, the oxidation reaction in the existing bromofen synthesis method is a hazardous process, and careless operation can easily lead to production accidents. Summary of the Invention

[0004] The purpose of the present invention is to provide a safe and clean preparation method for bromofen.

[0005] The technical solution adopted in the present invention is:

[0006] A safe and clean method for preparing bromofen technical comprises dissolving 4,4′-dibromodiphenylacetic acid isopropyl ester in DMF solvent and pumping it simultaneously with hydrogen peroxide into a microreactor at a controlled flow rate to produce bromofen technical. The reaction equation for the synthesis process is shown in the figure:

[0007]

[0008] The present invention uses 4,4'-isopropyl dibromodiphenylacetate as a reaction raw material and hydrogen peroxide as an oxidant, thereby avoiding the use of oxygen. The hydrogen peroxide is in liquid form, and if leakage occurs, it can be discovered and handled in time, thereby reducing safety risks.

[0009] The preparation method of the present invention uses hydrogen peroxide as the oxidant for a liquid-liquid reaction with the raw material, resulting in a single-phase reaction that significantly reduces the amount of oxidant used. Furthermore, the process of the present invention employs continuous feeding and discharging within a microreactor, reducing the contact time between excess oxidant and the product, bromofen, thereby controlling the production of peroxides and avoiding safety accidents.

[0010] The preparation method of the present invention is easy to control and improves the safety factor of the preparation process while ensuring that the purity and yield of the reactants are not reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is the chromatogram of bromofen standard.

[0012] Figure 2 It is the chromatogram of the sample of Example 1 of the present invention. DETAILED DESCRIPTION

[0013] Example 1

[0014] First, 84.1 kg of 98% isopropyl 4,4′-dibromodiphenylacetate was uniformly dissolved in 200 kg of N,N-dimethylformamide. The temperature of the microreactor was controlled at 0-5°C. A flow pump was started to pump the DMF solution of 4,4′-dibromodiphenylacetate into the microreactor at a flow rate of 300 g / min. Simultaneously, a hydrogen peroxide flow pump was started to pump 16.3 kg of 50% hydrogen peroxide into the microreactor at a flow rate of 17.2 g / min. An appropriate amount of sodium sulfite was added to the microreactor outlet to destroy the excess hydrogen peroxide, and the solvent was then recovered under reduced pressure. After solvent recovery, 200 kg of water was added, and the mixture was heated to dissolve. The mixture was then cooled to 15-20°C, filtered, and the filter cake was dried to yield 85.6 kg of 95% technical bromopyralid, a yield of 95%.

[0015] Example 2

[0016] First, 84.1 kg of 98% isopropyl 4,4′-dibromodiphenylacetate was uniformly dissolved in 200 kg of N,N-dimethylformamide. The temperature of the microreactor was controlled at 25-30°C. The DMF solution of isopropyl 4,4′-dibromodiphenylacetate was pumped into the microreactor at a flow rate of 300 g / min using a flow pump. Simultaneously, 16.3 kg of 50% hydrogen peroxide was pumped into the microreactor at a flow rate of 17.2 g / min using a hydrogen peroxide pump. An appropriate amount of sodium sulfite was added to the microreactor outlet to destroy excess hydrogen peroxide, and the DMF solvent was then recovered under reduced pressure. After solvent recovery, 200 kg of water was added, and the mixture was heated to dissolve. The mixture was then cooled to 15-20°C, filtered, and the filter cake dried to yield 82.6 kg of 95.5% technical bromopyralid, a yield of 92.2%.

[0017] Example 3

[0018] First, 84.1 kg of 98% isopropyl 4,4'-dibromodiphenylacetate was uniformly dissolved in 200 kg of N,N-dimethylformamide. The temperature of the microreactor was controlled at 0-5°C. A flow pump was started to pump the DMF solution of 4,4'-dibromodiphenylacetate into the microreactor at a flow rate of 300 g / min. Simultaneously, a hydrogen peroxide flow pump was started to pump 24.5 kg of 50% hydrogen peroxide into the microreactor at a flow rate of 25.8 g / min. An appropriate amount of sodium sulfite was added to the outlet of the microreactor to destroy the excess hydrogen peroxide. The DMF solvent was then recovered under reduced pressure. After solvent recovery, 200 kg of water was added, and the mixture was heated to dissolve. The mixture was then cooled to 15-20°C, filtered, and the filter cake was dried to yield 82.1 kg of 95.2% technical bromopyralid, a yield of 91.3%.

[0019] refer to Figure 1 and Figure 2 As can be seen from Examples 1-3, the purity of bromofen obtained by the preparation method of the present invention reaches over 95%, and the product yield is high when the reaction temperature is controlled between 0°C and 5°C. In summary, the preparation method of the present invention improves the safety factor of the preparation process while ensuring the purity and yield of the reactants are not reduced.

Claims

1. A safe preparation method of bromofen technical, characterized by: 4,4'-dibromodiphenylacetic acid isopropyl ester is dissolved in DMF solvent at a controlled flow rate, and the mixture is simultaneously pumped into a microreactor at a temperature controlled at 0-30°C to react, thereby obtaining bromofen technical, wherein the pumping flow rate of the 4,4'-dibromodiphenylacetic acid isopropyl ester solution is 300 g / min, the pumping flow rate of the hydrogen peroxide is 17.2-25.8 g / min, the mass fraction of the 4,4'-dibromodiphenylacetic acid isopropyl ester is 98%, the mass fraction of the hydrogen peroxide is 50%, the molar ratio of the 4,4'-dibromodiphenylacetic acid isopropyl ester to the hydrogen peroxide is 1:1.2-1.8, and the added weight of the DMF solvent is 2.38 times that of the 4,4'-dibromodiphenylacetic acid isopropyl ester. The reaction equation is: 。

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