Synthesis method of sulfur-free 2-bromo-4-fluoroacetanilide

Abstract

The invention discloses a synthesis method of sulfur-free 2-bromo-4-fluoroacetanilide, and belongs to the technical field of chemical engineering. The synthesis method of sulfur-free 2-bromo-4-fluoroacetanilide comprises: step 1, adding a palladium catalyst into p-fluoroaniline, adding acetic anhydride and gasified bromine into p-fluoroaniline according to a molar ratio of 1:1-1:3 at a temperatureranging from room temperature to 50DEG C, then performing heating to 60-80DEG C and conducting heat preservation for 1-24h until the p-fluoroaniline is completely reacted, and then filtering out thepalladium catalyst; and step 2, adding a sodium formate or sodium oxalate aqueous solution for decoloration and crystallization, and carrying out solid-liquid separation on the crystal to obtain 2-bromo-4-fluoroacetanilide without sulfur residue. According to the method, the 2-bromo-4-fluoroacetanilide can be synthesized in a green and efficient manner, and no sulfur residue exists.

Description

technical field

[0001] The invention relates to a technology in the field of chemical industry, in particular to a method for synthesizing sulfur-free 2-bromo-4-fluoroacetanilide. Background technique

[0002] 2-Bromo-4-fluoroacetanilide (BFA) is an important fluorine-containing fine chemical intermediate. It is not only the raw material of sulfa drugs, but also used as an analgesic and antipyretic. A new type of fluorine-containing pesticide with high efficiency, non-toxicity and low residue.

[0003] There are many synthetic methods of 2-bromo-4-fluoroacetanilide, among which there are mainly three synthetic methods of bromination, acetylation, fluorination, acetylation and bromination. These three synthetic methods are used to improve bromine Efficiency requires the use of oxidants, so subsequent use requires the use of sulfur-containing reducing agents, so sulfur is inevitably contained in the product. If the content of sulfur in the product cannot be effectively contr...

Examples

Embodiment 1

[0022] Add 200L of chlorobenzene, 100L of p-fluoroaniline, and 1kg of palladium catalyst in a 1000L kettle, stir evenly for use, raise the temperature to 50 degrees Celsius, add acetic anhydride dropwise through the high-level tank, and bromine passes through the vaporizer and gas distributor to control the concentration of acetic anhydride and bromine. The adding speed is a molar ratio of 1:2, the molar ratio of acetic anhydride to p-fluoroaniline is 1:1.05, and the molar ratio of bromine to p-fluoroaniline is 1:2.1. After the dropwise addition, the temperature was raised to 70 degrees centigrade and kept for 4 hours to react. During the reaction, air was bubbled at a rate of 0.5 L / min to replenish oxygen. After the reaction, the palladium catalyst was removed by filtration. Then add 200L of 10% sodium formate, and more precipitates are generated at this time. After solid-liquid separation, the solid is 2-bromo-4-fluoroacetanilide, and the content of 2-bromo-4-fluoroacetanilid...

Embodiment 2

[0024] Add 200L of chlorobenzene, 100L of p-fluoroaniline, and 1kg of palladium catalyst in a 1000L kettle, stir evenly for use, raise the temperature to 50 degrees Celsius, add acetic anhydride dropwise through the high-level tank, and bromine passes through the vaporizer and gas distributor to control the concentration of acetic anhydride and bromine. The adding speed is a molar ratio of 1:2, the molar ratio of acetic anhydride to p-fluoroaniline is 1:1.05, and the molar ratio of bromine to p-fluoroaniline is 1:2.1. After the dropwise addition, the temperature was raised to 70 degrees centigrade and kept for 4 hours to react. During the reaction, air was bubbled at a rate of 0.5 L / min to replenish oxygen. After the reaction, the palladium catalyst was removed by filtration. Then add 200L of 10% sodium oxalate, more precipitates are generated at this time, after solid-liquid separation, the solid is 2-bromo-4-fluoroacetanilide, the content of 2-bromo-4-fluoroacetanilide is hig...

Embodiment 3

[0026] Add 200L of chlorobenzene, 100L of p-fluoroaniline, and 1kg of palladium catalyst in a 1000L kettle, stir evenly for use, raise the temperature to 50 degrees Celsius, add acetic anhydride dropwise through the high-level tank, and bromine passes through the vaporizer and gas distributor to control the concentration of acetic anhydride and bromine. The adding speed is a molar ratio of 1:1, the molar ratio of acetic anhydride to p-fluoroaniline is 1:1.05, and the molar ratio of bromine to p-fluoroaniline is 1:1.05. After the dropwise addition, the temperature was raised to 70 degrees centigrade and kept for 4 hours to react. During the reaction, air was bubbled at a rate of 0.5 L / min to replenish oxygen. After the reaction, the palladium catalyst was removed by filtration. Then add 200L of 10% sodium formate, and more precipitates are generated at this time. After solid-liquid separation, the solid is 2-bromo-4-fluoroacetanilide, and the content of 2-bromo-4-fluoroacetanili...

technical field

[0001] The invention relates to a technology in the field of chemical industry, in particular to a method for synthesizing sulfur-free 2-bromo-4-fluoroacetanilide. Background technique

[0002] 2-Bromo-4-fluoroacetanilide (BFA) is an important fluorine-containing fine chemical intermediate. It is not only the raw material of sulfa drugs, but also used as an analgesic and antipyretic. A new type of fluorine-containing pesticide with high efficiency, non-toxicity and low residue.

[0003] There are many synthetic methods of 2-bromo-4-fluoroacetanilide, among which there are mainly three synthetic methods of bromination, acetylation, fluorination, acetylation and bromination. These three synthetic methods are used to improve bromine Efficiency requires the use of oxidants, so subsequent use requires the use of sulfur-containing reducing agents, so sulfur is inevitably contained in the product. If the content of sulfur in the product cannot be effectively contr...

Examples

Embodiment 1

[0022] Add 200L of chlorobenzene, 100L of p-fluoroaniline, and 1kg of palladium catalyst in a 1000L kettle, stir evenly for use, raise the temperature to 50 degrees Celsius, add acetic anhydride dropwise through the high-level tank, and bromine passes through the vaporizer and gas distributor to control the concentration of acetic anhydride and bromine. The adding speed is a molar ratio of 1:2, the molar ratio of acetic anhydride to p-fluoroaniline is 1:1.05, and the molar ratio of bromine to p-fluoroaniline is 1:2.1. After the dropwise addition, the temperature was raised to 70 degrees centigrade and kept for 4 hours to react. During the reaction, air was bubbled at a rate of 0.5 L / min to replenish oxygen. After the reaction, the palladium catalyst was removed by filtration. Then add 200L of 10% sodium formate, and more precipitates are generated at this time. After solid-liquid separation, the solid is 2-bromo-4-fluoroacetanilide, and the content of 2-bromo-4-fluoroacetanilid...

Embodiment 2

[0024] Add 200L of chlorobenzene, 100L of p-fluoroaniline, and 1kg of palladium catalyst in a 1000L kettle, stir evenly for use, raise the temperature to 50 degrees Celsius, add acetic anhydride dropwise through the high-level tank, and bromine passes through the vaporizer and gas distributor to control the concentration of acetic anhydride and bromine. The adding speed is a molar ratio of 1:2, the molar ratio of acetic anhydride to p-fluoroaniline is 1:1.05, and the molar ratio of bromine to p-fluoroaniline is 1:2.1. After the dropwise addition, the temperature was raised to 70 degrees centigrade and kept for 4 hours to react. During the reaction, air was bubbled at a rate of 0.5 L / min to replenish oxygen. After the reaction, the palladium catalyst was removed by filtration. Then add 200L of 10% sodium oxalate, more precipitates are generated at this time, after solid-liquid separation, the solid is 2-bromo-4-fluoroacetanilide, the content of 2-bromo-4-fluoroacetanilide is hig...

Embodiment 3

[0026] Add 200L of chlorobenzene, 100L of p-fluoroaniline, and 1kg of palladium catalyst in a 1000L kettle, stir evenly for use, raise the temperature to 50 degrees Celsius, add acetic anhydride dropwise through the high-level tank, and bromine passes through the vaporizer and gas distributor to control the concentration of acetic anhydride and bromine. The adding speed is a molar ratio of 1:1, the molar ratio of acetic anhydride to p-fluoroaniline is 1:1.05, and the molar ratio of bromine to p-fluoroaniline is 1:1.05. After the dropwise addition, the temperature was raised to 70 degrees centigrade and kept for 4 hours to react. During the reaction, air was bubbled at a rate of 0.5 L / min to replenish oxygen. After the reaction, the palladium catalyst was removed by filtration. Then add 200L of 10% sodium formate, and more precipitates are generated at this time. After solid-liquid separation, the solid is 2-bromo-4-fluoroacetanilide, and the content of 2-bromo-4-fluoroacetanili...

Images