Novel synthesis method of 1, 5-dibromo-2, 4-bis (bromomethyl)-3-fluorobenzene

Abstract

The invention relates to the technical field of organic photoelectric materials, and particularly discloses a novel synthesis method of 1, 5-dibromo-2, 4-bis (bromomethyl)-3-fluorobenzene, which comprises the following steps: adding 1, 5-dibromo-3-fluoro-2, 4-xylene into a reaction flask, then adding a solvent, heating to 40-70 DEG C in an inert atmosphere, adding a first batch of initiator, stirring for 2-10 minutes, adding a second batch of initiator, stirring for 2-10 minutes, adding a second batch of initiator, stirring for 2-10 minutes, adding a third batch of initiator, stirring for 2-10 minutes, and cooling to room temperature to obtain the 1, 5-dibromo-2, 4-bis (bromomethyl)-3-fluorobenzene. Adding a first batch of bromine substitution reagent, adding the bromine substitution reagent and the initiator in batches at the same time after the reaction liquid is refluxed and the refluxing phenomenon disappears, keeping the temperature at 50-80 DEG C until the reaction is finished, and performing post-treatment to obtain a target product; according to the method, 1, 5-dibromo-3-fluoro-2, 4-xylene is used as a raw material, the high-purity target product is obtained by controlling the adding sequence, the adding amount and the adding batch of the initiator and the bromine substitution reagent, the process route is mature and stable, and industrial stable production is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of organic photoelectric materials, and more specifically to a novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene. Background Art

[0002] 1,5-Dibromo-2,4-bis(bromomethyl)-3-fluorobenzene has a unique chemical structure and excellent optoelectronic properties, which makes it have good application prospects in many fields, especially in the development of OLED materials. This type of compound can be used as an efficient light-emitting material to improve the photoelectric conversion efficiency and luminescence stability of the device. This type of compound can be effectively used as an active layer material, a light-emitting layer material or an electron transport layer material to manufacture thin-film transistors, light-emitting diodes (LEDs), solar cells, sensors and photorefractive devices. These materials have advantages in specific photoelectric conversion efficiency, stability and cost-effectiveness, and play an important role in modern optoelectronic technology.

[0003] The patent with the prior art patent publication number CN 118388315 A discloses a method for synthesizing 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene and its application. The technology uses 4-fluoro-3,5-dimethylaniline as raw material, undergoes bromine substitution, and then undergoes deamination to prepare 1,5-dibromo-3-fluoro-2,4-dimethylbenzene, and then undergoes bromine substitution to prepare 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene; although the technology aims to improve the yield and purity of the final product, the purity of the product is not described in any way throughout the process. In addition, the amount of reactants used in the technical reaction is extremely small, and it cannot prove the feasibility of its scale-up or production. Based on the above statement, it is of great significance to explore a suitable process route to synthesize 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene, obtain high-purity and high-yield products, and ensure that it is easy to scale up for industrial production. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene. By optimizing the reactant addition sequence, a stable process route suitable for industrial production is determined, and the obtained product has high purity and is easy to use.

[0005] The present invention provides a novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene, which adopts the following technical scheme: A novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene comprises the following steps: Add 1,5-dibromo-3-fluoro-2,4-dimethylbenzene to the reactor, then add the solvent, raise the temperature to 40-70°C under an inert atmosphere, add the first batch of initiator, stir for 2-10 minutes, then add the first batch of bromine substitution reagent, the reaction solution refluxes, after the reflux disappears, add the bromine substitution reagent and initiator in batches at the same time until the addition is completed, keep the temperature at 50-80°C until the reaction is completed, and obtain the target product through post-treatment.

[0006] According to the present invention, after the first batch of initiators are added and stirred for 2-10 minutes, the first batch of bromination reagents are added, thereby effectively avoiding the occurrence of unsuccessful initiation. The unsuccessful initiation is mainly judged based on the color and state of the reaction liquid. When the color of the reaction liquid gradually changes and then becomes clear, accompanied by the phenomenon of boiling of the reaction liquid, the temperature of the reaction liquid is 58-65°C.

[0007] After the initiation is successful, the bromine substitution reagent and the initiator are added in batches, mainly to prevent the occurrence of unilateral substitution products. The bromine substitution reagent and the initiator are added simultaneously in each batch mainly to fully activate the free radicals and improve the substitution yield. If the remaining bromine substitution reagent and the remaining initiator are added at one time, multiple substitution products will appear.

[0008] Preferably, the weight ratio of the 1,5-dibromo-3-fluoro-2,4-dimethylbenzene to the total initiator is 1:0.05-0.2.

[0009] Preferably, the weight ratio of the 1,5-dibromo-3-fluoro-2,4-dimethylbenzene to the total initiator is 1:0.10-0.15.

[0010] Preferably, the molar ratio of the 1,5-dibromo-3-fluoro-2,4-dimethylbenzene to the total bromine substitution reagent is 1:2.0-4.0.

[0011] Preferably, the molar ratio of the 1,5-dibromo-3-fluoro-2,4-dimethylbenzene to the total bromine substitution reagent is 1:2.1-2.4.

[0012] Preferably, the first batch of initiators is used in an amount of 15%-30% by weight of the total initiators.

[0013] Preferably, the first batch of initiators is used in an amount of 20%-30% by weight of the total initiators.

[0014] Preferably, the amount of the first batch of bromine substitution reagent is 10%-20% by weight of the total bromine substitution reagent.

[0015] Preferably, the amount of the first batch of bromine substitution reagent is 15%-20% by weight of the total bromine substitution reagent.

[0016] Preferably, the adding of the bromine substitution reagent and the initiator in batches simultaneously specifically means: adding the initiator first, and then quickly adding the bromine substitution reagent after the addition is completed, and the weight ratio of the initiator to the bromine substitution reagent in each batch is 1:5-15.

[0017] Preferably, the weight ratio of each batch of initiator to bromine substitution reagent is 1:8-12.

[0018] Preferably, the initiator is at least one of azobisisobutyronitrile, dibenzoyl peroxide and hydrogen peroxide.

[0019] Preferably, the initiator is azobisisobutyronitrile.

[0020] Preferably, the bromine substitution reagent is at least one of N-bromosuccinimide, carbon tetrabromide, and 1,3-dibromo-5,5-dimethylhydantoin.

[0021] Preferably, the bromine substitution reagent is N-bromosuccinimide and / or 1,3-dibromo-5,5-dimethylhydantoin. Preferably, the solvent is at least one of chloroform, carbon tetrachloride and trifluorotoluene.

[0022] Preferably, the solvent is chloroform and / or carbon tetrachloride.

[0023] Preferably, the post-treatment includes steps such as quenching, liquid separation, purification, and drying.

[0024] In summary, the present invention has the following beneficial effects: The invention uses 1,5-dibromo-3-fluoro-2,4-dimethylbenzene as a raw material, controls the adding order, adding amount and adding batch of an initiator and a bromine substitution reagent, so as to obtain a high-purity target product. The synthesis method of the invention is simple, the reaction conditions are mild, the purity of the obtained target product is as high as 99.1%, the yield is as high as 83%, and the process route of the invention is mature and stable, which is conducive to stable industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the GS-MS chart of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene prepared in Example 1 of the present invention.

[0026] Figure 2 This is the LC-MS chart of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene prepared in Example 1 of the present invention.

[0027] Figure 3 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene prepared in Example 1 of the present invention 1 H NMR spectra. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to the embodiments.

[0029] Example 1 A novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene comprises the following steps: Take a 500ml dry three-necked flask, add 1,5-dibromo-3-fluoro-2,4-dimethylbenzene (39.2g, 0.139mol), chloroform (200ml), use nitrogen to replace 3 times, then start to heat up to 55℃, add the first batch of azobisisobutyronitrile (1.9g, 29% of the total initiator weight, the total initiator weight is 6.55g) after the temperature reaches, stir for 3min, add the first batch of N-bromosuccinimide (10g, 18.2% of the total bromine substitution reagent weight, the total bromine substitution reagent weight is 54.9g, 0.308mol); at this time, the reaction liquid turned red and then gradually became clear. The reaction liquid had a violent reflux phenomenon, which disappeared after 4 minutes. Next, the remaining azobisisobutyronitrile and the remaining N-bromosuccinimide were added in 10 batches. Specifically, azobisisobutyronitrile was added first to each batch. After the addition was completed, N-bromosuccinimide was quickly added. After each batch was added, the violent reflux phenomenon in the reaction bottle disappeared before adding the next batch, until all 10 batches were added, and then kept warm at 69°C until the reaction was completed.

[0030] The reaction solution was returned to room temperature, and then sodium hydroxide aqueous solution (200 ml, mass concentration 10%) was added dropwise with stirring. After the addition was completed, the mixture was stirred for 30 minutes, and the mixture was allowed to stand for stratification. The organic phase was dried and concentrated until there was no solvent to obtain a solid. Chloroform (60 ml) was directly added to the solid, and the temperature was raised to reflux to dissolve, and then the temperature was lowered to 5°C to precipitate a solid, which was dried to obtain a dry product. Chloroform (40 ml) was then added to the dry product, and the temperature was raised to dissolve, and then the temperature was lowered to 5°C again to crystallize, and the target product 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene (48.89 g, purity 99%, yield 80%) was obtained by filtration and drying.

[0031] Example 2 A novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene comprises the following steps: Take a 500ml dry three-necked flask, add 1,5-dibromo-3-fluoro-2,4-dimethylbenzene (39.2g, 0.139mol), chloroform (200ml), use nitrogen to replace 3 times, then start to heat up to 55℃, add the first batch of azobisisobutyronitrile (1.3g, 20% of the total initiator weight, the total initiator weight is 6.5g) after the temperature reaches, stir for 3min, add the first batch of N-bromosuccinimide (10g, 18.2% of the total bromine substitution reagent weight, the total bromine substitution reagent weight is 54.9g, 0.308mol); at this time, the reaction liquid turned red and then gradually became clear. The reaction liquid had a violent reflux phenomenon, which disappeared after 4 minutes. Next, the remaining azobisisobutyronitrile and the remaining N-bromosuccinimide were added in 10 batches. Specifically, azobisisobutyronitrile was added first to each batch. After the addition was completed, N-bromosuccinimide was quickly added. After each batch was added, the violent reflux phenomenon in the reaction bottle disappeared before adding the next batch, until all 10 batches were added, and then kept warm at 69°C until the reaction was completed.

[0032] The reaction solution was returned to room temperature, and then sodium hydroxide aqueous solution (200 ml, mass concentration 10%) was added dropwise with stirring. After the addition was completed, the mixture was stirred for 30 minutes, and the mixture was allowed to stand for stratification. The organic phase was dried and concentrated until there was no solvent to obtain a solid. Chloroform (60 ml) was directly added to the solid, and the temperature was raised to reflux to dissolve, and then the temperature was lowered to 5°C to precipitate a solid, which was dried to obtain a dry product. Chloroform (40 ml) was then added to the dry product, and the temperature was raised to dissolve, and then the temperature was lowered to 5°C again to crystallize, and the target product 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene (47.85 g, purity 98.7%, yield 78.3%) was obtained by filtration and drying.

[0033] Example 3 A novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene comprises the following steps: Take a 500ml dry three-necked flask, add 1,5-dibromo-3-fluoro-2,4-xylene (39.2g, 0.139mol), carbon tetrachloride (200ml), use nitrogen to replace 3 times, then start to heat up to 70℃, add the first batch of azobisisobutyronitrile (1.17g, 15% of the total initiator weight, the total initiator weight is 7.8g) after the temperature reaches, stir for 3min, add the first batch of 1,3-dibromo-5,5-dimethylhydantoin (12.52g, 15% of the total bromine substitution reagent weight, the total bromine substitution reagent weight is 7.8g) The weight of the agent is 83.47g, 0.292mol); at this time, the reaction solution turns brown and then gradually becomes clear. The reaction solution has a violent reflux phenomenon, which disappears after 4 minutes. Next, the remaining azobisisobutyronitrile and the remaining N-bromosuccinimide are added in 10 batches on average. Specifically, azobisisobutyronitrile is added to each batch first. After the addition is completed, N-bromosuccinimide is quickly added. After each batch is added, ensure that the violent reflux phenomenon in the reaction bottle disappears before adding the next batch, until all 10 batches are added, and then keep warm at 75°C until the reaction is completed.

[0034] The reaction solution was returned to room temperature, and then sodium hydroxide aqueous solution (200 ml, mass concentration 10%) was added dropwise with stirring. After the addition was completed, the mixture was stirred for 30 minutes, and the mixture was allowed to stand for stratification. The organic phase was dried and concentrated until there was no solvent to obtain a solid. Chloroform (60 ml) was directly added to the solid, and the temperature was raised to reflux to dissolve, and then the temperature was lowered to 5°C to precipitate a solid, which was dried to obtain a dry product. Chloroform (40 ml) was then added to the dry product, and the temperature was raised to dissolve, and then the temperature was lowered to 5°C again to crystallize, and the target product 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene (45.16 g, purity 99%, yield 73.9%) was obtained by filtration and drying.

[0035] Example 4 A novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene comprises the following steps: Prepare a 30L glass reactor, add 1,5-dibromo-3-fluoro-2,4-dimethylbenzene (1070g, 3.808mol), chloroform (8.8L), use nitrogen to replace 6 times, then start to heat up to 55°C, add the first batch of azobisisobutyronitrile (44.138g, 25% of the total initiator weight, the total initiator weight is 176.55g) after the temperature reaches, stir for 9 minutes, add the first batch of N-bromosuccinimide (355.23g, 22% of the total bromine substitution reagent weight, the total bromine substitution reagent weight is 176.55g) The reaction liquid turned red and then gradually became clear. There was a violent reflux phenomenon in the reaction liquid. The reflux phenomenon disappeared after 13 minutes. Then, the remaining azobisisobutyronitrile and the remaining N-bromosuccinimide were added in 8 batches. Specifically, azobisisobutyronitrile was added first to each batch. After the addition was completed, N-bromosuccinimide was quickly added. After each batch was added, the violent reflux phenomenon in the reaction bottle disappeared before adding the next batch until all 8 batches were added. Then, the mixture was kept warm at 69°C until the reaction was completed.

[0036] The reaction solution was returned to room temperature, and then sodium hydroxide aqueous solution (6L, mass concentration 10%) was added dropwise with stirring. After the addition was completed, the mixture was stirred for 50 minutes, and the mixture was allowed to stand for stratification. The organic phase was dried and concentrated until there was no solvent to obtain a solid. Chloroform (2L) was directly added to the solid, and the temperature was raised to reflux to dissolve, and then the temperature was lowered to 5°C to precipitate a solid, which was dried to obtain a dry product. Chloroform (1.5L) was then added to the dry product, and the temperature was raised to dissolve, and then the temperature was lowered to 5°C again to crystallize, and the target product 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene (1390.6g, purity 99.1%, yield 83%) was obtained by filtration and drying.

[0037] Comparative Example 1 Compared with Example 1, azobisisobutyronitrile and N-bromosuccinimide are all added at once, as follows: Take a 500ml dry three-necked flask, add 1,5-dibromo-3-fluoro-2,4-xylene (39.2g, 0.139mol), chloroform (200ml), use nitrogen to replace 3 times, then start to heat up to 55℃, add azobisisobutyronitrile (6.55g) at a time after the temperature reaches 55℃, stir for 3min and add N-bromosuccinimide (54.9g, 0.308mol) at a time; at this time, the reaction liquid turns red and then gradually dissolves, the reaction liquid has a violent reflux phenomenon, then the reaction liquid is cooled to 69℃ and kept at 69℃ until the reaction is completed.

[0038] The reaction solution was returned to room temperature, and then sodium hydroxide aqueous solution (200 ml, mass concentration 10%) was added dropwise with stirring. After the addition was completed, stirring was carried out for 30 minutes, and the mixture was allowed to stand for stratification. The organic phase was dried and concentrated until there was no solvent to obtain a viscous substance. Chloroform (60 ml) was directly added to the viscous substance, and the temperature was raised to reflux to dissolve, and then the temperature was lowered to 5°C to precipitate a solid, which was dried to obtain a dry product. Chloroform (40 ml) was added to the dry product, and the temperature was raised to dissolve, and then the temperature was lowered to 5°C again to crystallize. The substance was filtered and dried to obtain a gray-yellow substance, which was characterized by NMR as a mixture, not 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene.

[0039] Comparative Example 2 Compared with Example 1, azobisisobutyronitrile and N-bromosuccinimide are added all at once, as follows: Take a 500ml dry three-necked flask, add 1,5-dibromo-3-fluoro-2,4-dimethylbenzene (39.2g, 0.139mol), chloroform (200ml), use nitrogen to replace 3 times, then start to heat up to 55℃, add azobisisobutyronitrile (6.55g) at one time after the temperature is reached, after the addition is completed, quickly add N-bromosuccinimide (54.9g, 0.308mol) at one time; at this time, the reaction liquid turns red and then gradually dissolves, the reaction liquid has violent reflux, violent boiling, and rushing, then the reaction liquid is cooled to 69℃, and kept at 69℃ until the reaction is completed.

[0040] The reaction solution was returned to room temperature, and then sodium hydroxide aqueous solution (200 ml, mass concentration 10%) was added dropwise with stirring. After the addition was completed, stirring was carried out for 30 minutes, and the mixture was allowed to stand for stratification. The organic phase was dried and concentrated until there was no solvent to obtain a viscous substance. Chloroform (60 ml) was directly added to the viscous substance, and the temperature was raised to reflux to dissolve, and then the temperature was lowered to 5°C to precipitate a solid, which was dried to obtain a viscous substance. Chloroform (40 ml) was then added to the viscous substance, and the temperature was raised to dissolve, and then the temperature was lowered to 5°C again to crystallize. The viscous substance was filtered and dried to obtain a viscous substance, which was not a dry product. The obtained viscous substance was not 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene, but a mixture.

[0041] Comparative Example 3 Compared with Example 1, the amount of azobisisobutyronitrile added in the first batch and the amount of the remaining batches added are different, as follows: Take a 500ml dry three-necked flask, add 1,5-dibromo-3-fluoro-2,4-dimethylbenzene (39.2g, 0.139mol), chloroform (200ml), use nitrogen to replace 3 times, then start to heat up to 55℃, add the first batch of azobisisobutyronitrile (0.32g, 5% of the total initiator weight, the total initiator weight is 6.55g) after the temperature reaches, stir for 3min, add the first batch of N-bromosuccinimide (10g, 18.2% of the total bromine substitution reagent weight, the total bromine substitution reagent weight is 54.9g, 0.308mol); at this time, the reaction liquid turned red and then gradually became clear. The reaction liquid had a violent reflux phenomenon, which disappeared after 4 minutes. Next, the remaining azobisisobutyronitrile and the remaining N-bromosuccinimide were added in 10 batches. Specifically, azobisisobutyronitrile was added first to each batch. After the addition was completed, N-bromosuccinimide was quickly added. After each batch was added, the violent reflux phenomenon in the reaction bottle disappeared before adding the next batch, until all 10 batches were added, and then kept warm at 69°C until the reaction was completed.

[0042] The reaction solution was returned to room temperature, and then sodium hydroxide aqueous solution (200 ml, mass concentration 10%) was added dropwise with stirring. After the addition was completed, the mixture was stirred for 30 minutes, and the mixture was allowed to stand for stratification. The organic phase was dried and concentrated until there was no solvent to obtain a solid. Chloroform (60 ml) was directly added to the solid, and the temperature was raised to reflux to dissolve, and then the temperature was lowered to 5°C to precipitate a solid, which was dried to obtain a dry product. Chloroform (40 ml) was then added to the dry product, and the temperature was raised to dissolve, and then the temperature was lowered to 5°C again to crystallize, and the target product 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene (29.95 g, purity 88%, yield 49%) was obtained by filtration and drying.

[0043] Comparative Example 4 Compared with Example 1, the amount of N-bromosuccinimide added in the first batch and the amount added in the remaining batches are different, as follows: Take a 500ml dry three-necked flask, add 1,5-dibromo-3-fluoro-2,4-xylene (39.2g, 0.139mol), chloroform (200ml), use nitrogen to replace 3 times, then start to heat up to 55℃, add the first batch of azobisisobutyronitrile (1.9g, 29% of the total initiator weight, the total initiator weight is 6.55g) after the temperature reaches, stir for 3min, add the first batch of N-bromosuccinimide (16.47g, 30% of the total bromine substitution reagent weight, the total bromine substitution reagent weight At this time, the reaction solution turned red and then gradually became clear. The reaction solution had a violent reflux phenomenon, which disappeared after 4 minutes. Next, the remaining azobisisobutyronitrile and the remaining N-bromosuccinimide were added in 10 batches. Specifically, azobisisobutyronitrile was added first to each batch. After the addition was completed, N-bromosuccinimide was quickly added. After each batch was added, the violent reflux phenomenon in the reaction bottle disappeared before adding the next batch until all 10 batches were added. Then, the mixture was kept warm at 69°C until the reaction was completed.

[0044] The reaction solution was returned to room temperature, and then sodium hydroxide aqueous solution (200 ml, mass concentration 10%) was added dropwise with stirring. After the addition was completed, the mixture was stirred for 30 minutes, and the mixture was allowed to stand for stratification. The organic phase was dried and concentrated until there was no solvent to obtain a solid. Chloroform (60 ml) was directly added to the solid, and the temperature was raised to reflux to dissolve, and then the temperature was lowered to 5°C to precipitate a solid, which was dried to obtain a dry product. Chloroform (40 ml) was then added to the dry product, and the temperature was raised to dissolve, and then the temperature was lowered to 5°C again to crystallize, and the target product 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene (24.44 g, purity 53%, yield 40%) was obtained by filtration and drying.

[0045] It can be seen from Examples 1-4 that the present invention controls the amount ratio of reactants, controls the amount of the first batch of initiator and the bromine substitution reagent added, and the remaining amount added in batches, and optimizes the order of adding reactants, that is, after adding the first batch of initiator and stirring for 2-10 minutes, the first batch of bromination reagent is added, which can effectively avoid the occurrence of unsuccessful initiation, and the target product 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene is obtained with high purity and high yield.

[0046] It can be seen from Comparative Examples 1-2 that in Comparative Example 1, the initiator and the bromine substitution reagent are all added at once (i.e., the method of adding in batches is not adopted), and in Comparative Example 2, the initiator and the bromine substitution reagent are all added at once (i.e., the method of adding in batches is not adopted, and the bromine substitution is not added after stirring for several minutes after adding the initiator). Finally, the NMR standards of the product crystals obtained in Comparative Examples 1 and 2 are both mixtures, not 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene.

[0047] It can be seen from Comparative Examples 3-4 that in Comparative Example 3, the amount of initiator added in the first batch and the amount added in the remaining batches are different (i.e., the amount of initiator in the first batch only accounts for 5% of the total initiator weight), and the amount of bromine substitution reagent added in the first batch and the amount added in the remaining batches are different (i.e., the amount of bromine substitution reagent in the first batch accounts for 30% of the total initiator weight), resulting in a large amount of mono-substituted products in Comparative Examples 3 and 4, and the purity and yield of the final target product 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene are greatly reduced.

[0048] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A novel method for synthesizing 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene, characterized in that: The following steps are involved: Add 1,5-dibromo-3-fluoro-2,4-dimethylbenzene to the reactor, then add the solvent, raise the temperature to 40-70°C under an inert atmosphere, add the first batch of initiator, stir for 2-10 minutes, then add the first batch of bromine substitution reagent, the reaction solution refluxes, after the reflux disappears, add the bromine substitution reagent and initiator in batches at the same time until the addition is completed, keep the temperature at 50-80°C until the reaction is completed, and obtain the target product through post-treatment.

2. The novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene according to claim 1, characterized in that: The weight ratio of the 1,5-dibromo-3-fluoro-2,4-dimethylbenzene to the total initiator is 1:0.05-0.2; the molar ratio of the 1,5-dibromo-3-fluoro-2,4-dimethylbenzene to the total bromine substitution reagent is 1:2.0-4.

0.

3. The novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene according to claim 1, characterized in that: The amount of the first batch of initiators used is 15%-30% by weight of the total initiators, and the amount of the first batch of bromine substitution reagents used is 10%-20% by weight of the total bromine substitution reagents.

4. The novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene according to claim 1, characterized in that: The simultaneous addition of the bromine substitution reagent and the initiator in batches specifically refers to: first adding the initiator, and then quickly adding the bromine substitution reagent after the addition is completed, and the weight ratio of the initiator to the bromine substitution reagent in each batch is 1:5-15.

5. The novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene according to claim 1, characterized in that: The initiator is at least one of azobisisobutyronitrile, dibenzoyl peroxide and hydrogen peroxide.

6. The novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene according to claim 1, characterized in that: The bromine substitution reagent is at least one of N-bromosuccinimide, carbon tetrabromide, and 1,3-dibromo-5,5-dimethylhydantoin.

7. The novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene according to claim 1, characterized in that: The solvent is at least one of chloroform, carbon tetrachloride and trifluorotoluene.

8. The novel synthesis method of 1,5-dibromo-2,4-bis(bromomethyl)-3-fluorobenzene according to claim 1, characterized in that: The post-treatment includes quenching, liquid separation, purification and drying.

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