A method for purifying m-bromotoluene
By using mordenite zeolite adsorbent and vacuum distillation technology, the problem of low purity of m-bromotrifluorotoluene was solved, achieving efficient separation and purification, and significantly improving product purity and yield.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JINGBO AGROCHEM TECH CO LTD
- Filing Date
- 2026-04-28
- Publication Date
- 2026-07-24
AI Technical Summary
Existing technologies produce intermediate bromotrifluorotoluene products with low purity, making them difficult to purify through distillation, especially the para-isomer, which is difficult to remove effectively.
Mordenite zeolite was used as the adsorbent. Crude m-bromotrifluorotoluene was vaporized and separated by adsorption after vacuum distillation and zeolite adsorption column. The fraction was collected to obtain high-purity m-bromotrifluorotoluene.
The method achieves efficient separation of bromotrifluorotoluene and m-bromotrifluorotoluene, with a product purity of over 99.7% and a yield of over 90%.
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Figure CN122444571A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of separation and purification, and specifically to a purification method for m-bromotrifluorotoluene. Background Technology
[0002] m-Brominated trifluorotoluene is a very important chemical intermediate used in pesticides and pharmaceuticals, such as m-trifluoromethyl acetophenone, an intermediate in the synthesis of oxime ester, methyl m-trifluoromethyl benzoate, an intermediate in cyfluthrin, and fenfluramine, a weight-loss drug.
[0003] The common synthetic method for m-bromotrifluorotoluene is direct bromination: this method involves the electrophilic substitution reaction of trifluorotoluene with bromine using iron powder as a catalyst. This method has low production costs, but it contains para-isomer impurities (typically the ratio of meta to para products is approximately 96:4). The boiling range (154℃~155℃) is similar to that of the meta-isomer (151℃~152℃), making it difficult to separate and purify the product to obtain a purity exceeding 99% through distillation.
[0004] Various industries, including petrochemicals, synthetic materials, biopharmaceuticals, and gas manufacturing, require a large number of isomers with similar boiling points. Zeolite adsorption separation can effectively separate and purify these isomers, yielding products with high purity.
[0005] Therefore, developing a highly efficient method for separating and purifying m-bromotrifluorotoluene using zeolite adsorption is of great significance for meeting the needs of the pesticide and pharmaceutical industries. Summary of the Invention
[0006] To address the technical problem of poor product purity caused by the difficulty in separating and purifying the para-isomer when preparing m-bromotrifluorotoluene using the direct bromination method, this invention provides a purification method for m-bromotrifluorotoluene to solve the above-mentioned problem.
[0007] The technical solution of this invention is as follows: A method for purifying m-bromotrifluorotoluene involves vaporizing crude m-bromotrifluorotoluene containing p-bromotrifluorotoluene, passing it through a zeolite column, and collecting the distillate to obtain purified m-bromotrifluorotoluene; wherein the p-bromotrifluorotoluene content is ≤4%.
[0008] In one specific implementation, the zeolite is mordenite.
[0009] As a specific implementation method, the purification method is as follows: crude m-bromotrifluorotoluene is added to a reactor, zeolite is packed into an adsorption column, the vacuum degree and heating temperature are controlled, and the adsorption and purification are carried out by vacuum distillation and vaporization, and the distillate is collected.
[0010] Further preferred, the vacuum degree is -0.098MPa to -0.09MPa.
[0011] More preferably, the heating temperature for vacuum distillation is 80℃~100℃.
[0012] More preferably, the heating temperature for vacuum distillation is 90℃~100℃.
[0013] In one specific implementation, the zeolite is packed into an adsorption column with a column diameter ratio of 10 to 12:1.
[0014] As a specific implementation method, the preparation method of the crude m-bromotrifluorotoluene is as follows: using trifluorotoluene as raw material, the crude m-bromotrifluorotoluene is obtained by reactive distillation with liquid bromine under the action of a catalyst; the catalyst is iron powder, ferric chloride or ferric tribromide.
[0015] As a specific implementation method, the preparation method of the mordenite zeolite is as follows: Prepare an initial gel according to a specified ratio, control the temperature, mix the aluminum source with deionized water, and stir until homogeneous; add the silicon source and template agent sequentially to the mixture, stir until homogeneous, adjust the pH value to 8-14 with acid or alkali solution, and continue stirring until homogeneous to obtain the initial gel mixture; add the initial gel to a high-pressure reactor, control the temperature, and stir to crystallize; cool, filter, wash with deionized water, and dry to obtain the synthetic raw powder; calcine the synthetic raw powder at high temperature in air to obtain granular high-silica mordenite zeolite.
[0016] In one specific embodiment, the aluminum source is an aluminate or aluminum salt; the silicon source is water glass or silica sol; the template agent is tetraethylammonium bromide or hexamethyleneimine; the initial gel raw material ratio (based on oxide molecules) is SiO2 / Al2O3=25~40, Na2O / Al2O3=2~15, H2O / Al2O3=1000~1300, and template agent:Al2O3=2~4.
[0017] Further, the specific method is as follows: Trifluorotoluene and iron powder are added to a reactor, the temperature is raised to the reaction temperature, liquid bromine is added, and after the addition is complete, the reaction is stirred at the reaction temperature until the trifluorotoluene reacts completely. Then, the reaction solution is slowly added to a 10% sodium sulfite aqueous solution, stirred, allowed to stand and separated, and the organic phase is dried and distilled to obtain crude m-bromotrifluorotoluene.
[0018] Furthermore, the molar ratio of the catalyst to trifluorotoluene is 0.45~0.55:1.
[0019] Furthermore, the reaction temperature is 45℃~55℃.
[0020] Furthermore, the molar ratio of liquid bromine to trifluorotoluene is 1:1.4~1.6.
[0021] Furthermore, the temperature for a 10% sodium sulfite aqueous solution is 5℃~10℃.
[0022] The beneficial effects of this invention are as follows: The present invention provides a method for the separation and purification of m-bromotrifluorotoluene. Using the mordenite zeolite provided by the invention, it achieves efficient separation of bromotrifluorotoluene and m-bromotrifluorotoluene, with a high yield of m-bromotrifluorotoluene. We speculate that this is because the pore size of the mordenite zeolite provided by the invention is slightly larger than the diameter of a p-bromotrifluorotoluene molecule but smaller than the diameter of a m-bromotrifluorotoluene molecule. By removing isomeric impurities from m-bromotrifluorotoluene using the method of the present invention, high-purity m-bromotrifluorotoluene can be obtained. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 This is the HPLC chromatogram of the crude m-bromotrifluorotoluene prepared in Example 4 of this invention. In the figure, RT=6.971 min represents p-bromotrifluorotoluene, and RT=7.128 min represents m-bromotrifluorotoluene.
[0025] Figure 2 This is the HPLC chromatogram of m-bromotrifluorotoluene prepared in Example 4 of this invention.
[0026] Figure 3 This is the HPLC chromatogram of m-bromotrifluorotoluene prepared in Comparative Example 1 of this invention.
[0027] Figure 4 This is the HPLC chromatogram of m-bromotrifluorotoluene prepared in Comparative Example 2 of this invention. Detailed Implementation
[0028] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.
[0029] Example 1 Mordenite zeolite is prepared by the following method: Under controlled temperature of 20℃, 1500ml of deionized water was added to 180ml of sodium aluminate solution (containing 1.0mol / L Al2O3 and 2.0mol / L Na2O), and stirred for 3 hours. Then, 1500ml of water glass solution (containing 3.15mol / L SiO2 and 0.99mol / L Na2O) and 116.0g of tetraethylammonium bromide were slowly added and stirred until homogeneous. Next, 150ml of sulfuric acid solution (containing 4mol / L H2SO4) was added, and stirring continued until homogeneous, yielding an initial gel mixture (with oxide molecular weight ratios of SiO2 / Al2O3 = 26, Na2O / Al2O3 = 6.9, H2O / Al2O3 = 1074, and tetraethylammonium bromide / Al2O3 = 2). The initial gel was added to a high-pressure reactor, and the temperature was controlled at 140℃ for stirring and crystallization for 8 hours. The mixture was then cooled to 20℃, filtered, washed, and dried to obtain the synthetic raw powder. The synthetic raw powder was calcined in air at 500°C for 2 hours to obtain granular high-silica mordenite.
[0030] Example 2 Mordenite zeolite is prepared by the following method: Under controlled temperature of 30℃, 200g of aluminum sulfate was added to 2500ml of deionized water and stirred for 4 hours. Then, 3000ml of water glass solution (SiO2 3.15mol / L, Na2O 0.99mol / L) and 753.5g of tetraethylammonium bromide were slowly added and stirred until homogeneous. Next, 300ml of sodium hydroxide solution (containing Na2O 3mol / L) was added and stirred until homogeneous, yielding an initial gel mixture (with oxide molecular raw material ratios of SiO2 / Al2O3=31.5, Na2O / Al2O3=14.9, H2O / Al2O3=1074, tetraethylammonium bromide / Al2O3=4). The initial gel was added to a high-pressure reactor and stirred at 170℃ for crystallization for 20 hours. The mixture was then cooled to 30℃, filtered, washed, and dried to obtain the synthetic raw powder. The synthetic raw powder was calcined in air at 600℃ for 8 hours to obtain granular high-silica mordenite zeolite.
[0031] Example 3 The silica source water glass was replaced with silica sol, and the template agent tetraethylammonium bromide was replaced with hexamethyleneimine. The operation was the same as in Example 2, and an initial gel was prepared (with the following oxide molecular raw material ratios: SiO2 / Al2O3=39, Na2O / Al2O3=11, H2O / Al2O3=1300, hexamethyleneimine / Al2O3=2). The initial gel was added to a high-pressure reactor, and the temperature was controlled at 170°C for stirring and crystallization for 30 hours. The temperature was then lowered to 30°C, filtered, washed, and dried to obtain the synthetic raw powder. The synthetic raw powder was calcined in air at 600°C for 5 hours to obtain granular high-silica mordenite zeolite.
[0032] Example 4 Trifluorotoluene (600.0 g, 4.1 mol, 1.0 eq.) and iron powder (103.2 g, 1.85 mol, 0.45 eq.) were added to a reaction flask, and the reaction temperature was raised to 45°C. Liquid bromine (918.8 g, 5.74 mol, 1.4 eq.) was then added. The reaction was carried out at 45°C for 4 h until completion. The reaction solution was cooled to 5°C, and the temperature was controlled. Then, the reaction solution was slowly added to a 10% sodium sulfite aqueous solution, stirred, allowed to stand, and separated. The organic phase was dried and concentrated, and then distilled to obtain crude m-bromotrifluorotoluene. Figure 1 As shown, the content of intermediate-bromotrifluorotoluene in the crude m-bromotrifluorotoluene was 96.3%. Detailed HPLC detection data are shown in Table 1 below: Table 1 - Detection results of crude m-bromotrifluorotoluene
[0033] Crude m-bromotrifluorotoluene was added to a reaction flask. 120.0 g of mordenite zeolite prepared in Example 1 was packed into an adsorption column with a diameter of 2 cm. Under a vacuum of -0.098 MPa and a heating temperature of 90 °C, the crude m-bromotrifluorotoluene gas was adsorbed through the adsorption column, yielding a product with a purity of 99.7% and a yield of 92.2%. HPLC detection data are detailed in Table 2 below. Table 2 - Detection results of m-bromotrifluorotoluene
[0034] Example 5 Trifluorotoluene (600.0 g, 4.1 mol, 1.0 eq.) and iron powder (125.9 g, 2.26 mol, 0.55 eq.) were added to a reaction flask, and the reaction temperature was raised to 55 °C. Liquid bromine (918.8 g, 5.74 mol, 1.4 eq.) was then added. The reaction was carried out at 55 °C for 4 hours until completion. The reaction solution was cooled to 5 °C, and the temperature was controlled. Then, the reaction solution was slowly added to a 10% sodium sulfite aqueous solution, stirred, allowed to stand, and separated. The organic phase was dried and concentrated to obtain crude m-bromotrifluorotoluene, which was then distilled to obtain crude m-bromotrifluorotoluene. Crude m-bromotrifluorotoluene was added to a reaction flask, and 120.0 g of mordenite zeolite prepared in Example 2 was packed into an adsorption column with a diameter of 2 cm. Under a vacuum of -0.098 MPa and a heating temperature of 90 °C, the crude m-bromotrifluorotoluene gas was adsorbed through the adsorption column, yielding a product with a purity of 99.8% and a yield of 91.3%. Example 6 Trifluorotoluene (600.0 g, 4.1 mol, 1.0 eq.) and iron powder (103.2 g, 1.85 mol, 0.45 eq.) were added to a reaction flask, and the reaction temperature was raised to 45°C. Liquid bromine (1050.1 g, 6.56 mol, 1.6 eq.) was then added. The reaction was carried out at 45°C for 4 hours until completion. The reaction solution was cooled to 10°C, and the temperature was controlled. The reaction solution was then slowly added to a 10% sodium sulfite aqueous solution, stirred, allowed to stand, and separated. The organic phase was dried and concentrated to obtain crude m-bromotrifluorotoluene, which was then distilled to obtain crude m-bromotrifluorotoluene. The crude m-bromotrifluorotoluene was added to a reaction flask, and 120.0 g of mordenite zeolite prepared in Example 3 was filled into an adsorption column with a diameter of 2 cm. Under a vacuum of -0.098 MPa and a heating temperature of 90 °C, the crude m-bromotrifluorotoluene gas was adsorbed through the adsorption column, and the product purity was 99.7% with a yield of 90.1%.
[0035] Example 7 Trifluorotoluene (600.0 g, 4.1 mol, 1.0 eq.) and ferric chloride (299.8 g, 1.848 mol, 0.45 eq.) were added to a reaction flask, and the reaction temperature was raised to 45°C. Liquid bromine (918.8 g, 5.74 mol, 1.4 eq.) was then added. The reaction was carried out at 45°C for 4 hours until completion. The reaction solution was cooled to 10°C, and the temperature was controlled. The reaction solution was then slowly added to a 10% sodium sulfite aqueous solution, stirred, allowed to stand, and separated. The organic phase was dried and concentrated to obtain crude m-bromotrifluorotoluene, which was then further purified by distillation. The crude m-bromotrifluorotoluene was added to a reaction flask, and 120.0 g of mordenite zeolite prepared in Example 2 was filled into an adsorption column with a diameter of 2 cm. Under a vacuum of -0.098 MPa and a heating temperature of 100 °C, the crude m-bromotrifluorotoluene gas was adsorbed through the adsorption column, and the product purity was 99.7% and the yield was 91.5%.
[0036] Example 8 Trifluorotoluene (600.0 g, 4.1 mol, 1.0 eq.) and ferric tribromide (546.2 g, 1.848 mol, 0.45 eq.) were added to a reaction flask, and the reaction temperature was raised to 45 °C. Liquid bromine (918.8 g, 5.74 mol, 1.4 eq.) was then added. The reaction was carried out at 45 °C for 4 h until completion. The reaction solution was cooled to 10 °C, and the temperature was controlled. The reaction solution was then slowly added to a 10% sodium sulfite aqueous solution, stirred, allowed to stand, and separated. The organic phase was dried and concentrated to obtain crude m-bromotrifluorotoluene, which was then further purified by distillation. The crude m-bromotrifluorotoluene was added to a reaction flask, and 120 g of mordenite zeolite prepared in Example 2 was filled into an adsorption column with a diameter of 2 cm. The vacuum degree was -0.090 MPa, and the heating temperature was 95 °C. The crude m-bromotrifluorotoluene gas was adsorbed through the adsorption column to obtain 99.6% of the product, with a yield of 92.0%.
[0037] Comparative Example 1 Trifluorotoluene (600.0 g, 4.1 mol, 1.0 eq.) and iron powder (103.2 g, 1.848 mol, 0.45 eq.) were added to a reaction flask, and the reaction temperature was raised to 45 °C. Liquid bromine (918.8 g, 5.74 mol, 1.4 eq.) was then added. The reaction was carried out at 45 °C for 4 h until completion. The reaction solution was cooled to 10 °C, and the temperature was controlled. The reaction solution was then slowly added to a 10% sodium sulfite aqueous solution, stirred, allowed to stand, and separated. The organic phase was dried, concentrated, and distilled to obtain crude m-bromotrifluorotoluene. The crude m-bromotrifluorotoluene was added to a reaction flask, and 120.0 g of 4A zeolite was packed into an adsorption column with a diameter of 2 cm. Under a vacuum of -0.098 MPa and a heating temperature of 90 °C, the crude m-bromotrifluorotoluene gas was adsorbed through the adsorption column, yielding a product with a purity of 96.1% and a yield of 93.0%. Detailed HPLC detection data are shown in Table 3 below: Table 3 - Detection results of m-bromotrifluorotoluene
[0038] Comparative Example 2 Trifluorotoluene (600.0 g, 4.1 mol, 1.0 eq.) and iron powder (103.2 g, 1.848 mol, 0.45 eq.) were added to a reaction flask, and the reaction temperature was raised to 45°C. Liquid bromine (918.8 g, 5.74 mol, 1.4 eq.) was then added. The reaction was carried out at 45°C for 4 h until completion. The reaction solution was cooled to 10°C, and the temperature was controlled before slowly adding the reaction solution to a 10% sodium sulfite aqueous solution. The mixture was stirred, allowed to stand, and separated. The organic phase was dried, concentrated, and then distilled to obtain crude m-bromotrifluorotoluene. The crude m-bromotrifluorotoluene was added to a reaction flask, and 120.0 g of 13X zeolite was packed into an adsorption column with a diameter of 2 cm. Under a vacuum of -0.098 MPa and a heating temperature of 90°C, the crude m-bromotrifluorotoluene gas was adsorbed through the adsorption column, yielding a product with a purity of 96.3% and a yield of 84%. Detailed HPLC detection data are shown in Table 4 below: Table 4 - Detection results of m-bromotrifluorotoluene
[0039] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.
Claims
1. A method for purifying m-bromotrifluorotoluene, characterized in that, The crude m-bromotrifluorotoluene containing p-bromotrifluorotoluene is vaporized and passed through zeolite. The fractions are collected to obtain the refined m-bromotrifluorotoluene.
2. The purification method for m-bromotrifluorotoluene as described in claim 1, characterized in that, The zeolite is mordenite.
3. The purification method for m-bromotrifluorotoluene as described in claim 1, characterized in that, The purification method is as follows: crude m-bromotrifluorotoluene is added to the reactor, zeolite is packed into the adsorption column, the vacuum degree and heating temperature are controlled, and the adsorption and purification are carried out by vacuum distillation and vaporization, and the fraction is collected.
4. The purification method for m-bromotrifluorotoluene as described in claim 3, characterized in that, The vacuum level is -0.098MPa to -0.09MPa.
5. The purification method for m-bromotrifluorotoluene as described in claim 3, characterized in that, The heating temperature for vacuum distillation is 80℃~100℃.
6. The purification method for m-bromotrifluorotoluene as described in claim 5, characterized in that, The heating temperature for vacuum distillation is 90℃~100℃.
7. The purification method for m-bromotrifluorotoluene as described in claim 3, characterized in that, The zeolite is packed into the adsorption column with a column diameter ratio of 10~12:
1.
8. The purification method for m-bromotrifluorotoluene as described in claim 1 or 2, characterized in that, The preparation method of the mordenite zeolite is as follows: Prepare the initial gel according to the specified ratio, control the temperature, mix the aluminum source with deionized water, and stir until homogeneous; add the silicon source and template agent to the mixture sequentially, stir until homogeneous, adjust the pH value to 8-14 with acid or alkali solution, and continue stirring until homogeneous to obtain the initial gel mixture; add the initial gel to a high-pressure reactor, control the temperature, and stir to crystallize; cool, filter, wash with deionized water, and dry to obtain the synthetic raw powder; calcine the synthetic raw powder at high temperature in air to obtain granular high-silica mordenite zeolite.
9. The purification method for m-bromotrifluorotoluene as described in claim 8, characterized in that, The aluminum source is an aluminate or aluminum salt; the silicon source is water glass or silica sol; the template agent is tetraethylammonium bromide or hexamethyleneimine; the initial gel raw material ratio (based on oxide molecules) is SiO2 / Al2O3=25~40, Na2O / Al2O3=2~15, H2O / Al2O3=1000~1300, and template agent:Al2O3=2~4.
10. The purification method for m-bromotrifluorotoluene as described in claim 1, characterized in that, The preparation method of the crude m-bromotrifluorotoluene is as follows: using trifluorotoluene as raw material, the crude m-bromotrifluorotoluene is obtained by reaction distillation with liquid bromine under the action of a catalyst; the catalyst is iron powder, ferric chloride or ferric tribromide.