Preparation method of p-bromoanisole

Abstract

The invention discloses a preparation method of p-bromoanisole, and relates to the technical field of preparation of p-bromoanisole, and the preparation method comprises the following steps: S1, preparing anisole; s2, preparing a sodium bromide solution; s3, material preparation: extracting anisole in S1, and performing synthesis preparation on the sodium bromide solution, hydrochloric acid and hydrogen peroxide in S2; 4, material synthesis: anisole, the sodium bromide solution and hydrochloric acid in the step 3 are put into a reaction kettle, hydrogen peroxide is dropwise added after cooling, standing is performed after the reaction is finished, liquid separation is performed, and a lower-layer crude product is obtained after liquid separation; s5, distillation: putting the crude product in S4 into a reaction kettle for separation and distillation to obtain the product p-bromoanisole. According to the method, the anisole, the sodium bromide solution and the hydrochloric acid are put into the reaction kettle, the hydrogen peroxide is dropwise added after cooling, the high-content and high-yield p-bromoanisole product is obtained after preparation, the waste rate of raw materials consumed for preparation is low, the obtained p-bromoanisole is high in quality, the operation process is simple, and the environmental protection performance is high.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of p-bromoanisole, and in particular to a method for preparing p-bromoanisole. Background Art

[0002] p-Bromoanisole is an important organic compound, which is widely used in industry and scientific research. The main uses of p-Bromoanisole include solvent and organic synthesis. It can also be used as an intermediate of gynecological drug Tazo. In addition, it can also be used to prepare ultraviolet absorber p-methoxycinnamate isooctyl ester, which can isolate the skin from the contact of ultraviolet rays in the sun, avoid skin damage and prevent skin cancer. The preparation of p-Bromoanisole is very important in the chemical industry.

[0003] In the actual production process of p-bromoanisole, suitable parameters such as raw material ratio, reaction temperature and reaction time are selected according to specific needs and conditions. Traditionally, p-bromoanisole is generally prepared by direct bromination of toluene, i.e., toluene, catalyst and appropriate amount of water solvent are added to a reactor, and bromine is introduced after the temperature is raised to boiling. This method has a fast reaction speed, but poor selectivity, may produce a variety of isomers and polybrominated impurities, low content, and serious equipment corrosion, and difficult environmental protection treatment.

[0004] And use toluene catalytic dehydrogenation bromination method to prepare p-bromoanisole, first add toluene and dehydrating agent in toluene dehydrogenation reactor, make toluene partial oxidation dehydrogenation generate anisole by the effect of catalyst, then, in another reactor, generate anisole and bromine are carried out bromination reaction.But this method has more steps, longer flow process, and toluene conversion rate is lower, only 30%-40%, resulting in large waste of raw materials, and the yield of prepared p-bromoanisole is lower.Now propose a preparation method of p-bromoanisole, to improve the yield and quality of p-bromoanisole. Summary of the invention

[0005] The object of the present invention is to provide a kind of preparation method of p-bromoanisole, to solve the problem proposed in above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical scheme: a method for preparing p-bromoanisole, comprising the following steps:

[0007] S1, preparing anisole;

[0008] S2, preparing sodium bromide solution;

[0009] S3, material preparation: extract anisole in S1, sodium bromide solution, hydrochloric acid and hydrogen peroxide in S2 for synthesis preparation;

[0010] S4, material synthesis: put anisole, sodium bromide solution and hydrochloric acid in S3 into a reaction kettle, add hydrogen peroxide dropwise after cooling, let stand for liquid separation after the reaction, and obtain a crude product in the lower layer after liquid separation;

[0011] S5, distillation: the crude product in S4 is put into a reaction kettle for separation and distillation to obtain the product p-bromoanisole.

[0012] Preferably, the preparation of anisole in S1 comprises the following steps:

[0013] Step 1, mixing benzyl alcohol and sodium hydroxide and heating;

[0014] Step 2, slowly adding dimethyl sulfate dropwise, controlling the dropping speed to keep the reaction temperature stable;

[0015] Step 3: After the reaction is completed, the mixture is cooled to room temperature, and the reaction solution is washed with an acidic aqueous solution to separate anisole;

[0016] Step 4: purify by distillation, collect the fraction with a boiling point of 154-156° C., and obtain purified anisole.

[0017] Preferably, the preparation of the sodium bromide solution in S2 comprises the following steps:

[0018] Weighing sodium bromide: Use an electronic balance to accurately weigh the required amount of sodium bromide;

[0019] Dissolve sodium bromide: Add the weighed sodium bromide into a beaker, add 100 mL of distilled water, and stir with a magnetic stirrer or a glass rod until the sodium bromide is completely dissolved;

[0020] Make up the volume: transfer the dissolved sodium bromide solution to a volumetric flask, wash the beaker and glass rod with distilled water, and make sure all the sodium bromide has been transferred to the volumetric flask; continue to add distilled water to the scale line of the volumetric flask;

[0021] Shake well: Close the lid of the volumetric flask tightly, shake it upside down several times to ensure that the solution is evenly mixed to obtain a 20% sodium bromide solution.

[0022] Preferably, the anisole solution extracted in S3 is 216 g, the 20% sodium bromide solution is 1061 g, the 31% hydrochloric acid is 247 g, and the 30% hydrogen peroxide is 234 g.

[0023] Preferably, the chemical reaction equation generated in the reactor in S4 is as follows:

[0024]

[0025] Preferably, anisole, 20% sodium bromide solution and hydrochloric acid in S4 are put into a reaction kettle, cooled to 10°C, and then 30% hydrogen peroxide is added dropwise, with the dropping temperature being controlled not to exceed 15°C, and the addition is completed in about 6-8 hours.

[0026] Preferably, after the 30% hydrogen peroxide in S4 is added dropwise, the temperature in the reactor is controlled at 10-15° C. and kept warm for 3-6 hours.

[0027] Preferably, in S4, the residual amount of the raw material anisole in the reactor is less than 0.1%, the reaction is completed, and the solution in the reactor is allowed to stand for 1 hour before separation.

[0028] Preferably, the crude product after separation in S4 has a main content of 96%, a weight of 372 g, and a crude product yield of 95.49%.

[0029] Preferably, the reactor in S5 is decompressed with a distillation column for separation and distillation, and the fraction between 100-110° C. at a reactor pressure of -0.092 MPa is collected to obtain the product. The obtained p-bromoanisole is a colorless transparent liquid with a weight of 332 g, a main content of 99.8%, and a finished product total yield of 88.77%.

[0030] Technical effects and advantages of the present invention:

[0031] (1) The present invention is by putting anisole, sodium bromide solution and hydrochloric acid into a reactor, dripping hydrogen peroxide after cooling, controlling the dropping temperature and then keeping warm, after the raw material anisole remains below 0.1%, standing liquid separation, obtaining the lower floor as a crude product, and the crude product is put into a reactor, and a vacuum zone rectifying column is used for separation and distillation, collecting fractions, i.e. a p-bromoanisole product with high content and high yield, the material waste rate consumed in the preparation is low, the p-bromoanisole obtained is of high quality, the operating procedure is simple, and the environmental performance is high;

[0032] (2) The present invention can quickly obtain anisole and sodium bromide solution of required concentration by preparing anisole and sodium bromide solution respectively, and the reaction conditions of the synthesized bromoanisole are milder, simpler to operate, and higher in yield, and can be used for large-scale preparation, and has good promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart for preparing p-bromoanisole of the present invention.

[0034] Figure 2 It is a flow chart of the preparation of anisole of the present invention.

[0035] Figure 3 The present invention is a flow chart for preparing the sodium bromide solution. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The present invention provides Figure 1-3 A method for preparing p-bromoanisole is shown, comprising the following steps:

[0038] S1, prepare anisole, prepare anisole comprises the following steps:

[0039] Step 1, mixing benzyl alcohol and sodium hydroxide and heating, wherein the concentration of the sodium hydroxide is 10%-20%;

[0040] Step 2: slowly add dimethyl sulfate dropwise, control the dropwise addition speed to keep the reaction temperature stable, and keep the temperature between 30°C and 40°C, wherein the reaction equation is:

[0041] C6H5CH2OH+(CH3O)2SO2+NaOH→C6H5CH2OCH3+NaSO4+H2O

[0042] Dimethyl sulfate is used as a methylating agent and sodium hydroxide is used as an alkaline catalyst. Dimethyl sulfate will hydrolyze under alkaline conditions to produce methanol and dimethyl sulfate anion (an intermediate with a negatively charged methyl group connected to a sulfate group, simplified here as CH3O- to represent its reactive part), but this step is usually not written into the overall reaction equation because it is a fast and reversible step. Then the methyl anion will nucleophilically attack the hydrogen atom on the hydroxyl group of benzyl alcohol to form a tetrahedral intermediate. This intermediate then loses a molecule of water to form the final product anisole and sodium sulfate;

[0043] Step 3: After the reaction is completed, the mixture is cooled to room temperature, and the reaction solution is washed with an acidic aqueous solution to separate anisole;

[0044] Step 4: purify by distillation, collect the fraction with a boiling point of 154° C.-156° C., and obtain purified anisole.

[0045] S2, prepare sodium bromide solution, prepare sodium bromide solution comprises the following steps:

[0046] Weighing sodium bromide: Use an electronic balance to accurately weigh the required weight of sodium bromide, and accurately weigh 20g of sodium bromide solid. There are many ways to prepare sodium bromide. The first method for preparing sodium bromide is the reaction method of bromine and sodium hydroxide. The specific preparation method is as follows:

[0047] Add a slight excess of bromine directly to a saturated hot sodium hydroxide solution to generate a mixture of bromide and bromate, the reaction equation is: 3Br2+6NaOH=5NaBr+NaBrO3+3H20. Evaporate the reaction mixture to dryness, mix the obtained solid residue with carbon powder and heat it to reduce the bromate to a compound, the reaction equation is: NaBr03+3C=NaBr+3C0↑. Dissolve the reduced product with water, filter and crystallize it, place the crystals in a drying bottle for drying, and control the drying temperature at 110 to 130°C to obtain the finished sodium bromide;

[0048] The second method for preparing sodium bromide is the neutralization method of sodium bicarbonate and hydrobromic acid, and its specific preparation method is as follows:

[0049] Dissolve sodium bicarbonate in water, then neutralize with 35%-40% hydrobromic acid to obtain sodium bromide solution. The reaction equation is: HBr+NaHC03→NaBr+CO2↑+H20. Concentrate the sodium bromide solution and cool it to precipitate sodium bromide dihydrate. Filter the obtained sodium bromide dihydrate, dissolve it with a small amount of water, and then drop bromine water until the color of bromine just appears. Heat the solution, decolorize it with sulfide gas aqueous solution and boil it. Precipitate anhydrous crystals at high temperature, dry it, move it into a desiccator, keep it at 110℃ for 1 hour, and then cool it in a desiccator equipped with calcium bromide desiccant to obtain anhydrous sodium bromide.

[0050] Dissolve sodium bromide: Add the weighed sodium bromide into a beaker, add 100 mL of distilled water, and stir with a magnetic stirrer or a glass rod until the sodium bromide is completely dissolved;

[0051] Make up the volume: transfer the dissolved sodium bromide solution to a volumetric flask, wash the beaker and glass rod with distilled water, and make sure all the sodium bromide has been transferred to the volumetric flask; continue to add distilled water to the scale line of the volumetric flask;

[0052] Shake well: Close the lid of the volumetric flask tightly, shake it upside down several times to ensure that the solution is evenly mixed to obtain a 20% sodium bromide solution.

[0053] S3, material preparation: extract anisole from S1, sodium bromide solution from S2, hydrochloric acid and hydrogen peroxide for synthesis preparation, wherein the sodium bromide solution is a 20% sodium bromide solution, the hydrochloric acid is a 31% hydrochloric acid, and the hydrogen peroxide is a 30% hydrogen peroxide. In the laboratory, 31% hydrochloric acid can be prepared by the hydrochloric acid analytical method, and the specific steps are: add a certain amount of industrial-grade 31% hydrochloric acid to a round-bottom flask and heat it to boiling, and the hydrochloric acid gas passes through the steps of tower plate impurity removal, primary water reflux, chilled water cooling, etc. in the distillation equipment to remove water vapor and other impurities, and the obtained high-purity hydrogen chloride gas is absorbed with high-purity water to obtain 31% hydrochloric acid. In the laboratory, 30% hydrogen peroxide is usually prepared by electrolysis or barium peroxide method. The preparation steps of barium peroxide method are as follows: add ice cubes to 100 ml of 15%-18% sulfuric acid to cool it, then gradually add barium peroxide, the amount added is about 40 grams, and keep the solution weakly acidic; after the reaction, pour out the upper solution to obtain hydrogen peroxide solution. Through multiple extraction and evaporation treatments, 30% hydrogen peroxide can be obtained, and the preparation process is simple;

[0054] S4, material synthesis: put anisole, sodium bromide solution and hydrochloric acid in S3 into a reaction kettle, add 30% hydrogen peroxide dropwise after cooling, let stand for separation after the reaction, and obtain a crude product in the lower layer after separation;

[0055] S5, distillation: the crude product in S4 is put into a reaction kettle for separation and distillation to obtain the product p-bromoanisole.

[0056] Embodiment 1

[0057] S1, preparing anisole;

[0058] S2, prepare 20% sodium bromide solution;

[0059] S3, material preparation: extract anisole in S1, 20% sodium bromide solution, 31% hydrochloric acid and 30% hydrogen peroxide in S2 for synthesis preparation, and the extracted anisole solution is 216g, the 20% sodium bromide solution is 1061g, the 31% hydrochloric acid is 247g, and the 30% hydrogen peroxide is 234g;

[0060] S4, material synthesis: put the anisole, 20% sodium bromide solution and hydrochloric acid in S3 into a reactor, cool to 10°C, and then add 30% hydrogen peroxide dropwise. After the addition of 30% hydrogen peroxide is completed, the temperature is controlled not to exceed 15°C, and the addition is completed in about 6-8 hours. The raw material anisole in the reactor remains below 0.1%, and the reaction is completed. The solution in the reactor is allowed to stand for 1 hour and then separated. The lower layer is a crude product, the main content of the crude product is 96%, the weight is 372g, and the crude product yield is 95.49%;

[0061] S5, distillation: the crude product in S4 is put into a reactor, the reactor is decompressed with a rectification column for separation and distillation, and the fraction between 100-110° C. at a pressure of -0.092 MPa in the reactor is collected to obtain the product p-bromoanisole.

[0062] The p-bromoanisole prepared by the above method is a colorless transparent liquid, weighs 332g, has a main content of 99.8%, and a finished product total yield of 88.77%. The specific gravity of the p-bromoanisole obtained is 1.5, the melting point is 12 degrees, the boiling point is 215 degrees, and the flash point is 94 degrees.

[0063] And the chemical reaction equation generated in the reactor in S4 is as follows:

[0064]

[0065] Embodiment 2

[0066] S1, preparing anisole;

[0067] S2, prepare 20% sodium bromide solution;

[0068] S3, material preparation: extract anisole in S1, 20% sodium bromide solution, 31% hydrochloric acid and 30% hydrogen peroxide in S2 for synthesis preparation, and the extracted anisole solution is 216g, the 20% sodium bromide solution is 1061g, the 31% hydrochloric acid is 247g, and the 30% hydrogen peroxide is 234g;

[0069] S4, material synthesis: put the anisole, 20% sodium bromide solution and hydrochloric acid in S3 into a reactor, cool to 10°C, and then add 30% hydrogen peroxide dropwise. After the addition of 30% hydrogen peroxide is completed, the temperature is controlled not to exceed 15°C, and the addition is completed in about 6-8 hours. The raw material anisole in the reactor remains below 0.1%, and the reaction is completed. The solution in the reactor is allowed to stand for 1 hour and then separated. The lower layer is a crude product, the main content of the crude product is 96%, the weight is 372g, and the crude product yield is 95.49%;

[0070] S5, distillation: the crude product in S4 is put into a reactor, the reactor is decompressed with a rectification column for separation and distillation, and the fraction between 70-80° C. at a pressure of -0.092 MPa in the reactor is collected to obtain the product p-bromoanisole.

[0071] The p-bromoanisole prepared by the method is a colorless transparent liquid with a weight of 318 g, a main content of 85%, and a finished product total yield of 82.3%.

[0072] Embodiment 3

[0073] S1, preparing anisole;

[0074] S2, prepare 20% sodium bromide solution;

[0075] S3, material preparation: extract anisole in S1, 20% sodium bromide solution, 31% hydrochloric acid and 30% hydrogen peroxide in S2 for synthesis preparation, and the extracted anisole solution is 216g, the 20% sodium bromide solution is 1061g, the 31% hydrochloric acid is 247g, and the 30% hydrogen peroxide is 234g;

[0076] S4, material synthesis: put the anisole, 20% sodium bromide solution and hydrochloric acid in S3 into a reactor, cool to 10°C, and then add 30% hydrogen peroxide dropwise. After the addition of 30% hydrogen peroxide is completed, the temperature is controlled not to exceed 15°C, and the addition is completed in about 6-8 hours. The raw material anisole in the reactor remains below 0.1%, and the reaction is completed. The solution in the reactor is allowed to stand for 1 hour and then separated. The lower layer is a crude product, the main content of the crude product is 96%, the weight is 372g, and the crude product yield is 95.49%;

[0077] S5, distillation: the crude product in S4 is put into a reactor, the reactor is decompressed with a rectification column for separation and distillation, and the fractions between 140-150° C. at a pressure of -0.092 MPa in the reactor are collected to obtain the product p-bromoanisole.

[0078] The p-bromoanisole prepared by the above method is a colorless transparent liquid, weighing 347g, with a main content of 76%, and a finished product total yield of 69.4%

[0079] It can be seen that the reaction temperature for preparing p-bromoanisole is preferably controlled at 100-110° C., which can obtain a higher yield and a high content of p-bromoanisole. The effect of the reaction temperature on the yield of the product is shown in the following table.

[0080]

[0081] Embodiment 4

[0082] S1, preparing anisole;

[0083] S2, prepare 20% sodium bromide solution;

[0084] S3, material preparation: extract anisole in S1, 20% sodium bromide solution, 31% hydrochloric acid and 30% hydrogen peroxide in S2 for synthesis preparation, and the extracted anisole solution is 216g, the 20% sodium bromide solution is 1552g, the 31% hydrochloric acid is 247g, and the 30% hydrogen peroxide is 234g;

[0085] S4, material synthesis: put anisole, 20% sodium bromide solution and hydrochloric acid in S3 into a reactor, cool to 10°C, and then add 30% hydrogen peroxide dropwise. After the addition of 30% hydrogen peroxide is completed, the temperature is controlled not to exceed 15°C. The addition is completed in about 6-8 hours, and the reaction is completed. The solution in the reactor is allowed to stand for 1 hour and then separated. The lower layer is a crude product, the main content of the crude product is 92%, the weight is 393g, and the crude product yield is 90.9%;

[0086] S5, distillation: the crude product in S4 is put into a reactor, the reactor is decompressed with a rectification column for separation and distillation, and the fraction between 100-110° C. at a pressure of -0.092 MPa in the reactor is collected to obtain the product p-bromoanisole.

[0087] The p-bromoanisole prepared by the method is a colorless transparent liquid with a weight of 316 g, a main content of 98.5%, and a finished product total yield of 82.7%.

[0088] Embodiment 5

[0089] S1, preparing anisole;

[0090] S2, prepare 20% sodium bromide solution;

[0091] S3, material preparation: extract anisole in S1, 20% sodium bromide solution, 31% hydrochloric acid and 30% hydrogen peroxide in S2 for synthesis preparation, and the extracted anisole solution is 216g, the 20% sodium bromide solution is 1061g, the 31% hydrochloric acid is 356g, and the 30% hydrogen peroxide is 234g;

[0092] S4, material synthesis: put the anisole, 20% sodium bromide solution and hydrochloric acid in S3 into a reactor, cool to 10°C, and then add 30% hydrogen peroxide dropwise. After the addition of 30% hydrogen peroxide is completed, the temperature is controlled not to exceed 15°C, and the addition is completed in about 6-8 hours. The raw material anisole in the reactor remains below 0.1%, and the reaction is completed. The solution in the reactor is allowed to stand for 1 hour and then separated. The lower layer is a crude product, the main content of the crude product is 96%, the weight is 372g, and the crude product yield is 95.49%;

[0093] S5, distillation: the crude product in S4 is put into a reactor, the reactor is decompressed with a rectification column for separation and distillation, and the fraction between 100-110° C. at a pressure of -0.092 MPa in the reactor is collected to obtain the product p-bromoanisole.

[0094] The p-bromoanisole prepared by the method is a colorless transparent liquid with a weight of 351 g, a main content of 97.75%, and a finished product total yield of 80.3%.

[0095] Experiments show that increasing the amount of sodium bromide solution or hydrochloric acid does not increase the total yield and content of p-bromoanisole. The effect of the increase on the product yield is shown in the table below.

[0096]

[0097] Embodiment 6

[0098] S1, preparing anisole;

[0099] S2, prepare 20% sodium bromide solution;

[0100] S3, material preparation: extract anisole in S1, 20% sodium bromide solution, 31% hydrochloric acid and 30% hydrogen peroxide in S2 for synthesis preparation, and the extracted anisole solution is 216g, the 30% sodium bromide solution is 1061g, the 31% hydrochloric acid is 247g, and the 30% hydrogen peroxide is 234g;

[0101] S4, material synthesis: put the anisole, 30% sodium bromide solution and hydrochloric acid in S3 into a reactor, cool to 10°C, and then add 30% hydrogen peroxide dropwise. After the addition of 30% hydrogen peroxide is completed, the temperature is controlled not to exceed 15°C, and the addition is completed in about 6-8 hours. The raw material anisole in the reactor remains below 0.1%, and the reaction is completed. The solution in the reactor is allowed to stand for 1 hour and then separated. The lower layer is a crude product, the main content of the crude product is 92.6%, the weight is 382g, and the crude product yield is 91.49%;

[0102] S5, distillation: the crude product in S4 is put into a reactor, the reactor is decompressed with a rectification column for separation and distillation, and the fraction between 100-110° C. at a pressure of -0.092 MPa in the reactor is collected to obtain the product p-bromoanisole.

[0103] The p-bromoanisole prepared by the method is a colorless transparent liquid with a weight of 338 g, a main content of 93.1%, and a finished product total yield of 82.9%.

[0104] Experiments show that increasing the concentration of sodium bromide solution does not increase the total yield and content of p-bromoanisole.

[0105] Working principle of the present invention:

[0106] First, extract and weigh anisole: 216 g; 20% sodium bromide solution, 1061 g; hydrochloric acid (31%): 247 g; 30% hydrogen peroxide: 234 g.

[0107] Then the synthesis is carried out: anisole, sodium bromide solution and hydrochloric acid are put into a reaction kettle, cooled to 10°C, and 30% hydrogen peroxide is added dropwise, and the dropping temperature is controlled not to exceed 15°C. The addition is completed in about 6-8 hours, and the temperature is controlled to be 10-15°C for 3-6 hours. The raw material anisole remains less than 0.1%, the reaction is completed, and the reaction is allowed to stand for 1 hour. The liquid is separated, and the lower layer is a crude product with a main content of about 96%, a weight of 372g, and a crude product yield of 95.49%.

[0108] Finally, distillation is performed: the crude product is put into a reaction kettle, and separation distillation is performed with a vacuum distillation column, and a fraction between 100 and 110 DEG C under -0.092MPa is collected, i.e., p-bromoanisole. The p-bromoanisole is a colorless transparent liquid, weighs 332g, has a main content of 99.8%, and has a finished product total yield of 88.77%. A p-bromoanisole product with high content and high yield is obtained, the waste rate of raw materials consumed in the preparation is low, the obtained p-bromoanisole is of high quality, and simultaneously meets the high content and high total yield of p-bromoanisole, has a simple operation process, is high in environmental protection performance, can be used for large-scale preparation, and has good promotion value.

[0109] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing p-bromoanisole, characterized in that, The following steps are involved: S1, preparing anisole; S2, preparing sodium bromide solution; S3, material preparation: extract anisole in S1, sodium bromide solution, hydrochloric acid and hydrogen peroxide in S2 for synthesis preparation; S4, material synthesis: put anisole, sodium bromide solution and hydrochloric acid in S3 into a reaction kettle, add hydrogen peroxide dropwise after cooling, let stand for liquid separation after the reaction, and obtain a lower layer crude product after liquid separation; S5, distillation: the crude product in S4 is put into a reaction kettle for separation and distillation to obtain the product p-bromoanisole.

2. a kind of preparation method of p-bromoanisole according to claim 1, is characterized in that, The preparation of anisole in S1 comprises the following steps: Step 1, mixing benzyl alcohol and sodium hydroxide and heating; Step 2, slowly adding dimethyl sulfate dropwise, controlling the dropping speed to keep the reaction temperature stable; Step 3: After the reaction is completed, the mixture is cooled to room temperature, and the reaction solution is washed with an acidic aqueous solution to separate anisole; Step 4: purify by distillation, collect the fraction with a boiling point of 154-156° C., and obtain purified anisole.

3. A method for preparing p-bromoanisole according to claim 1, characterized in that, The preparation of sodium bromide solution in S2 comprises the following steps: Weighing sodium bromide: Use an electronic balance to accurately weigh the required amount of sodium bromide; Dissolve sodium bromide: Add the weighed sodium bromide into a beaker, add 100 mL of distilled water, and stir with a magnetic stirrer or a glass rod until the sodium bromide is completely dissolved; Make up the volume: transfer the dissolved sodium bromide solution to a volumetric flask, wash the beaker and glass rod with distilled water, and make sure all the sodium bromide has been transferred to the volumetric flask; continue to add distilled water to the scale line of the volumetric flask; Shake well: Close the lid of the volumetric flask tightly, shake it upside down several times to ensure that the solution is evenly mixed to obtain a 20% sodium bromide solution.

4. a kind of preparation method of p-bromoanisole according to claim 1, is characterized in that, The anisole solution extracted in S3 is 216 g, the 20% sodium bromide solution is 1061 g, the 31% hydrochloric acid is 247 g, and the 30% hydrogen peroxide is 234 g.

5. A method for preparing p-bromoanisole according to claim 1, characterized in that, The chemical reaction equation generated in the reactor in S4 is as follows:

6. A method for preparing p-bromoanisole according to claim 1, characterized in that, The anisole, 20% sodium bromide solution and hydrochloric acid in S4 are put into a reaction kettle, cooled to 10°C, and then 30% hydrogen peroxide is added dropwise, with the dropping temperature controlled not to exceed 15°C, and the addition is completed in about 6-8 hours.

7. A method for preparing p-bromoanisole according to claim 1, characterized in that, After the 30% hydrogen peroxide in S4 is added dropwise, the temperature in the reactor is controlled at 10-15° C. and kept warm for 3-6 hours.

8. A method for preparing p-bromoanisole according to claim 1, characterized in that, In the step S4, the remaining amount of the raw material anisole in the reaction kettle is less than 0.1%, and the reaction is finished. The solution in the reaction kettle is allowed to stand for 1 hour before separation.

9. A method for preparing p-bromoanisole according to claim 1, characterized in that, The crude product after separation in S4 has a main content of 96%, a weight of 372 g, and a crude product yield of 95.49%.

10. A method for preparing p-bromoanisole according to claim 1, characterized in that, The reactor in S5 is decompressed with a rectifying column for separation and distillation, and the fraction between 100-110° C. at a reactor pressure of -0.092 MPa is collected to obtain the product. The obtained p-bromoanisole is a colorless transparent liquid with a weight of 332 g, a main content of 99.8%, and a total yield of the finished product of 88.77%.

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