A device for producing benzyl bromide

Abstract

The utility model discloses a kind of production devices of benzyl bromide, it is related to benzyl bromide production technical field, the inlet of reaction kettle is respectively communicated with formic acid tank, sulfuric acid tank, benzyl alcohol tank, purified water tank and bromine tank by pipeline, the top gas phase outlet of reaction kettle is communicated with reflux condenser by pipeline, the bottom outlet of reaction kettle is communicated with first liquid separator tank by pipeline, the oil phase outlet of first liquid separator tank is communicated with benzyl bromide product tank by pipeline.Using benzyl alcohol and bromine as main raw material, benzyl bromide is prepared by reaction, reaction selectivity is higher, by-product is significantly reduced, solve the problem that conventional toluene free radical halogenation method has many by-products, purification is complex, can directly obtain higher purity crude product by liquid separation initially.

Description

Technical Field

[0001] This utility model relates to the field of benzyl bromide production technology, specifically to a benzyl bromide production apparatus. Background Technology

[0002] Benzyl bromide (also known as benzyl bromide, α-bromotoluene, or benzyl bromide), with the molecular formula C6H5CH2Br or C7H7Br, a molecular weight of 171, and a relative density of 1.44, is a heavy liquid. At room temperature, it is a colorless, transparent liquid with strong lachrymatory properties and an unpleasant, pungent odor. Benzyl bromide is primarily prepared via a free radical halogenation reaction. The most common industrial method is the reaction of toluene and bromine. This process generates numerous byproducts, making purification complex and indirectly affecting product purity. However, the readily available and inexpensive raw materials make it widely accepted by most manufacturers. Alternatively, the Wohl-Ziegler bromination method is used, reacting N-bromosuccinimide with toluene in the presence of a catalyst such as peroxide to prepare benzyl bromide. However, because N-bromosuccinimide itself has a strong irritant and unpleasant odor, it is difficult to control in actual production, and the reaction conditions are relatively complex; therefore, this method is generally not used. Summary of the Invention

[0003] The technical problem to be solved by this utility model is to provide a benzyl bromide production device that is simple in structure and produces benzyl bromide products with high purity, in order to address the shortcomings of the existing technology.

[0004] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows:

[0005] A benzyl bromide production apparatus includes a reaction vessel. The inlet of the reaction vessel is connected to a formic acid tank, a sulfuric acid tank, a benzyl alcohol tank, a purified water tank, and a bromine tank via pipelines. The top gas phase outlet of the reaction vessel is connected to a reflux condenser via a pipeline. The bottom outlet of the reaction vessel is connected to a first separating tank via a pipeline. The oil phase outlet of the first separating tank is connected to a benzyl bromide product tank via a pipeline.

[0006] The reaction principle is as follows:

[0007] First, formic acid is used to reduce bromine to produce hydrogen bromide. The equation is as follows:

[0008] H₂CO₂ + Br₂ → 2HBr + CO₂↑ ①

[0009] Benzyl alcohol reacts with hydrogen bromide in the presence of sulfuric acid catalyst to produce benzyl bromide. The reaction formula is as follows:

[0010] C7H8O + HBr → C7H7Br + H2O ②

[0011] Combining reaction equations ① and ②, the resulting reaction equation is:

[0012] H2CO2+Br2+2C7H8O→2C7H7Br+2H2O+CO2↑ ③

[0013] As an improved technical solution, the top outlet of the reflux condenser is connected to a tail gas adsorption tower via a pipeline.

[0014] As an improved technical solution, the bottom outlet of the reactor is connected to a circulation pump via a pipeline, and the outlet of the circulation pump is connected to the reactor and the first separator via pipelines respectively.

[0015] As an improved technical solution, the outlet pipe of the circulating pump is equipped with a heat exchanger.

[0016] As an improved technical solution, the aqueous phase outlet of the first separator is connected to the inlet of the reactor via a pipeline.

[0017] As an improved technical solution, the outlet of the benzyl bromide product tank is connected to an alkaline washing tank via a pipeline, the inlet of the alkaline washing tank is connected to an alkaline solution tank via a pipeline, the outlet of the alkaline washing tank is connected to a second separating tank via a pipeline, and the oil phase outlet of the second separating tank is connected to a benzyl bromide pure product tank via a pipeline.

[0018] As an improved technical solution, the oil phase outlet of the second separator is connected to a water washing tank via a pipeline, the inlet of the water washing tank is connected to a rinsing water tank via a pipeline, the outlet of the water washing tank is connected to a third separator via a pipeline, and the oil phase outlet of the third separator is connected to the benzyl bromide pure product tank via a pipeline.

[0019] Due to the adoption of the above technical solution, the beneficial effects of this utility model are:

[0020] This invention discloses a benzyl bromide production apparatus, comprising a reaction vessel. The inlet of the reaction vessel is connected via pipelines to a formic acid tank, a sulfuric acid tank, a benzyl alcohol tank, a purified water tank, and a bromine tank. The top gas phase outlet of the reaction vessel is connected via pipelines to a reflux condenser, and the bottom outlet of the reaction vessel is connected via pipelines to a first separating tank. The oil phase outlet of the first separating tank is connected via pipelines to a benzyl bromide product tank. Using benzyl alcohol and bromine as the main raw materials, benzyl bromide is prepared through reaction. The reaction selectivity is higher, and the by-products are significantly reduced. This solves the problems of numerous by-products and complex purification in the conventional toluene free radical halogenation method, and allows for the direct preliminary acquisition of a high-purity crude product through liquid-liquid separation.

[0021] The top outlet of the reflux condenser of this invention is connected to a tail gas adsorption tower via a pipeline. Addressing the volatile nature of bromine, the tail gas adsorption tower efficiently recovers small amounts of unreacted bromine vapor and acidic tail gas, avoiding the waste of raw materials and environmental pollution caused by direct tail gas emissions in conventional processes. Furthermore, unlike the Wohl-Ziegler process, which suffers from difficulty in controlling tail gas due to the strong irritation of raw materials, this design is more environmentally friendly.

[0022] The bottom outlet of the reactor is connected to a circulation pump via a pipeline, and the outlet of the circulation pump is connected to both the reactor and the first separatory tank via pipelines. The circulation pump enables forced circulation of the reactants, resulting in more uniform mixing of the reaction system. This solves the side reaction problem caused by excessively high local concentrations in conventional stirred reactions. It also allows for flexible control of the discharge rhythm, improving the reaction conversion rate, unlike the product purity fluctuations caused by uneven reaction in the toluene halogenation process.

[0023] The outlet pipe of the circulating pump is equipped with a heat exchanger. The reaction temperature is precisely controlled by the heat exchanger, avoiding the local high temperature caused by concentrated exothermic heat in conventional processes (which can easily trigger side reactions such as benzyl alcohol dehydration). In particular, it is different from the free radical halogenation method, which is sensitive to temperature and prone to exacerbating side reactions due to temperature runaway, thus further improving product purity and yield.

[0024] The aqueous phase outlet of the first separator is connected to a recovery tank via a pipeline, and the outlet of the recovery tank is connected to the inlet of the reactor via a pipeline. The separated aqueous phase (mainly dilute sulfuric acid) is returned to the reactor, realizing the recycling of raw materials. This solves the problems of low single-pass utilization rate of raw materials and high waste liquid treatment costs in conventional processes, thereby reducing production costs.

[0025] The outlet of the benzyl bromide product tank is connected to an alkaline washing tank via a pipeline. The inlet of the alkaline washing tank is connected to an alkaline solution tank via a pipeline. The outlet of the alkaline washing tank is connected to a second separating tank via a pipeline. The oil phase outlet of the second separating tank is connected to a benzyl bromide pure product tank via a pipeline. Benzyl alcohol has a higher solubility in alkaline solution. After separation in the second separating tank, benzyl alcohol and other impurities enter the aqueous phase, further improving the purity of the benzyl bromide product.

[0026] The oil phase outlet of the second separator is connected to a water washing tank via a pipeline. The inlet of the water washing tank is connected to a rinsing water tank via a pipeline. The outlet of the water washing tank is connected to a third separator via a pipeline. The oil phase outlet of the third separator is connected to the benzyl bromide pure product tank via a pipeline. Water washing further removes residual salt impurities after alkali washing, ensuring product purity. Compared to conventional processes that rely solely on distillation for purification, this step is simpler and more efficient. It effectively avoids the risk of benzyl bromide decomposition due to high temperatures during distillation, and solves the problem of complex purification steps and potential impact on product stability in conventional methods. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] Figure 1 This is a structural schematic diagram of an embodiment of the present utility model;

[0029] The components are as follows: 1. Reactor; 2. Formic acid tank; 3. Sulfuric acid tank; 4. Benzyl alcohol tank; 5. Purified water tank; 6. Bromine tank; 7. Reflux condenser; 8. First separatory tank; 9. Benzyl bromide product tank; 10. Tail gas adsorption tower; 11. Circulation pump; 12. Heat exchanger; 13. Alkali washing tank; 14. Alkali solution tank; 15. Second separatory tank; 16. Benzyl bromide pure product tank; 17. Water washing tank; 18. Rinse water tank; 19. Third separatory tank; 20. Recovery tank. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] like Figure 1 As shown, a benzyl bromide production apparatus includes a reaction vessel 1. The inlet of the reaction vessel 1 is connected via pipelines to a formic acid tank 2, a sulfuric acid tank 3, a benzyl alcohol tank 4, a purified water tank 5, and a bromine tank 6. The top gas phase outlet of the reaction vessel 1 is connected via a pipeline to a reflux condenser 7. The bottom outlet of the reaction vessel 1 is connected via a pipeline to a first separating tank 8. The oil phase outlet of the first separating tank 8 is connected via a pipeline to a benzyl bromide product tank 9. Using benzyl alcohol and bromine as the main raw materials, benzyl bromide is prepared through reaction. This method exhibits higher reaction selectivity and significantly reduced byproducts, solving the problems of numerous byproducts and complex purification in the conventional toluene free radical halogenation method. A high-purity crude product can be directly obtained through preliminary separation.

[0032] The top outlet of the reflux condenser 7 is connected to the tail gas adsorption tower 10 via a pipeline. Given the volatile nature of bromine, the tail gas adsorption tower 10 efficiently recovers small amounts of unreacted bromine vapor and acidic tail gas, avoiding the waste of raw materials and environmental pollution caused by direct tail gas emissions in conventional processes. Furthermore, unlike the Wohl-Ziegler process, which suffers from difficulty in controlling tail gas due to the strong irritation of raw materials, this method is more environmentally friendly.

[0033] The bottom outlet of the reactor 1 is connected to a circulation pump 11 via a pipeline. The outlet of the circulation pump 11 is connected to both the reactor 1 and the first separatory tank 8 via pipelines. The circulation pump 11 enables forced circulation of the reactants, resulting in more uniform mixing of the reaction system. This solves the side reaction problem caused by excessively high local concentrations in conventional stirred reactions. It also allows for flexible control of the discharge rhythm, improving the reaction conversion rate, unlike the product purity fluctuations caused by uneven reaction in the toluene halogenation process.

[0034] The outlet pipe of the circulating pump 11 is equipped with a heat exchanger 12. The reaction temperature is precisely controlled by the heat exchanger 12, avoiding the local high temperature caused by concentrated exothermic heat in conventional processes (which can easily trigger side reactions such as benzyl alcohol dehydration). In particular, it is different from the free radical halogenation method, which is sensitive to temperature and prone to exacerbating side reactions due to temperature runaway, thus further improving product purity and yield.

[0035] The aqueous phase outlet of the first separator is connected to a recovery tank 20 via a pipeline, and the outlet of the recovery tank 20 is connected to the inlet of the reactor 1 via a pipeline. The aqueous phase (mainly dilute sulfuric acid) after separation is returned to the reactor 1, realizing the recycling of raw materials. This solves the problems of low single-pass utilization rate of raw materials and high waste liquid treatment cost in conventional processes, and reduces production costs.

[0036] The outlet of the benzyl bromide product tank 9 is connected to an alkaline washing tank 13 via a pipeline. The inlet of the alkaline washing tank 13 is connected to an alkaline solution tank 14 via a pipeline. The outlet of the alkaline washing tank 13 is connected to a second separating tank 15 via a pipeline. The oil phase outlet of the second separating tank 15 is connected to a water washing tank 17 via a pipeline. The inlet of the water washing tank 17 is connected to a rinsing water tank 18 via a pipeline. The outlet of the water washing tank 17 is connected to a third separating tank 19 via a pipeline. The oil phase outlet of the third separating tank 19 is connected to the benzyl bromide pure product tank 16 via a pipeline. Benzyl alcohol has a higher solubility in alkaline solution. After separation in the second separating tank 15, benzyl alcohol and other impurities enter the aqueous phase, further improving the purity of the benzyl bromide product. Water washing further removes residual salt impurities after alkaline washing, ensuring product purity. Compared to conventional processes that rely solely on distillation for purification, this step is simpler and more efficient, effectively avoiding the risk of benzyl bromide decomposition due to high temperatures during distillation. It solves the problem of complex purification steps and the potential impact on product stability in conventional methods.

[0037] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A production apparatus for benzyl bromide, comprising a reaction vessel, characterized in that: The inlet of the reactor is connected to a formic acid tank, a sulfuric acid tank, a benzyl alcohol tank, a purified water tank, and a bromine tank via pipelines. The top gas phase outlet of the reactor is connected to a reflux condenser via a pipeline. The bottom outlet of the reactor is connected to a first separatory tank via a pipeline. The oil phase outlet of the first separator is connected to a benzyl bromide product tank via a pipeline.

2. The benzyl bromide production apparatus as described in claim 1, characterized in that: The top outlet of the reflux condenser is connected to a tail gas adsorption tower via a pipeline.

3. The benzyl bromide production apparatus as described in claim 1, characterized in that: The bottom outlet of the reactor is connected to a circulation pump via a pipeline, and the outlet of the circulation pump is connected to the reactor and the first separator via pipelines.

4. The benzyl bromide production apparatus as described in claim 3, characterized in that: The outlet pipe of the circulating pump is equipped with a heat exchanger.

5. The benzyl bromide production apparatus as described in claim 1, characterized in that: The aqueous phase outlet of the first separator is connected to a recovery tank via a pipeline, and the outlet of the recovery tank is connected to the inlet of the reactor via a pipeline.

6. The benzyl bromide production apparatus as described in claim 1, characterized in that: The outlet of the benzyl bromide product tank is connected to an alkaline washing tank via a pipeline, the inlet of the alkaline washing tank is connected to an alkaline solution tank via a pipeline, the outlet of the alkaline washing tank is connected to a second separating tank via a pipeline, and the oil phase outlet of the second separating tank is connected to a benzyl bromide pure product tank via a pipeline.

7. The benzyl bromide production apparatus as described in claim 6, characterized in that: The oil phase outlet of the second separator is connected to a water washing tank via a pipeline. The inlet of the water washing tank is connected to a rinsing water tank via a pipeline. The outlet of the water washing tank is connected to a third separator via a pipeline. The oil phase outlet of the third separator is connected to the benzyl bromide pure product tank via a pipeline.

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