Environment-friendly benzethonium chloride production method capable of recycling solvent
By using a composite solvent system and a multi-tower distillation recovery process, the problem of mismatch between solubility and reaction selectivity in the traditional benzyl chloride production has been solved, achieving high purity, high yield, and efficient solvent recovery, thereby reducing environmental impact and production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WEIFANG HUITAO CHEM
- Filing Date
- 2025-12-31
- Publication Date
- 2026-05-12
AI Technical Summary
In the traditional benzyl chloride production process, a single solvent system is difficult to balance the solubility of raw materials and the selectivity of the reaction, resulting in slow reaction rate, increased side reactions, low product yield and purity, and difficulty in solvent recovery and purification.
By employing a composite solvent system and a multi-tower distillation recovery process, the reaction conditions are optimized through the combined use of ethanol and ethyl acetate, and isopropanol and acetone. The solvent is then separated and recovered through multi-tower distillation, achieving a closed-loop recycling of the solvent.
It improves reaction selectivity, reduces by-product formation, achieves product purity of over 99.0%, increases yield, achieves solvent recovery rate of over 95%, and reduces environmental impact and production costs.
Smart Images
Figure CN122010750A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic synthesis technology, specifically an environmentally friendly production method for benzyl chloride using solvent recycling. Background Technology
[0002] Benzyl chloride, chemically known as N-benzyl-N,N-dimethyldodecane-1-ammonium chloride, is a commonly used quaternary ammonium salt cationic surfactant with excellent bactericidal, disinfectant, and preservative properties. It is widely used in pharmaceuticals, hygiene, food processing, and water treatment. Currently, the industrial production of benzyl chloride typically employs a multi-step synthesis process, generally involving core steps such as ethylene oxide addition, chlorination, and quaternization. First, a phenol derivative containing a tert-octyl group (such as p-tert-octylphenol) undergoes an addition reaction with ethylene oxide, epichlorohydrin, or other epoxide compounds in a solvent to generate a chloride intermediate containing a phenoxyethyl or phenoxyethoxyethyl structure. Then, this intermediate undergoes a quaternization reaction with a quaternizing agent to produce benzyl chloride.
[0003] However, traditional processes generally use a single solvent (such as ethanol, isopropanol, etc.) as the reaction medium. Although the reaction selectivity is mainly determined by the catalyst, temperature and material ratio, a single solvent system is difficult to achieve synergistic optimization of raw material solubility and reaction selectivity. Insufficient solubility may lead to a slow reaction rate, or polarity mismatch may exacerbate side reactions, ultimately resulting in an increased amount of by-products. This not only keeps the product yield at only 80%-83% and the purity at 96%-97%, but also significantly increases the difficulty of subsequent solvent recovery and product purification due to the strong interaction between by-products and solvent. Summary of the Invention
[0004] The purpose of this invention is to provide an environmentally friendly production method for benzyl chloride using solvent recycling, in order to solve the technical problems mentioned in the background art.
[0005] An environmentally friendly method for producing benzyl chloride using solvent recycling, comprising the following steps: (1) Addition reaction: p-tert-octylphenol, ethylene oxide and epichlorohydrin are mixed in a molar ratio of 1:(1.2-1.5):(1.05-1.35) and added to composite solvent A. An addition reaction is carried out under the action of a catalyst to obtain a reaction solution containing a chloride intermediate. The composite solvent A is composed of ethanol and ethyl acetate in a volume ratio of (3-5):1. The mass of the composite solvent A is 1.2-2.0 times the total mass of p-tert-octylphenol, ethylene oxide and epichlorohydrin. (2) Quaternization reaction: The reaction solution containing the chloride intermediate is mixed with N,N-dimethylbenzylamine at a molar ratio of 1:(1.12-1.23) and then added to composite solvent B to carry out the quaternization reaction to obtain a crude benzyl chloride mixture; the composite solvent B is composed of isopropanol and acetone mixed at a volume ratio of (2-4):1, and the mass of the composite solvent B is 1.5-2.5 times the total mass of the chloride intermediate and N,N-dimethylbenzylamine; (3) Crude product purification: The crude benzyl chloride mixture is filtered to obtain filtrate and filter residue. The filter residue is washed and dried to obtain pure benzyl chloride and washing solution. (4) Solvent recovery: The filtrate and the washing liquid are combined and the composite solvent A and composite solvent B are recovered by distillation separation process. The recovered solvent is recycled for the reaction in steps (1) and (2). (5) Residue treatment: The residue generated after distillation separation is treated to obtain industrial-grade by-products.
[0006] As a preferred embodiment of the above technical solution, the purity of p-tert-octylphenol in step (1) is ≥98%; the purity of ethylene oxide is ≥99.5%; and the purity of epichlorohydrin is ≥98.5%.
[0007] As a preferred embodiment of the above technical solution, the ethanol purity in the composite solvent A in step (1) is ≥99%, and the ethyl acetate purity is ≥98%.
[0008] As a preferred embodiment of the above technical solution, the catalyst in step (1) is a boron trifluoride diethyl ether complex with a purity ≥98%, the amount of catalyst used is 0.5%-1.5% of the mass of p-tert-octylphenol, the addition reaction temperature is 40-60℃, the reaction time is 3-5h, the pH value of the system is controlled at 3.5-4.5 during the reaction, and the pH is adjusted by hydrochloric acid.
[0009] As a preferred embodiment of the above technical solution, the purity of N,N-dimethylbenzylamine in step (2) is ≥98%, the quaternization reaction temperature is 60-80℃, the reaction time is 4-6h, the pH value of the system is controlled at 7.0-7.5 during the reaction, and the pH is adjusted by sodium hydroxide solution.
[0010] As a preferred embodiment of the above technical solution, the purity of isopropanol in the composite solvent B in step (2) is ≥99%, and the purity of acetone is ≥99%.
[0011] As a preferred embodiment of the above technical solution, in step (3), a precision filter membrane is used for filtration with a filtration accuracy of 0.22-0.45μm; ethanol is used for gradient washing, and the washing is performed 2-3 times; the drying temperature is 60-80℃, the drying time is 2-3h, and the drying pressure is 0.08-0.1MPa.
[0012] As a preferred embodiment of the above technical solution, the specific steps of the distillation separation process in step (4) are as follows: S1. Combine the filtrate from step (3) with the washing liquid to obtain a mixed waste liquid containing ethanol, ethyl acetate, isopropanol and acetone; S2. Add 0.1%-0.3% by mass of 2,6-di-tert-butyl-p-cresol to the mixed waste liquid, heat to 50-60°C, and stir for 30 minutes; S3, Multi-tower sequential distillation separation: The temperature at the top of the first distillation column is controlled at 56-58℃, the temperature at the bottom of the column is controlled at 75-78℃, and the operating pressure is controlled at 0.1MPa. Acetone is distilled from the top of the first distillation column and the acetone fraction is collected. The bottom liquid of the first distillation column is fed into the second distillation column. The top temperature of the second distillation column is controlled at 71-72℃, the bottom temperature at 85-90℃, and the operating pressure at 0.1MPa. The ethanol-ethyl acetate azeotrope is distilled off from the top of the second distillation column. The bottom liquid from the second distillation column is fed into the third distillation column. The top temperature of the third distillation column is controlled at 81-83℃, the bottom temperature at 95-100℃, and the operating pressure at 0.1MPa. Isopropanol is distilled off from the top of the third distillation column, and the isopropanol fraction is collected. The bottom of the third distillation column is the distillation residue.
[0013] As a preferred embodiment of the above technical solution, the residue treatment in step (5) is as follows: the distillation residue is mixed with 10wt%-20wt% sodium hydroxide solution at a mass ratio of 1:(3-5), reacted at 80-100℃ for 2-3 hours, filtered to obtain sodium salt product, concentrated and crystallized to obtain industrial grade sodium chloride, and the filtrate is neutralized and discharged in compliance with standards.
[0014] As a preferred embodiment of the above technical solution, the recovered composite solvent A and composite solvent B are tested for purity before recycling. When the solvent purity is ≥98%, they are recycled; when the purity is below 98%, they are purified by distillation again.
[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses a composite solvent system and optimizes the multi-tower distillation recovery process, achieving a solvent recovery rate of over 95%, thus realizing the closed-loop recycling of the solvent.
[0016] 2. The synergistic effect of composite solvent A and composite solvent B improves the selectivity of the reaction, reduces the generation of by-products, and the product purity can reach more than 99.0%, which is 2-3 percentage points higher than the 96%-97% of the traditional single solvent process; the product yield is further improved compared with the traditional single solvent process, significantly improving the utilization rate of raw materials and production efficiency.
[0017] 3. This invention treats distillation residues and obtains industrial-grade sodium chloride through processes such as saponification, concentration, and crystallization, thus achieving waste recycling. Taking a 1000-ton-per-year benzyl ammonium chloride production line as an example, approximately 60 tons of industrial-grade sodium chloride can be recycled annually, further reducing environmental impact and improving production economics.
[0018] 4. The production process of this invention has clear steps and mild operating conditions. It does not require special high-end equipment. Benzyl chloride production enterprises only need to make simple modifications to existing equipment to carry out industrial production, and it has good prospects for industrial application. Attached Figure Description
[0019] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation
[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.
[0021] Example 1 An environmentally friendly method for producing benzyl chloride using solvent recycling, comprising the following steps: (1) Addition reaction: 190g of p-tert-octylphenol (pure substance mass 187.15g, 0.907mol, purity 98.5%), 48.4g of ethylene oxide (pure substance mass 48.21g, 1.094mol, purity 99.6%), and 92.5g of epichlorohydrin (pure substance mass 91.18g, 0.986mol, purity 98.6%) were added to the reaction vessel. Then, 397.1g of composite solvent A (ethanol purity 99.2% and ethyl acetate purity 98.3%, volume ratio 3:1) (1.216 times the total pure substance mass of p-tert-octylphenol, ethylene oxide, and epichlorohydrin (326.54g)) was added. After stirring evenly, 0.9g of... 5g (0.508% of pure p-tert-octylphenol by mass) of boron trifluoride diethyl ether complex (purity 98.2%) was used. The pH of the system was adjusted to 4.0 with hydrochloric acid, and the temperature was raised to 40℃ and maintained at this temperature for 5 hours. The pH was monitored every hour during the reaction to maintain it within the range of 3.5-4.5. After 2 hours of reaction, samples were taken every hour, and the residual amount of p-tert-octylphenol was detected by gas chromatography. At 4.5 hours of reaction, the conversion rate of p-tert-octylphenol was 98.2%, reaching the endpoint. Heating was then stopped, yielding a reaction solution containing a chloride intermediate with a phenoxyethoxyethyl structure. Sampling analysis showed that the content of the chloride intermediate in the reaction solution was 286.7g (based on molecular weight C). 18 H 29 (Approximately 0.872 mol of O3Cl was consumed), and the yield of this step was 98.0% based on the amount of p-tert-octylphenol consumed.
[0022] (2) Quaternization reaction: 149g of chloride intermediate was added to the reaction solution containing (286.7g, 0.872mol) chloride intermediate. N,N-Dimethylbenzylamine (pure substance mass 146.62 g, 0.984 mol, purity 98.4%) was added, along with 651.5 g of composite solvent B (isopropanol purity 99.3% and acetone purity 99.1%, volume ratio 2:1) (1.5 times the estimated total mass of the chloride intermediate and N,N-dimethylbenzylamine (approximately 433.3 g)). The pH of the system was adjusted to 7.2 using sodium hydroxide solution, and the temperature was raised to 60°C and maintained for 6 hours. The pH was monitored every hour during the reaction to maintain it within the range of 7.0-7.5. After 3 hours of reaction, samples were taken every hour to detect the residual amount of the chloride intermediate using high performance liquid chromatography. At 5.5 hours of reaction, the conversion rate of the chloride intermediate was detected to be 99.1%, reaching the endpoint, and the heating was stopped. A crude benzyl chloride mixture was obtained, with a benzyl chloride yield of 98.5% in this step.
[0023] (3) Crude product purification: S1. Filtration: Cool the crude benzyl chloride solution to room temperature and filter it using a 0.22μm precision filter membrane to obtain filtrate and filter residue; S2. Washing: Add the filter residue to the washing vessel and wash twice with ethanol to obtain wet benzyl chloride crude product and washing solution; S3. Drying: Place the wet crude benzyl chloride in a vacuum drying oven and dry it at 60℃ and -0.1MPa for 3 hours to obtain 358.4g of pure benzyl chloride.
[0024] (4) Solvent recovery: S1. Combine the filtrate and washing liquid from step (3) to obtain a mixed waste liquid containing ethanol, ethyl acetate, isopropanol and acetone.
[0025] S2. Add 0.1% by mass of 2,6-di-tert-butyl-p-cresol to the mixed waste liquid, heat to 50°C, and stir for 30 minutes to decompose any possible peroxides and inhibit polymerization, ensuring the safety of subsequent distillation and the quality of the solvent.
[0026] In practice, the mixed waste liquid contains isopropanol and acetone. These two solvents, especially isopropanol, are easily oxidized by prolonged contact with light and air (oxygen) to form unstable organic peroxides (such as acetone peroxide and cumene hydroperoxide). These peroxides are highly prone to decomposition and explosion under the heating and concentration conditions of a distillation column, posing a significant safety hazard in chemical production. 2,6-Di-tert-butyl-p-cresol (BHT) is a highly efficient free radical scavenger and peroxide decomposer. Heating it to 50°C and stirring it can fully disperse it and promote the gentle decomposition of the trace peroxides that have already been generated. At the same time, BHT itself preferentially reacts with free radicals, blocking the formation of new peroxide chains and eliminating safety hazards for subsequent high-temperature distillation.
[0027] The mixed waste liquid may also contain trace amounts of acidic substances, metal ions, or residual catalysts (such as boron trifluoride derivatives). Under heating conditions, these substances may catalyze the polymerization of solvents (especially olefin impurities) or cause hydrolysis of ester solvents (ethyl acetate). The resulting colloidal polymers can clog the trays or packing of the distillation column, severely reducing separation efficiency and even causing shutdown. Solvent decomposition directly affects the purity of the recovered product. BHT effectively inhibits the occurrence of polymerization side reactions by eliminating free radicals that initiate polymerization. The pretreatment heating and stirring process also ensures that any acidic substances and other impurities are more evenly dispersed, and some are removed in subsequent steps.
[0028] S3, Multi-tower sequential distillation separation: Acetone removal column: The pretreated mixed waste liquid is fed into the first distillation column. The temperature at the top of the first distillation column is controlled at 56-58℃, the temperature at the bottom of the first distillation column is controlled at 75-78℃, and the operating pressure is 0.1 MPa. Acetone is distilled off from the top of the first distillation column, and the acetone fraction is collected.
[0029] Ethanol-ethyl acetate azeotrope column: The bottom liquid of the first distillation column is fed into the second distillation column. The top temperature of the second distillation column is controlled at 71-72℃, the bottom temperature at 85-90℃, and the operating pressure at 0.1 MPa. The ethanol-ethyl acetate azeotrope (azeotropic composition is approximately 30 wt% ethanol and 70 wt% ethyl acetate) is distilled from the top of the second distillation column, and the azeotropic fraction is collected.
[0030] Isopropanol recovery column: The bottom liquid of the second distillation column is fed into the third distillation column. The top temperature of the third distillation column is controlled at 81-83℃, the bottom temperature at 95-100℃, and the operating pressure at 0.1 MPa. Isopropanol is distilled off from the top of the third distillation column, and the isopropanol fraction is collected. The bottom of the third distillation column is the distillation residue.
[0031] The recovered acetone fraction had a purity of 98.8%, the isopropanol fraction had a purity of 98.7%, and the ethanol-ethyl acetate azeotrope fraction had a stable composition. A composite solvent B was prepared by mixing acetone and isopropanol at a volume ratio of 1:2. An appropriate amount of ethanol or ethyl acetate was added to the ethanol-ethyl acetate azeotrope fraction to adjust the volume ratio to 3:1, thus preparing composite solvent A. Both solvents were recycled.
[0032] (5) Residue treatment: Add the bottom residue of the third distillation column to the reaction vessel, add 10wt% sodium hydroxide solution, the mass ratio of residue to sodium hydroxide solution is 1:3, heat to 80℃, react for 3h, filter to obtain sodium salt solution and filter residue, the filter residue is dried and used as fuel; concentrate the sodium salt solution under reduced pressure to saturation, cool to crystallize, filter to obtain industrial grade sodium chloride; neutralize the crystallization mother liquor with hydrochloric acid to pH=6-8 and then discharge.
[0033] In this embodiment, the theoretical yield of benzyl chloride based on p-tert-octylphenol was 406.4 g, and the actual yield of pure product (with a purity of 99.1%) was 358.4 g, with a benzyl chloride yield of 88.2% and a solvent recovery rate of 95.3%.
[0034] Example 2 An environmentally friendly method for producing benzyl chloride using solvent recycling, comprising the following steps: (1) Addition reaction: 190g of p-tert-octylphenol (pure substance mass 187.15g, 0.907mol, purity 98.5%), 57.2g of ethylene oxide (pure substance mass 56.97g, 1.293mol, purity 99.6%) and 104g of epichlorohydrin (pure substance mass 102.54g, 1.109mol, purity 98.6%) were added to the reaction vessel, and then 641.1g of composite solvent A (ethanol purity 99.2% and ethyl acetate purity 98.3%, volume ratio 4:1) was added (which is 1 / 3 of the total pure substance mass of p-tert-octylphenol, ethylene oxide and epichlorohydrin (346.66g)). After stirring thoroughly (85 times the volume of the solution), 2.05 g (1.096% of the mass of pure p-tert-octylphenol) of boron trifluoride diethyl ether complex (purity 98.2%) was added. The pH of the system was adjusted to 3.8 with hydrochloric acid, and the temperature was raised to 50°C and reacted at this temperature for 4 hours. The pH was monitored every hour during the reaction to maintain it within the range of 3.5-4.5. After 2 hours of reaction, samples were taken every hour, and the residual amount of p-tert-octylphenol was detected by gas chromatography. After 3.5 hours of reaction, the conversion rate of p-tert-octylphenol was 98.5%, reaching the endpoint. Heating was stopped, yielding a reaction solution containing a chloride intermediate with a phenoxyethoxyethyl structure. Sampling analysis showed that the chloride intermediate content in the reaction solution was 288.4 g (approximately 0.877 mol), and the yield of this step, based on the consumed p-tert-octylphenol, was 98.3%.
[0035] (2) Quaternization reaction: 156.45g of chloride intermediate containing (288.4g, 0.877mol) was added. N,N-Dimethylbenzylamine (pure substance mass 153.95g, 1.034mol, purity 98.4%) was added, along with 1068.2g of composite solvent B (isopropanol purity 99.3% and acetone purity 99.1%, volume ratio 3:1) (twice the estimated total mass of the chloride intermediate and N,N-dimethylbenzylamine (approximately 534.1g)). The pH of the system was adjusted to 7.3 using sodium hydroxide solution, and the temperature was raised to 70℃ and maintained for 5 hours. The pH was monitored every hour during the reaction to maintain it within the range of 7.0-7.5. After 3 hours of reaction, samples were taken every hour to detect the residual amount of chloride intermediate using high performance liquid chromatography. At 4.5 hours of reaction, the conversion rate of chloride intermediate was detected to be 99.3%, reaching the endpoint, and the heating was stopped. The yield of benzyl chloride in this step was 98.8%, resulting in a mixture containing crude benzyl chloride.
[0036] (3) Crude product purification: S1. Filtration: Cool the crude benzyl chloride solution to room temperature and filter it using a 0.3μm precision filter membrane to obtain filtrate and filter residue; S2. Washing: Add the filter residue to the washing vessel and wash three times with ethanol to obtain wet benzyl chloride crude product and washing solution; S3. Drying: The wet crude benzyl chloride was placed in a vacuum drying oven and dried at 70℃ and -0.09MPa for 2.5h to obtain 395.0g of crude benzyl chloride.
[0037] (4) Solvent recovery: S1. Combine the filtrate and washing liquid from step (3) to obtain a mixed waste liquid containing ethanol, ethyl acetate, isopropanol and acetone.
[0038] S2. Add 0.2% by mass of 2,6-di-tert-butyl-p-cresol to the mixed waste liquid, heat to 55°C, and stir for 30 minutes to decompose any possible peroxides and inhibit polymerization, ensuring the safety of subsequent distillation and the quality of the solvent.
[0039] S3, Multi-tower sequential distillation separation: Acetone removal column: The pretreated mixed waste liquid is fed into the first distillation column. The temperature at the top of the first distillation column is controlled at 56-58℃, the temperature at the bottom of the first distillation column is controlled at 75-78℃, and the operating pressure is 0.1 MPa. Acetone is distilled off from the top of the first distillation column, and the acetone fraction is collected.
[0040] Ethanol-ethyl acetate azeotrope column: The bottom liquid of the first distillation column is fed into the second distillation column. The top temperature of the second distillation column is controlled at 71-72℃, the bottom temperature at 85-90℃, and the operating pressure at 0.1 MPa. The ethanol-ethyl acetate azeotrope (azeotropic composition is approximately 30 wt% ethanol and 70 wt% ethyl acetate) is distilled from the top of the second distillation column, and the azeotropic fraction is collected.
[0041] Isopropanol recovery column: The bottom liquid of the second distillation column is fed into the third distillation column. The top temperature of the third distillation column is controlled at 81-83℃, the bottom temperature at 95-100℃, and the operating pressure at 0.1 MPa. Isopropanol is distilled off from the top of the third distillation column, and the isopropanol fraction is collected. The bottom of the third distillation column is the distillation residue.
[0042] Purity testing and recycling: The recovered acetone fraction had a purity of 99.0%, the isopropanol fraction had a purity of 98.9%, and the ethanol-ethyl acetate azeotrope fraction exhibited stable composition. A composite solvent B was prepared by mixing acetone and isopropanol at a volume ratio of 1:3. Ethanol or ethyl acetate was added to the ethanol-ethyl acetate azeotrope fraction to adjust the volume ratio to 4:1, thus preparing composite solvent A. Both solvents were recycled.
[0043] (5) Residue treatment: Add the bottom residue of the third distillation column to the reaction vessel, add 15wt% sodium hydroxide solution, the mass ratio of residue to sodium hydroxide solution is 1:4, heat to 90℃, react for 2.5h, filter to obtain sodium salt solution and filter residue, the filter residue is dried and used as fuel; concentrate the sodium salt solution under reduced pressure to saturation, cool to crystallize, filter to obtain industrial grade sodium chloride; neutralize the crystallization mother liquor with hydrochloric acid to pH=6-8 and then discharge.
[0044] In this embodiment, the theoretical yield of benzyl chloride based on p-tert-octylphenol was 406.4 g, and the actual yield of pure product (with a purity of 99.3%) was 367.8 g, with a benzyl chloride yield of 90.5% and a solvent recovery rate of 96.8%.
[0045] Example 3 An environmentally friendly method for producing benzyl chloride using solvent recycling, comprising the following steps: (1) Addition reaction: 190g of p-tert-octylphenol (pure substance mass 187.15g, 0.907mol, purity 98.5%), 52g of ethylene oxide (pure substance mass 51.79g, 1.175mol, purity 99.6%), and 112g of epichlorohydrin (pure substance mass 110.43g, 1.194mol, purity 98.6%) were added to the reaction vessel, followed by 1050.0g of composite solvent A (ethanol purity 99.2% and ethyl acetate purity 98.3%, volume ratio 5:1) (which is 3.0% of the total pure substance mass of p-tert-octylphenol, ethylene oxide, and epichlorohydrin (349.37g)). After stirring thoroughly, 2.85 g (1.523% of pure p-tert-octylphenol by mass) of boron trifluoride diethyl ether complex (purity 98.2%) was added. The pH of the system was adjusted to 3.6 with hydrochloric acid, and the temperature was raised to 60℃ and reacted at this temperature for 3 hours. The pH was monitored every hour during the reaction to maintain it within the range of 3.5-4.5. After 2 hours of reaction, samples were taken every hour, and the residual amount of p-tert-octylphenol was detected by gas chromatography. After 2.5 hours of reaction, the conversion rate of p-tert-octylphenol was 98.8%, reaching the endpoint. Heating was stopped, and a reaction solution containing a chloride intermediate with a phenoxyethoxyethyl structure was obtained. Sampling analysis showed that the content of the chloride intermediate in the reaction solution was 290.5 g (approximately 0.884 mol), and the yield of this step, based on the consumed p-tert-octylphenol, was 98.6%.
[0046] (2) Quaternization reaction: 163.9g of N,N-dimethylbenzylamine (pure substance mass 161.28g, 1.083mol, purity 98.4%) was added to the reaction solution containing (290.5g, 0.884mol) chloride intermediate. Then, 1862.6g of composite solvent B (isopropanol purity 99.3% and acetone purity 99.1%, volume ratio 4:1) was added (this is the estimated total mass of chloride intermediate and N,N-dimethylbenzylamine, approximately 621g). The pH of the system was adjusted to 7.4 using sodium hydroxide solution (3 times the concentration of 5g), and the temperature was raised to 80℃. The reaction was maintained at this temperature for 4 hours. The pH was monitored every hour during the reaction to maintain it within the range of 7.0-7.5. After 3 hours of reaction, samples were taken every hour to detect the residual amount of chloride intermediate using high-performance liquid chromatography (HPLC). At 3.5 hours of reaction, the conversion rate of chloride intermediate was detected to be 99.5%, indicating that the endpoint had been reached. Heating was then stopped, yielding a crude benzyl chloride mixture. The yield of benzyl chloride in this step was 99.0%.
[0047] (3) Crude product purification: S1. Filtration: Cool the crude benzyl chloride solution to room temperature and filter it using a 0.45μm precision filter membrane to obtain filtrate and filter residue. S2. Washing: Add the filter residue to the washing vessel and wash three times with ethanol to obtain wet benzyl chloride crude product and washing solution; S3. Drying: The wet crude benzyl chloride was placed in a vacuum drying oven and dried at 80℃ and -0.08MPa for 2 hours to obtain 398.5g of crude benzyl chloride.
[0048] (4) Solvent recovery: S1. Combine the filtrate and washing liquid from step (3) to obtain a mixed waste liquid containing ethanol, ethyl acetate, isopropanol and acetone.
[0049] S2. Add 0.3% by mass of 2,6-di-tert-butyl-p-cresol to the mixed waste liquid, heat to 60°C, and stir for 30 minutes to decompose any possible peroxides and inhibit polymerization, ensuring the safety of subsequent distillation and the quality of the solvent.
[0050] S3, Multi-tower sequential distillation separation: Acetone removal column: The pretreated mixed waste liquid is fed into the first distillation column. The temperature at the top of the first distillation column is controlled at 56-58℃, the temperature at the bottom of the first distillation column is controlled at 75-78℃, and the operating pressure is 0.1 MPa. Acetone is distilled off from the top of the first distillation column, and the acetone fraction is collected.
[0051] Ethanol-ethyl acetate azeotrope column: The bottom liquid of the first distillation column is fed into the second distillation column. The top temperature of the second distillation column is controlled at 71-72℃, the bottom temperature at 85-90℃, and the operating pressure at 0.1 MPa. The ethanol-ethyl acetate azeotrope (azeotropic composition is approximately 30 wt% ethanol and 70 wt% ethyl acetate) is distilled from the top of the second distillation column, and the azeotropic fraction is collected.
[0052] Isopropanol recovery column: The bottom liquid of the second distillation column is fed into the third distillation column. The top temperature of the third distillation column is controlled at 81-83℃, the bottom temperature at 95-100℃, and the operating pressure at 0.1 MPa. Isopropanol is distilled off from the top of the third distillation column, and the isopropanol fraction is collected. The bottom of the third distillation column is the distillation residue.
[0053] The recovered acetone fraction had a purity of 99.2%, the isopropanol fraction had a purity of 99.1%, and the ethanol-ethyl acetate azeotrope fraction exhibited stable composition. A composite solvent B was prepared by mixing acetone and isopropanol at a volume ratio of 1:4. Ethanol or ethyl acetate was then added to the ethanol-ethyl acetate azeotrope fraction to adjust the volume ratio to 5:1, thus preparing composite solvent A. Both solvents were recycled.
[0054] (5) Residue treatment: Add the bottom residue of the third distillation column to the reaction vessel, add 20% sodium hydroxide solution, the mass ratio of residue to sodium hydroxide solution is 1:5, heat to 100℃, react for 2 hours, filter to obtain sodium salt solution and filter residue, and use the filter residue as fuel after drying; concentrate the sodium salt solution under reduced pressure to saturation, cool to crystallize, and filter to obtain industrial grade sodium chloride; neutralize the crystallization mother liquor with hydrochloric acid to pH=6-8 and then discharge.
[0055] In this embodiment, the theoretical yield of benzyl chloride based on p-tert-octylphenol was 406.4 g, and the actual yield of pure product (with a purity of 99.5%) was 371.0 g, with a benzyl chloride yield of 91.3% and a solvent recovery rate of 97.5%.
[0056] Application examples Using the recovered and reformulated composite solvent A (ethanol or ethyl acetate was added to the ethanol-ethyl acetate azeotrope to adjust the volume ratio of ethanol to ethyl acetate to 4:1) and composite solvent B (a mixture of recovered acetone and isopropanol at a volume ratio of 1:3), benzyl chloride was produced in a cyclic process according to the process parameters of Example 2, for 10 consecutive cycles. The product yield, purity, and solvent recovery rate of each production were measured, and the results are shown in Table 1.
[0057] Table 1
[0058] As shown in Table 1, after the solvent recovered by this invention is continuously recycled 10 times, the product yield remains above 89.8%, the purity remains above 98.9%, and the solvent recovery rate remains above 96.3%. This indicates that the recycling of the recovered solvent is stable and will not have a significant impact on product quality and solvent recovery effect, further verifying the feasibility and stability of the process of this invention.
[0059] Comparative Example 1 In this comparative example, a traditional single ethanol solvent is used instead of the composite solvent A and composite solvent B of the present invention. Other process parameters are completely consistent with those in Example 2, and the steps are as follows: (1) Addition reaction: 190g (pure substance mass 187.15g) of p-tert-octylphenol, 57.2g (pure substance mass 56.97g) of ethylene oxide and 104g (pure substance mass 102.54g) of epichlorohydrin were added to the reaction vessel, along with 641.1g of ethanol solvent (purity 99.2%). After stirring evenly, 2.05g of boron trifluoride diethyl ether complex was added. The pH of the system was adjusted to 3.8 with hydrochloric acid, and the temperature was raised to 50℃. The reaction was kept at a constant temperature for 4h. After 3.5h of reaction, the conversion rate of p-tert-octylphenol was 95.1%. After extending the reaction by 1h, the conversion rate reached 97.8%, and the reaction was stopped.
[0060] (2) Quaternization reaction: 156.45g of N,N-dimethylbenzylamine (pure substance mass 153.95g) was added to the reaction solution, along with 1068.2g of ethanol solvent (purity 99.2%). The pH of the system was adjusted to 7.3 using sodium hydroxide solution, and the temperature was raised to 70℃. The reaction was kept at a constant temperature for 5h. After 4.5h of reaction, the conversion rate of the chloride intermediate was 97.2%. After extending the reaction by 1h, the conversion rate reached 98.5%, and the reaction was stopped.
[0061] (3) Purification of crude product: Same as in Example 2.
[0062] (4) Solvent recovery: Ethanol is recovered by single-tower distillation.
[0063] The results showed that the yield of benzyl chloride was 81.2%, the product purity was 96.5%, and the solvent recovery rate was 86.3%.
[0064] Comparative Example 2 In this comparative example, a traditional single isopropanol solvent was used instead of the composite solvent A and composite solvent B of the present invention. Other process parameters were completely consistent with those in Example 2, and the steps are as follows: (1) Addition reaction: 190g (pure substance mass 187.15g) of p-tert-octylphenol, 57.2g (pure substance mass 56.97g) of ethylene oxide and 104g (pure substance mass 102.54g) of epichlorohydrin were added to the reaction vessel, along with 641.1g of isopropanol solvent (purity 99.1%). After stirring evenly, 2.05g of boron trifluoride diethyl ether complex was added. The pH of the system was adjusted to 3.8 with hydrochloric acid, the temperature was raised to 50℃, and the reaction was kept at a constant temperature for 4h. After 3.5h of reaction, the conversion rate of p-tert-octylphenol was 95.1%. After extending the reaction by 1h, the conversion rate reached 97.8%, and the reaction was stopped.
[0065] (2) Quaternization reaction: 156.45g of N,N-dimethylbenzylamine (pure substance mass 153.95g) was added to the reaction solution, along with 1068.2g of isopropanol solvent (purity 99.1%). The pH of the system was adjusted to 7.3 using sodium hydroxide solution, and the temperature was raised to 70℃. The reaction was kept at a constant temperature for 5h. After 4.5h of reaction, the conversion rate of the chloride intermediate was 97.2%. After extending the reaction by 1h, the conversion rate reached 98.5%, and the reaction was stopped.
[0066] (3) Purification of crude product: Same as in Example 2.
[0067] (4) Solvent recovery: Isopropanol is recovered by single-tower distillation.
[0068] Results: The yield of benzyl chloride was 80.5%, the product purity was 96.3%, and the solvent recovery rate was 85.7%.
[0069] Comparative Example 3 In this comparative example, a composite solvent C with a volume ratio of ethanol to ethyl acetate of 2:1 was used instead of composite solvent A in Example 2, and the remaining process parameters were completely consistent with those in Example 2.
[0070] Results: The yield of benzyl chloride was 87.1%, the product purity was 98.2%, and the solvent recovery rate was 93.5%.
[0071] Comparative Example 4 In this comparative example, a composite solvent D with a volume ratio of isopropanol to acetone of 1:1 was used instead of composite solvent B in Example 2. All other process parameters were exactly the same as in Example 2.
[0072] Results: The yield of benzyl chloride was 85.6%, the product purity was 97.8%, and the solvent recovery rate was 91.2%.
[0073] Example 2 and Comparative Examples 1 to 4 were produced using different solvent systems for benzyl chloride production. The performance results are shown in Table 2.
[0074] Table 2
[0075] As shown in Table 2, the product yield, purity and solvent recovery rate of the composite solvent system with a specific ratio used in Example 2 of the present invention are significantly better than those of the traditional single solvent systems in Comparative Example 1 and Comparative Example 2.
[0076] The results of Comparative Examples 3 and 4 show that not all composite solvents in any ratio can achieve the excellent results of Example 2. The ratio range of composite solvent A (ethanol: ethyl acetate = (3-5): 1) and composite solvent B (isopropanol: acetone = (2-4): 1) defined in this invention produced an unexpected synergistic effect, which is the key to achieving high conversion rate, high purity and high solvent recovery rate.
[0077] In summary, the specific ratio of composite solvent system used in this invention is significantly superior to traditional single solvent systems and non-preferred ratio composite solvent systems in terms of product yield, purity, and solvent recovery rate. At the same time, it greatly reduces the solvent cost per unit product, demonstrating obvious technical advantages and proving the non-obviousness of solvent ratio selection.
[0078] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. An environmentally friendly production method for benzyl chloride using solvent recycling, characterized in that, The steps are as follows: (1) Addition reaction: p-tert-octylphenol, ethylene oxide and epichlorohydrin are mixed in a molar ratio of 1:(1.2-1.5):(1.05-1.35) and added to composite solvent A. An addition reaction is carried out under the action of a catalyst to obtain a reaction solution containing a chloride intermediate. The composite solvent A is composed of ethanol and ethyl acetate in a volume ratio of (3-5):
1. The mass of the composite solvent A is 1.2-2.0 times the total mass of p-tert-octylphenol, ethylene oxide and epichlorohydrin. (2) Quaternization reaction: The reaction solution containing the chloride intermediate is mixed with N,N-dimethylbenzylamine at a molar ratio of 1:(1.12-1.23) and then added to composite solvent B to carry out the quaternization reaction to obtain a crude benzyl chloride mixture; the composite solvent B is composed of isopropanol and acetone mixed at a volume ratio of (2-4):1, and the mass of the composite solvent B is 1.5-2.5 times the total mass of the chloride intermediate and N,N-dimethylbenzylamine; (3) Crude product purification: The crude benzyl chloride mixture is filtered to obtain filtrate and filter residue. The filter residue is washed and dried to obtain pure benzyl chloride and washing solution. (4) Solvent recovery: The filtrate and the washing liquid are combined and the composite solvent A and composite solvent B are recovered by distillation separation process. The recovered solvent is recycled for the reaction in steps (1) and (2). (5) Residue treatment: The residue generated after distillation separation is treated to obtain industrial-grade by-products.
2. The environmentally friendly production method of benzyl chloride using solvent recycling as described in claim 1, characterized in that, The purity of p-tert-octylphenol in step (1) is ≥98%; the purity of ethylene oxide is ≥99.5%; and the purity of epichlorohydrin is ≥98.5%.
3. The environmentally friendly production method of benzyl chloride using solvent recycling as described in claim 2, characterized in that, The ethanol purity in the composite solvent A mentioned in step (1) is ≥99%, and the ethyl acetate purity is ≥98%.
4. The environmentally friendly production method of benzyl chloride using solvent recycling according to claim 3, characterized in that, The catalyst in step (1) is a boron trifluoride diethyl ether complex with a purity ≥98%. The amount of catalyst used is 0.5%-1.5% of the mass of p-tert-octylphenol. The addition reaction temperature is 40-60℃, the reaction time is 3-5h, and the pH of the system is controlled at 3.5-4.5 during the reaction. The pH is adjusted by hydrochloric acid.
5. The environmentally friendly production method of benzyl chloride using solvent recycling as described in claim 1, characterized in that, The purity of N,N-dimethylbenzylamine mentioned in step (2) is ≥98%, the quaternization reaction temperature is 60-80℃, the reaction time is 4-6h, the pH value of the system is controlled at 7.0-7.5 during the reaction, and the pH is adjusted by sodium hydroxide solution.
6. The environmentally friendly production method of benzyl chloride using solvent recycling as described in claim 5, characterized in that, The purity of isopropanol in the composite solvent B described in step (2) is ≥99%, and the purity of acetone is ≥99%.
7. The environmentally friendly production method of benzyl chloride using solvent recycling as described in claim 1, characterized in that, In step (3), a precision filter membrane is used for filtration with a filtration accuracy of 0.22-0.45μm; ethanol is used for gradient washing, and the washing is performed 2-3 times; the drying temperature is 60-80℃, the drying time is 2-3h, and the drying pressure is 0.08-0.1MPa.
8. The environmentally friendly production method of benzyl chloride using solvent recycling as described in claim 1, characterized in that, The specific steps of the distillation separation process in step (4) are as follows: S1. Combine the filtrate from step (3) with the washing liquid to obtain a mixed waste liquid containing ethanol, ethyl acetate, isopropanol and acetone; S2. Add 0.1%-0.3% by mass of 2,6-di-tert-butyl-p-cresol to the mixed waste liquid, heat to 50-60°C, and stir for 30 minutes; S3, Multi-tower sequential distillation separation: The temperature at the top of the first distillation column is controlled at 56-58℃, the temperature at the bottom of the column is controlled at 75-78℃, and the operating pressure is controlled at 0.1MPa. Acetone is distilled from the top of the first distillation column and the acetone fraction is collected. The bottom liquid of the first distillation column is fed into the second distillation column. The top temperature of the second distillation column is controlled at 71-72℃, the bottom temperature at 85-90℃, and the operating pressure at 0.1MPa. The ethanol-ethyl acetate azeotrope is distilled off from the top of the second distillation column. The bottom liquid from the second distillation column is fed into the third distillation column. The top temperature of the third distillation column is controlled at 81-83℃, the bottom temperature at 95-100℃, and the operating pressure at 0.1MPa. Isopropanol is distilled off from the top of the third distillation column, and the isopropanol fraction is collected. The bottom of the third distillation column is the distillation residue.
9. The environmentally friendly production method of benzyl chloride using solvent recycling according to claim 1, characterized in that, The specific treatment of residue in step (5) is as follows: the distillation residue is mixed with 10wt%-20wt% sodium hydroxide solution at a mass ratio of 1:(3-5), reacted at 80-100℃ for 2-3 hours, filtered to obtain sodium salt product, concentrated and crystallized to obtain industrial grade sodium chloride, and the filtrate is neutralized and discharged in compliance with standards.
10. The environmentally friendly production method of benzyl chloride based on solvent recycling according to any one of claims 1-9, characterized in that, The recovered composite solvents A and B are tested for purity before being recycled. If the solvent purity is ≥98%, they are recycled. If the purity is below 98%, they are purified by distillation again.