Industrial production process of 2, 4-dichloro-5-nitrophenyl isopropyl ether
By reacting 2,4-dichloro-5-nitrophenol with liquid alkali to form a sodium salt, followed by etherification with isobromopropane, and combining azeotropic dehydration and pressurized etherification reactions, the problems of high cost and long reaction time in existing technologies have been solved, and the industrial production of 2,4-dichloro-5-nitrophenyl isopropyl ether has been achieved in a highly efficient and environmentally friendly manner.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GANSU WEST XINYU CHEM CO LTD
- Filing Date
- 2026-01-21
- Publication Date
- 2026-04-28
AI Technical Summary
The existing synthesis process for 2,4-dichloro-5-nitrophenyl isopropyl ether uses expensive acid-binding agents and excessive reactant solvents, resulting in high costs, long reaction times, and environmental problems, making it difficult to industrialize.
Toluene is used as a solvent. Sodium nitrophenolate is generated by azeotropic dehydration and then etherified with isobromopropane. Tetrabutylammonium bromide is used as a catalyst. The etherification reaction is carried out under pressure. After the etherification reaction is completed, the solvent and by-products are recovered by filtration and distillation, which simplifies the process.
This method enables efficient recovery and utilization of isobromopropane, reduces production costs, shortens reaction time, and improves product yield and purity, making it suitable for large-scale industrial production.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of pesticide intermediate synthesis technology, and in particular to an industrial production process for 2,4-dichloro-5-nitrophenyl isopropyl ether. Background Technology
[0002] Oxadiazon is a broad-spectrum herbicide with advantages such as high efficiency, low toxicity, low dosage, low residue, no impact on subsequent crops, good ecological benefits, and ease of use, making it popular among users. Oxadiazon requires a series of complex synthetic processes to obtain, among which 2,4-dichloro-5-nitrophenyl isopropyl ether is a key intermediate.
[0003] Currently, most existing processes for the synthesis of 2,4-dichloro-5-nitrophenyl isopropyl ether use potassium carbonate and triethylamine as acid-binding agents, both of which are expensive. Their large molecular weight necessitates large quantities, further increasing the cost of the acid-binding agents. Potassium hydroxide, as an acid-binding agent, results in a strongly alkaline system due to the presence of water, which easily leads to the decomposition of isobromopropane during the reaction. Furthermore, under normal pressure, the reaction time in industrial production is over 7 hours, which is time-consuming and yields are difficult to achieve at the scale-up rates. The reaction process uses excess isobromopropane as a solvent, which is difficult to recover and is environmentally unfriendly. To reduce costs, the expensive bromine needs to be recovered, requiring the recovery of byproduct bromine salts. Traditional techniques use isopropanol and concentrated sulfuric acid to generate isobromopropane, a cumbersome process that is not conducive to industrial production.
[0004] In actual production, cost reduction and waste management are the directions for continuous improvement for enterprises, as well as requirements for enhancing product competitiveness and environmental benefits. How to reduce production costs and improve synthesis efficiency has become the current research and development goal for the industrial production of 2,4-dichloro-5-nitrophenyl isopropyl ether. Summary of the Invention
[0005] In view of this, the technical problem to be solved by the present invention is to provide an industrial production process for 2,4-dichloro-5-nitrophenyl isopropyl ether, which realizes the recovery and utilization of isobromopropane and the recovery of by-product bromide salt, reduces production costs, is more environmentally friendly, has a short reaction time, and is suitable for industrial-scale production.
[0006] This invention provides an industrial-scale production process for 2,4-dichloro-5-nitrophenyl isopropyl ether, comprising the following steps:
[0007] Using toluene as a solvent, 2,4-dichloro-5-nitrophenol reacts with liquid alkali to form a sodium salt, which is then azeotropically dehydrated. A catalyst is then directly added to etherify it with isobromopropane to obtain 2,4-dichloro-5-nitrophenyl isopropyl ether.
[0008] The reaction equations for the above reaction process are as follows:
[0009]
[0010] This invention divides the reaction into two steps. The first step generates sodium nitrophenolate (2,4-dichloro-5-nitrophenolate sodium). Azeotropic dehydration is achieved through the formation of an azeotrope between toluene and water, promoting the formation of 2,4-dichloro-5-nitrophenolate sodium while simultaneously removing water from the system and reducing its alkalinity. This increases reactivity and avoids the hydrolysis of isobromopropane. The etherification reaction is carried out in a toluene-only system, avoiding the use of multi-component systems such as DMF + toluene or isopropanol + water + toluene, simplifying production and facilitating the recovery and reuse of solvents, isobromopropane, and the byproduct sodium bromide.
[0011] The liquid alkali refers to an aqueous solution of NaOH.
[0012] The concentration of the liquid alkali is preferably 30% to 32%, and in some specific embodiments, the concentration of the liquid alkali is 30%, 31%, or 32%. The concentration refers to the mass concentration.
[0013] This invention uses liquid alkali within the above concentration range as an acid-binding agent, which significantly reduces production costs. Furthermore, the byproduct sodium bromide is easy to recover, has high recovery value, and can be sold directly.
[0014] The preferred molar ratio of NaOH to 2,4-dichloro-5-nitrophenol in the liquid alkali is (1~1.5):1, more preferably (1.05~1.2):1. For example, it can be 1.05:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, or any of the above values as the upper or lower limit.
[0015] This invention uses toluene as a solvent for the reaction of 2,4-dichloro-5-nitrophenol with liquid alkali and for the etherification reaction. Toluene can form an azeotrope with water to achieve azeotropic dehydration.
[0016] The azeotropic dehydration is preferably carried out until the moisture content of the system is ≤0.1%.
[0017] The azeotropic dehydration is carried out in a toluene-water system, and the boiling point of the toluene-water azeotrope is 84±2℃.
[0018] The above-described azeotropic dehydration step can form sodium 2,4-dichloro-5-nitrophenolate and reduce the alkalinity of the system, which increases the reactivity and ensures that isobromopropane will not be hydrolyzed.
[0019] The catalyst is preferably tetrabutylammonium bromide or tetrabutylammonium chloride, more preferably tetrabutylammonium bromide.
[0020] The amount of catalyst used is preferably 3% to 5% of the 100% amount of 2,4-dichloro-5-nitrophenol. For example, it can be 3%, 4% or 5%, or any of the above values can be the upper or lower limit.
[0021] 2,4-Dichloro-5-nitrophenol (100% concentration) = 2,4-Dichloro-5-nitrophenol dry weight × dry weight content.
[0022] It should be noted that the 2,4-dichloro-5-nitrophenol material obtained during the production process contains moisture, generally around 5%-8%, which does not affect the process and does not require drying. When calculating material weight, it can be weighed after drying; the weight containing moisture is referred to as wet weight, and the weight after drying is referred to as dry weight. When testing content, the moisture content should be measured first, and then the dry weight content should be measured after drying.
[0023] 2,4-Dichloro-5-nitrophenol dry weight = 2,4-dichloro-5-nitrophenol wet weight × (1 - percentage of moisture content in wet weight).
[0024] The molar ratio of isobromopropane to 2,4-dichloro-5-nitrophenol is preferably (1.2~1.4):1. For example, it can be 1.2:1, 1.3:1, 1.4:1, or any of the above values as the upper or lower limit.
[0025] The preferred temperature for the etherification reaction is 100~130℃. For example, it can be 100, 110, 120, 125 or 130℃, or any of the above values as the upper or lower limit.
[0026] The etherification reaction takes 4 to 6 hours, for example, 4 hours.
[0027] The pressure of the etherification reaction is 150~350 kPa. For example, it can be 150, 200, 250, 300, 350 kPa, or any of the above values as the upper or lower limit.
[0028] The etherification reaction is carried out under pressure, which can shorten the industrial production time and improve production efficiency. The yield and purity of the etherification reaction are both greater than 97%, which reduces the overall cost.
[0029] After the etherification reaction is completed, the system is filtered, the filter cake is recovered sodium bromide, and the filtrate is subjected to distillation.
[0030] In some specific implementations, the material is passed to a distillation kettle via a plate and frame filter, and the plate and frame filter cake is recovered sodium bromide. The sodium bromide content in the method provided by this invention is above 96%, and it can be sold directly.
[0031] Preferably, after the etherification reaction is completed, excess isobromopropane is recovered by a distillation column and reused in subsequent production. Based on this, the present invention achieves the recovery and utilization of isobromopropane, and the industrial-scale recovery process is simple.
[0032] In some specific implementations, excess isobromopropane is recovered via a distillation column. The preferred endpoint temperature of the distillation column is 112-115°C at the bottom and 85-90°C at the top.
[0033] After the filtrate is distilled to recover excess isobromopropane, the remaining material is washed with water until neutral and distilled to remove toluene to obtain 2,4-dichloro-5-nitrophenyl isopropyl ether.
[0034] In some specific implementations, toluene is removed by negative pressure distillation. The temperature of the negative pressure distillation is less than or equal to 125°C, and the pressure at the end of the negative pressure distillation is -0.09 MPa.
[0035] Compared with the prior art, the present invention provides an industrial production process for 2,4-dichloro-5-nitrophenyl isopropyl ether, comprising the following steps: using toluene as a solvent, 2,4-dichloro-5-nitrophenol reacts with liquid alkali to generate sodium salt, followed by azeotropic dehydration, and then directly adding a catalyst to carry out an etherification reaction with isobromopropane to obtain 2,4-dichloro-5-nitrophenyl isopropyl ether.
[0036] The method provided by this invention is applicable to large-scale industrial production and has the following beneficial effects:
[0037] 1. Reduced production costs and improved environmental friendliness. Liquid alkali replaces potassium carbonate or triethylamine, reducing acid-binding agent costs by 70%; excess isobromopropane achieves over 88% recovery and is processed in a simple manner (traditional processes do not recover it, and the recovery process is cumbersome and costly); byproducts without potassium bromide are easily recyclable; and the single toluene system solvent is easily recyclable. The recovery and utilization of excess reactants, byproducts, and solvents significantly reduces the pressure of industrial-scale waste treatment, effectively lowering production costs. The cost of 2,4-dichloro-5-nitrophenyl isopropyl ether is reduced by 12,000 yuan / ton.
[0038] 2. The industrial production cycle is shortened to 3-4 hours (the traditional process requires 6-8 hours), improving production efficiency, and the content and yield are higher. Detailed Implementation
[0039] To further illustrate the present invention, a detailed description is provided below with reference to embodiments. However, it should be understood that these descriptions are merely for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims.
[0040] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.
[0041] Example 1
[0042] 1. Add 2,4-dichloro-5-nitrophenol (582.3 kg (6% water content, 95% dry weight), 2.5 kmol), 30% NaOH aqueous solution (400 kg, 3 kmol), and 3000 L of toluene to the dehydration vessel, and heat to reflux for dehydration;
[0043] 2. Azeotropically dehydrate until the water content of the system is ≤0.1% (final temperature 110-112℃), cool down to below 60℃, and then transfer the material to an autoclave;
[0044] 3. Add tetrabutylammonium bromide (15 kg) and isobromopropane (404 K, 3.25 kmol), then seal and heat to about 125 °C and maintain the temperature for 4 hours (reaction pressure is about 250 kPa).
[0045] 4. After sampling and testing, if the 2,4-dichloro-5-nitrophenol residue is less than 0.5%, the reaction is complete. Cool the system to below 40°C, depressurize to atmospheric pressure, and then pass the material through a plate and frame filter press to a distillation kettle. The plate and frame filter cake is recovered sodium bromide (dry weight 265 kg, content ≥96.1%, pale yellow powder).
[0046] 5. The distillation kettle is heated, and excess isobromopropane is recovered through a distillation column (9 meters high, 600 mm in diameter, metal wire mesh packing, atmospheric pressure distillation, reflux ratio of 10, final temperature at the bottom of the column is 112-115℃, and at the top of the column is 85-90℃). 200 kg of toluene-isobromopropane solution is collected from the top of the column (isobromopropane content 41.3%, excess isobromopropane recovery rate 89.3%).
[0047] 6. After distillation, cool to room temperature, then transfer the material to a distillation vessel. Add 500L of water to wash the toluene phase until neutral (500L*2, wash twice). Then, evaporate the toluene under negative pressure (endpoint: -0.09mpa, temperature ≤125℃) to obtain 633kg of pale yellow 2,4-dichloro-5-nitrophenyl isopropyl ether product with HPLC purity of 97.3% and yield of 98.5%.
[0048] Example 2
[0049] 1. Add 2,4-dichloro-5-nitrophenol (wet weight 582.3 kg (moisture content 6%, dry weight 95%), 2.5 kmol), 30% NaOH aqueous solution (400 kg, 3 kmol), and 3000 L of toluene to the dehydration vessel, and heat to reflux for dehydration;
[0050] 2. Azeotropically dehydrate until the water content of the system is ≤0.1% (final temperature 110-112℃), cool down to below 60℃, and then transfer the material to an autoclave;
[0051] 3. Add tetrabutylammonium bromide (25 kg) and isobromopropane (404 kg, 3.25 kmol), then seal and heat to about 125°C and maintain the temperature for 3 hours (reaction pressure 250 kPa).
[0052] 4. After sampling and testing, if the 2,4-dichloro-5-nitrophenol residue is less than 0.5%, the reaction is complete. Cool the system to below 40°C, depressurize to atmospheric pressure, and then pass the material through a plate and frame filter press to a distillation kettle. The plate and frame filter cake is recovered sodium bromide (dry weight 261 kg, content ≥96.5%, pale yellow powder).
[0053] 5. The distillation kettle is heated, and excess isobromopropane is recovered through a distillation column (atmospheric pressure distillation, reflux ratio of 10, endpoint temperature at the bottom of the column is 112-115℃, and at the top of the column is 85-90℃). 203 kg of toluene-isobromopropane solution is collected from the top of the column (isobromopropane content 42.1%, excess isobromopropane recovery rate 92.4%).
[0054] 6. After distillation, cool to room temperature, then transfer the material to a distillation vessel. Add 500L of water to wash the toluene phase until neutral (500L*2, wash twice). Then, evaporate the toluene under negative pressure (endpoint: -0.09mpa, temperature ≤125℃) to obtain 635kg of pale yellow 2,4-dichloro-5-nitrophenyl isopropyl ether product with HPLC purity of 97.5% and yield of 99.1%.
[0055] Example 3
[0056] 1. Add 2,4-dichloro-5-nitrophenol (wet weight 582.3 kg (moisture content 6%, dry weight 95%), 2.5 kmol), 30% NaOH aqueous solution (400 kg, 3 kmol), and 3000 L of toluene to the dehydration vessel, and heat to reflux for dehydration;
[0057] 2. Azeotropically dehydrate until the water content of the system is ≤0.1% (final temperature 110-112℃), cool down to below 60℃, and then transfer the material to an autoclave;
[0058] 3. Add tetrabutylammonium bromide (15 kg) and isobromopropane (404 kg, 3.25 kmol), then seal and heat to about 115°C and maintain the temperature for 8 hours (reaction pressure is about 200 kPa).
[0059] 4. After sampling and testing, if the 2,4-dichloro-5-nitrophenol residue is less than 0.5%, the reaction is complete. Cool the system to below 40°C, depressurize to atmospheric pressure, and then pass the material through a plate and frame filter press to a distillation kettle. The plate and frame filter cake is recovered sodium bromide (dry weight 268 kg, content ≥96.1%, pale yellow powder).
[0060] 5. The distillation kettle is heated, and excess isobromopropane is recovered through a distillation column (atmospheric pressure distillation, reflux ratio of 10, endpoint temperature at the bottom of the column is 112-115℃, and at the top of the column is 85-90℃). Approximately 195 kg of toluene-isobromopropane solution is collected from the top of the column (isobromopropane content 41.8%, excess isobromopropane recovery rate 88.1%).
[0061] 6. After distillation, cool to room temperature, then transfer the material to a distillation vessel. Add 500L of water to wash the toluene phase until neutral (500L*2, wash twice). Then, evaporate the toluene under negative pressure (endpoint: -0.09mpa, temperature ≤125℃) to obtain 625kg of pale yellow 2,4-dichloro-5-nitrophenyl isopropyl ether product with HPLC purity of 97.3% and yield of 97.7%.
[0062] Comparative Example 1
[0063] The reaction parameters for each step are the same as in Example 1, except that azeotropic dehydration is not performed.
[0064] 1. Add 2,4-dichloro-5-nitrophenol (wet weight 582.3 kg (moisture content 6%, dry weight 95%), 2.5 kmol), 30% NaOH aqueous solution (400 kg, 3 kmol), toluene 3000 L, and tetrabutylammonium bromide (15 kg) to the dehydration reactor, stir for 0.5 h, and then slowly raise the temperature;
[0065] 2. Slowly raise the temperature to about 125°C, and slowly add isobromopropane (404 kg, 3.25 kmol) dropwise under reflux. Then, seal the container and raise the temperature to about 125°C and maintain the temperature for 4 hours (reaction pressure is about 250 kPa).
[0066] 4. After sampling and testing, if the 2,4-dichloro-5-nitrophenol residue is less than 0.5%, the reaction is complete. Cool the system to below 40°C, depressurize to atmospheric pressure, and then pass the material through a plate and frame filter press to a distillation kettle. The plate and frame filter cake is recovered sodium bromide (dry weight 290 kg, content ≥85%, light yellow powder).
[0067] 5. The distillation kettle is heated, and excess isobromopropane is recovered through a distillation column (9 meters high, 600 mm in diameter, metal wire mesh packing, atmospheric pressure distillation, reflux ratio of 10, final temperature at the bottom of the column is 112-115℃, and at the top of the column is 85-90℃). 200 kg of toluene-isobromopropane solution is collected from the top of the column (isobromopropane content 10.5%, excess isobromopropane recovery rate 22.7%).
[0068] 6. After distillation, cool to room temperature, then transfer the material to a distillation vessel. Add 500L of water to wash the toluene phase until neutral (500L*2, wash twice). Then, evaporate the toluene under negative pressure (endpoint: -0.09mpa, temperature ≤125℃) to obtain 593kg of pale yellow 2,4-dichloro-5-nitrophenyl isopropyl ether product with HPLC purity of 86.4% and yield of 82.0%.
[0069] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. An industrial-scale production process for 2,4-dichloro-5-nitrophenyl isopropyl ether, comprising the following steps: Using toluene as a solvent, 2,4-dichloro-5-nitrophenol reacts with liquid alkali to form a sodium salt, which is then azeotropically dehydrated. A catalyst is then directly added to etherify it with isobromopropane to obtain 2,4-dichloro-5-nitrophenyl isopropyl ether.
2. The industrial production process of 2,4-dichloro-5-nitrophenyl isopropyl ether according to claim 1, characterized in that, The concentration of the liquid alkali is 30%~32%.
3. The industrial production process of 2,4-dichloro-5-nitrophenyl isopropyl ether according to claim 1, characterized in that, The molar ratio of NaOH to 2,4-dichloro-5-nitrophenol in the liquid alkali is (1~1.5):
1.
4. The industrial production process of 2,4-dichloro-5-nitrophenyl isopropyl ether according to claim 1, characterized in that, The azeotropic dehydration is performed until the moisture content of the system is ≤0.1%.
5. The industrial production process of 2,4-dichloro-5-nitrophenyl isopropyl ether according to claim 1, characterized in that, The catalyst is tetrabutylammonium bromide or tetrabutylammonium chloride.
6. The industrial production process of 2,4-dichloro-5-nitrophenyl isopropyl ether according to claim 1, characterized in that, The amount of catalyst used is 3% to 5% of the 100% amount of 2,4-dichloro-5-nitrophenol.
7. The industrial production process of 2,4-dichloro-5-nitrophenyl isopropyl ether according to claim 1, characterized in that, The etherification reaction is carried out at a temperature of 100~130℃; The etherification reaction takes 4-6 hours. The pressure of the etherification reaction is 150~350 kPa.
8. The industrial production process of 2,4-dichloro-5-nitrophenyl isopropyl ether according to claim 1, characterized in that, After the etherification reaction is completed, excess isobromopropane is recovered through a distillation column and reused in subsequent production.
9. The industrial production process of 2,4-dichloro-5-nitrophenyl isopropyl ether according to claim 1, characterized in that, After the etherification reaction is completed, the mixture is filtered, the filter cake is sodium bromide recovered, and the filtrate is subjected to distillation.
10. The industrial production process of 2,4-dichloro-5-nitrophenyl isopropyl ether according to claim 9, characterized in that, After the filtrate is distilled to recover excess isobromopropane, the remaining material is washed with water until neutral and distilled to remove toluene to obtain 2,4-dichloro-5-nitrophenyl isopropyl ether.