A green process for preparing triclopyr butoxyethyl ester

Abstract

The application provides a triclopyr butoxyethyl ether green etherification process and relates to the field of agricultural science, and comprises the following steps: triclopyr sodium and methyl chloroacetate are subjected to nucleophilic substitution etherification condensation to generate intermediate dicamba methyl ester crude product; the dicamba methyl ester crude product is subjected to vacuum rectification desolventization refining post-treatment to remove residual methanol and free acid impurities in the crude product, and the dicamba methyl ester intermediate is obtained; the dicamba methyl ester intermediate is mixed with ethylene glycol monobutyl ether, and ester exchange etherification reaction is carried out in the presence of an ester exchange catalyst to generate ester exchange etherification reaction liquid; after the reaction, the ester exchange etherification reaction liquid is cooled by using a gradient temperature control cooling process; the cooled ester exchange etherification reaction liquid is sent into a rectification tower for batch step pressure rectification treatment; the refined material collected from the rectification tower is subjected to constant temperature standing, filtration after removal of residual suspended impurities, and triclopyr butoxyethyl ester finished product is obtained. The raw material conversion rate is high, the side reaction is few, and the application meets the green pesticide manufacturing requirements.

Description

Technical Field

[0001] This invention relates to the field of agricultural science and technology, specifically to a green etherification process for triclopyroxyacetic acid butoxyethyl ester. Background Technology

[0002] Triclopyr-butotyl is a butoxyethyl ester derivative of the systemic herbicide triclopyr-butotyl. It is widely used to control broadleaf weeds in gramineous fields, and also in non-cultivated land and forests for controlling broadleaf weeds, shrubs, and woody plants, especially effective against *Quercus*, *Quercus*, and other sprouting woody plants. Triclopyr-butotyl is rapidly absorbed by leaves and roots, translocated within the plant, and acts on nucleic acid metabolism.

[0003] Solubility of trichloropyroxyacetic acid butoxyethyl ester: 440 mg / L in water, 989 g / kg in acetone, 27.3 g / kg in chloroform, 410 mg / kg in ethane, and 307 g / kg in octanol. Stability: Stable under normal temperature storage conditions. Chemical name: [(3,5,6-trichloropyridin-2-yl)oxy]acetic acid-2-butoxyethyl ester; Molecular formula: C13H16C13NO4; Relative molecular mass: 356.63. Its structural formula is as follows:

[0004]

[0005] A review of domestic and international literature reveals three synthetic routes for triclopyroxyacetic acid butoxyethyl ester:

[0006] Route 1: Dehydration and esterification of triclopyroxyacetic acid and ethylene glycol monobutyl ether.

[0007]

[0008] The process involves reacting sodium trichloropyridinol with methyl chloroacetate to produce chloropyridin methyl ester, followed by alkaline hydrolysis to produce chloropyridinic acid, which then undergoes esterification with ethylene glycol monobutyl ether to produce chloropyridin ester. This route yields chloropyridin ester with a purity exceeding 98.5%, but it generates large amounts of high-salinity wastewater, posing significant environmental challenges and incurring high treatment costs.

[0009] Route 2: Exchange of methyl triclopyroxyacetate with ethylene glycol monobutyl ether.

[0010]

[0011] Route 2 involves reacting sodium trichloropyridinol with methyl chloroacetate to produce chloropyridin methyl ester, which is then reacted with ethylene glycol monobutyl ether under an ester exchange catalyst to produce chloropyridin ester. This process route produces chloropyridin with a purity of approximately 98.0%. The reaction steps eliminate the hydrolysis and acidification processes, but the intermediate chloropyridin methyl ester needs to be dried, resulting in significant investment in labor, equipment, and utilities.

[0012] Route 3: Etherification of sodium trichloropyridinol and chloroacetic acid-2-butoxyethyl ester.

[0013]

[0014] Route 3 involves esterifying chloroacetic acid and diethanol monobutyl ether to produce chloroacetic acid butoxyethyl ester, which is then reacted with sodium trichloropyridinol to produce chloropyridinyl ester. This process route produces less wastewater and has relatively simple equipment with no solid output. However, due to steric hindrance, chloropyridinyl ester isomers are produced. The chloropyridinyl ester content is generally around 96.5% to 97.5%, which is relatively low.

[0015] In summary, the original route 1 suffers from severe pollution from waste, and the original route 3 produces products with substandard purity. Route 2 offers superior product purity and reduces waste, but the existing original route 2 process has high intermediate drying and refining costs, poor industrial economics, and crude post-processing for impurity removal. Therefore, the industry urgently needs an improved green etherification process for the original route 2 transesterification process, which can retain the advantages of route 2—no hydrolysis and acidification, low waste, and high purity—while solving the problems of high investment in intermediate drying and crude post-processing for impurity removal. Summary of the Invention

[0016] This invention provides a green etherification process for triclopyroxyacetic acid butoxyethyl ester to solve at least one of the technical problems mentioned in the background art.

[0017] To solve the above-mentioned technical problems, this invention discloses a green etherification process for triclopyroxyacetic acid butoxyethyl ester, comprising:

[0018] Step 1: Sodium trichloropyridinol reacts with methyl chloroacetate in a nucleophilic substitution etherification condensation to produce the intermediate crude chloropyridinium methyl ester.

[0019] Step 2: The crude chlorometholone methyl ester is subjected to vacuum distillation to remove residual methanol and free acidic impurities, thereby obtaining the chlorometholone methyl ester intermediate.

[0020] Step 3: Mix the chlorophyll methyl ester intermediate with ethylene glycol monobutyl ether and carry out transesterification etherification reaction in the presence of transesterification catalyst to generate transesterification etherification reaction solution;

[0021] Step 4: After the reaction in Step 3, the transesterification etherification reaction solution is cooled using a gradient temperature control process;

[0022] Step 5: The cooled transesterification etherification reaction solution is sent to a distillation column for batch and stepwise pressure swing distillation.

[0023] First, control the distillation column at atmospheric pressure and the material temperature in the column bottom at 65-70°C. Collect the light methanol component from the top of the distillation column until the methanol is completely removed.

[0024] Switch to negative pressure reduced pressure distillation mode, vacuum degree -0.09~-0.07MPa, material temperature in distillation column 125℃~150℃, distillation removes ethylene glycol monobutyl ether and secondary impurities M355 and M413;

[0025] Step 6: The purified material collected from the distillation column is allowed to stand at a constant temperature to remove residual suspended impurities, and then filtered to obtain triclopyroxyacetic acid butoxyethyl ester product.

[0026] Preferably, in step 4, the refined material collected from the distillation column is kept at a constant temperature of 80-90°C for 1-2 hours to remove residual suspended impurities and then filtered to obtain triclopyroxyacetic acid butoxyethyl ester product.

[0027] Preferably, the vacuum distillation desolventizing and refining conditions are a vacuum degree of -0.09 to -0.07 MPa and a material temperature ≤65℃ inside the distillation column.

[0028] Preferably, in the gradient temperature control cooling process, the cooling rate is controlled at 0.5 to 1℃ / min for segmented gradient cooling.

[0029] Preferably, in step 1, the molar ratio of sodium trichloropyridinol to methyl chloroacetate is 1:1.05-1.2, the etherification condensation reaction temperature is 50-60℃, and the reaction time is 2-3 hours.

[0030] Preferably, in step 3, the molar ratio of the active ingredient of chlorophyll methyl ester intermediate to ethylene glycol monobutyl ether is 1:1.1 to 1.3, the transesterification etherification reaction temperature is 80 to 85°C, and the reaction time is 4 to 6 hours.

[0031] Preferably, the transesterification catalyst is sodium methoxide or sodium ethoxide, and the amount of catalyst used is 0.5 to 1.0% of the mass of the purified intermediate.

[0032] Preferably, step 3 includes:

[0033] Step 31: Add the methyl chlorpyrifos intermediate and ethylene glycol monobutyl ether to the reaction vessel, stir and mix, and determine the conductivity when the mixture is uniform based on the detection.

[0034] Step 32: Keep the material temperature in the reactor ≤40℃, keep the stirring speed 100~120r / min, add the catalyst to the first proportion of the total amount of catalyst produced in step 3 at the preset addition rate, and detect the conductivity until the conductivity response rate is less than the preset conductivity response rate. Construct a detection time-conductivity dataset, and determine the effective reaction time period and effective reaction rate. Determine the effective reaction rate characteristic value and effective reaction time characteristic value based on the effective reaction rate and effective reaction time.

[0035] Step 33: Determine the adjustment addition rate based on the effective reaction rate characteristic value and the effective reaction time characteristic value, and continue to add the catalyst at the adjustment addition rate until the total amount of catalyst produced in a single production in Step 3 is reached;

[0036] Step 34: Determine the first duration and the second duration based on the effective reaction rate characteristic value and the effective reaction time characteristic value;

[0037] Step 35: After the catalyst is added, a gradient segmented temperature control is adopted. First, the temperature is raised to 60-65°C at the first heating rate and the reaction is maintained at this temperature for the first time. Then, the temperature is raised to 80-85°C at the second heating rate and the reaction is maintained at this temperature for the second time.

[0038] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] Step 1 of this invention employs a precise ratio and mild temperature control SN2 nucleophilic substitution etherification condensation process, which can effectively suppress the hydrolysis side reaction of sodium trichloropyridinol. At the same time, the appropriate temperature avoids the high-temperature decomposition of methyl chloroacetate, reducing the generation of impurities from the source of the reaction and ensuring the purity of crude chloropyridinol methyl ester.

[0041] Step 2 of this invention completely replaces the original high-temperature drying process of route 2 with vacuum distillation desolventizing and refining. Under mild and low-temperature conditions of vacuum degree -0.09 to -0.07 MPa and material temperature ≤65℃ in the distillation column, residual methanol and free acidic impurities in crude chlorometholone methyl ester are removed in one step. This eliminates the need for high-energy-consuming investments in the original drying equipment, manual operation, and utilities, thereby reducing costs. At the same time, the low-temperature environment avoids high-temperature thermal decomposition and thermal isomerization of chlorometholone methyl ester.

[0042] Step 3 of this invention optimizes the transesterification etherification reaction system, controlling the molar ratio of chlorothalonil methyl ester intermediate to ethylene glycol monobutyl ether at 1:1.1-1.3 and the reaction at 80-85℃ for a mild reaction. The precise ratio promotes the forward shift of the reversible equilibrium of transesterification. Combined with sodium methoxide / sodium ethoxide as an efficient and inexpensive alkaline catalyst, the reaction is mild and controllable, with high raw material conversion rate and few side reactions, efficiently and directionally generating the target product triclopyroxyacetic acid butoxyethyl ester.

[0043] Step 4 of this invention employs a segmented gradient temperature control cooling process of 0.5–1 °C / min, gradually and slowly cooling down from the final transesterification temperature of 85 °C to 40 °C. This slow gradient cooling effectively suppresses the isomerization side reaction of the target product, reduces the content of isomer impurities, and allows trace impurities in the system to slowly precipitate, avoiding the formation of ultrafine suspended particles that are difficult to filter or separate by distillation due to sudden cooling.

[0044] In step 5 of this invention, methanol light components are first efficiently removed at atmospheric pressure and 65-70℃, and then excess ethylene glycol monobutyl ether is removed at negative pressure of -0.09 to -0.07 MPa and 125-150℃. At the same time, characteristic byproducts M355 (etherification dimerization byproduct) and M413 (green oxadiazine isomerization byproduct) are completely removed. Subsequently, the product is kept at a constant temperature of 80-90℃ to further remove residual suspended impurities. The final product has a stable content of triclopyroxyacetic acid butoxyethyl ester ≥98.0%.

[0045] This invention provides a complete transesterification and etherification route, completely eliminating the alkaline hydrolysis and acidification steps of route 1. It eliminates the consumption of large amounts of acid and alkali reagents, does not produce high-salt, high-COD organic wastewater, and significantly reduces the amount of wastewater compared to route 1, thus meeting the requirements for green pesticide manufacturing. Attached Figure Description

[0046] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0047] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0048] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0049] Furthermore, in this invention, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the invention. They are merely used to distinguish components or operations described using the same technical terms and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions and features of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If a combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0050] The present invention provides the following embodiments:

[0051] Example 1: This embodiment of the invention provides a green etherification process for triclopyroxyacetic acid butoxyethyl ester, such as... Figure 1 As shown, it includes:

[0052] Step 1: Sodium trichloropyridinol undergoes a nucleophilic substitution etherification condensation with methyl chloroacetate to produce the intermediate crude chloropyridinol methyl ester. The SN2 nucleophilic substitution etherification condensation reaction between sodium trichloropyridinol and methyl chloroacetate is a classic and mature industrial reaction for the synthesis of chloropyridinol methyl ester.

[0053] Step 2: The crude chlorometholone methyl ester is subjected to vacuum distillation to remove residual methanol and free acidic impurities, thereby obtaining the chlorometholone methyl ester intermediate.

[0054] Step 3: Mix the chlorophyll methyl ester intermediate with ethylene glycol monobutyl ether and carry out transesterification etherification reaction in the presence of transesterification catalyst to generate transesterification etherification reaction solution;

[0055] Step 4: After the reaction in Step 3, the transesterification etherification reaction solution is cooled using a gradient temperature control process;

[0056] Step 5: The cooled transesterification etherification reaction solution is sent to a distillation column for batch and stepwise pressure swing distillation.

[0057] First, control the distillation column at atmospheric pressure and the material temperature inside the distillation column (referring to the bottom material temperature) at 65-70°C. Collect the light methanol component from the top of the distillation column until the methanol is completely removed.

[0058] Switch to negative pressure reduced pressure distillation mode, vacuum degree -0.09~-0.07MPa, material temperature in the distillation column 125℃~150℃, distillation removes ethylene glycol monobutyl ether and by-products M355 (monoether dimer by-product, molecular weight 355) and M413 (green oxadiene isomer dimer impurity, molecular weight 413)).

[0059] Step 6: The purified material collected from the distillation column is allowed to stand at a constant temperature to remove residual suspended impurities, and then filtered to obtain triclopyroxyacetic acid butoxyethyl ester product.

[0060] In step 4, the refined material collected from the distillation column is kept at a constant temperature of 80-90℃ for 1-2 hours to remove residual suspended impurities and then filtered to obtain triclopyroxyacetic acid butoxyethyl ester product.

[0061] The vacuum distillation desolventizing and refining conditions are: vacuum degree -0.09 to -0.07 MPa, and material temperature in the distillation column ≤ 65℃.

[0062] In the gradient temperature control cooling process, the cooling rate is controlled at 0.5–1℃ / min in segmented gradient cooling. Specifically, the gradient temperature control cooling process is as follows: the cooling rate is 0.8–1.0℃ / min for the stage from 85℃ to 65℃, 0.6–0.8℃ / min for the stage from 65℃ to 45℃, and 0.5–0.6℃ / min for the stage from 45℃ to 40℃.

[0063] In step 1, the molar ratio of sodium trichloropyridinol to methyl chloroacetate is 1:1.05-1.2, the etherification condensation reaction temperature is 50-60℃, and the reaction time is 2-3 hours.

[0064] In step 3, the molar ratio of the effective components of the chlorothalonil methyl ester intermediate to ethylene glycol monobutyl ether is 1:1.1 to 1.3, the transesterification etherification reaction temperature is 80 to 85°C, and the reaction time is 4 to 6 hours. The transesterification catalyst is sodium methoxide or sodium ethoxide, and the amount of catalyst used is 0.5 to 1.0% of the mass of the purified intermediate.

[0065] The beneficial effects of the above technical solution are as follows:

[0066] Step 1 of this invention employs a precise ratio and mild temperature control SN2 nucleophilic substitution etherification condensation process, which can effectively suppress the hydrolysis side reaction of sodium trichloropyridinol. At the same time, the appropriate temperature avoids the high-temperature decomposition of methyl chloroacetate, reducing the generation of impurities from the source of the reaction and ensuring the purity of crude chloropyridinol methyl ester.

[0067] Step 2 of this invention completely replaces the original high-temperature drying process of route 2 with vacuum distillation desolventizing and refining. Under mild and low-temperature conditions of vacuum degree -0.09 to -0.07 MPa and material temperature ≤65℃ in the distillation column, residual methanol and free acidic impurities in crude chlorometholone methyl ester are removed in one step. This eliminates the need for high-energy-consuming investments in the original drying equipment, manual operation, and utilities, thereby reducing costs. At the same time, the low-temperature environment avoids high-temperature thermal decomposition and thermal isomerization of chlorometholone methyl ester.

[0068] Step 3 of this invention optimizes the transesterification etherification reaction system, controlling the molar ratio of chlorothalonil methyl ester intermediate to ethylene glycol monobutyl ether at 1:1.1-1.3 and the reaction at 80-85℃ for a mild reaction. The precise ratio promotes the forward shift of the reversible equilibrium of transesterification. Combined with sodium methoxide / sodium ethoxide as an efficient and inexpensive alkaline catalyst, the reaction is mild and controllable, with high raw material conversion rate and few side reactions, efficiently and directionally generating the target product triclopyroxyacetic acid butoxyethyl ester.

[0069] Step 4 of this invention employs a segmented gradient temperature control cooling process of 0.5–1 °C / min, gradually and slowly cooling down from the final transesterification temperature of 85 °C to 40 °C. This slow gradient cooling effectively suppresses the isomerization side reaction of the target product, reduces the content of isomer impurities, and allows trace impurities in the system to slowly precipitate, avoiding the formation of ultrafine suspended particles that are difficult to filter or separate by distillation due to sudden cooling.

[0070] In step 5 of this invention, methanol light components are first efficiently removed at atmospheric pressure and 65-70℃, and then excess ethylene glycol monobutyl ether is removed at negative pressure of -0.09 to -0.07 MPa and 125-150℃. At the same time, characteristic byproducts M355 (etherification dimerization byproduct) and M413 (green oxadiazine isomerization byproduct) are completely removed. Subsequently, the product is kept at a constant temperature of 80-90℃ to further remove residual suspended impurities. The final product has a stable content of triclopyroxyacetic acid butoxyethyl ester ≥98.0%.

[0071] This invention provides a complete transesterification and etherification route, completely eliminating the alkaline hydrolysis and acidification steps of route 1. It eliminates the consumption of large amounts of acid and alkali reagents, does not produce high-salt, high-COD organic wastewater, and significantly reduces the amount of wastewater compared to route 1, thus meeting the requirements for green pesticide manufacturing.

[0072] Example 2, based on Example 1, step 3 includes:

[0073] Step 31: Add the methyl chlorpyrifos intermediate and ethylene glycol monobutyl ether to the reaction vessel, stir and mix, and determine the conductivity when the mixture is uniform based on the detection.

[0074] Step 32: Keep the material temperature in the reactor ≤40℃, keep the stirring speed 100~120r / min, add the catalyst to the first proportion of the total amount of catalyst produced in step 3 at the preset addition rate, and detect the conductivity until the conductivity response rate is less than the preset conductivity response rate. Construct a detection time-conductivity dataset, and determine the effective reaction time period and effective reaction rate. Determine the effective reaction rate characteristic value and effective reaction time characteristic value based on the effective reaction rate and effective reaction time.

[0075] Step 33: Determine the adjustment addition rate based on the effective reaction rate characteristic value and the effective reaction time characteristic value, and continue to add the catalyst at the adjustment addition rate until the total amount of catalyst produced in a single production in Step 3 is reached;

[0076] Step 34: Determine the first duration and the second duration based on the effective reaction rate characteristic value and the effective reaction time characteristic value;

[0077] Step 35: After the catalyst is added, a gradient segmented temperature control is adopted. First, the temperature is raised to 60-65℃ at the first heating rate (range), and the reaction is held at this temperature for the first time. Then, the temperature is raised to 80-85℃ at the second heating rate (range 0.5-1℃ / min), and the reaction is held at this temperature for the second time.

[0078] 1. When the conductivity fluctuates within 3 to 5 minutes (i.e., within 3 to 5 minutes: (maximum conductivity - minimum conductivity) ÷ average conductivity) ≤ ±0.8%, without a continuous upward or downward unidirectional trend, and only has small random fluctuations of the instrument itself, it can be determined that the chlorothalonil methyl ester intermediate and ethylene glycol monobutyl ether liquid phase are uniformly mixed, and the average value of this interval is taken as the conductivity when the mixture is uniform.

[0079] 2. The preset addition rate is the optimal catalyst feeding rate determined in advance through parallel laboratory experiments. These parallel laboratory experiments involved multiple sets of gradient feeding rate control experiments to test the system's conductivity response, the amount of byproducts M355 / M413, the product isomerization rate, and reaction stability under different catalyst addition rates. The optimal feeding rate was selected at low temperatures (≤40℃) to ensure sufficient catalyst dissolution and dispersion while avoiding excessively high local ester exchange catalyst concentrations that could trigger isomerization side reactions. Based on the total catalyst mass in a single production run, the preset addition rate ranged from 3% to 5% of the total catalyst mass per minute.

[0080] The first ratio is set to 0.2 to 0.3; a small amount of alkali is added as an experiment, which will not cause localized alkali blooming or the generation of secondary impurities; the change in conductivity is significant enough to stably measure the response rate and accurately calibrate the activity of the system.

[0081] 3. Under completely consistent operating conditions—temperature ≤ 40℃, stirring speed 100–120 r / min, same preset catalyst addition rate, same first-proportion catalyst feeding ratio, same catalyst type, and same feed system ratio—the following critical minimum value of conductivity response rate (preset conductivity response rate) was determined through experimental statistics when the alkaline catalyst in the system is completely dissolved, completely uniformly dispersed, and the conductivity no longer changes significantly. The conductivity response rate is defined as the change in conductivity per unit time. A typical value for the preset conductivity response rate threshold is: preset response rate threshold = 0.1%K / min, where K is the conductivity at which the mixture is uniformly mixed, as determined in step 31.

[0082] In the initial stage of feeding, the catalyst dissolves and ionizes rapidly, resulting in a high conductivity response rate. As the catalyst gradually disperses evenly, the response rate continues to decrease. When the real-time response rate is ≤ the preset lower limit threshold, it is determined that the catalyst has been completely dispersed and uniform, and the low-temperature trial feeding calibration stage ends.

[0083] The detection time-conductivity dataset consists of all raw discrete data collected continuously at equal time intervals from the moment the first proportional catalyst is added until the moment when the real-time conductivity response rate decreases to less than the preset conductivity response rate. Each set of data contains a unique collection timestamp and the corresponding real-time conductivity detection value, thus forming a time-conductivity dataset.

[0084] 4. Calculate the conductivity response rate (conductivity difference between adjacent detection time points ÷ time interval between adjacent detection time points) based on the detection time-conductivity dataset. Remove the detection time when the absolute value of the conductivity response rate is less than the preset conductivity response rate. The remaining detection time is determined as the effective response period, and the arithmetic mean of the conductivity response rates of the effective period is determined as the effective response rate.

[0085] The first detection time of the detection time-conductivity dataset is the first conductivity detection time in step 32;

[0086] The effective reaction rate characteristic value and the effective reaction time characteristic value are determined based on the effective reaction rate and effective reaction time, respectively:

[0087] Effective reaction rate characteristic value = Effective reaction rate obtained in step 32 ÷ Baseline effective reaction rate;

[0088] Effective reaction time characteristic value = Effective reaction time obtained in step 32 ÷ Baseline effective reaction time;

[0089] The baseline effective reaction rate and baseline effective reaction time are obtained under completely consistent operating conditions, including temperature ≤40℃, stirring speed 100~120r / min, same preset catalyst addition rate, same first proportion catalyst feeding ratio, same catalyst type, and same feed system ratio. The baseline effective reaction rate is obtained by repeatedly measuring the actual effective reaction rate corresponding to the qualified test data through multiple batches of parallel qualified tests using laboratory standard qualified raw materials. The baseline effective reaction time is obtained by calculating the arithmetic mean of the actual effective reaction rate corresponding to the qualified test data.

[0090] Effective reaction rate characteristic value: represents the rate of reaction.

[0091] Effective reaction time characteristic value: represents the duration of the system's activity.

[0092] 5. Determine the adjustment addition rate (the preferred value verified by the process of this invention) based on the effective reaction rate characteristic value and the effective reaction time characteristic value, specifically as follows:

[0093] When 0.8 ≤ effective reaction rate characteristic value < 0.95, the feed rate is adjusted once = preset feed rate × 1.10;

[0094] When 0.95 ≤ effective reaction rate characteristic value ≤ 1.05, the feed rate is adjusted once = preset feed rate × 1.00;

[0095] When 1.05 < effective reaction rate characteristic value ≤ 1.2, the feed rate is adjusted once = preset feed rate × 0.90;

[0096] When 0.8 ≤ effective reaction time characteristic value < 0.95, the secondary adjustment of the feeding rate = the primary adjustment of the feeding rate × 0.95;

[0097] When 0.95 ≤ effective reaction time characteristic value ≤ 1.05, the secondary adjustment of the feeding rate = the primary adjustment of the feeding rate × 1.00;

[0098] When 1.05 < effective reaction time characteristic value ≤ 1.2, the secondary adjustment of the feeding rate = the primary adjustment of the feeding rate × 1.05;

[0099] The second adjustment of the feeding rate is the adjusted feeding rate.

[0100] Slow reaction, low activity, therefore, accelerate the feeding rate;

[0101] Fast reaction, high activity, and reduced feeding rate;

[0102] Adjusting the feeding rate: This does not change the activity of the raw materials, but controls the speed at which the catalyst is added, thereby controlling the intensity of the actual reaction in the system.

[0103] 6. The first duration and the second duration are determined based on the characteristic values ​​of the effective reaction rate and the effective reaction time, specifically (the preferred values ​​verified by the process of this invention):

[0104] When 0.8 ≤ effective reaction time characteristic value < 0.95, the first time is 30 to 40 min; the system has a short duration of catalytic activity, fast decay of alkali activity, and weak low-temperature pre-reaction maintenance ability, so the low-temperature holding time should be shortened.

[0105] When 0.95 ≤ effective reaction time characteristic value ≤ 1.05, the first duration = 40~50min;

[0106] When 1.05 < effective reaction time characteristic value ≤ 1.2, the first time is 50 to 70 min; the system has a long duration of catalytic activity, stable and slow alkali activity, strong low-temperature pre-reaction ability, and extended low-temperature holding time;

[0107] When 0.8 ≤ effective reaction rate characteristic value < 0.95, the second time duration is 240~290min; the system reaction rate is too slow and the high-temperature raw material conversion is incomplete, so the high-temperature main reaction holding time is extended to ensure that the raw material is fully converted.

[0108] When 0.95 ≤ effective reaction rate characteristic value ≤ 1.05, the second duration = 210~240 min;

[0109] When 1.05 < effective reaction rate characteristic value ≤ 1.2, the second time duration = 180~210 min; the system reaction rate is relatively fast and the high temperature alkali activity is intense, shortening the high temperature residence time can effectively suppress high temperature isomerization side reactions;

[0110] The beneficial effects of this embodiment are:

[0111] Step 31: The intermediate of chlorothalonil methyl ester and ethylene glycol monobutyl ether are pre-added and stirred. The liquid phase of the system is accurately determined to be uniformly mixed by the criterion that the conductivity fluctuates within ≤±0.8% for 3-5 minutes and has no unidirectional trend. The conductivity when the mixture is uniformly mixed is extracted as the unified reference conductivity for subsequent detection and adjustment.

[0112] Step 32 is the quantitative calibration step of activity. Under constant operating conditions of low temperature inertia ≤40℃ and fixed stirring speed of 100~120r / min, a small amount of catalyst with a trial ratio of 0.2~0.3 is used and fed at the preset optimal feeding rate. The construction time-conductivity dataset is collected continuously at equal time intervals throughout the process. The effective reaction period is screened, the effective reaction rate and effective reaction duration are calculated, and finally the effective reaction rate characteristic value (characterizing the speed of reaction) and the effective reaction duration characteristic value (characterizing the duration of activity of the system) are quantified.

[0113] Accurately distinguishing the inherent properties of the system, such as reaction speed and duration of activity, provides data basis for subsequent feeding speed adjustment and precise matching of heat preservation time.

[0114] Step 33 builds upon the inherent characteristic values ​​determined in Step 32, employing a dual-characteristic-value linkage speed regulation logic based on both the effective reaction rate characteristic value and the effective reaction time characteristic value. The core objective is to determine a stable and suitable catalyst feeding state for the system, ensuring initial stability and reliability. When the reaction rate is too fast and the activity is too high, the catalyst release is slowed down by adjusting the speed to avoid excessively high local alkali concentrations that could trigger isomerization side reactions. When the reaction rate is too slow and the activity is too low, the catalyst is added by adjusting the speed to provide stable reaction motive force for the system.

[0115] The dual eigenvalue synergistic adjustment can accurately match the inherent reaction properties of different batches of raw materials, providing a stable and realistic basis for the heat preservation time matching in the subsequent step 34, achieving stable control from the source of catalyst feeding, and ensuring a smooth and controllable reaction process.

[0116] Step 34 follows the actual operating conditions after the feeding speed adjustment in Step 33. The first low-temperature duration (60-65℃) is independently determined by the effective reaction time characteristic value, and the second high-temperature duration (80-85℃) is independently determined by the effective reaction rate characteristic value. The holding time is fully linked and adapted to the feeding speed adjustment conditions at the front end: First low-temperature duration: For systems with short-duration activity and rapid decay, the holding time is shortened to avoid ineffective low-temperature holding; for systems with long-duration activity and slow decay, the holding time is extended to fully utilize the sustained activity. Second high-temperature duration: For systems with slower reaction rates, the holding time is extended to ensure full conversion of the raw materials; for systems with faster reaction rates, the holding time is shortened to effectively suppress high-temperature isomerization side reactions.

[0117] It solves the shortcomings of traditional processes with fixed and extensive reaction times. The front-end feeding speed regulation based on dual characteristic values ​​ensures that the catalyst is in a stable and appropriate addition reaction state, while the back-end heat preservation time is independently and precisely controlled according to the inherent properties of the raw materials. The two are continuously and progressively coordinated, with reasonable control of pre-reaction in the low-temperature stage and strict control of M413 isomer impurities in the high-temperature stage, while ensuring complete conversion of raw materials and achieving a two-way balance between impurity control and reaction completeness.

[0118] Step 35 employs gradient segmented heating control. By controlling the heating rate in stages, it avoids the problems of violent local reactions and a surge in side reactions caused by rapid heating at once. It also matches the heating rhythm according to the reaction progress of the system, ensuring the stability and controllability of the overall reaction process and achieving a synergistic improvement in product conversion rate and selectivity.

[0119] In the initial low-temperature feeding stage, the catalyst is fully dissolved and dispersed at ≤40℃. The 60-65℃ holding stage allows for the slow release of catalyst activity, ensuring full contact with the reaction system and the formation of stable catalytic active centers. This provides a uniform and stable catalytic environment for the subsequent main reaction stage, avoiding reaction rate differences caused by uneven catalyst distribution and improving the consistency of feed conversion. The reaction system completes most of the pre-reaction in the 60-65℃ stage. Upon entering the 80-85℃ high-temperature stage, the main reaction rate is fast and the residence time is short. The high-temperature exposure time of the target product, triclopyroxyacetic acid butoxyethyl ester, is significantly shortened, effectively reducing problems such as product thermal decomposition and isomerization. The final product content is consistently ≥98.0%, resulting in superior product quality.

[0120] Example 3, based on Example 1, switches to negative pressure reduced pressure distillation condition, with a vacuum degree of -0.09 to -0.07 MPa, and a material temperature (referring to the bottom material temperature) of 125℃ to 150℃ in the distillation column. Distillation removes ethylene glycol monobutyl ether and byproducts M355 and M413, including: bottom material temperature...

[0121] Step 501: Evacuate the distillation column to a pressure of -0.08 to -0.085 MPa, heat the material in the reboiler to 125 to 132°C, and start distillation based on the preset reflux ratio; detect the vapor space in the reboiler and the vapor pressure at the top of the distillation column to determine the actual pressure difference inside the column; and detect the material temperature (reboiler material temperature) and the vapor temperature at the top of the distillation column to determine the actual temperature difference inside the column.

[0122] Actual pressure difference inside the column = actual pressure in the bottom gas phase space - actual pressure in the top gas phase;

[0123] Actual temperature difference inside the column = actual temperature of the material in the bottom of the column - temperature of the vapor phase at the top of the distillation column;

[0124] Step 502: Based on the actual pressure difference inside the column corresponding to the current detection period (the detection period is a preset fixed time interval, which analyzes data within a segment to ensure reliable analysis; the current detection period is the time interval between the start of the above detection and the execution of the preset fixed time interval (the value range is 5-15 min)), construct the detection time-actual column pressure difference curve; based on the actual column temperature difference corresponding to the current detection period, construct the detection time-actual column temperature difference curve; during continuous distillation, steps 502-504 can be executed periodically once;

[0125] Step 503: Determine the average value of the actual pressure difference in the tower and the fluctuation coefficient of the actual pressure difference in the tower from the detection time-actual tower pressure difference curve finally obtained in Step 502; determine the average value of the actual temperature difference in the tower from the detection time-actual tower temperature difference curve finally obtained in Step 502.

[0126] Actual tower pressure difference fluctuation coefficient = detection time obtained in step 502 - "difference between maximum and minimum values ​​÷ average value" in the actual tower pressure difference curve;

[0127] Step 504: Determine the distillation adjustment strategy based on the actual average pressure difference in the column, the actual pressure difference fluctuation coefficient in the column, and the actual average temperature difference in the column, and continue to perform distillation based on the distillation adjustment strategy;

[0128] Distillation adjustment strategies include:

[0129] When the average actual pressure difference in the column, the actual pressure difference fluctuation coefficient in the column, and the average actual temperature difference in the column all meet the corresponding allowable ranges, the adjusted vacuum value is equal to the vacuum value corresponding to step 501, and the final adjusted reflux ratio is equal to the preset reflux ratio; the allowable range for the average actual pressure difference in the column is 1.5–3.0 kPa; the allowable range for the average actual temperature difference in the column is 8–15℃; and the allowable range for the actual pressure difference fluctuation coefficient in the column is less than or equal to 5%.

[0130] Main adjustment based on differential pressure parameters:

[0131] When either the actual average pressure difference inside the tower is lower than the lower limit of the corresponding preset requirement range or the actual pressure difference fluctuation coefficient inside the tower is higher than the upper limit of the corresponding preset requirement range, the main adjustment reflux ratio = preset reflux ratio × 0.90; at the same time, within the range of -0.09 to -0.07 MPa, the adjusted vacuum value = the vacuum value corresponding to step 501 × 0.98;

[0132] When the actual average pressure difference inside the tower is higher than the preset upper limit, the main adjustment reflux ratio = preset reflux ratio × 1.10; at the same time, within the range of -0.09 to -0.07 MPa, the adjusted vacuum value = the vacuum value corresponding to step 501 × 1.02.

[0133] Auxiliary adjustments are made based on temperature difference parameters: when the actual average temperature difference in the tower is lower than the corresponding preset requirement range, the final adjustment reflux ratio = main adjustment reflux ratio × 1.05; when the actual average temperature difference in the tower is higher than the preset upper limit, the final adjustment reflux ratio = primary adjustment reflux ratio × 0.95.

[0134] When the actual average temperature difference inside the tower is within the corresponding preset requirement range, the final adjustment reflux ratio equals the first adjustment reflux ratio.

[0135] Ultimately, the distillation process continues by combining the final adjusted reflux ratio and the adjusted vacuum value.

[0136] The preset reflux ratio (ranging from 2 to 4, preferably 3) is a baseline reflux ratio determined through preliminary process experiments under the negative pressure distillation conditions (vacuum degree -0.09 to -0.07 MPa, column temperature 125 to 150°C) and raw material composition conditions of this embodiment. This reflux ratio ensures that after distillation to remove ethylene glycol monobutyl ether and byproducts M355 and M413, the purity of the triclopyroxyacetic acid butoxyethyl ester product meets the preset requirements, providing a baseline value for subsequent reflux ratio adjustment.

[0137] Reflux ratio = reflux rate after condensation at the top of the distillation column ÷ product amount collected from the top of the column;

[0138] Low pressure differential indicates insufficient vapor-liquid load in the tower, too little rising vapor, no stable liquid layer forming on the tray, poor separation efficiency, and incomplete removal of light components.

[0139] Excessive fluctuation coefficient indicates unstable operation within the tower, resulting in a significant decrease in separation efficiency.

[0140] Reduce the reflux ratio: decrease the reflux flow rate at the top of the column, reduce the liquid load in the column, avoid excessive liquid layer on the tray leading to poor vapor-liquid contact, and reduce energy consumption.

[0141] Increasing vacuum reduces the operating pressure inside the column, increases the volatility of light components, makes ethylene glycol monobutyl ether and impurities more easily vaporized, increases the vapor load inside the column, increases the pressure difference inside the column, and allows the column to restore a stable vapor-liquid balance.

[0142] Differential pressure control addresses the issues of vapor-liquid load and stability within the column, while differential temperature control addresses the issues of separation accuracy and product purity. The combination of the two can achieve closed-loop control of the distillation column, ensuring product purity while balancing column stability and energy consumption, and ensuring complete removal of ethylene glycol monobutyl ether and byproducts, thus achieving the target product purity standard.

[0143] The beneficial effects of this embodiment are:

[0144] This solution introduces periodic monitoring periods, using the average pressure difference, pressure difference fluctuation coefficient, and average temperature difference as core control indicators to achieve dynamic monitoring of the vapor-liquid load and operational stability within the distillation column. The pressure difference fluctuation coefficient is controlled within a reasonable range of ≤5%, effectively avoiding the risks of leakage, mist entrainment, or flooding caused by excessive pressure difference fluctuations in traditional distillation processes. This ensures long-term stable operation of the distillation column within a vacuum range of -0.09 to -0.07 MPa and a temperature range of 125 to 150°C, significantly reducing safety hazards and shutdown risks during production.

[0145] This scheme adopts a control strategy of "pressure difference as the main control and temperature difference as the auxiliary control": In the pressure difference main control stage, the vapor-liquid load in the column is quickly corrected by adjusting the reflux ratio and vacuum degree to ensure the complete vaporization and removal of ethylene glycol monobutyl ether and by-products M355 and M413 at 125-150℃; In the temperature difference auxiliary control stage, the reflux ratio is further optimized based on the temperature difference between the bottom and top of the column to strengthen the temperature gradient in the column and ensure that the purity of the heavy components in the bottom of the column consistently meets the preset index requirements.

[0146] Using a high vacuum and suitable medium temperature as a unified start-up anchor point, a stable vapor-liquid load and reflux balance can be quickly established in the column, shortening the distillation column stabilization time; at the same time, it provides a stable benchmark for subsequent pressure difference and temperature difference monitoring and dynamic fine-tuning of reflux ratio and vacuum degree, making the subsequent operating condition adjustment range more abundant and the control more sensitive, adapting to small fluctuations in raw material composition, and the overall separation stability stronger.

[0147] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A green etherification process for triclopyroxyacetic acid butoxyethyl ester, characterized in that: include: Step 1: Sodium trichloropyridinol reacts with methyl chloroacetate in a nucleophilic substitution etherification condensation to produce the intermediate crude chloropyridinium methyl ester. Step 2: The crude chlorometholone methyl ester is subjected to vacuum distillation to remove residual methanol and free acidic impurities, thereby obtaining the chlorometholone methyl ester intermediate. Step 3: Mix the chlorophyll methyl ester intermediate with ethylene glycol monobutyl ether and carry out transesterification etherification reaction in the presence of transesterification catalyst to generate transesterification etherification reaction solution; Step 4: After the reaction in Step 3, the transesterification etherification reaction solution is cooled using a gradient temperature control process; Step 5: The cooled transesterification etherification reaction solution is sent to a distillation column for batch and stepwise pressure swing distillation. First, control the distillation column at atmospheric pressure and the material temperature in the column bottom at 65-70°C. Collect the light methanol component from the top of the distillation column until the methanol is completely removed. Switch to negative pressure reduced pressure distillation mode, vacuum degree -0.09~-0.07MPa, material temperature in distillation column 125℃~150℃, distillation removes ethylene glycol monobutyl ether and secondary impurities M355 and M413; Step 6: The purified material collected from the distillation column is allowed to stand at a constant temperature to remove residual suspended impurities, and then filtered to obtain triclopyroxyacetic acid butoxyethyl ester product.

2. The green etherification process for triclopyroxyacetic acid butoxyethyl ester according to claim 1, characterized in that: In step 4, the refined material collected from the distillation column is kept at a constant temperature of 80-90℃ for 1-2 hours to remove residual suspended impurities and then filtered to obtain triclopyroxyacetic acid butoxyethyl ester product.

3. The green etherification process for triclopyroxyacetic acid butoxyethyl ester according to claim 1, characterized in that: The vacuum distillation desolventizing and refining conditions are a vacuum degree of -0.09 to -0.07 MPa and a material temperature ≤65℃ inside the distillation column.

4. The green etherification process for triclopyroxyacetic acid butoxyethyl ester according to claim 1, characterized in that: In the gradient temperature control cooling process, the cooling rate is controlled at 0.5 to 1℃ / min in a segmented gradient cooling manner.

5. The green etherification process for triclopyroxyacetic acid butoxyethyl ester according to claim 1, characterized in that: In step 1, the molar ratio of the active ingredients sodium trichloropyridinol to methyl chloroacetate is 1:1.05-1.2, the etherification condensation reaction temperature is 50-60℃, and the reaction time is 2-3 hours.

6. The green etherification process for triclopyroxyacetic acid butoxyethyl ester according to claim 1, characterized in that: In step 3, the molar ratio of the active ingredient of chlorophyll methyl ester intermediate to ethylene glycol monobutyl ether is 1:1.1-1.3, the transesterification etherification reaction temperature is 80-85℃, and the reaction time is 4-6h.

7. The green etherification process for triclopyroxyacetic acid butoxyethyl ester according to claim 6, characterized in that: The transesterification catalyst is sodium methoxide or sodium ethoxide, and the amount of catalyst used is 0.5 to 1.0% of the mass of the purified intermediate.

8. The green etherification process for triclopyroxyacetic acid butoxyethyl ester according to claim 1, characterized in that: Step 3 includes: Step 31: Add the methyl chlorpyrifos intermediate and ethylene glycol monobutyl ether to the reaction vessel, stir and mix, and determine the conductivity when the mixture is uniform based on the detection. Step 32: Keep the material temperature in the reactor ≤40℃, keep the stirring speed 100~120r / min, add the catalyst to the first proportion of the total amount of catalyst produced in step 3 at the preset addition rate, and detect the conductivity until the conductivity response rate is less than the preset conductivity response rate. Construct a detection time-conductivity dataset, and determine the effective reaction time period and effective reaction rate. Determine the effective reaction rate characteristic value and effective reaction time characteristic value based on the effective reaction rate and effective reaction time. Step 33: Determine the adjustment addition rate based on the effective reaction rate characteristic value and the effective reaction time characteristic value, and continue to add the catalyst at the adjustment addition rate until the total amount of catalyst produced in a single production in Step 3 is reached; Step 34: Determine the first duration and the second duration based on the effective reaction rate characteristic value and the effective reaction time characteristic value; Step 35: After the catalyst is added, a gradient segmented temperature control is adopted. First, the temperature is raised to 60-65°C at the first heating rate and the reaction is maintained at this temperature for the first time. Then, the temperature is raised to 80-85°C at the second heating rate and the reaction is maintained at this temperature for the second time.

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