Method for recovering basic catalyst triethylamine in methyl acetoacetate product
In the production process of methyl acetoacetate products, the triethylamine catalyst is recovered from the crude product by using Lewis acid-base reaction and metathesis reaction, which solves the problems of high catalyst cost and failure to be recycled and utilized, and achieves efficient catalyst recovery and cost savings.
Patent Information
- Application Number
- CN202311732566.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-15
- Publication Date
- 2025-06-17
AI Technical Summary
In the industrial production of methyl acetoacetate products, the basic catalyst triethylamine has a high cost and has not been effectively recycled, resulting in increased waste of raw materials and difficulty in treating waste liquids.
The triethylamine catalyst was recovered from the crude methyl acetoacetate by using a simple Lewis acid-base reaction, metathesis reaction and extraction and separation methods, including adding an acidic aqueous solution to the Lewis acid-base reaction to form triethylamine salt, and separating it from the organic layer through the aqueous phase; extracting and separation in the residual solution to obtain a triethylamine brine solution; mixing all the aqueous phase solutions and adding an appropriate amount of alkali to perform metathesis reaction to form triethylamine.
The recovery rate of more than 95% of the triethylamine catalyst is achieved, the catalyst is fully utilized, the cost is reduced, and the entire recycling process is low in energy consumption and has good recycling effect.
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Figure CN120157584A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for recovering triethylamine, an alkaline catalyst, from methyl acetoacetate products, belonging to the field of chemical engineering technology. Background Art
[0002] Methyl acetoacetate, also known as dimethyl acetoacetate, has the chemical name methyl 3-oxobutanoate.
[0003] English name: Methyl acetoacetate
[0004] Appearance property: Colorless liquid
[0005] Solubility: Soluble in water, 460 g / L (20 °C)
[0006] CAS No.: 105-45-3
[0007] Molecular formula: C5H8O3
[0008] Structural formula:
[0009]
[0010] Molecular weight: 116
[0011] Melting point (°C): -28 °C
[0012] Boiling point (°C): 170 °C
[0013] Relative density (water = 1): 1.077
[0014] Functions and uses: Methyl acetoacetate is an intermediate for fungicides such as hymexazol, dimethirimol, ethirimol, insecticides such as diazinon, coumaphos, pyrimitate, herbicide imazethapyr, rodenticides such as warfarin, coumatetralyl, etc., used as a solvent for cellulose ethers and a component of the mixed solvent of cellulose resins, and also used in organic syntheses such as pesticides, pharmaceuticals, dyes, and polymer stabilizers.
[0015] Currently, the production of methyl acetoacetate products basically involves reacting diketene (DK) with methanol under the action of a basic catalyst, triethylamine, to obtain crude methyl acetoacetate, followed by rectification. Since methyl acetoacetate is prone to decomposition during rectification at high temperatures, an acidic stabilizer is added before rectification in production to cause partial flocculation of triethylamine, which helps prevent the decomposition of methyl acetoacetate. Then rectification is carried out to prevent decomposition during the rectification process, and finally, the finished product, the head (specifically referring to the liquid containing more low-boiling components that is first rectified from the crude methyl acetoacetate in the low-boiling tower during the rectification process of crude methyl acetoacetate), and the residue (specifically referring to the liquid containing more high-boiling and other polymer impurities remaining after the finished product ester is obtained during the rectification process of crude methyl acetoacetate) are obtained through rectification. Due to the relatively low boiling point of the triethylamine catalyst, during the rectification process, most of the triethylamine in the crude product is distilled out together with the head, and the distilled head is pumped into the head storage tank. After storing a certain amount, the head is rectified and purified to recover some of the methyl esters therein. The low-boiling components distilled out during the purification of the head contain a relatively large amount of triethylamine, but they are directly treated as waste liquid. Since an acidic stabilizer is added before rectification, the acid also reacts with some triethylamine to form salts, and the salts remain in the residue after rectification and are not treated and are directly treated as waste liquid. The recovery and utilization of the triethylamine catalyst are not considered throughout the entire process of the traditional process, resulting in waste of raw materials and increasing the difficulty of treating waste liquid.
[0016] CN 108299200A discloses a method for the clean production of methyl acetoacetate. After using a small amount of triethylamine instead of triethylenediamine as the catalyst, it is no longer necessary to add concentrated sulfuric acid to precipitate and filter out the catalyst triethylenediamine, which greatly reduces the burden of sewage treatment and improves the environment. However, this invention does not further consider the recycling of the triethylamine catalyst to reduce the use cost of the catalyst.
[0017] Generally speaking, during the industrial production of methyl acetoacetate products, there are problems such as the relatively high cost of the basic catalyst triethylamine. It is necessary to recover the catalyst triethylamine from the crude methyl acetoacetate. Summary of the Invention
[0018] The purpose of the present invention is to develop a method for recovering the basic catalyst triethylamine in methyl acetoacetate products. The present invention can achieve the full recycling of the triethylamine catalyst by using simple Lewis acid-base reactions, metathesis reactions, and extraction separation methods, saving costs.
[0019] The technological process and working principle of the present invention are as follows:
[0020] (1) Take the crude methyl acetoacetate obtained by reacting diketene (DK) with an alcohol under the action of a basic catalyst triethylamine, and carry out rectification to obtain the finished product of methyl acetoacetate, the head, and the residue; an acidic stabilizer is added before rectifying the crude methyl acetoacetate to cause partial flocculation of triethylamine, which can effectively inhibit the decomposition of the crude ester;
[0021] (2) Re-purify and recycle part of the finished product in the head subset; a certain amount of low-boiling waste liquid is generated during the purification of the head. An appropriate amount of acidic aqueous solution is mixed with the low-boiling waste liquid, and the acid reacts with triethylamine in a Lewis acid-base reaction to form triethylamine salt. At this time, the aqueous phase and the organic waste liquid are layered, and the salt solution 1 (aqueous solution of triethylamine salt) and the organic layer 1 are separated respectively.
[0022] The reaction equation for the formation of triethylamine salt by the Lewis acid-base reaction of acid and triethylamine is as follows:
[0023]
[0024] (3) Since an acidic auxiliary agent is added to the crude ester before distillation, the auxiliary agent reacts with part of the triethylamine in the crude ester to form a salt, and the salt remains in the residue after distillation; water is added to the residue for extraction and separation, and after extraction and layering, the salt solution 2 (aqueous solution of triethylamine salt) and the organic layer 2 are obtained.
[0025] (4) Mix all the obtained aqueous solutions (salt solution 1 and salt solution 2), add an appropriate amount of NaOH, and carry out a double decomposition reaction with the salt in the water to form triethylamine. Triethylamine is layered with the aqueous solution, and triethylamine can be recycled; the double decomposition reaction equation of NaOH and triethylamine salt is as follows:
[0026]
[0027] The present invention provides a method for recycling triethylamine, a basic catalyst, in methyl acetoacetate products. The method includes:
[0028] Take the head after distillation of the crude methyl acetoacetate, add an acidic aqueous solution to the low-boiling waste liquid generated during the purification of the head, and make the acid react with triethylamine in a Lewis acid-base reaction to form the corresponding triethylamine salt, and layer to obtain the salt solution 1 of triethylamine salt.
[0029] Take the residue after distillation of the crude methyl acetoacetate, add water, mix and layer to obtain the salt solution 2 of triethylamine salt.
[0030] Combine the salt solution 1 and the salt solution 2, add an appropriate amount of basic solution, react with the triethylamine salt to form triethylamine, and triethylamine is layered with the aqueous phase to obtain triethylamine.
[0031] In one embodiment, the crude methyl acetoacetate refers to the crude methyl acetoacetate prepared by the reaction of diketene (DK) and alcohol under the action of a basic catalyst triethylamine. The crude methyl acetoacetate is distilled to obtain the finished product of methyl acetoacetate, the head, and the residue. Before distillation of the crude methyl acetoacetate, an acidic stabilizer is added to flocculate part of the triethylamine, which can effectively inhibit the decomposition of the crude ester.
[0032] In one embodiment, the rectification of the crude methyl acetoacetate is specifically as follows: First, an acidic stabilizer is added to the crude methyl acetoacetate to inhibit the decomposition of methyl ester during rectification. Then, it passes through a low-boiling-point removal tower. A certain temperature and vacuum are maintained inside the tower, and a certain reflux ratio is maintained at the top of the tower. The head product starts to be distilled out. In this step, low-boiling impurities such as triethylamine, methanol, and acetone are removed. After the removal of low-boiling components, the crude product is fed into the finished product rectification tower. A certain temperature and pressure are still maintained inside the tower, and the finished product ester is taken out at a certain reflux ratio at the top of the tower, and finally, the residue remains.
[0033] In one embodiment, the content of esters in the head product is 90%, and the content of the remaining low-boiling components such as triethylamine, methanol, acetone, and methyl ester is about 10% - 20%. Therefore, the head product needs to be further purified to recover most of the esters therein to avoid waste. The specific process for purifying the head product is: concentrating the head products obtained from multiple batches of rectification, and then distilling and purifying them together through an evaporation tower. A certain temperature and pressure are maintained inside the tower, and most of the low-boiling waste liquids such as methanol, acetone, and triethylamine are directly distilled out at the top of the tower, and the remaining in the tower is the methyl acetoacetate product with qualified purity.
[0034] In one embodiment, the acidic aqueous solution selected can be an acidic aqueous solution such as HCl, H2SO4, HNO3, etc. that can react with triethylamine to form triethylamine salts. Preferably, it is HCl, which is more likely to form salts with triethylamine and is easier to extract.
[0035] In one embodiment, in the acidic aqueous solution, the content of H + is controlled to be 0.1 mol / L, and the pH is controlled to be about 1.
[0036] In one embodiment, the acidic aqueous solution accounts for more than 20% of the mass of the low-boiling waste liquid, and optionally 20% - 35%. If the addition amount of the acidic aqueous solution is insufficient, it will cause incomplete reaction of triethylamine in the low-boiling waste liquid, thus affecting the recovery rate of triethylamine.
[0037] In one embodiment, the layering after treatment with the acidic aqueous solution is to stir and then let it stand for layering. Optionally, it is to stir and react for 30 - 60 min, and then let it stand for 30 - 45 min for layering.
[0038] In one embodiment, the mass of water added to the residue is more than 30% of the mass of the residue, and optionally 30% - 45%. In the residue, if the amount of water added is too small, it will cause the layering boundary to be unclear during layering, affecting the recovery rate of triethylamine.
[0039] In one embodiment, when water is added to the residue and the mixture is allowed to stand for layering, it is to mix and let it stand for 40 - 60 min for layering. Sufficient layering time can ensure a clear boundary line during layering, facilitating the recovery of triethylamine.
[0040] In one embodiment, the base added to the salt solution can be NaOH, KOH, Ca(OH)₂, etc., which can react with the triethylamine salt to form triethylamine. Preferably, it is the strong base NaOH or KOH.
[0041] In one embodiment, for the base added to the salt solution, control the concentration of the initially added base solution (about pH 13.3, OH - content is 0.2 mol / L); control the pH to reduce side reactions and avoid being too acidic or too basic. Under this condition, it is easier to react to form triethylamine without causing excessive hydrolysis.
[0042] In one embodiment, in the aqueous solution of triethylamine salt (m 三乙胺盐 ), add an alkali solution (m 碱溶液 ) accounting for 50% - 60% of the total mass of the salt solution.
[0043] In one embodiment, after adding the alkali solution, the layering of triethylamine and the aqueous phase is as follows: stir and react for 30 - 60 min, and then let it stand for 20 - 25 min to separate layers.
[0044] In one embodiment, according to the above method, more than 95% of the total amount of triethylamine can be recovered. Among them, 70% - 80% of the total amount of triethylamine can be recovered from Salt Solution 1.
[0045] Advantageous effects of the present invention:
[0046] In the present invention, an acid is added to the low boilers generated from the purification head to carry out a Lewis acid-base reaction with the triethylamine in the low boilers to form the corresponding triethylamine salt, and then let it stand for layering to obtain an aqueous solution of the salt; then water is added to the residue obtained from the previous rectification, and after mixing and letting it stand for layering, an aqueous solution of the triethylamine salt is also obtained; after mixing all the obtained aqueous solutions of the triethylamine salt, an appropriate amount of base is added thereto to react with the triethylamine salt to form triethylamine, and the triethylamine is layered with the aqueous phase, and thus triethylamine can be obtained.
[0047] The present invention utilizes simple Lewis acid-base reactions, metathesis reactions, and extraction separation techniques, enabling the recovery rate of triethylamine to reach more than 95%, enabling the catalyst to be fully recycled, effectively saving costs, and having low energy consumption and good recovery effect during the entire recovery process. Description of the Drawings
[0048] Figure 1 It is a schematic diagram of the triethylamine recovery process of the present invention. Detailed Embodiments
[0049] Triethylamine recovery rate = [(amount of triethylamine recovered from the head + amount of triethylamine recovered from the residue) · wt1%] / [amount of triethylamine fed in the esterification reaction · wt2%]
[0050] wt1% represents the content of recovered triethylamine, and wt2% represents the content of triethylamine catalyst fed into the esterification reaction.
[0051] like Figure 1 The figure shows a schematic diagram of the recovery process of the alkaline catalyst triethylamine in the methyl acetoacetate product according to an embodiment of the present invention.
[0052] (1) taking a crude methyl acetoacetate product prepared by reacting diketene (DK) and an alcohol under the action of a basic catalyst, triethylamine, and performing distillation to obtain a finished methyl acetoacetate product, a head, and a residual liquid; wherein an acidic stabilizer is added before distillation of the crude methyl acetoacetate product to flocculate part of the triethylamine, thereby effectively inhibiting the decomposition of the crude ester;
[0053] (2) Purifying the heads and recovering part of the methyl acetoacetate product; a certain amount of low-boiling waste liquid is generated in the process of purifying the heads, and an appropriate amount of acidic aqueous solution (such as hydrochloric acid aqueous solution) is mixed with the low-boiling waste liquid, and the acid and triethylamine undergo a Lewis acid-base reaction to generate triethylamine salt, and the aqueous phase and the organic waste liquid are extracted and separated to obtain a salt solution 1 (i.e., a triethylamine salt aqueous solution) and an organic layer 1;
[0054] (3) adding water to the residual liquid for extraction and separation, and obtaining a salt solution 2 (i.e., a triethylamine salt solution) and an organic layer 2 after extraction and stratification;
[0055] (4) All the obtained aqueous phase solutions (salt solution 1 and salt solution 2) are combined, and an appropriate amount of base (such as NaOH aqueous solution) is added to react with the salt in the water to produce triethylamine, and the triethylamine and the aqueous solution are separated to recover the triethylamine.
[0056] Embodiment 1:
[0057] The triethylamine recovery method of the present embodiment is as follows:
[0058] (1) taking crude methyl acetoacetate, wherein the preparation process of crude methyl acetoacetate is as follows:
[0059] Initially, methanol and triethylamine catalyst are fully mixed, wherein triethylamine accounts for about 0.6% (about 0.2% of the total feed amount), and then spread on the bottom of the kettle, and stirring begins. After gradually heating to above 50°C, diketene is slowly added dropwise and the reaction begins to generate crude methyl acetoacetate.
[0060] (2) The crude methyl acetoacetate is distilled, and the distillation process is as follows: first, the crude methyl ester is transported to a low-boiling tower, the vacuum degree in the tower is maintained at -88.2 Kpa, the tower is heated to 95°C, the reflux ratio is controlled to be about 1, and the head is discharged from the top of the tower and transported to the head storage tank; after the low-boiling tower is discharged, the crude product is transported to a finished product tower, the vacuum degree in the tower is maintained at -99.5 Kpa, the tower is heated to 100°C, the reflux ratio is also maintained at 1, and the finished product is discharged from the top of the tower; the remaining residual liquid is transported to a residual liquid storage tank for centralized treatment;
[0061] After distillation, most of the methyl acetoacetate product, heads and residual liquid are obtained.
[0062] (3) Purifying the heads obtained in (2), wherein the purification process is as follows: transporting the heads to a distillation tower, maintaining a vacuum degree of -82 KPa in the tower, heating to 90° C., and removing low boiling water from the top of the tower. After removing all low boiling water, a purified methyl ester product is obtained in the tower;
[0063] After purification, part of the methyl acetoacetate product and low-boiling waste liquid are obtained.
[0064] (4) adding an acidic aqueous solution to the low-boiling waste liquid obtained in (3) to allow the acid to react with triethylamine to produce a corresponding triethylamine salt by Lewis acid-base reaction, and extracting and stratifying to obtain a salt solution 1 of the triethylamine salt;
[0065] The acidic aqueous solution selected is HCl, and the H+ content in the acidic aqueous solution is controlled to be 0.1 mol / L; the amount of the acidic aqueous solution added accounts for 35% of the mass of the low-boiling waste liquid; the extraction and stratification are first stirred for 60 minutes, and then allowed to stand for 45 minutes for stratification.
[0066] (5) taking the residual liquid obtained in (2), adding water, mixing and layering, and obtaining a salt solution 2 of triethylamine salt;
[0067] The mass of water added is 45% of the mass of the residual liquid, and the stratification after mixing is performed by standing the mixture for 60 minutes.
[0068] (6) combining salt solution 1 and salt solution 2, adding an appropriate amount of alkaline solution, reacting with triethylamine salt to generate triethylamine, and separating triethylamine and aqueous phase to obtain triethylamine;
[0069] The alkali added to the salt solution is NaOH solution, wherein OH in the NaOH aqueous solution is - The content is 0.2mol / L;
[0070] Add 60% of the total mass of the alkaline solution to the aqueous solution of triethylamine salt; separate the layers by stirring the reaction for 60 minutes and then letting it stand for 25 minutes to separate the layers.
[0071] According to the method of this embodiment, 96.6% of the total amount of triethylamine was recovered.
[0072] Embodiment 2:
[0073] Compared with Example 1, only the following changes are made, and the other steps and conditions remain the same as those in Example 1:
[0074] In step (4), the acidic aqueous solution selected is H2SO4, and the H+ content in the acidic aqueous solution is controlled to be 0.1 mol / L; the acidic aqueous solution accounts for 25% of the mass of the low-boiling waste liquid; stir and react for 40 min, and then let it stand for 35 min for stratification;
[0075] In step (5), the mass of water added to the residual liquid is 35% of the mass of the residual liquid, and the mixing and standing stratification time is 45 min;
[0076] In step (6), the base added to the aqueous solution of the salt is KOH, and the OH- content in the aqueous solution is controlled to be 0.2 mol / L; a base solution accounting for 53% of the total mass of the salt solution is added to the aqueous solution of the triethylamine salt. Stir and react for 40 min, and then let it stand for 22 min for stratification.
[0077] According to the method of this example, 95.2% of the total amount of triethylamine is recovered.
[0078] Example 3:
[0079] Compared with Example 1, only the following changes are made, and other steps and conditions are the same as those in Example 1:
[0080] In step (4), the acidic aqueous solution selected is HCl, and the H+ content in the acid is controlled to be 0.1 mol / L; the acidic aqueous solution accounts for 30% of the mass of the low-boiling liquid; stir and react for 50 min, and then let it stand for 40 min for stratification;
[0081] In step (5), the mass of water added to the residual liquid is 40% of the mass of the residual liquid, and the mixing and standing stratification time is 50 min;
[0082] In step (6), the base added to the aqueous solution of the salt is NaOH, and the OH- content in the aqueous solution is controlled to be 0.2 mol / L; a base solution accounting for 56% of the total mass of the salt solution is added to the aqueous solution of the triethylamine salt. Stir and react for 50 min, and then let it stand for 23 min for stratification.
[0083] According to the method of this example, 95.4% of the total amount of triethylamine is recovered.
[0084] Example 4:
[0085] Compared with Example 1, only the following changes are made, and other steps and conditions are the same as those in Example 1:
[0086] In step (4), the acidic aqueous solution selected is HNO3, and the H + content is controlled to be 0.1 mol / L; the acidic aqueous solution accounts for 20% of the mass of the low-boiling liquid; stir and react for 30 min, and then let it stand for 30 min for stratification;
[0087] In step (5), 30% of the mass of the residual liquid is added to the residual liquid, and the mixing and stratification time is 40 minutes;
[0088] In step (6), the base added to the aqueous solution of the salt is Ca(OH)2, which reacts with the triethylamine salt to form triethylamine, thereby controlling the OH in the aqueous solution. - The content is 0.2 mol / L; add 50% of the total mass of the alkaline solution to the aqueous solution of triethylamine salt, stir and react for 30 minutes, and then stand for 20 minutes to separate the layers.
[0089] According to the method of this embodiment, 95% of the total amount of triethylamine was recovered.
[0090] Comparative Example 1: The amount of acidic aqueous solution added affects the recovery effect
[0091] Compared with Example 1, only the following changes are made, and the other steps and conditions remain the same as those in Example 1:
[0092] In step (4), the acidic aqueous solution accounts for 15% of the mass of the low-boiling waste liquid.
[0093] According to the method, 84.8% of the total amount of triethylamine was recovered. Since the amount of the acidic aqueous solution added was reduced, the acid was not sufficiently excessive, and part of the triethylamine failed to react with the hydrochloric acid to form a salt, resulting in the failure to fully recover the triethylamine.
[0094] Comparative Example 2: The amount of water added to the residual liquid affects the recovery effect
[0095] Compared with Example 1, only the following changes are made, and the other steps and conditions remain the same as those in Example 1:
[0096] In step (5), the mass of water added to the residual liquid is 25% of the mass of the residual liquid.
[0097] According to this method, 83.1% of the total amount of triethylamine was recovered. Due to the reduction in the amount of water added, the water failed to fully mix with the residual night and the triethylamine salt in the residual night could not be fully extracted, resulting in a decrease in the final triethylamine yield.
[0098] Comparative Example 3: The amount of alkali added to the salt solution affects the recovery effect
[0099] Compared with Example 1, only the following changes are made, and the other steps and conditions remain the same as those in Example 1:
[0100] In step (6), an alkali solution accounting for 40% of the total mass of the salt solution is added to the aqueous solution of triethylamine salt.
[0101] According to this method, 85.7% of the total amount of triethylamine was recovered. Since the amount of the alkali solution added was too small, it failed to react fully with the salt in the aqueous solution, resulting in less triethylamine being generated and a decrease in the recovery rate of triethylamine.
[0102] Comparative Example 4:
[0103] Compared with Example 1, step (5) was omitted, and the other steps and conditions were the same as those in Example 1:
[0104] According to this method, 78% of the total amount of triethylamine was recovered.
[0105] The present invention has been disclosed in the above preferred embodiments, but it is not intended to limit the present invention. Any technical solutions obtained by using equivalent substitutions or equivalent transformations fall within the protection scope of the present invention.
Claims
1. A method for recovering triethylamine, an alkaline catalyst, from methyl acetoacetate product, characterized in that, The method includes: Taking the head product after rectification of the crude methyl acetoacetate, adding an acidic aqueous solution to the low-boiling waste liquid generated during the purification of the head product, allowing the acid to undergo a Lewis acid-base reaction with triethylamine to form the corresponding triethylamine salt, and separating the layers to obtain salt solution 1 of the triethylamine salt; Taking the residual liquid after rectification of the crude methyl acetoacetate, adding water, mixing and then separating the layers to obtain salt solution 2 of the triethylamine salt; Combining salt solution 1 and salt solution 2, adding an appropriate amount of alkaline solution, reacting with the triethylamine salt to form triethylamine, and separating the triethylamine from the aqueous phase to obtain triethylamine.
2. The recovery method according to claim 1, characterized in that, In the acidic aqueous solution, the H⁺ content in the acid is controlled to be 0.1 mol / L, and the acidic aqueous solution accounts for more than 20% of the mass of the low-boiling waste liquid.
3. The recovery method according to claim 2, characterized in that, The acidic aqueous solution accounts for 20% - 35% of the mass of the low-boiling waste liquid.
4. The recovery method according to claim 1, characterized in that, OH in the alkaline solution added to the salt solution - has a content of 0.2 mol / L.
5. The recovery method according to claim 1, characterized in that, Add 50% - 60% of the alkaline solution based on the total mass of the salt solution to the combined salt solution.
6. The recovery method according to claim 1, characterized in that, The mass of water added to the residual liquid is more than 30% of the mass of the residual liquid.
7. The recovery method according to claim 6, characterized in that, The mass of water added to the residual liquid is 30% - 45% of the mass of the residual liquid.
8. The recovery method according to claim 1, characterized in that, The layer separation after treatment with the acidic aqueous solution is to stir and then let it stand for layer separation; optionally, stir and react for 30 - 60 min, and then let it stand for 30 - 45 min for layer separation.
9. The recovery method according to claim 1, characterized in that, Adding water to the residual liquid and separating the layers after mixing is to mix and let it stand for 40 - 60 min for layer separation.
10. The recovery method according to claim 1, characterized in that, The acidic aqueous solution can be an acidic aqueous solution such as HCl, H₂SO₄, HNO₃, etc. that can react with triethylamine to form a triethylamine salt; optionally, the base added to the salt solution can be NaOH, KOH, Ca(OH)₂, etc.
Citation Information
Patent Citations
Clean production method of methyl acetoacetate
CN108299200A