A process for the production of liquid sodium morpholino dithiocarbamate

Abstract

This invention discloses a method for producing liquid morpholino-dithiocarbamate sodium, relating to the field of fine chemical synthesis technology. The method includes adding morpholine and an aqueous solution of sodium hydroxide to a synthesis reactor and stirring to obtain a reaction base liquid; cooling the reaction base liquid to -5°C to 5°C; adding carbon disulfide dropwise to the reaction base liquid while stirring to form a reactant, controlling the temperature of the reactant to not exceed 20°C; stopping the dropwise addition of carbon disulfide when the cumulative amount added reaches 30% to 37% of the total carbon disulfide feed, and continuing to stir the reactant for 20 to 30 minutes; continuing to add carbon disulfide dropwise to the reactant, stopping the dropwise addition again when the cumulative amount added reaches 63% to 70% of the total carbon disulfide feed, and continuing to stir the reactant for 30 to 50 minutes. This invention reduces the formation of byproducts such as sodium trithiocarbonate and improves the purity and appearance stability of the target product.

Description

Technical Field

[0001] This invention relates to the field of fine chemical synthesis technology, and in particular to a method for producing liquid sodium morpholinodithiocarbamate. Background Technology

[0002] Sodium morpholinodithiocarbamate, or morpholino DTC for short, is a sulfur- and nitrogen-containing fine chemical intermediate that combines the structures of a six-membered heterocyclic morpholino and a dithiocarbamate. Its unique molecular structure endows this compound with high reactivity and multifunctional application potential. In the pesticide field, morpholino DTC can be used as an intermediate for fungicides, herbicides, and other sulfur- and nitrogen-containing active compounds. In the fields of non-ferrous metal mineral flotation and environmental water treatment, the sulfur and nitrogen atoms in its molecule can form stable complexes with heavy metal ions for the capture, enrichment, and separation of metal ions. In the fields of lubricant additives and rubber auxiliaries, morpholino DTC derivatives can improve material properties and provide anti-wear, anti-corrosion, and vulcanization-promoting functions. Furthermore, morpholino DTC and its derivatives also have important application value in organic functional materials, polymer materials, and analytical chemistry, such as in the preparation of epoxy resin curing agents, metal ion color developers, and functional thin film materials.

[0003] Existing preparation methods mainly include organic solvent systems and aqueous systems. Traditional organic solvent methods can prepare solid or liquid morpholine DTC in laboratory-scale trials, but they suffer from problems such as high solvent toxicity, flammability and explosiveness, significant volatilization losses, and difficulties in solvent recovery and residue control. Furthermore, the reaction feeding method and temperature control are not easily scaled up for industrial production. While aqueous methods offer advantages in safety, environmental friendliness, and cost reduction, they still have shortcomings in carbon disulfide dropping acceleration, local dispersion, mass and heat transfer, and byproduct suppression, leading to poor liquid product color, poor stability, high sodium trithiocarbonate impurity content, and batch-to-batch quality fluctuations. Especially under industrial scale-up conditions, traditional one-time or continuous carbon disulfide addition methods easily lead to local enrichment and excessively rapid temperature rise, affecting the main reaction efficiency and product yield. Additionally, a controllable process parameter system suitable for industrial operation has not been established.

[0004] In summary, existing morpholine DTC technology still suffers from high safety risks, difficulty in process control, and insufficient product purity and appearance stability in the industrial preparation of liquid products. To address these technical deficiencies, this invention provides a method for producing liquid morpholino dithiocarbamate sodium based on an aqueous system and employing segmented dropwise addition of carbon disulfide. This method achieves sufficient dispersion of carbon disulfide, controllable reaction temperature, reduced by-product formation, and improved product appearance and content stability. This invention belongs to the field of fine chemical engineering and the preparation technology of sulfur- and nitrogen-containing organic intermediates, and is particularly suitable for the industrial production of liquid morpholine DTC. Summary of the Invention

[0005] This invention provides a method for producing liquid sodium morpholinodithiocarbamate, comprising the following steps: S1. Add morpholine and sodium hydroxide aqueous solution to the synthesis vessel, stir and mix to obtain the reaction base liquid; S2. Cool the reaction base liquid to -5℃~5℃; S3. Add carbon disulfide dropwise to the reaction base liquid under stirring to form a reaction material, and control the temperature of the reaction material to not exceed 20°C. When the cumulative amount of carbon disulfide added reaches 30% to 37% of the total amount of carbon disulfide added, stop adding carbon disulfide and continue stirring the reaction material for 20 to 30 minutes. S4. Continue to add carbon disulfide dropwise to the reactants. When the cumulative amount of carbon disulfide added reaches 63% to 70% of the total amount of carbon disulfide added, stop adding carbon disulfide dropwise again and continue to stir the reactants for 30 to 50 minutes. S5. Continue to add the remaining carbon disulfide to the reactants. After the carbon disulfide is added, heat the reactants to no more than 30°C and continue to stir the reaction for 30-50 minutes to obtain a high-concentration reaction solution. S6. Take samples of the high-concentration reaction solution for analysis. Calculate the amount of water to add based on the content of sodium morpholinodithiocarbamate in the high-concentration reaction solution. After the high-concentration reaction solution settles, add water to adjust the solution and filter it to obtain the liquid sodium morpholinodithiocarbamate product. In steps S1 to S6, no organic solvent is used as the reaction medium, and no external catalyst is added.

[0006] In a preferred embodiment of the production method of liquid morpholinodithiocarbamate sodium according to the present invention, the mass concentration of the sodium hydroxide aqueous solution is 30%; and the molar ratio of morpholine, carbon disulfide and sodium hydroxide, based on purity, is 1:(1.005~1.015):(1.03~1.08).

[0007] In a preferred embodiment of the production method of liquid morpholinodithiocarbamate sodium according to the present invention, the content of morpholino is not less than 98%, the content of carbon disulfide is not less than 98%, and the water used for water addition and preparation in step S6 is tap water that meets drinking water standards.

[0008] In a preferred embodiment of the production method of liquid morpholino dithiocarbamate according to the present invention, in step S2, the reaction base liquid is cooled to -5℃~0℃; In steps S3 and S4, the carbon disulfide dripping stage, the stirring reaction stage after stopping the carbon disulfide dripping, and the dripping stage before the carbon disulfide dripping is completed in step S5, the temperature of the reactants is controlled to not exceed 15°C.

[0009] In a preferred embodiment of the production method of liquid morpholino dithiocarbamate sodium described in this invention, in step S3, when the cumulative amount of carbon disulfide added reaches 1 / 3 of the total amount of carbon disulfide fed, the addition of carbon disulfide is stopped. In step S4, when the cumulative amount of carbon disulfide added reaches 2 / 3 of the total amount of carbon disulfide fed, the addition of carbon disulfide is stopped again.

[0010] In a preferred embodiment of the production method of liquid morpholinodithiocarbamate according to the present invention, the cumulative amount of carbon disulfide added is determined by at least one of the following: the scale of the dropping funnel, the liquid level of the carbon disulfide metering tank, or the weighing data.

[0011] In a preferred embodiment of the production method of liquid morpholino dithiocarbamate sodium according to the present invention, the carbon disulfide is first added to a carbon disulfide metering tank, and then added dropwise from the carbon disulfide metering tank to the reaction base liquid or the reaction material through a dropper. The carbon disulfide metering tank is equipped with a water layer, and the water level is not lower than 20 mm. The outlet of the dripping pipeline is located below the surface of the reaction base liquid or the reaction material.

[0012] In a preferred embodiment of the method for producing liquid morpholino dithiocarbamate according to the present invention, the synthesis reactor is provided with a venting pipeline, which is connected to a carbon disulfide recovery and condensation system.

[0013] In a preferred embodiment of the method for producing liquid morpholino dithiocarbamate according to the present invention, the synthesis reactor is provided with a double-layer combined stirrer, which includes a paddle stirrer in the upper layer and a propeller stirrer in the lower layer.

[0014] In a preferred embodiment of the production method of liquid morpholino dithiocarbamate sodium according to the present invention, in step S6, the sampling analysis includes: taking 10g of the high-concentration reaction solution, drying it at 105℃ for 4h to obtain the dried solid, analyzing the content of morpholino dithiocarbamate sodium in the dried solid by liquid chromatography, analyzing the content of sodium trithiocarbonate in the dried solid by chemical titration, and the sedimentation time of the high-concentration reaction solution is 4h. When adding water for preparation, add the high-concentration reaction solution and water to the mixing vessel and stir for 20 minutes; During filtration, the prepared materials are filtered through a precision filter; The liquid sodium morpholinodithiocarbamate product contains no less than 20.0% sodium morpholinodithiocarbamate by mass, and has a density of 1.05–1.10 g / cm³. 3 The pH value of a 5% aqueous solution is 9.0 to 11.5.

[0015] The beneficial effects of this invention are as follows: This invention uses morpholine, carbon disulfide and sodium hydroxide as raw materials to prepare liquid sodium morpholinodithiocarbamate in an aqueous system. No organic solvent is used as a reaction medium during the reaction process, and no external catalyst is added. Compared with the process using organic solvents such as acetonitrile, tetrahydrofuran, methanol, and ethanol, this invention can reduce the problems of toxicity, flammability and explosiveness, volatilization loss, solvent recovery energy consumption and residue control caused by the introduction of organic solvents, simplify the post-processing process, reduce production costs, and improve the safety and environmental friendliness of the production process. By controlling the staged addition of carbon disulfide and stopping the addition while continuing to stir the reaction when the cumulative amount of carbon disulfide added reaches a set ratio, the carbon disulfide that has entered the reaction system can continue to disperse and participate in the main reaction during the stopping stage. This method does not simply extend or shorten the feeding time, but rather matches the carbon disulfide addition rate, the dispersion state of the system, and the consumption rate of the main reaction, thereby reducing the local enrichment of carbon disulfide in the strong alkaline aqueous phase system and reducing the chance of it reacting with sodium hydroxide to generate impurities such as sodium trithiocarbonate. By pre-cooling the reaction solution and controlling the temperature during the carbon disulfide dropwise addition and stop-drop stirring stages, the rate of carbon disulfide volatilization and its side reaction with sodium hydroxide can be reduced. After the carbon disulfide dropwise addition is completed, a gentle temperature rise and ripening process can be performed to ensure the main reaction proceeds fully while reducing the formation of by-products. This invention can increase the content and yield of the target product sodium morpholinodithiocarbamate, reduce the content of by-products such as sodium trithiocarbonate, and improve the color, clarity, and appearance stability of the liquid product. This invention optimizes the feeding ratio of morpholine, carbon disulfide, and sodium hydroxide, so that carbon disulfide and sodium hydroxide are in moderate excess relative to morpholine. This is beneficial to improving the conversion degree of morpholine, while avoiding the risk of side reactions due to excessive carbon disulfide or sodium hydroxide, thus taking into account both the formation of the target product and the inhibition of by-products. This invention controls the cumulative amount of carbon disulfide added by metering, and can be combined with industrial configurations such as a water layer in the carbon disulfide metering tank, submerged dripping, venting and recovery, and a double-layer combined stirrer. This reduces the volatilization loss of carbon disulfide, improves the dispersion and utilization efficiency of carbon disulfide after entering the liquid phase, enhances mass and heat transfer during the reaction process, reduces the risk of excessively high local carbon disulfide concentration and local temperature rise, and matches the segmented dripping, low-temperature reaction and industrial batch production process. It is suitable for the stable industrial production of liquid morpholinodithiocarbamate sodium. This invention involves sampling and analyzing a high-concentration reaction solution, calculating the amount of water to be added based on the measured sodium morpholinodithiocarbamate content, and then obtaining a liquid finished product through sedimentation, blending, and precision filtration. This avoids fluctuations in the finished product concentration caused by adding water based on experience, and improves the consistency of sodium morpholinodithiocarbamate content, density, pH value, and appearance quality in the finished product, making the quality of the obtained liquid sodium morpholinodithiocarbamate product more stable and controllable. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the production method of liquid morpholino dithiocarbamate sodium in Example 1; Figure 2 This is a diagram illustrating the architecture of the segmented dropping control of carbon disulfide in Example 1. Detailed Implementation

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] Example 1, referring to Figure 1 and Figure 2 This is the first embodiment of the present invention, which provides a method for producing liquid sodium morpholinodithiocarbamate, comprising the following steps: S1. Add morpholine and sodium hydroxide aqueous solution to the synthesis vessel, stir and mix to obtain the reaction base liquid; S2. Cool the reaction base liquid to -5℃~5℃; S3. Add carbon disulfide dropwise to the reaction base liquid under stirring to form a reaction material, and control the temperature of the reaction material to not exceed 20°C. When the cumulative amount of carbon disulfide added reaches 30% to 37% of the total amount of carbon disulfide added, stop adding carbon disulfide and continue stirring the reaction material for 20 to 30 minutes. S4. Continue to add carbon disulfide dropwise to the reactants. When the cumulative amount of carbon disulfide added reaches 63% to 70% of the total amount of carbon disulfide added, stop adding carbon disulfide dropwise again and continue to stir the reactants for 30 to 50 minutes. S5. Continue to add the remaining carbon disulfide to the reactants. After the carbon disulfide is added, heat the reactants to no more than 30°C and continue to stir the reaction for 30-50 minutes to obtain a high-concentration reaction solution. S6. Take samples of the high-concentration reaction solution for analysis. Calculate the amount of water to add based on the content of sodium morpholinodithiocarbamate in the high-concentration reaction solution. After the high-concentration reaction solution settles, add water to adjust the solution and filter it to obtain the liquid sodium morpholinodithiocarbamate product. In steps S1 to S6, no organic solvent is used as the reaction medium, and no external catalyst is added.

[0020] This embodiment was carried out in a 500mL four-necked glass bottle equipped with an adjustable-speed electric stirrer, a spherical reflux condenser, a pear-shaped dropping funnel and a thermometer, for the production process of liquid morpholinodithiocarbamate under conventional batch reaction conditions. No organic solvents were used as reaction media during the reaction, and no external catalysts were added.

[0021] Add 100g of morpholine and 157.8g of a 30% sodium hydroxide aqueous solution to a four-necked glass bottle. Turn on the stirrer and control the stirring speed at 600rpm to fully mix the morpholine and sodium hydroxide aqueous solution to obtain the reaction base liquid. Take another 87.8g of carbon disulfide and add it to a pear-shaped dropping funnel. Add 30mL of water to the pear-shaped dropping funnel to cover the carbon disulfide and form a water seal to reduce the volatilization of carbon disulfide.

[0022] The reaction solution in the four-necked glass bottle was cooled using an ice-salt bath. When the temperature of the reaction solution dropped to 0°C, carbon disulfide was added dropwise while stirring. During the addition, the temperature of the reactants was maintained at about 10°C by adjusting the dropping rate of the carbon disulfide and the cooling intensity of the ice-salt bath, and it was ensured that the temperature of the reactants did not exceed 20°C.

[0023] When the cumulative amount of carbon disulfide added is observed to be about one-third of the total amount of carbon disulfide added according to the scale of the pear-shaped dropping funnel, stop adding carbon disulfide, maintain the temperature of the reactants at about 10°C, and continue stirring for 20 minutes. This stage is used to promote the participation of the carbon disulfide that has entered the reaction system in the target salt formation reaction and reduce the accumulation of unreacted carbon disulfide in the strong alkaline system.

[0024] After the first stopping of the dripping and the end of the stirring reaction, carbon disulfide is added dropwise. When the cumulative amount of carbon disulfide added reaches about two-thirds of the total amount of carbon disulfide added, the dripping of carbon disulfide is stopped again. The temperature of the reactants is maintained at about 10°C, and the reaction is stirred for another 30 minutes. After the second stopping of the dripping, stirring is continued to allow the carbon disulfide already added to the system to further participate in the target reaction, thereby reducing the chance of carbon disulfide reacting with sodium hydroxide to form sodium trithiocarbonate.

[0025] After the second stop of the addition and the end of the stirring reaction, the remaining carbon disulfide was added dropwise. During the addition, the temperature of the reactants was maintained at about 10°C. After all the carbon disulfide was added, the ice-salt bath was removed, and the four-necked glass bottle was heated with fine adjustment to gradually raise the temperature of the reactants to 25°C. The reaction was then stirred at 25°C for 30 minutes to obtain a high-concentration reaction solution.

[0026] After the reaction was completed, 10g of the high-concentration reaction solution was taken and dried at 105℃ for 4h to obtain the dried solid. The content of sodium morpholinodithiocarbamate in the dried solid was analyzed by liquid chromatography, and the content of sodium trithiocarbonate in the dried solid was analyzed by chemical titration. The reacted material in the four-necked glass bottle was poured out and weighed, and the sample amount was included in the total amount. The yield of sodium morpholinodithiocarbamate was calculated based on morpholine.

[0027] The obtained high-concentration reaction solution was allowed to settle for 4 hours. The settled reaction solution was then prepared. The amount of water to be added was calculated based on the measured content of sodium morpholinodithiocarbamate in the high-concentration reaction solution. 680g of tap water was added to the high-concentration reaction solution and stirred for 20 minutes to prepare a liquid sodium morpholinodithiocarbamate material with a mass content of about 20%. The prepared material was then filtered through a precision filter to obtain the finished liquid sodium morpholinodithiocarbamate product.

[0028] The resulting product is a pale yellow transparent liquid with a sodium morpholinodithiocarbamate content of 20.06% and a density of 1.061 g / cm³. 3 The pH value of a 5% aqueous solution is 10.2.

[0029] To verify the effects of segmented drip stopping and temperature control in this embodiment, the following comparative example was set up. Except for the differences specifically mentioned, the material ratio, reaction device, stirring conditions, post-processing method and detection method in the comparative example are the same as those in Example 1.

[0030] In Comparative Example 1, carbon disulfide was added to the reaction system by continuous dripping. The dripping was not stopped when the total amount of carbon disulfide was one-third and two-thirds. After the carbon disulfide was completely added, the reaction continued for 50 minutes. It was observed that there were still obvious droplets in the reaction solution. After stirring was stopped, oily droplets settled to the bottom of the bottle. After stirring for another 30 minutes, the droplets disappeared. This comparative example is used to illustrate that carbon disulfide is prone to local accumulation in the system when continuously added, resulting in an uneven reaction process.

[0031] In Comparative Example 2, when the cumulative amount of carbon disulfide added reached about one-third of the total amount of carbon disulfide fed, the addition was stopped and the reaction was stirred for 20 minutes. Then the remaining carbon disulfide was added. When the cumulative amount of carbon disulfide added reached about two-thirds, the addition was not stopped a second time. After the addition of carbon disulfide was completed, the reaction continued for 70 minutes. This comparative example is used to illustrate that stopping the addition only once is not enough to reduce the side reactions caused by the subsequent accumulation of carbon disulfide.

[0032] In Comparative Example 3, the temperature of the reactants was controlled at approximately 25°C during both the carbon disulfide dropwise addition stage and the stirring reaction stage after the dropwise addition was stopped. The remaining reaction time and operation method were the same as in this example. This comparative example is used to illustrate that an increase in reaction temperature will accelerate the side reaction between carbon disulfide and sodium hydroxide and affect the appearance and purity of the product.

[0033] Table 1 lists the main process differences and test results between the present invention examples and the comparative examples.

[0034] As shown in Table 1, Example 1 used a method of adding carbon disulfide in stages and stopping the addition at approximately one-third and two-thirds of the stage. The resulting dried solid contained 98.87% sodium morpholinodithiocarbamate and only 0.52% sodium trithiocarbonate, with a yield of 96.64%. Compared with Comparative Example 1, Example 1 did not simply shorten or lengthen the reaction time. Instead, it set up two stopping reactions during the addition of carbon disulfide, allowing the added carbon disulfide to participate in the main reaction in a timely manner. This avoided the local aggregation or formation of oily droplets caused by continuous addition of carbon disulfide, thereby increasing the content of the main product and reducing the content of sodium trithiocarbonate.

[0035] Compared to Comparative Example 2, Example 1 added a second stop when carbon disulfide was added to about two-thirds of its total volume, allowing sufficient reaction time for the carbon disulfide entering the system in the latter half of the reaction. Comparative Example 2 only stopped the addition once at about one-third of the total volume, and the subsequent continuous addition of carbon disulfide to the strong alkali system still easily led to side reactions with sodium hydroxide. As a result, the sodium trithiocarbonate content increased to 3.29%, and the sodium morpholinodithiocarbamate content decreased to 94.39%. The two staged stops were not arbitrary operations, but rather a feeding control method that matched the amount of carbon disulfide added and the reaction consumption rate.

[0036] Compared with Comparative Example 3, Example 1 completed the carbon disulfide dropwise addition and stop-drop reaction under low temperature conditions, which can reduce the rate of carbon disulfide volatilization and its side reaction with sodium hydroxide. Comparative Example 3 carried out the dropwise addition and stop-drop reaction at about 25°C, and the sodium trithiocarbonate content increased to 4.06%. The product appearance changed from a pale yellow transparent liquid to brownish-yellow, indicating that the side reaction and coloring impurities increased at higher temperatures. Example 1, through a combination of low-temperature dropwise addition, staged stop-drop, and gentle heating and ripening after dropwise addition, reduced the formation of by-products while ensuring the completion of the main reaction.

[0037] Example 2 Based on the production method of Example 1, this embodiment further limits the concentration of sodium hydroxide aqueous solution, raw material mass, feed molar ratio, cooling conditions, dropping stage temperature, and carbon disulfide segmented dropping stop point.

[0038] The mass concentration of the sodium hydroxide aqueous solution is 30%; the molar ratio of morpholine, carbon disulfide and sodium hydroxide, based on purity, is 1:(1.005~1.015):(1.03~1.08). The content of morpholine is not less than 98%, the content of carbon disulfide is not less than 98%, and the water used for mixing in step S6 is tap water that meets drinking standards. In step S2, the reaction substrate is cooled to -5℃ to 0℃; In steps S3 and S4, the carbon disulfide dripping stage and the stirring reaction stage after stopping the carbon disulfide dripping, as well as in step S5, the dripping stage before the carbon disulfide dripping is completed, the temperature of the reactants is controlled to not exceed 15°C. In step S3, when the cumulative amount of carbon disulfide added reaches 1 / 3 of the total amount of carbon disulfide fed, the addition of carbon disulfide is stopped. In step S4, when the cumulative amount of carbon disulfide added reaches 2 / 3 of the total amount of carbon disulfide fed, the addition of carbon disulfide is stopped again.

[0039] In this embodiment, a 500mL four-necked glass bottle was used as the synthesis vessel. The four-necked glass bottle was equipped with an adjustable-speed electric stirrer, a spherical reflux condenser, a pear-shaped dropping funnel, and a thermometer. The morpholine used was an industrial grade with a measured content of 99.1%; the carbon disulfide used was an industrial grade with a measured content of 98.8%; the sodium hydroxide aqueous solution used had a mass concentration of 30%; and the water used for preparation was tap water that met drinking water standards. In this embodiment, no organic solvents were used as the reaction medium, and no external catalyst was added.

[0040] Based on pure weight, the molar ratio of morpholine, carbon disulfide and sodium hydroxide should be controlled at 1:1.010:1.05.

[0041] Specifically, 100g of morpholine and 159.3g of a 30% sodium hydroxide aqueous solution were added to a four-necked glass bottle. Stirring was started at 600 rpm to ensure thorough mixing of the morpholine and sodium hydroxide solution, resulting in a reaction base solution. Separately, 88.5g of carbon disulfide was added to a pear-shaped dropping funnel, and 30mL of water was added to the funnel to form a water seal over the carbon disulfide, thereby reducing the volatilization of the carbon disulfide.

[0042] The reaction solution was cooled to -3°C using an ice-salt bath. Once the temperature of the reaction solution stabilized, carbon disulfide was added dropwise to the reaction solution while stirring. During the dropwise addition, the temperature of the reactants was maintained between 8°C and 13°C by adjusting the carbon disulfide dropwise addition rate and the cooling intensity of the ice-salt bath. The temperature of the reactants was ensured not to exceed 15°C during the carbon disulfide dropwise addition stage, the stirring reaction stage after the carbon disulfide dropwise addition was stopped, and the subsequent dropwise addition stage before the carbon disulfide dropwise addition was completed.

[0043] When the cumulative amount of carbon disulfide added is confirmed by the scale of the pear-shaped dropping funnel and reaches 1 / 3 of the total amount of carbon disulfide added, stop adding carbon disulfide and continue stirring for 25 minutes while keeping the temperature of the reactants below 15°C. Then continue adding carbon disulfide. When the cumulative amount of carbon disulfide added reaches 2 / 3 of the total amount of carbon disulfide added, stop adding carbon disulfide again and continue stirring for 35 minutes while keeping the temperature of the reactants below 15°C. Then continue adding the remaining carbon disulfide. After the addition is complete, remove the ice-salt bath, gradually raise the temperature of the reactants to 27°C, and continue stirring for 30 minutes to obtain a high-concentration reaction solution.

[0044] In this embodiment, a 30% sodium hydroxide aqueous solution serves as both the alkali source and the aqueous reaction medium, enabling the formation of an aqueous system suitable for the contact reaction of morpholine, carbon disulfide, and sodium hydroxide without the introduction of organic solvents. Slight excesses of both carbon disulfide and sodium hydroxide relative to morpholine are used to improve the conversion degree of morpholine, while avoiding excessive amounts of either carbon disulfide or sodium hydroxide that could increase the risk of side reactions. Pre-cooling the reaction substrate to -5°C to 0°C and controlling the addition and stopping of carbon disulfide during the stirring phase to no more than 15°C reduces the probability of carbon disulfide volatilization and the formation of sodium trithiocarbonate from it. Stopping the addition of carbon disulfide at 1 / 3 and 2 / 3 of the reaction volume allows the carbon disulfide already in the reaction system time to continue reacting, thereby reducing the instantaneous accumulation of carbon disulfide in the strong alkali system.

[0045] After the reaction was completed, 10g of the high-concentration reaction solution was taken and dried at 105℃ for 4 hours to obtain the dried solid. The content of sodium morpholinodithiocarbamate in the dried solid was analyzed by liquid chromatography, and the content of sodium trithiocarbonate in the dried solid was analyzed by chemical titration. The reacted material was weighed and the sample amount was included in the total amount. The yield was calculated based on morpholine. The high-concentration reaction solution was then allowed to settle for 4 hours. The settled reaction solution was then prepared. The amount of water to be added was calculated based on the measured content of sodium morpholinodithiocarbamate in the high-concentration reaction solution. Tap water that meets drinking water standards was added and stirred in a mixing vessel for 20 minutes to prepare a liquid sodium morpholinodithiocarbamate material with a mass content of approximately 20%. The prepared material was then filtered through a precision filter to obtain the finished liquid sodium morpholinodithiocarbamate product.

[0046] The following comparative examples are set up. Except for the differences listed in Table 1, the reaction equipment, stirring conditions, post-processing methods and detection methods of each comparative example are the same as those in this embodiment.

[0047] Table 2. Impact of feed molar ratio, low temperature control, and drip cessation point on product quality

[0048] As shown in Table 1, under the combined effects of 30% sodium hydroxide aqueous solution, a feed molar ratio of 1:1.010:1.05, pre-cooling at -5℃ to 0℃, dropwise addition and stop-drop reaction conditions not exceeding 15℃, and the 1 / 3 and 2 / 3 segmented stop-drop points, the content of sodium morpholinodithiocarbamate in the dried solid obtained in Example 2 reached 98.64%, while the content of sodium trithiocarbonate was only 0.68%, with a yield of 96.52%. The product after preparation was a pale yellow transparent liquid, indicating that the process conditions can stably prepare liquid sodium morpholinodithiocarbamate.

[0049] In Comparative Example 4, the amount of sodium hydroxide added was lower than that in this example. Although the content of sodium trithiocarbonate did not increase significantly, the amount of alkali in the system was insufficient, which may have led to the incomplete conversion of the acidic intermediate generated in the reaction into the corresponding sodium salt. This resulted in a significant decrease in the content and yield of sodium morpholinodithiocarbamate. A slight morpholine odor could still be detected in the product. This result indicates that controlling the amount of sodium hydroxide in a moderate excess relative to morpholine is beneficial to the full generation of the target product.

[0050] In Comparative Example 5, the amount of sodium hydroxide added was significantly higher than that in this embodiment, which increased the alkalinity of the system and the chance of side reactions between carbon disulfide and sodium hydroxide. The content of sodium trithiocarbonate increased to 2.91%, and the content of the target product decreased. This result shows that more sodium hydroxide is not necessarily better. The molar ratio range of 1.03 to 1.08 in this embodiment can balance the conversion of morpholine and the inhibition of side reactions.

[0051] In Comparative Example 6, although the molar ratio of the feed and the stopping point were the same as in Example 2, the temperature during the carbon disulfide dripping and stopping stirring stages was increased to 18°C ​​to 23°C, the sodium trithiocarbonate content increased to 3.86%, and the product appearance changed from light yellow to brownish-yellow. This indicates that higher temperatures promote the side reactions of carbon disulfide and the generation of coloring impurities. In Example 2, by pre-cooling the reaction base liquid to -5°C to 0°C and controlling the dripping and stopping stirring stages before the carbon disulfide dripping was completed to no more than 15°C, the purity and appearance of the product could be effectively improved.

[0052] In Comparative Example 7, the stopping points were adjusted to approximately 1 / 4 and 3 / 4. Although this still constitutes segmented addition, the premature stopping of the first stage and the delayed stopping of the second stage resulted in insufficient control over the accumulation of carbon disulfide in the system during the intermediate stage. A small number of droplets appeared in the later stage of the reaction, and the content of the target product was lower than that in Example 2, while the content of sodium trithiocarbonate was higher than that in Example 2. This result indicates that Example 2, by stopping the addition of carbon disulfide when the cumulative amount added reached 1 / 3 and 2 / 3 of the total amount of feed, can better match the rate of addition of carbon disulfide with the rate of consumption of the main reaction, and is not an arbitrary segmentation.

[0053] Example 3 Based on the production method of Example 1, this embodiment further defines the metering method, dripping method, venting and recovery method, and stirring method of the synthesis reactor for carbon disulfide.

[0054] The cumulative amount of carbon disulfide added is determined by at least one of the following: the scale of the dropping funnel, the liquid level in the carbon disulfide metering tank, or the weighing data. Carbon disulfide is first added to the carbon disulfide metering tank, and then added dropwise from the carbon disulfide metering tank to the reaction base liquid or reaction material through the dropping pipeline; The carbon disulfide metering tank is equipped with a water layer, and the water level is not lower than 20 mm. The outlet of the dropper is located below the surface of the reaction base liquid or the reactants; The synthesis reactor is equipped with a venting pipeline, which is connected to the carbon disulfide recovery and condensation system; The synthesis reactor is equipped with a double-layer combined agitator, which includes a paddle agitator in the upper layer and a propeller agitator in the lower layer.

[0055] In this embodiment, a glass-lined synthesis reactor is used as the reaction equipment. The synthesis reactor is equipped with a jacketed cooling and heating system, a venting pipeline, a carbon disulfide dripping pipeline, and a double-layer combined agitator. The double-layer combined agitator includes a paddle agitator in the upper layer and a propeller agitator in the lower layer. The lower propeller agitator is used to promote axial circulation of the materials at the bottom and bottom of the reactor, while the upper paddle agitator is used to enhance radial mixing of the materials in the middle and upper layers, so that morpholine, sodium hydroxide aqueous solution, and carbon disulfide can fully contact each other in the synthesis reactor. Through the above-mentioned double-layer combined agitation method, the risk of carbon disulfide enrichment in local areas is reduced, local temperature rise is reduced, and the carbon disulfide dripping process is matched with the low-temperature reaction process.

[0056] Before production, carbon disulfide is added to the carbon disulfide metering tank.

[0057] The carbon disulfide metering tank is equipped with a liquid level display device and a weighing device is installed below the carbon disulfide metering tank. During metering, the cumulative amount of carbon disulfide added can be determined by the liquid level change in the carbon disulfide metering tank, or by the cumulative amount of carbon disulfide added by weighing data.

[0058] The cumulative amount of carbon disulfide added is determined by the graduations of the pear-shaped dropping funnel. In industrial production, the weighing data is used as the main measurement basis, and the liquid level of the carbon disulfide metering tank is used as an auxiliary verification basis. This allows us to determine whether the cumulative amount of carbon disulfide added has reached 1 / 3 and 2 / 3 of the total amount of carbon disulfide fed, so as to execute the first and second stop-dropping operations.

[0059] A water layer is installed inside the carbon disulfide metering tank, covering the carbon disulfide and maintaining a water level of at least 20 mm. This water layer creates a water seal within the metering tank, reducing the volatilization of carbon disulfide during metering and transport, and minimizing the amount of carbon disulfide entering the upper gas phase space of the equipment. The carbon disulfide is then transported from the metering tank to the synthesis reactor via a dripping pipeline. The outlet of the dripping pipeline extends into the synthesis reactor and is positioned below the surface of the bottom liquid or reactants, allowing the carbon disulfide to directly enter the liquid phase system.

[0060] During operation, following the feeding ratio and reaction conditions of Example 1 or Example 2, morpholine and sodium hydroxide aqueous solution are first added to the synthesis reactor, and the double-layer combined stirrer is turned on to form a reaction base liquid. Then, a cooling medium is introduced into the jacket of the synthesis reactor to cool the reaction base liquid to the required process temperature. When carbon disulfide is added dropwise, the carbon disulfide enters the reaction base liquid through the dropper located below the liquid surface and is dispersed into the reactants under the action of the double-layer combined stirrer. Since the carbon disulfide is not added directly from above the liquid surface, but enters the reaction system from below the liquid surface, the amount of carbon disulfide volatilized in the upper space of the reactor can be reduced, and it is beneficial for the carbon disulfide to disperse in time and participate in the reaction after entering the liquid phase.

[0061] During the dripping process, the cumulative amount of carbon disulfide added is determined by observing the changes in the liquid level in the carbon disulfide metering tank or by weighing data. When the cumulative amount of carbon disulfide added reaches 1 / 3 of the total amount of carbon disulfide fed, the carbon disulfide dripping valve is closed to stop the dripping of carbon disulfide, while maintaining the stirring reaction. After the stirring reaction ends after the first cessation of dripping, the carbon disulfide dripping valve is reopened to continue the dripping of carbon disulfide. When the cumulative amount of carbon disulfide added reaches 2 / 3 of the total amount of carbon disulfide fed, the carbon disulfide dripping valve is closed again to stop the dripping of carbon disulfide, while maintaining the stirring reaction. Subsequently, the remaining carbon disulfide is added dripping until all the carbon disulfide has been added.

[0062] The above metering method enables accurate control of the two drip cessation points, avoiding premature or late drip cessation due to human estimation errors.

[0063] The synthesis reactor is equipped with a venting pipeline, which is connected to the carbon disulfide recovery and condensation system. During the reaction, a small amount of carbon disulfide in the upper space of the synthesis reactor enters the carbon disulfide recovery and condensation system with the venting gas. After condensation, it is recovered, reducing the direct emission of carbon disulfide. This venting and recovery structure, used in conjunction with the submerged dripping method, can reduce carbon disulfide volatilization loss and operating environment risks while ensuring normal venting and pressure balance of the synthesis reactor.

[0064] In this embodiment, the determination of the cumulative amount of carbon disulfide added, the water layer in the carbon disulfide metering tank, submerged dripping, venting and recovery, and the double-layer combined stirrer all serve the low-temperature segmented dripping reaction process of carbon disulfide. The liquid level or weighing data of the carbon disulfide metering tank ensures that the segmented dripping stop points are controllable; the water layer and submerged dripping reduce the volatilization of carbon disulfide and improve the utilization efficiency of carbon disulfide after entering the liquid phase; the venting pipeline is connected to the carbon disulfide recovery and condensation system to improve the safety of industrial operation; the double-layer combined stirrer enhances the mixing of reactants, reduces local excessive carbon disulfide concentration and local temperature rise. This embodiment can realize the metering, dripping, recovery and dispersion mixing of carbon disulfide in a conventional glass-lined synthesis reactor, which is suitable for the industrial production of liquid morpholinodithiocarbamate sodium.

[0065] Example 4 This embodiment further illustrates the sampling and analysis, sedimentation, water addition and preparation, filtration and finished product quality control steps of the high-concentration reaction solution produced by the production method of Example 1.

[0066] In step S6, the sampling analysis includes: taking 10g of high-concentration reaction solution, drying it at 105℃ for 4h to obtain the dried solid, analyzing the content of sodium morpholinodithiocarbamate in the dried solid by liquid chromatography, analyzing the content of sodium trithiocarbonate in the dried solid by chemical titration, and the sedimentation time of the high-concentration reaction solution is 4h. When adding water for preparation, add the high-concentration reaction solution and water to the mixing vessel and stir for 20 minutes; During filtration, the prepared materials are filtered through a precision filter; The liquid sodium morpholinodithiocarbamate product contains no less than 20.0% sodium morpholinodithiocarbamate by mass, and has a density of 1.05–1.10 g / cm³. 3 The pH value of a 5% aqueous solution is 9.0 to 11.5.

[0067] After the reaction was completed, the high-concentration reaction solution was kept in a state of uniform stirring. 10g of the high-concentration reaction solution was taken from the synthesis vessel as a test sample. The test sample was dried at 105℃ for 4h to remove the moisture in the sample and obtain the dried solid. The content of sodium morpholinodithiocarbamate in the dried solid was analyzed by liquid chromatography, and the content of sodium trithiocarbonate in the dried solid was analyzed by chemical titration.

[0068] The above tests can determine the formation of the target product and the byproduct sodium trithiocarbonate in the front-end reaction, and provide a calculation basis for subsequent water addition and preparation.

[0069] When calculating the amount of water added, first calculate the mass content of sodium morpholinodithiocarbamate in the high-concentration reaction solution based on the mass of the dried solid sample and the measured content of sodium morpholinodithiocarbamate in the dried solid. If the mass of the high-concentration reaction solution is M, the mass content of sodium morpholinodithiocarbamate in the high-concentration reaction solution is W, and the mass content of sodium morpholinodithiocarbamate in the target finished product is... The formula for calculating the amount of water to be added, m, is as follows: ; Among them, W and All are expressed as mass fraction. Based on the finished product quality requirements, it is preferred that the mass content of sodium morpholinodithiocarbamate in the liquid sodium morpholinodithiocarbamate product is not less than 20.0%. By using the above methods, we can avoid adding water based on experience, which could result in an excessively high or low concentration of the final product, thus making the blending process repeatable and controllable.

[0070] After sampling and analysis, the high-concentration reaction liquid in the synthesis vessel is placed in a settling container or settling tank and allowed to settle naturally for 4 hours. During the settling process, a small amount of mechanical impurities, trace suspended matter, or insoluble impurities gradually separate from the liquid body, which helps to reduce the subsequent filtration load and improve the appearance of the finished product. After the settling is completed, the high-concentration reaction liquid after settling is transferred to a metering container for weighing, and the required amount of water to be added is determined according to the aforementioned calculation results.

[0071] Add the weighed high-concentration reaction solution and the calculated amount of water to the mixing vessel, turn on the stirrer, and stir for 20 minutes to fully mix the water and the high-concentration reaction solution to obtain the mixed material. The water used for mixing is preferably tap water that meets drinking standards to reduce the introduction of external impurities and ensure the stability of the finished product quality. During the mixing process, the high-concentration reaction solution and water should be mixed evenly to avoid local concentrations that are too high or too low, thereby ensuring the consistency of sodium morpholinodithiocarbamate content in the finished product.

[0072] After blending, the blended material is transported to a precision filter for filtration. During filtration, the blended material passes through the precision filter to remove a small amount of suspended solids and mechanical impurities. The filtered liquid enters the finished product storage tank, thus obtaining the liquid sodium morpholinodithiocarbamate product. Using a precision filter can further improve the clarity of the finished product, keeping its appearance as a pale yellow transparent liquid.

[0073] In one specific operation of this embodiment, a sample of the high-concentration reaction solution prepared using the industrial apparatus conditions of Example 3 was taken for testing. After conversion, the mass content of sodium morpholinodithiocarbamate in the high-concentration reaction solution was approximately 61.2%. The high-concentration reaction solution was allowed to settle for 4 hours. 870 kg of the settled high-concentration reaction solution was added to a mixing vessel, followed by 1730 kg of tap water. After stirring for 20 minutes, the mixture was filtered through a precision filter to obtain liquid sodium morpholinodithiocarbamate. The resulting product was a pale yellow transparent liquid with a sodium morpholinodithiocarbamate mass content of 20.49% and a density of 1.078 g / cm³. 3 The pH value of the 5% aqueous solution is 10.2. In this embodiment, the sampling, drying, and analysis steps are used to determine the content of the target product and by-products; the sedimentation step is used to initially remove insoluble impurities; the water replenishment amount calculated according to the test results ensures the stability of the finished product concentration; the mixing and stirring step ensures the homogeneity of the system; the precision filtration step ensures the clarity and appearance quality of the finished product; and the high-concentration reaction solution obtained from the reaction can be stably processed to a mass content of not less than 20.0% and a density of 1.05–1.10 g / cm³. 3 The presence of a 5% aqueous solution of sodium morpholinodithiocarbamate with a pH of 9.0–11.5 demonstrates that this embodiment has clearly defined operating conditions and a feasible industrial implementation method.

Claims

1. A method for producing liquid sodium morpholinodithiocarbamate, characterized in that, Includes the following steps: S1. Add morpholine and sodium hydroxide aqueous solution to the synthesis vessel, stir and mix to obtain the reaction base liquid; S2. Cool the reaction base liquid to -5℃~5℃; S3. Add carbon disulfide dropwise to the reaction base liquid under stirring to form a reaction material, and control the temperature of the reaction material to not exceed 20°C. When the cumulative amount of carbon disulfide added reaches 30% to 37% of the total amount of carbon disulfide added, stop adding carbon disulfide and continue stirring the reaction material for 20 to 30 minutes. S4. Continue to add carbon disulfide dropwise to the reactants. When the cumulative amount of carbon disulfide added reaches 63% to 70% of the total amount of carbon disulfide added, stop adding carbon disulfide dropwise again and continue to stir the reactants for 30 to 50 minutes. S5. Continue to add the remaining carbon disulfide to the reactants. After the carbon disulfide is added, heat the reactants to no more than 30°C and continue to stir the reaction for 30-50 minutes to obtain a high-concentration reaction solution. S6. Take samples of the high-concentration reaction solution for analysis. Calculate the amount of water to add based on the content of sodium morpholinodithiocarbamate in the high-concentration reaction solution. After the high-concentration reaction solution settles, add water to adjust the solution and filter it to obtain the liquid sodium morpholinodithiocarbamate product. In steps S1 to S6, no organic solvent is used as the reaction medium, and no external catalyst is added.

2. The method for producing liquid morpholinodithiocarbamate sodium according to claim 1, characterized in that, The sodium hydroxide aqueous solution has a mass concentration of 30%; the molar ratio of morpholine, carbon disulfide and sodium hydroxide, based on pure weight, is 1:(1.005~1.015):(1.03~1.08).

3. The method for producing liquid morpholino dithiocarbamate sodium according to claim 1, characterized in that, The content of morpholine is not less than 98%, the content of carbon disulfide is not less than 98%, and the water used for mixing in step S6 is tap water that meets drinking standards.

4. The method for producing liquid morpholino dithiocarbamate sodium according to claim 1, characterized in that, In step S2, the reaction substrate is cooled to -5℃ to 0℃; In steps S3 and S4, the carbon disulfide dripping stage, the stirring reaction stage after stopping the carbon disulfide dripping, and the dripping stage before the carbon disulfide dripping is completed in step S5, the temperature of the reactants is controlled to not exceed 15°C.

5. The method for producing liquid morpholino dithiocarbamate sodium according to claim 1, characterized in that, In step S3, when the cumulative amount of carbon disulfide added reaches 1 / 3 of the total amount of carbon disulfide fed, the addition of carbon disulfide is stopped. In step S4, when the cumulative amount of carbon disulfide added reaches 2 / 3 of the total amount of carbon disulfide fed, the addition of carbon disulfide is stopped again.

6. The method for producing liquid morpholino dithiocarbamate sodium according to claim 1, characterized in that, The cumulative amount of carbon disulfide added is determined by at least one of the following: the scale of the dropping funnel, the liquid level in the carbon disulfide metering tank, or the weighing data.

7. The method for producing liquid morpholinodithiocarbamate sodium according to claim 1, characterized in that, The carbon disulfide is first added to the carbon disulfide metering tank, and then added dropwise from the carbon disulfide metering tank to the reaction base liquid or the reaction material through the drop pipe; The carbon disulfide metering tank is equipped with a water layer, and the water level is not lower than 20 mm. The outlet of the dripping pipeline is located below the surface of the reaction base liquid or the reaction material.

8. The method for producing liquid morpholinodithiocarbamate sodium according to claim 1, characterized in that, The synthesis reactor is equipped with a venting pipeline, which is connected to a carbon disulfide recovery and condensation system.

9. The method for producing liquid morpholinodithiocarbamate sodium according to claim 1, characterized in that, The synthesis reactor is equipped with a double-layer combined agitator, which includes a paddle agitator in the upper layer and a propeller agitator in the lower layer.

10. The method for producing liquid morpholinodithiocarbamate sodium according to claim 1, characterized in that, In step S6, the sampling analysis includes: taking 10g of the high-concentration reaction solution, drying it at 105℃ for 4h to obtain the dried solid, analyzing the content of sodium morpholinodithiocarbamate in the dried solid using liquid chromatography, analyzing the content of sodium trithiocarbonate in the dried solid using chemical titration, and the sedimentation time of the high-concentration reaction solution is 4h. When adding water for preparation, add the high-concentration reaction solution and water to the mixing vessel and stir for 20 minutes; During filtration, the prepared materials are filtered through a precision filter; The liquid sodium morpholinodithiocarbamate product contains no less than 20.0% sodium morpholinodithiocarbamate by mass, and has a density of 1.05–1.10 g / cm³. 3 The pH value of a 5% aqueous solution is 9.0 to 11.5.

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