CN111362839A - Preparation method of O-methyl-N-nitroisourea - Google Patents
Preparation method of O-methyl-N-nitroisourea Download PDFInfo
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- CN111362839A CN111362839A CN202010136700.9A CN202010136700A CN111362839A CN 111362839 A CN111362839 A CN 111362839A CN 202010136700 A CN202010136700 A CN 202010136700A CN 111362839 A CN111362839 A CN 111362839A
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C273/00—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
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- B01J19/0093—Microreactors, e.g. miniaturised or microfabricated reactors
Abstract
The invention relates to the field of chemical intermediate preparation, and in particular relates to a preparation method of O-methyl-N-nitroisourea. The invention provides a preparation method of O-methyl-N-nitroisourea, which comprises the following steps: dissolving O-methylisourea sulfate in fuming sulfuric acid to obtain O-methylisourea sulfate solution; dissolving fuming nitric acid in concentrated sulfuric acid to obtain a mixed acid solution; mixing the O-methyl isourea sulfate solution with the mixed acid solution to obtain a reaction raw material solution, and reacting the reaction raw material solution in a microchannel reactor at the temperature of 30-60 ℃ to obtain the O-methyl-N-nitroisourea. The preparation method of the O-methyl-N-nitroisourea provided by the invention has the advantages that the reaction is easy to control, the reaction time can be shortened from a plurality of original hours to tens of minutes, and the reaction yield is obviously improved.
Description
Technical Field
The invention relates to the field of chemical intermediate preparation, and in particular relates to a preparation method of O-methyl-N-nitroisourea.
Background
The O-methyl-N-nitroisourea is an important novel pesticide and a medical intermediate, is used as an important derivative for synthesizing a novel low-toxicity pesticide, and is widely used for synthesizing pesticides such as clothianidin and dinotefuran. In recent years, domestic chemical safety accidents are frequent, and the national strict control production of dangerous traditional process products such as nitrification and the like is realized. However, the domestic market has a large demand for O-methyl-N-nitroisourea, which often results in a short supply and demand state.
The existing process for preparing O-methyl-N-nitroisourea mainly comprises the steps of placing fuming sulfuric acid in a dry reaction kettle, adding O-methyl isourea 1/2 sulfate, dropwise adding mixed acid of fuming nitric acid and sulfuric acid at 0-10 ℃ after materials are dissolved, dropwise adding for 5-7 hours, then continuously stirring and reacting for 6 hours at 0-10 ℃, after the reaction is finished, slowly pouring reaction liquid into crushed ice while stirring, standing, filtering, washing a filter cake for 2-3 times with a small amount of sodium carbonate aqueous solution, washing for 2-3 times with water, draining, and drying to obtain the O-methyl-N-nitroisourea. However, the nitration reaction is a strong exothermic reaction, and the O-methyl isourea sulfate is unstable in the nitration reaction process and is easy to generate side reactions, so that the yield is low, therefore, the existing processes for preparing O-methyl-N-nitroisourea are all prepared by reacting for several hours in a low-temperature environment, which undoubtedly increases the energy consumption of equipment and the complexity of the processes, and therefore, how to prepare O-methyl-N-nitroisourea rapidly and with high yield at high temperature becomes a great research hotspot.
Disclosure of Invention
The invention aims to overcome the defect that the prior preparation method of O-methyl-N-nitroisourea needs to react for a long time at low temperature to obtain O-methyl-N-nitroisourea with higher yield, and further provides a novel preparation method of O-methyl-N-nitroisourea.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of O-methyl-N-nitroisourea comprises the following steps:
1) dissolving O-methylisourea sulfate in fuming sulfuric acid to obtain O-methylisourea sulfate solution; dissolving fuming nitric acid in concentrated sulfuric acid to obtain a mixed acid solution;
2) mixing the O-methyl isourea sulfate solution with the mixed acid solution to obtain a reaction raw material solution, and reacting the reaction raw material solution in a microchannel reactor at the temperature of 30-60 ℃ to obtain the O-methyl-N-nitroisourea.
The concentrated sulfuric acid is a sulfuric acid solution with the mass fraction of more than or equal to 70%. It is apparent that fuming nitric acid contains nitric acid and fuming sulfuric acid contains sulfur trioxide.
Preferably, SO is in said O-methylisourea sulfate solution3And O-methylisourea sulfate in a molar ratio of 2-3: 1;
HNO in the mixed acid solution3And H2SO4The molar ratio of (A) to (B) is 1: 1-3.
Preferably, HNO in the reaction raw material liquid3And the molar ratio of O-methylisourea sulfate is 1-1.4: 1.
Preferably, the concentration of sulfuric acid in the concentrated sulfuric acid is 98-100 wt%;
the concentration of sulfur trioxide in the oleum is 20-65 wt%;
the concentration of nitric acid in the fuming nitric acid is 90-98 wt%.
Preferably, in the step 2), the residence time of the reaction raw material liquid in the microchannel reactor is 15-40 s. The reaction gauge pressure is 0.2-1.1 MPa.
Preferably, in the step 2), the O-methyl isourea sulfate solution and the mixed acid solution are respectively introduced into the micro mixer through two channels to be mixed, so as to obtain a reaction raw material solution, and then the reaction raw material solution is introduced into the micro channel reactor to react, so as to obtain the O-methyl-N-nitroisourea.
Preferably, the flow rate of the O-methylisourea sulfate solution is 5-8 ml/min; the flow rate of the mixed acid solution is 3-8 ml/min.
Preferably, the step 2) further comprises the steps of cooling the reaction solution with ice water after the reaction is finished, filtering to obtain a crude product, and washing the crude product with water.
Preferably, the method further comprises the steps of extracting the filtered filtrate with an organic solvent, separating the extract, and distilling the obtained organic phase.
Preferably, the O-methylisourea sulfate is O-methylisourea hemisulfate.
Preferably, the microchannel reactor has at least two grid plates which are stacked and staggered to form an intercommunicated channel structure. The hydraulic diameter of the microchannel reactor is 0.5-5 mm.
The micro mixer and the micro channel reactor are conventional devices.
Preferably, the microchannel reactor is a microreactor disclosed in chinese patent CN 107224950A.
Preferably, the micro mixer is a micro mixer disclosed in chinese patent CN 107626250A.
The invention has the beneficial effects that:
1) the preparation method of O-methyl-N-nitroisourea provided by the invention comprises the steps of respectively preparing a specific O-methylisourea sulfate solution and a specific mixed acid solution, mixing the solutions to obtain a reaction raw material solution, reacting the reaction raw material solution in a microchannel reactor at 30-60 ℃, effectively avoiding the defect that the O-methylisourea sulfate needs to react for several hours in a low-temperature environment in the nitration process, dissolving the O-methylisourea sulfate in fuming sulfuric acid, wherein sulfur trioxide in the fuming sulfuric acid has stronger dehydration capability than sulfuric acid, nitric acid is almost converted into nitropositive ions in the fuming sulfuric acid, the increase of the concentration of the nitropositive ions can greatly improve the nitration reaction rate and shorten the reaction time, and simultaneously, as the nitration reaction is a strong exothermic reaction, a large amount of heat is released in a short time, the reaction temperature can be stably controlled to be 30-60 ℃ by matching with the efficient heat exchange of the microchannel reactor, and the proportion of other side reactions of materials in a high-temperature strong-oxidizing environment for a long time can be greatly reduced by matching several steps, so that the reaction yield is improved.
The preparation method of the O-methyl-N-nitroisourea provided by the invention adopts a microchannel reactor continuous flow process, the reaction time is shortened from original hours to less than 1 minute, the reaction time is greatly shortened, and meanwhile, the microchannel reactor has the advantages of small channel volume, small equipment floor area, low energy consumption, safer reaction and economy.
2) The invention further provides a preparation method of the O-methyl-N-nitroisourea, which is characterized in that SO in the O-methyl isourea sulfate solution is controlled3And O-methylisourea sulfate in a molar ratio of 2-3: 1; HNO in the mixed acid solution3And H2SO4Is 1:1-3, further by controlling HNO in the reaction raw material liquid3The molar ratio of the O-methyl isourea sulfate to the O-methyl isourea sulfate is 1-1.4:1, so that the yield and the product purity of the O-methyl-N-nitroisourea are effectively improved, and the reaction is continuously and rapidly carried out at high temperature.
3) The preparation method of O-methyl-N-nitroisourea provided by the invention further comprises the step 2), respectively introducing an O-methyl isourea sulfate solution and a mixed acid solution into a micro mixer from two channels to be mixed to obtain a reaction raw material solution, and then introducing the reaction raw material solution into a micro channel reactor to react to obtain the O-methyl-N-nitroisourea; the flow rate of the O-methylisourea sulfate solution is 5-8 ml/min; the flow rate of the mixed acid solution is 3-8 ml/min. The invention is introduced into a micro mixer for mixing through the specific mode, and then introduced into a microchannel reactor for reaction, so that the O-methyl-N-nitroisourea with high yield can be prepared in a short time at a higher temperature.
Detailed Description
The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
The micro-mixer used in the following examples 1-5 of the present invention was obtained from Shen's energy saving technology, Inc. of Hangzhou, model No. SS-0005WH-H-P, and the micro-channel reactor was obtained from Shen's energy saving technology, Inc. of Hangzhou, model No. SS-0010 WR-H-P-A.
Example 1
This example provides a method for preparing O-methyl-N-nitroisourea, comprising the following steps:
1) dissolving 123(g) O-methylisourea 1/2 sulfate in oleum (the concentration of sulfur trioxide in oleum is 65 wt.%), to obtain O-methylisourea sulfate solution (SO in the O-methylisourea sulfate solution)3And O-methylisourea sulfate in a molar ratio of 2: 1); dissolving fuming nitric acid (the concentration of nitric acid in the fuming nitric acid is 98 wt%) in concentrated sulfuric acid (the concentration of sulfuric acid in the concentrated sulfuric acid is 98 wt%) to obtain a mixed acid solution (HNO in the mixed acid solution)3And H2SO4In a 1:1 molar ratio);
2) simultaneously introducing an O-methylisourea sulfate solution and a mixed acid solution into a micro mixer from two channels by using metering pumps respectively (the introduction flow rate of the O-methylisourea sulfate solution is 6.2 ml/min; the mixed acid solution is mixed in the inlet flow of 3.8ml/min) to obtain reaction raw material liquid (HNO in the reaction raw material liquid)3And O-methylisourea sulfate in a molar ratio of 1:1), and then introducing the reaction raw material liquid into a microchannel reactor (the reaction surface pressure of the microchannel reactor is 0.2Mpa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 20 s; the reaction temperature is 45 ℃, after the reaction is finished, the reaction liquid is cooled by ice water to quench and crystallize, so that discharge liquid containing O-methyl-N-nitroisourea is obtained, the discharge liquid is filtered, so that a crude O-methyl-N-nitroisourea product is obtained, and the crude O-methyl-N-nitroisourea product is washed by waterWashing to obtain a part of refined O-methyl-N-nitroisourea, extracting the filtrate obtained after filtering with ethyl acetate, separating liquid after extraction, distilling organic phase under reduced pressure to obtain another part of O-methyl-N-nitroisourea, combining the two parts of O-methyl-N-nitroisourea to obtain the O-methyl-N-nitroisourea, wherein the yield of the O-methyl-N-nitroisourea is 95.0%, the purity of the O-methyl-N-nitroisourea is 95.5%, the appearance of the O-methyl-N-nitroisourea is white-like solid, and the conversion rate of 1/2 sulfate of the O-methyl isourea is more than 99% by liquid chromatography and IR (infrared) detection on the discharge liquid containing the O-methyl-N-nitroisourea in the step 2).
Example 2
This example provides a method for preparing O-methyl-N-nitroisourea, comprising the following steps:
1) dissolving 123(g) O-methylisourea 1/2 sulfate in oleum (the concentration of sulfur trioxide in oleum is 65 wt.%), to obtain O-methylisourea sulfate solution (SO in the O-methylisourea sulfate solution)3And O-methylisourea sulfate in a molar ratio of 2:1) (ii) a Dissolving fuming nitric acid (the concentration of nitric acid in the fuming nitric acid is 98 wt%) in concentrated sulfuric acid (the concentration of sulfuric acid in the concentrated sulfuric acid is 98 wt%) to obtain a mixed acid solution (HNO in the mixed acid solution)3And H2SO4In a molar ratio of 1: 3);
2) simultaneously introducing an O-methylisourea sulfate solution and a mixed acid solution into a micro mixer from two channels by using metering pumps respectively (the introduction flow rate of the O-methylisourea sulfate solution is 6.2 ml/min; the mixed acid solution is mixed in the inlet flow of 3.8ml/min) to obtain reaction raw material liquid (HNO in the reaction raw material liquid)3And O-methylisourea sulfate with the molar ratio of 1:1), and then introducing the reaction raw material liquid into a microchannel reactor (the reaction surface pressure of the microchannel reactor is 1.1Mpa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 20 s; the reaction temperature is 60 ℃, after the reaction is finished, the reaction liquid is cooled by ice water to quench and crystallize to obtain a discharged liquid containing O-methyl-N-nitroisourea, the discharged liquid is filtered to obtain a crude O-methyl-N-nitroisourea product, the crude O-methyl-N-nitroisourea product is washed by water to obtain a part of refined O-methyl-N-nitroisourea, and the part of refined O-methyl-N-nitroisourea is obtained by washing the crude O-methyl-N-nitroisourea productExtracting the filtrate obtained after filtering with ethyl acetate, separating liquid after extraction, distilling organic phase under reduced pressure to obtain the other part of O-methyl-N-nitroisourea, combining the two parts of O-methyl-N-nitroisourea to obtain the O-methyl-N-nitroisourea, wherein the yield of the O-methyl-N-nitroisourea is 95.1%, the purity of the O-methyl-N-nitroisourea is 95.5%, the appearance of the O-methyl-N-nitroisourea is white-like solid, and the conversion rate of O-methyl-N-nitroisourea 1/2 sulfate is more than 99% by liquid chromatography analysis and IR (infrared) detection on the discharge liquid containing the O-methyl-N-nitroisourea in the step 2).
Example 3
This example provides a method for preparing O-methyl-N-nitroisourea, comprising the following steps:
1) dissolving 123(g) O-methylisourea 1/2 sulfate in oleum (the concentration of sulfur trioxide in oleum is 65 wt.%), to obtain O-methylisourea sulfate solution (SO in the O-methylisourea sulfate solution)3And O-methylisourea sulfate in a molar ratio of 2:1) (ii) a Dissolving fuming nitric acid (the concentration of nitric acid in the fuming nitric acid is 98 wt%) in concentrated sulfuric acid (the concentration of sulfuric acid in the concentrated sulfuric acid is 98 wt%) to obtain a mixed acid solution (HNO in the mixed acid solution)3And H2SO4In a 1:1 molar ratio);
2) simultaneously introducing an O-methylisourea sulfate solution and a mixed acid solution into a micro mixer from two channels by using metering pumps respectively (the introduction flow rate of the O-methylisourea sulfate solution is 6.2 ml/min; the mixed acid solution is mixed in the inlet flow of 7.6ml/min) to obtain reaction raw material liquid (HNO in the reaction raw material liquid)3And O-methylisourea sulfate in a molar ratio of 2:1) then introducing the reaction raw material liquid into a micro-channel reactor (the reaction surface pressure of the micro-channel reactor is 1.1Mpa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 20 s; the reaction temperature is 45 ℃, after the reaction is finished, the reaction liquid is cooled by ice water to quench and crystallize, so that discharged liquid containing O-methyl-N-nitroisourea is obtained, the discharged liquid is filtered, so that a crude O-methyl-N-nitroisourea product is obtained, the crude O-methyl-N-nitroisourea product is washed by water, so that a part of refined O-methyl-N-nitroisourea is obtained, the filtrate obtained after filtration is extracted by ethyl acetate, and after extraction, the filtrate is subjected to extractionSeparating liquid, distilling organic phase under reduced pressure to obtain another part of O-methyl-N-nitroisourea, combining the two parts of O-methyl-N-nitroisourea to obtain the O-methyl-N-nitroisourea, wherein the yield of the O-methyl-N-nitroisourea is 95.4%, the purity of the O-methyl-N-nitroisourea is 96.5%, the appearance of the O-methyl-N-nitroisourea is a white solid, and the conversion rate of O-methyl-N-nitroisourea 1/2 sulfate is more than 99% by performing liquid chromatography analysis and IR (infrared) detection on the discharged liquid containing the O-methyl-N-nitroisourea in the step 2).
Example 4
This example provides a method for preparing O-methyl-N-nitroisourea, comprising the following steps:
1) dissolving 123(g) O-methylisourea 1/2 sulfate in oleum (the concentration of sulfur trioxide in oleum is 25t percent) to obtain O-methylisourea sulfate solution (SO in the O-methylisourea sulfate solution)3And O-methylisourea sulfate in a molar ratio of 2: 1; dissolving fuming nitric acid (the concentration of nitric acid in the fuming nitric acid is 90 wt%) in concentrated sulfuric acid (the concentration of sulfuric acid in the concentrated sulfuric acid is 100 wt%) to obtain a mixed acid solution (HNO in the mixed acid solution)3And H2SO4In a molar ratio of 1: 3);
2) simultaneously introducing an O-methylisourea sulfate solution and a mixed acid solution into a micro mixer from two channels by using metering pumps respectively (the introduction flow rate of the O-methylisourea sulfate solution is 5.2 ml/min; the mixed acid solution is mixed in the inlet flow of 8.0ml/min) to obtain reaction raw material liquid (HNO in the reaction raw material liquid)3And O-methylisourea sulfate in a molar ratio of 1.1: 1) then introducing the reaction raw material liquid into a micro-channel reactor (the reaction surface pressure of the micro-channel reactor is 1.2Mpa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 15 s; the reaction temperature is 60 ℃, after the reaction is finished, the reaction liquid is cooled by ice water to quench and crystallize to obtain a discharged liquid containing O-methyl-N-nitroisourea, the discharged liquid is filtered to obtain a crude O-methyl-N-nitroisourea product, the crude O-methyl-N-nitroisourea product is washed by water to obtain a part of refined O-methyl-N-nitroisourea, the filtered filtrate is extracted by ethyl acetate, liquid is separated after extraction, and the organic phase is subjected to vacuum distillation to obtain another part of O-methylAnd (3) combining two parts of O-methyl-N-nitroisourea to obtain the O-methyl-N-nitroisourea, wherein the yield of the O-methyl-N-nitroisourea is 60.5%, the purity of the O-methyl-N-nitroisourea is 80.1%, the appearance of the O-methyl-N-nitroisourea is a white solid, and the conversion rate of O-methyl-N-nitroisourea 1/2 sulfate is 71% when the discharged liquid containing the O-methyl-N-nitroisourea in the step 2) is analyzed by liquid chromatography and detected by IR (infrared).
Example 5
This example provides a method for preparing O-methyl-N-nitroisourea, comprising the following steps:
1) dissolving 123(g) O-methylisourea 1/2 sulfate in oleum (the concentration of sulfur trioxide in oleum is 50 wt%) to obtain O-methylisourea sulfate solution (SO in the O-methylisourea sulfate solution)3And O-methylisourea sulfate in a molar ratio of 2.2: 1) (ii) a Dissolving fuming nitric acid (the concentration of nitric acid in the fuming nitric acid is 95 wt%) in concentrated sulfuric acid (the concentration of sulfuric acid in the concentrated sulfuric acid is 99 wt%) to obtain a mixed acid solution (HNO in the mixed acid solution)3And H2SO4In a molar ratio of 1: 2);
2) simultaneously introducing an O-methylisourea sulfate solution and a mixed acid solution into a micro mixer from two channels by using metering pumps respectively (the introduction flow rate of the O-methylisourea sulfate solution is 8.0 ml/min; the mixed acid solution is mixed in the inlet flow rate of 5.0ml/min) to obtain reaction raw material liquid (HNO in the reaction raw material liquid)3And O-methylisourea sulfate in a molar ratio of 1.4: 1) then introducing the reaction raw material liquid into a micro-channel reactor (the reaction surface pressure of the micro-channel reactor is 1.5Mpa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 40 s; the reaction temperature is 45 ℃, after the reaction is finished, the reaction liquid is cooled by ice water to quench and crystallize to obtain a discharged liquid containing O-methyl-N-nitroisourea, the discharged liquid is filtered to obtain a crude O-methyl-N-nitroisourea product, the crude O-methyl-N-nitroisourea product is washed by water to obtain a part of refined O-methyl-N-nitroisourea, the filtered filtrate is extracted by ethyl acetate, liquid is separated after extraction, organic phase is subjected to vacuum distillation to obtain another part of O-methyl-N-nitroisourea, and the two parts of O-methyl-N-nitroisourea are synthesizedAnd then the O-methyl-N-nitroisourea is obtained, the yield of the O-methyl-N-nitroisourea is 78.7%, the purity of the O-methyl-N-nitroisourea is 86.4%, the appearance of the O-methyl-N-nitroisourea is white solid, and the conversion rate of O-methyl-isourea 1/2 sulfate is more than 85% by liquid chromatography analysis and IR (infrared) detection on the discharge liquid containing the O-methyl-N-nitroisourea in the step 2).
Example 6
This example provides a method for preparing O-methyl-N-nitroisourea, comprising the following steps:
1) dissolving 123(g) O-methylisourea 1/2 sulfate in oleum (the concentration of sulfur trioxide in oleum is 65 wt.%), to obtain O-methylisourea sulfate solution (SO in the O-methylisourea sulfate solution)3And O-methylisourea sulfate in a molar ratio of 3: 1) (ii) a Dissolving fuming nitric acid (the concentration of nitric acid in the fuming nitric acid is 96 wt%) in concentrated sulfuric acid (the concentration of sulfuric acid in the concentrated sulfuric acid is 99 wt%) to obtain a mixed acid solution (HNO in the mixed acid solution)3And H2SO4In a molar ratio of 1: 2.2);
2) simultaneously introducing an O-methylisourea sulfate solution and a mixed acid solution into a micro mixer from two channels by using metering pumps respectively (the introduction flow rate of the O-methylisourea sulfate solution is 6.5 ml/min; the flow of the mixed acid solution is 3.5ml/min, and the micro mixer is the micro mixer disclosed in the Chinese patent CN107626250A, so as to obtain a reaction raw material liquid (HNO in the reaction raw material liquid)3And O-methylisourea sulfate in a molar ratio of 1.1: 1) then introducing a reaction raw material liquid into a microchannel reactor (the microchannel reactor is provided with a channel structure formed by laminating and interleaving two grid plates, the hydraulic diameter of the microchannel reactor is 1.0mm, and the reaction gauge pressure of the microchannel reactor is 1.3Mpa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 20 s; the reaction temperature is 45 ℃, after the reaction is finished, the reaction liquid is cooled by ice water to quench and crystallize, so that discharged liquid containing O-methyl-N-nitroisourea is obtained, the discharged liquid is filtered, so that a crude O-methyl-N-nitroisourea product is obtained, the crude O-methyl-N-nitroisourea product is washed by water, so that a part of refined O-methyl-N-nitroisourea is obtained, and the filtrate obtained after filtration is used for washingExtracting with ethyl acetate, separating liquid after extraction, distilling organic phase under reduced pressure to obtain the other part of O-methyl-N-nitroisourea, combining the two parts of O-methyl-N-nitroisourea to obtain the O-methyl-N-nitroisourea, wherein the yield of the O-methyl-N-nitroisourea is 95.8%, the purity of the O-methyl-N-nitroisourea is 96.6%, the appearance of the O-methyl-N-nitroisourea is white-like solid, and the conversion rate of O-methyl-N-nitroisourea 1/2 sulfate is more than 99% by liquid chromatography analysis and IR (infrared) detection on the discharging liquid containing the O-methyl-N-nitroisourea in the step 2).
Example 7
This example provides a process for the preparation of O-methyl-N-nitroisourea, which differs from example 1 only in that the reaction temperature in step 2) is 30 ℃. The test shows that the yield of the O-methyl-N-nitroisourea is 84.7 percent, and the purity is 90.6 percent.
Comparative example 1
This comparative example provides a process for the preparation of O-methyl-N-nitroisourea, which differs from example 1 only in that 123(g) O-methylisourea 1/2 sulfate was dissolved in concentrated sulfuric acid (sulfuric acid concentration in concentrated sulfuric acid is 98% by weight) in step 1) to give an O-methylisourea sulfate solution (H in the O-methylisourea sulfate solution)2SO4And O-methylisourea sulfate in a 2:1 molar ratio). The yield of the O-methyl-N-nitroisourea is 56.2% and the purity is 62.6% through tests.
Comparative example 2
This comparative example provides a process for the preparation of O-methyl-N-nitroisourea, which differs from example 1 only in that nitric acid (nitric acid concentration 65 wt.%) is dissolved in concentrated sulfuric acid (sulfuric acid concentration 98 wt.% in concentrated sulfuric acid) in step 1) to give a mixed acid solution (HNO in the mixed acid solution)3And H2SO4In a 1:1 molar ratio). The O-methyl-N-nitroisourea was tested to have a yield of 78.7% and a purity of 75.6%.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (10)
1. A preparation method of O-methyl-N-nitroisourea is characterized by comprising the following steps:
1) dissolving O-methylisourea sulfate in fuming sulfuric acid to obtain O-methylisourea sulfate solution; dissolving fuming nitric acid in concentrated sulfuric acid to obtain a mixed acid solution;
2) mixing the O-methyl isourea sulfate solution with the mixed acid solution to obtain a reaction raw material solution, and reacting the reaction raw material solution in a microchannel reactor at the temperature of 30-60 ℃ to obtain the O-methyl-N-nitroisourea.
2. The method of claim 1, wherein SO is present in the O-methylisourea sulfate solution3And O-methylisourea sulfate in a molar ratio of 2-3: 1;
HNO in the mixed acid solution3And H2SO4The molar ratio of (A) to (B) is 1: 1-3.
3. The method according to claim 1 or 2, wherein HNO is contained in the reaction raw material liquid3And the molar ratio of O-methylisourea sulfate is 1-1.4: 1.
4. The process for producing O-methyl-N-nitroisourea according to any one of claims 1 to 3, wherein the concentration of sulfuric acid in the concentrated sulfuric acid is 98 to 100% by weight;
the concentration of sulfur trioxide in the oleum is 25-65 wt%;
the concentration of nitric acid in the fuming nitric acid is 90-98 wt%.
5. The process for producing O-methyl-N-nitroisourea according to any one of claims 1 to 4, wherein in the step 2), the residence time of the reaction raw material liquid in the microchannel reactor is 15 to 40 seconds.
6. The method for preparing O-methyl-N-nitroisourea according to any one of claims 1 to 5, wherein in the step 2), the O-methyl isourea sulfate solution and the mixed acid solution are respectively introduced into the micro mixer from two channels at the same time to be mixed to obtain a reaction raw material solution, and then the reaction raw material solution is introduced into the micro channel reactor to react to obtain the O-methyl-N-nitroisourea.
7. The process for producing O-methyl-N-nitroisourea according to any one of claims 1 to 6,
the flow rate of the O-methylisourea sulfate solution is 5-8 ml/min; the flow rate of the mixed acid solution is 3-8 ml/min.
8. The process for producing O-methyl-N-nitroisourea according to any one of claims 1 to 7,
in the step 2), after the reaction is finished, the method also comprises the steps of cooling the reaction liquid by using ice water, filtering to obtain a crude product, and washing the crude product by using water.
9. The method for producing O-methyl-N-nitroisourea according to any one of claims 1 to 8, wherein the O-methylisourea sulfate is O-methylisourea hemisulfate.
10. The method for preparing O-methyl-N-nitroisourea according to any one of claims 1 to 9, wherein the microchannel reactor has a structure in which at least two mesh plates are stacked and staggered to form an intercommunicating channel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202010136700.9A CN111362839B (en) | 2020-03-02 | 2020-03-02 | Preparation method of O-methyl-N-nitroisourea |
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