CN111362839B - Preparation method of O-methyl-N-nitroisourea - Google Patents
Preparation method of O-methyl-N-nitroisourea Download PDFInfo
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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 several 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 is performed on dangerous traditional process products such as nitrification and the like. However, the domestic market has a large demand for O-methyl-N-nitroisourea, which often leads to a state of short supply and demand.
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, stirring at the temperature, then standing, filtering, washing a filter cake for 2-3 times by using a small amount of sodium carbonate aqueous solution, then washing for 2-3 times by using 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 solution 3 And O-methylisourea sulfate in a molar ratio of 2 to 3;
HNO in the mixed acid solution 3 And H 2 SO 4 1 to 3 in a molar ratio of 1.
Preferably, HNO in the reaction raw material liquid 3 And the molar ratio of O-methylisourea sulfate is 1-1.4.
Preferably, the concentration of sulfuric acid in the concentrated sulfuric acid is 98-100wt%;
the concentration of sulfur trioxide in the oleum is 20-65wt%;
the concentration of nitric acid in the fuming nitric acid is 90-98wt%.
Preferably, in the step 2), the residence time of the reaction raw material liquid in the microchannel reactor is 15-40s. The gauge pressure of the reaction is 0.2-1.1MPa.
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 5-8ml/min; the flow rate of the mixed acid solution is 3-8ml/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 0.5-5mm.
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 the micro mixer disclosed in chinese patent CN 107626250A.
The invention has the beneficial effects that:
1) The preparation method of the 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, and then mixing the solutions to obtain a reaction raw material solution, wherein the reaction raw material solution reacts in a microchannel reactor at 30-60 ℃, so that the defect that the O-methylisourea sulfate needs to react for several hours in a low-temperature environment in the nitration process is effectively overcome.
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 O-methyl-N-nitroisourea, which is characterized in that SO in O-methyl isourea sulfate solution is controlled 3 And O-methylisourea sulfate in a molar ratio of 2 to 3; HNO in the mixed acid solution 3 And H 2 SO 4 1-3, and further by controlling HNO in the reaction raw material liquid to be in a range of 1 3 And the molar ratio of the O-methyl isourea sulfate to the O-methyl isourea sulfate is 1-1.4, 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 5-8ml/min; the flow rate of the mixed acid solution is 3-8ml/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 indicate specific experimental procedures or conditions, and can be performed according to the procedures or conditions of the conventional experimental procedures 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-0010WR-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) 3 And O-methylisourea sulfate in a molar ratio of 2); fuming nitric acid (the concentration of nitric acid in the fuming nitric acid is 98 wt%) is dissolved in the concentrated solutionSulfuric acid (the concentration of sulfuric acid in concentrated sulfuric acid is 98 wt%) to obtain a mixed acid solution (HNO in the mixed acid solution) 3 And H 2 SO 4 1) in a molar ratio of 1;
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 6.2ml/min; the mixed acid solution is mixed in the inlet flow of 3.8 ml/min) to obtain reaction raw material liquid (HNO in the reaction raw material liquid) 3 And O-methylisourea sulfate in a molar ratio of 1), and then introducing the reaction raw material liquid into a microchannel reactor (the reaction surface pressure of the microchannel reactor is 0.2 Mpa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 20s; the reaction temperature is 45 ℃, after the reaction is finished, the reaction liquid is cooled and quenched by ice water to 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 to obtain a part of refined O-methyl-N-nitroisourea, the filtered filtrate is extracted by ethyl acetate, liquid separation is performed after extraction, organic phase pressure distillation is performed to obtain another part of O-methyl-N-nitroisourea, the two parts of O-methyl-N-nitroisourea are combined to obtain the O-methyl-N-nitroisourea, 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 product is a white-like solid, and the discharged liquid containing the O-methyl-N-nitroisourea in the step 2) is subjected to liquid phase analysis and IR (infrared) detection, so that the conversion rate of O-methyl-N-nitroisourea sulfate is more than 99%.
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) 3 And O-methylisourea sulfate in a molar ratio of 2: 1) (ii) a Fuming nitric acid (the concentration of nitric acid in fuming nitric acid is 98 wt%) is dissolved in concentrated sulfuric acid (the concentration of sulfuric acid in concentrated sulfuric acid is 98 wt%) to obtain a mixtureAcid solution (HNO in the mixed acid solution) 3 And H 2 SO 4 In a molar ratio of 1;
2) Simultaneously introducing the O-methylisourea sulfate solution and the 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 6.2ml/min; the mixed acid solution is mixed in the inlet flow of 3.8 ml/min) to obtain reaction raw material liquid (HNO in the reaction raw material liquid) 3 And O-methylisourea sulfate in a molar ratio of 1), and then introducing the reaction raw material liquid into a microchannel reactor (the reaction surface pressure of the microchannel reactor is 1.1 MPa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 20s; the reaction temperature is 60 ℃, 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 filtered filtrate is extracted by ethyl acetate, liquid separation is carried out after extraction, organic phase pressure distillation is carried out, so that another part of O-methyl-N-nitroisourea is obtained, the two parts of O-methyl-N-nitroisourea are combined, so that the O-methyl-N-nitroisourea is obtained, 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 product is a white-like solid, and the discharged liquid containing the O-methyl-N-nitroisourea in the step 2) is subjected to liquid phase analysis and IR (infrared) detection, so that the conversion rate of O-methyl-N-nitroisourea sulfate is more than 99%.
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) 3 And 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) 3 And H 2 SO 4 1) in a molar ratio of 1;
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 6.2ml/min; the mixed acid solution is mixed in the inlet flow of 7.6 ml/min) to obtain reaction raw material liquid (HNO in the reaction raw material liquid) 3 And 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 1.1 Mpa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 20s; the reaction temperature is 45 ℃, after the reaction is finished, the reaction liquid is cooled and quenched by ice water to 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 to obtain a part of refined O-methyl-N-nitroisourea, the filtered filtrate is extracted by ethyl acetate, liquid separation is performed after extraction, organic phase pressure distillation is performed to obtain another part of O-methyl-N-nitroisourea, the two parts of O-methyl-N-nitroisourea are combined to obtain the O-methyl-N-nitroisourea, 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 product is a white-like solid, and the discharged liquid containing the O-methyl-N-nitroisourea in the step 2) is subjected to liquid phase analysis and IR (infrared) detection, so that the conversion rate of O-methyl-N-nitroisourea sulfate is more than 99%.
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 the oleum is 25 t%) to obtain O-methylisourea sulfate solution (SO in the O-methylisourea sulfate solution) 3 And O-methylisourea sulfate in a molar ratio of 2; 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) 3 And H 2 SO 4 1;
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 5.2ml/min; the mixed acid solution is mixed in the inlet flow of 8.0 ml/min) to obtain reaction raw material liquid (HNO in the reaction raw material liquid) 3 And 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 1.2 Mpa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 15s; the reaction temperature is 60 ℃, 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 filtered filtrate is extracted by ethyl acetate, liquid separation is performed after extraction, organic phase pressure distillation is performed, so that another part of O-methyl-N-nitroisourea is obtained, the two parts of O-methyl-N-nitroisourea are combined, so that the O-methyl-N-nitroisourea is obtained, 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 white-like solid, and the discharged liquid containing the O-methyl-N-nitroisourea in the step 2 is subjected to liquid phase chromatography and IR (infrared) detection, so that the conversion rate of O-methyl-N-nitroisourea sulfate is 71%.
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) 3 And 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) 3 And H 2 SO 4 In a molar ratio of 1;
2) Mixing an O-methylisourea sulfate solution withThe mixed acid solution is respectively and simultaneously introduced into a micro mixer through two channels by a metering pump (the introduction flow of the O-methyl isourea sulfate solution is 8.0ml/min, and the introduction flow of the mixed acid solution is 5.0 ml/min) for mixing to obtain a reaction raw material solution (HNO in the reaction raw material solution) 3 And 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 1.5 Mpa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 40s; 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 filtered filtrate is extracted by ethyl acetate, liquid separation is carried out after extraction, organic phase pressure distillation is carried out, so that another part of O-methyl-N-nitroisourea is obtained, the two parts of O-methyl-N-nitroisourea are combined, so that 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-like solid, and the discharged liquid containing the O-methyl-N-nitroisourea in the step 2) is subjected to liquid phase chromatography and IR (infrared) detection, so that the conversion rate of O-methyl-N-nitroisourea sulfate is more than 85%.
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) 3 And 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) 3 And H 2 SO 4 In a molar ratio of 1;
2) The O-methyl isourea sulfate solution and the mixed acid solution are respectively and simultaneously communicated by two channels by a metering pumpMixing in a micro mixer (the flow of the O-methylisourea sulfate solution is 6.5ml/min; the flow of the mixed acid solution is 3.5 ml/min; the micro mixer is the one disclosed in the Chinese patent CN 107626250A) to obtain a reaction raw material solution (HNO in the reaction raw material solution) 3 And O-methylisourea sulfate in a molar ratio of 1.1: 1) Then introducing the reaction raw material liquid into a microchannel reactor (the microchannel reactor has a channel structure formed by overlapping and staggering two grid plates, the hydraulic diameter of the microchannel reactor is 1.0mm, and the reaction surface pressure of the microchannel reactor is 1.3 Mpa) for reaction; the residence time of the reaction raw material liquid in the microchannel reactor is 20s; the reaction temperature is 45 ℃, after the reaction is finished, the reaction liquid is cooled and quenched by ice water to 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 to obtain a part of refined O-methyl-N-nitroisourea, the filtered filtrate is extracted by ethyl acetate, liquid separation is performed after extraction, organic phase pressure distillation is performed to obtain another part of O-methyl-N-nitroisourea, the two parts of O-methyl-N-nitroisourea are combined to obtain the O-methyl-N-nitroisourea, 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 product is a white-like solid, and the discharged liquid containing the O-methyl-N-nitroisourea in the step 2) is subjected to liquid phase analysis and IR (infrared) detection, so that the conversion rate of O-methyl-N-nitroisourea sulfate is more than 99%.
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 yield of the O-methyl-N-nitroisourea is 84.7 percent and the purity is 90.6 percent through testing.
Comparative example 1
This comparative example provides a process for producing O-methyl-N-nitroisourea, which is different from example 1 only in that 123 (g) O-methylisourea 1/2 sulfate is dissolved in concentrated sulfuric acid (the concentration of sulfuric acid in concentrated sulfuric acid is 98 wt%) in step 1) to obtain an O-methylisourea sulfate solution (the O-methylisourea sulfuric acidH in salt solution 2 SO 4 And the molar ratio of O-methylisourea sulfate is 2). The yield of the O-methyl-N-nitroisourea is 56.2% and the purity is 62.6% through testing.
Comparative example 2
This comparative example provides a process for producing O-methyl-N-nitroisourea, which is different from example 1 only in that nitric acid (the concentration of nitric acid is 65 wt%) is dissolved in concentrated sulfuric acid (the concentration of sulfuric acid in concentrated sulfuric acid is 98 wt%) in step 1) to obtain a mixed acid solution (HNO in the mixed acid solution) 3 And H 2 SO 4 1) is 1. 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 (5)
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) Respectively introducing an O-methyl isourea sulfate solution and a mixed acid solution into a micro mixer from two channels simultaneously for mixing to obtain a reaction raw material solution, and then introducing the reaction raw material solution into a micro channel reactor for reaction at the temperature of 45-60 ℃ to obtain the O-methyl-N-nitroisourea;
the concentration of sulfuric acid in the concentrated sulfuric acid is 98-100wt%;
the concentration of sulfur trioxide in the oleum is 65wt%;
the concentration of nitric acid in the fuming nitric acid is 96-98wt%;
the flow rate of the O-methylisourea sulfate solution is 5-8ml/min; the flow rate of the mixed acid solution is 3-8ml/min;
the microchannel reactor is provided with at least two grid plates which are stacked and staggered to form an intercommunicated channel structure;
in the step 2), the residence time of the reaction raw material liquid in the microchannel reactor is 15-40s.
2. The method of claim 1 for the production of O-methyl-N-nitroisourea, wherein SO is present in the O-methylisourea sulfate solution 3 And O-methylisourea sulfate in a molar ratio of 2 to 3;
HNO in the mixed acid solution 3 And H 2 SO 4 1 to 3 in a molar ratio of 1.
3. The process according to claim 1 or 2, wherein HNO is present in the reaction feed solution 3 And the molar ratio of O-methylisourea sulfate is 1-1.4.
4. The process for producing O-methyl-N-nitroisourea according to claim 1, wherein,
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.
5. The method of claim 1, wherein the O-methylisourea sulfate is O-methylisourea hemisulfate.
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