Method for continuously synthesizing diaminomaleonitrile

Abstract

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a method for continuously synthesizing diaminomaleonitrile, which comprises the following steps: step 1, controlling the temperature of a continuous reactor to be 30-130 DEG C, firstly dissolving a basic catalyst in a reaction solvent, then adding the reaction solvent dissolved with the basic catalyst and hydrocyanic acid from an inlet of the continuous reactor, and continuously reacting at the temperature of 30-130 DEG C; and 2, enabling a reaction product to flow out from an outlet of the continuous reactor, and carrying out concentration, cooling crystallization, filtration, decoloration hot filtration, cooling crystallization, centrifugation and drying to obtain the diaminomaleonitrile. The continuous synthesis of diaminomaleonitrile is realized, the heat release is easy to control, the operation is simple, and the yield is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of fine chemical industry, and particularly relates to a method for continuously synthesizing diamino maleonitrile. Background Art

[0002] Diamino maleonitrile, also known as diamino maleic dinitrile, abbreviated as DAMN in English, is an important fine chemical intermediate, which can be used to synthesize various nitrogen-containing heterocyclic compounds, such as imidazoles, pyrazines, purines, etc., and is widely used in fine chemical intermediates such as medicine, pesticide, dye, polymer, lithium battery, photovoltaic, and energetic materials.

[0003] Currently, there are two common processes for synthesizing diamino maleonitrile: one is to add a polar aprotic solvent and a catalyst to a synthesis kettle first, then drop hydrocyanic acid, and then keep the temperature for reaction to synthesize the product; the other is to use acetone cyanohydrin as the raw material and synthesize the product under the action of a basic catalyst.

[0004] Both of these two processes are batch operations and have the following four disadvantages: first, the heat release during the reaction is large, it is not easy to control, and it is extremely easy to exceed the temperature, resulting in further polymerization of the product into polymers, affecting the yield and content; second, the airtightness of the reaction equipment is poor, and there is a risk of hydrocyanic acid escaping at high temperatures; third, there are many reaction equipment and the occupied space is large; fourth, a large number of operators are required. The above disadvantages lead to high production costs of this product and are not conducive to large-scale industrial production. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a method for continuously synthesizing diamino maleonitrile.

[0006] The present invention is realized as follows: a method for continuously synthesizing diamino maleonitrile is provided, including the following steps: Step 1: Control the temperature of the continuous reactor at 30 - 130 °C. First, dissolve the basic catalyst in the reaction solvent, and then add the reaction solvent dissolved with the basic catalyst and hydrocyanic acid from the inlet of the continuous reactor, and control the residence time at 60 - 600 s. The hydrocyanic acid undergoes a continuous self-polymerization reaction: ; Step 2: The reaction product flows out from the outlet of the continuous reactor, and after concentration, cooling crystallization, filtration, decolorization hot filtration, cooling crystallization, centrifugation, and drying, diamino maleonitrile is obtained.

[0007] Preferably, in the above Step 1, the temperature of the continuous reactor is controlled at 80 - 90 °C, and the residence time is controlled at 240 - 300 s.

[0008] Preferably, in the step 1, the basic catalyst is one of triethylamine, diethylamine, sodium hydroxide, sodium carbonate, and sodium cyanide; the reaction solvent is one or more of DMF, DMAC, acetonitrile, and ethyl acetate; and the hydrocyanic acid is in a liquid or gaseous state.

[0009] More preferably, in the step 1, the basic catalyst is triethylamine, the reaction solvent is DMF, and the hydrocyanic acid is in a liquid state.

[0010] Preferably, in the step 1, the mass ratio of hydrocyanic acid, basic catalyst, and reaction solvent is 1: 0.01 - 0.2: 0.1 - 10.

[0011] More preferably, in the step 1, the mass ratio of hydrocyanic acid, basic catalyst, and reaction solvent is 1: 0.04 - 0.1: 0.5 - 1.5.

[0012] Preferably, in the step 1, the feeding rate of the reaction solvent dissolved with the basic catalyst is 5.5 - 550 kg / h, and the feeding rate of hydrocyanic acid is 13 - 69 kg / h.

[0013] Preferably, in the step 1, the continuous reactor is a tubular reactor or a microchannel reactor.

[0014] Preferably, the specific process of the step 2 is as follows: Concentration: The reaction product flows out from the outlet of the continuous reactor, the temperature is controlled below 100 °C, and the reaction solvent is concentrated under negative pressure until the remaining reaction solvent and hydrocyanic acid have the same weight, then the concentration of the solvent ends under negative pressure; Cooling crystallization: Cool down to 20 °C and crystallize for 3 hours; Filtration: Discharge the material and filter it. The filter cake is the crude product of diaminomaleonitrile; Decolorization and hot filtration: Put the crude product of diaminomaleonitrile into 10 times its weight of acetonitrile, add 0.01 times its weight of powdered activated carbon for decolorization, heat up to 50 °C, and discharge and hot filter after complete dissolution; Cooling crystallization: Cool the filtrate to 20 °C and crystallize for 3 hours; Centrifugation: Discharge the material and centrifuge it to obtain the wet product of diaminomaleonitrile; Drying: Dry with hot air at 90 °C for 5 hours to obtain a light brown to dark brown crystalline powder, which is diaminomaleonitrile.

[0015] Compared with the prior art, the advantages of the present invention are as follows: 1. The hold-up volume is small, the reaction heat release is easy to control, and the intrinsic safety of the hydrocyanic acid reaction is realized; 2. The reaction equipment has good airtightness and there is no risk of hydrocyanic acid escaping; 3. The reaction equipment has a small volume and occupies less space; 4. The process is simple and requires fewer operators; 5. High product yield, with a molar yield exceeding 92%, and good product quality. Description of the Drawings

[0016] Figure 1 It is the appearance diagram of the product in Example 1; Figure 2 It is the liquid chromatography diagram of the product in Example 1. Detailed Embodiments

[0017] The present invention will be further explained below in conjunction with specific implementation schemes, but it is not used to limit the protection scope of the present invention.

[0018] Example 1

[0019] Step 1: Control the temperature of the tubular reactor at 90 °C. First, dissolve the catalyst triethylamine (content > 99%; the feeding amount is 3% of DMF) in the reaction solvent DMF (content > 99%), and then use a plunger pump to add the DMF dissolved with triethylamine and hydrocyanic acid (content > 99%) to the inlet of the tubular reactor. The feeding rate of DMF is 76 kg / h, and the feeding rate of hydrocyanic acid is 55 kg / h. Control the residence time at 300 s, and the hydrocyanic acid undergoes continuous self-polymerization reaction: Step 2 is specifically as follows: Concentration: The reaction product flows out from the outlet of the continuous reactor. Control the temperature below 100 °C, and concentrate the reaction solvent under negative pressure until the remaining reaction solvent and hydrocyanic acid are of equal weight, then the negative pressure concentration of the solvent ends; Cooling crystallization: Cool down to 20 °C and crystallize for 3 hours; Filtration: Discharge the material and filter it. The filter cake is the crude product of diamino maleonitrile; Decolorization and hot filtration: Put the crude product of diamino maleonitrile into 10 times its weight of acetonitrile, add 0.01 times its weight of powdered activated carbon for decolorization, heat up to 50 °C, and discharge and hot filter after complete dissolution; Cooling crystallization: Cool the filtrate to 20 °C and crystallize for 3 hours; Centrifugation: Discharge the material and centrifuge it to obtain the wet product of diamino maleonitrile; Drying: Dry it with hot air at 90 °C for 5 hours to obtain a light brown to dark brown crystalline powder (see Figure 1 ), which is diamino maleonitrile with a content of 99.7% (see Figure 2 Liquid chromatography results, the peak area of diamino maleonitrile is 7436427, and the total peak area is 7458554), and the molar yield is 95.1%.

[0020] Example 2

[0021] The difference between this example and Example 1 is that sodium hydroxide is used instead of triethylamine as the catalyst. Finally, the obtained diamino maleonitrile has a content of 99.8% and a molar yield of 92.3%.

[0022] Example 3

[0023] The difference between this example and Example 1 is that acetonitrile is used instead of DMF as the synthesis solvent. Finally, the content of diamino maleonitrile is 99.7% and the molar yield is 94.2%.

[0024] Example 4

[0025] The difference between this example and Example 1 is that the feeding rate of DMF is increased from 76 kg / h to 550 kg / h. Finally, the content of diamino maleonitrile is 99.5% and the molar yield is 95.1%.

[0026] Example 5

[0027] The difference between this example and Example 1 is that the reaction temperature is decreased from 90 °C to 30 °C. Finally, the content of diamino maleonitrile is 99.1% and the molar yield is 92.2%.

[0028] Example 6

[0029] The difference between this example and Example 1 is that the residence time is decreased from 300 s to 60 s. Finally, the content of diamino maleonitrile is 99.4% and the molar yield is 92.9%.

[0030] Example 7

[0031] The difference between this example and Example 1 is that the feeding rate of DMF is decreased from 76 kg / h to 5.5 kg / h. Finally, the content of diamino maleonitrile is 99.2% and the molar yield is 92.4%.

[0032] Example 8

[0033] The difference between this example and Example 1 is that the reaction temperature is increased from 90 °C to 130 °C. Finally, the content of diamino maleonitrile is 99.3% and the molar yield is 93.1%.

[0034] Example 9

[0035] The difference between this example and Example 1 is that diethylamine is used instead of triethylamine as the catalyst. Finally, the content of diamino maleonitrile is 99.4% and the molar yield is 94.8%.

[0036] Example 10

[0037] The difference between this example and Example 1 is that sodium carbonate is used instead of triethylamine as the catalyst. Finally, the content of diamino maleonitrile is 99.2% and the molar yield is 93.1%.

[0038] Example 11

[0039] The difference between this example and Example 1 is that sodium cyanide is used instead of triethylamine as the catalyst. Finally, the content of diamino maleonitrile is 99.4% and the molar yield is 92.7%.

[0040] Example 12

[0041] The difference between this example and Example 1 is that DMAC is used instead of DMF as the synthesis solvent. Finally, the content of diamino maleonitrile is 99.3% and the molar yield is 94.0%.

[0042] Example 13

[0043] The difference between this example and Example 1 is that ethyl acetate is used instead of DMF as the synthesis solvent. Finally, the content of diamino maleonitrile is 99.1% and the molar yield is 92.6%.

[0044] Example 14

[0045] The difference between this example and Example 1 is that the dosage of the catalyst triethylamine is reduced from 3% of DMF to 0.7%. Finally, the content of diamino maleonitrile is 99.1% and the molar yield is 92.2%.

[0046] Example 15

[0047] The difference between this example and Example 1 is that the dosage of the catalyst triethylamine is increased from 3% of DMF to 14.5%. Finally, the content of diamino maleonitrile is 99.1% and the molar yield is 92.4%.

[0048] Example 16

[0049] The difference between this example and Example 1 is that the feeding rate of hydrocyanic acid is reduced from 55 kg / h to 13.8 kg / h. Finally, the content of diamino maleonitrile is 99.3% and the molar yield is 93.3%.

[0050] Example 17

[0051] The difference between this example and Example 1 is that the feeding rate of hydrocyanic acid is increased from 55 kg / h to 69 kg / h. Finally, the content of diamino maleonitrile is 99.4% and the molar yield is 94.5%.

[0052] Example 18

[0053] The difference between this example and Example 1 is that the residence time is increased from 300 s to 600 s. Finally, the content of diamino maleonitrile is 99.2% and the molar yield is 95.0%.

[0054] Example 19

[0055] The difference between this example and Example 1 lies in using gaseous hydrocyanic acid instead of liquid hydrocyanic acid. Finally, the content of diamino maleonitrile is 99.1% and the molar yield is 92.1%.

[0056] Example 20

[0057] The difference between this example and Example 1 lies in using a microchannel reactor instead of a tubular reactor. Finally, the content of diamino maleonitrile is 99.0% and the molar yield is 92.3%.

Claims

1. A method for continuously synthesizing diaminomaleonitrile, characterized in that, The steps include: Step 1: Control the temperature of the continuous reactor to 30-130°C, dissolve the alkaline catalyst in the reaction solvent, then add the reaction solvent containing the alkaline catalyst and hydrocyanic acid from the inlet of the continuous reactor, control the residence time to 60-600s, and the hydrocyanic acid undergoes a continuous self-polymerization reaction: ； Step 2: The reaction product flows out from the outlet of the continuous reactor, and is concentrated, cooled and crystallized, filtered, decolorized and hot filtered, cooled and crystallized, centrifuged, and dried to obtain diaminomaleonitrile.

2. The method for continuously synthesizing diaminomaleonitrile according to claim 1, wherein In the step 1, the temperature of the continuous reactor is controlled at 80-90° C., and the residence time is controlled at 240-300 s.

3. The method for continuously synthesizing diaminomaleonitrile according to claim 1, characterized in that In step 1, the alkaline catalyst is one of triethylamine, diethylamine, sodium hydroxide, sodium carbonate, and sodium cyanide; the reaction solvent is one or more of DMF, DMAC, acetonitrile, and ethyl acetate; and the hydrocyanic acid is in liquid or gaseous state.

4. The method for continuously synthesizing diaminomaleonitrile according to claim 3, wherein In the step 1, the alkaline catalyst is triethylamine, the reaction solvent is DMF, and the hydrocyanic acid is in liquid state.

5. The method for continuously synthesizing diaminomaleonitrile according to claim 1, characterized in that, In the step 1, the mass ratio of hydrocyanic acid, alkaline catalyst and reaction solvent is 1:0.01-0.2:0.1-10.

6. The method for continuously synthesizing diaminomaleonitrile according to claim 5, characterized in that: In the step 1, the mass ratio of hydrocyanic acid, alkaline catalyst and reaction solvent is 1:0.04-0.1:0.5-1.

5.

7. The method for continuously synthesizing diaminomaleonitrile according to claim 1, characterized in that: In the step 1, the feed rate of the reaction solvent containing the alkaline catalyst is 5.5-550 kg / h, and the feed rate of hydrocyanic acid is 13-69 kg / h.

8. The method for continuously synthesizing diaminomaleonitrile according to claim 1, characterized in that, In the step 1, the continuous reactor is a tubular reactor or a microchannel reactor.

9. The method for continuously synthesizing diaminomaleonitrile according to claim 1, characterized in that: The specific process of step 2 is: Concentration: The reaction product flows out from the outlet of the continuous reactor, the temperature is controlled below 100°C, and the reaction solvent is concentrated under negative pressure. When the weight of the remaining reaction solvent and the hydrocyanic acid is equal, the negative pressure concentration of the solvent is completed; Cooling crystallization: cool to 20℃ and crystallize for 3 hours; Filtration: Discharge, filter, and the filter cake is the crude diaminomaleonitrile; Decolorization and hot filtration: put the crude diaminomaleonitrile into 10 times the weight of acetonitrile, and add 0.01 times the weight of powdered activated carbon for decolorization, heat to 50°C, and after it is completely dissolved, discharge and hot filter; Cooling crystallization: cool the filtrate to 20°C and crystallize for 3 hours; Centrifugation: Discharge and centrifuge to obtain diaminomaleonitrile wet product; Drying: Dry with hot air at 90°C for 5 hours to obtain a light brown to dark brown crystalline powder, which is diaminomaleonitrile.

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