A green and efficient preparation method of 2,2 - diisopropylpropionitrile

Abstract

The present invention discloses a green and efficient preparation method of 2,2-diisopropylpropionitrile, which includes: adding an organic solvent into a stainless steel reaction kettle, and adding sodium amide and a metal organic ligand catalyst into the stainless steel reaction kettle under stirring. After stirring at room temperature for half an hour, a dropping reaction is carried out; mixing propionitrile and 2-bromopropane evenly, and then slowly dropping the mixed solution into the reaction kettle, and controlling the dropping time; after the dropping is completed, continue the heat preservation reaction, and sample during the reaction to monitor the end point of the reaction by gas chromatography; after the reaction is completed, cool down and put the reaction solution into a centrifuge to separate the solid and liquid phases, and add the washing solvent into the centrifuge for multiple times, and finally collect the organic phase uniformly; put the organic phase into a distillation kettle, first carry out desolvation under normal pressure, and then carry out vacuum rectification to obtain 2,2-diisopropylpropionitrile. By adopting the above preparation method, the present invention avoids the generation of side reactions under high temperature conditions, thereby achieving the purpose of improving the production yield, reducing the raw material consumption and energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of compound preparation, and particularly relates to a green and efficient method for preparing 2,2 - diisopropylpropionitrile. Background Art

[0002] 2,2 - Diisopropylpropionitrile, also known as 2 - isopropyl - 2,3 - dimethylbutyronitrile, with the trade name DIPPN and the CAS number 55897 - 64 - 8, is the main raw material for the production of the novel cooling agent N,2,3 - trimethyl - 2 - isopropylbutyramide (WS - 23), and is also an important pharmaceutical intermediate and organic intermediate.

[0003] The existing synthetic routes for the large - scale production of 2,2 - diisopropylpropionitrile at home and abroad mainly include the following two:

[0004] Method 1: Patent document CN 103242194A discloses a method for preparing 2,2 - diisopropylpropionitrile. An organic solvent is added to a reaction kettle, and then a strong base is added. Stirring is started to make the materials mix evenly and the temperature is raised to a certain temperature. Then, a mixed solution of propionitrile and isopropyl halide is added dropwise. After the addition is completed, the reaction is continued under insulation until the end. After cooling, water is added to destroy the reaction, and finally liquid separation is carried out. The organic phase is washed with weak acid and saturated brine respectively, and then desolvated under normal pressure and refined under reduced pressure to obtain 2,2 - diisopropylpropionitrile. The isopropyl halide used in this reaction is generally isopropyl bromide, and the organic solvent is methyl tert - butyl ether (MTBE). The reaction formula of Method 1 is as follows:

[0005]

[0006] Method 2: Patent document CN101823983A discloses a method for preparing 2,2 - diisopropylpropionitrile. The specific steps are as follows: Under deep - freezing conditions, that is, with liquid nitrogen refrigeration, a mixed system of liquid ammonia and sodium amide is added with propionitrile and isopropyl bromide until the reaction ends under deep - freezing conditions. Then, liquid ammonia is evaporated and recovered. Water is added to destroy the unreacted sodium amide and dissolve the by - product sodium bromide. The aqueous phase is then extracted with a solvent. Finally, the organic phase is dried, desolvated, and distilled under reduced pressure to obtain 2,2 - diisopropylpropionitrile. The reaction formula of Method 2 is as follows:

[0007]

[0008] Comparing these two methods comprehensively, both the process routes of Method 1 and Method 2 use sodium amide, propionitrile, and isopropyl bromide as raw materials, and obtain 2,2-diisopropylpropionitrile through alkylation. The solvent selected in Method 1 is methyl tert-butyl ether (MTBE), and the reaction conditions are heating under reflux. During the reaction process, steam is consumed and multi-stage condensation is required. This not only involves VOCs emissions, but also has high energy consumption and poor economic applicability. At the same time, a large number of side reactions occur after the reaction, and the yield is relatively low. The yield is 70-80% based on propionitrile, and about 60% based on sodium amide and 2-bromopropane.

[0009] The solvent selected in Method 2 is liquid ammonia, and the reaction conditions are liquid nitrogen refrigeration with a temperature of -35 to -42 °C. The yield of this method is slightly higher than that of Method 1 (about 90% based on propionitrile), but the reaction raw materials involve liquid ammonia and liquid nitrogen, which have certain safety hazards. When the storage and usage amount of liquid ammonia is greater than 10 tons, it is a major hazard source. The production device must be equipped with an independent SIS (safety instrument) system, which has high requirements for the production device. After the reaction, it is necessary to heat up to drive off ammonia and absorb it with water to form a 20% ammonia aqueous solution. The throughput of liquid ammonia, liquid nitrogen, by-product ammonia water, and sodium bromide solution has high requirements for the enterprise and no longer belongs to the fine chemical industry. Therefore, this process route is not suitable for large-scale production. Currently, this process route is mainly used to produce 2,2-diisopropylpropionitrile in China, but the scale is very small, and all are restricted by this.

[0010] Therefore, it is of great significance to develop a production process with simple operation, safety and reliability, economy and environmental protection. Summary of the Invention

[0011] The purpose of the present invention is to provide a green and efficient method for preparing 2,2-diisopropylpropionitrile. A metal-organic ligand catalyst is added to the raw materials, and the reaction is carried out at a normal temperature of 20-40 °C. Samples can be taken and detected at any time during the reaction process, so as to control the progress of the reaction, maximize the reaction efficiency, and subsequent addition of water to dissolve the by-product sodium bromide is not required, avoiding the generation of side reactions under high-temperature conditions, thereby achieving the purpose of improving the production yield, reducing raw material consumption and energy consumption.

[0012] To achieve the above purpose, the present invention provides a green and efficient method for preparing 2,2-diisopropylpropionitrile. The raw material components include propionitrile, 2-bromopropane, organic solvent, and metal-organic ligand catalyst, abbreviated as catalyst M;

[0013] The preparation method for preparing 2,2-diisopropylpropionitrile using the above raw material components includes the following steps:

[0014] S1. Add an organic solvent into a stainless - steel reactor, and add sodium amide and a metal - organic ligand catalyst into the stainless - steel reactor under stirring. After stirring at room temperature for half an hour, carry out a dropping reaction.

[0015] S2. Mix propionitrile and 2 - bromopropane evenly, and then slowly drop the evenly - mixed solution into the stainless - steel reactor, and control the dropping time of the mixed solution.

[0016] S3. After the dropping is completed, continue the heat - preservation reaction, and take samples during the reaction to monitor the end - point of the reaction by gas chromatography.

[0017] S4. After the reaction in step S3 ends, cool down and put the reaction solution into a centrifuge to separate the solid from the liquid. Add the washing solvent into the centrifuge multiple times, and finally collect the organic phase uniformly. The organic phase is the crude material of 2,2 - diisopropylpropionitrile.

[0018] S5. Put the organic phase into a distillation kettle, first carry out desolvation under normal pressure, and then carry out vacuum rectification to obtain 2,2 - diisopropylpropionitrile.

[0019] Its chemical reaction formula is:

[0020]

[0021] Further, in the step S1, the organic solvent is one of methyl tert - butyl ether (MTBE), ether solvents, or organic amine solvents, preferably methyl tert - butyl ether (MTBE).

[0022] Further, in the step S1, the metal - organic ligand catalyst is one of metal carbonyl compounds Ni(CO)4, Fe(CO)5, Ru(CO)5, Os(CO)5, preferably Ni(CO)4.

[0023] Further, in the steps S1 and S3, the reaction temperature range in the stainless - steel reactor is 0 - 60 °C, preferably 20 - 40 °C.

[0024] Further, in the step S4, during the process of adding the washing solvent into the centrifuge multiple times and collecting the organic phase uniformly, the centrifuge uses nitrogen replacement and real - time monitors the oxygen concentration, and is interlocked with the start - stop of the centrifuge.

[0025] Further, the washing solvent is the same as the organic solvent in the step S1, which is used to reduce the loss of reaction products.

[0026] Therefore, the present invention adopts the above-mentioned green and efficient preparation method of 2,2-diisopropylpropionitrile. A metal-organic ligand catalyst is added to the raw materials, and the reaction is carried out at a normal temperature of 20-40 °C. Samples can be taken at any time during the reaction process for detection, so as to control the progress of the reaction, maximize the reaction efficiency, and subsequent addition of water to dissolve the by-product sodium bromide is not required, avoiding the generation of side reactions under high-temperature conditions, thereby achieving the purpose of improving the production yield, reducing raw material consumption and energy consumption.

[0027] The technical solution of the present invention will be further described in detail below through the accompanying drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 It is a flow chart of a green and efficient preparation method of 2,2-diisopropylpropionitrile of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The technical solution of the present invention will be further described below through the accompanying drawings and examples.

[0031] Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meaning understood by those of ordinary skill in the art to which the present invention belongs.

[0032] Example 1

[0033] Figure 1 It is a flow chart of a green and efficient preparation method of 2,2-diisopropylpropionitrile of the present invention. As Figure 1 shown, the present invention provides a green and efficient preparation method of 2,2-diisopropylpropionitrile, including the following steps:

[0034] S1. Add an organic solvent to a stainless steel reaction kettle, and add sodium amide and a metal-organic ligand catalyst to the stainless steel reaction kettle under stirring. After stirring for half an hour within the temperature range of 20-40 °C, carry out a dropping reaction;

[0035] S2. Mix propionitrile and 2-bromopropane evenly, and then slowly drop the evenly mixed solution into the stainless steel reaction kettle, and control the dropping time of the mixed solution;

[0036] S3. After the dropping is completed, continue to keep the temperature at 20-40 °C for reaction, and sample during the reaction process to monitor the end point of the reaction by gas chromatography;

[0037] S4. After the reaction in step S3 is completed, cool down and place the reaction solution in a centrifuge to separate the solid from the liquid. Add the washing solvent (the washing solvent is the organic solvent used in step S1, which is used to reduce the loss of reaction products) to the centrifuge multiple times, and finally collect the organic phase uniformly. The organic phase is the crude material of 2,2 - diisopropylpropionitrile;

[0038] Involved in this is that the centrifuge uses nitrogen replacement and real - time monitors the oxygen solubility, and is interlocked with the start and stop of the centrifuge;

[0039] S5. Place the organic phase in a distillation kettle, first remove the solvent under normal pressure, and then carry out vacuum rectification to obtain 2,2 - diisopropylpropionitrile.

[0040] It should be noted that the raw material components for preparing 2,2 - diisopropylpropionitrile include propionitrile, 2 - bromopropane, an organic solvent, and a metal - organic ligand catalyst, abbreviated as catalyst M. Its chemical reaction formula is:

[0041]

[0042] In addition, in step S1, the organic solvent is one of methyl tert - butyl ether (MTBE), ether solvents, or organic amine solvents, preferably methyl tert - butyl ether (MTBE); the metal - organic ligand catalyst is one of metal carbonyl compounds Ni(CO)4, Fe(CO)5, Ru(CO)5, Os(CO)5, preferably Ni(CO)4.

[0043] The present invention will be further elaborated through specific embodiments below. It should be noted that MTBE is methyl tert - butyl ether.

[0044] Example 1

[0045] Check the sealing of the 1000L stainless steel reactor, confirm that the inside of the reactor is dry and free of water, and confirm that the equipment is working properly. Charge 320 kg of MTBE and 68 kg of sodium amide into the reactor, start low-speed stirring, and add 0.35 kg of the metal organic ligand Ni(CO)4. Then adjust the stirring speed to 200 revolutions per minute and stir for 0.5 hours at a temperature of 20 - 35°C. Subsequently, start pumping 44 kg of propionitrile and 225 kg of 2-bromopropane into the dropping tank, adjust the flow rate of the metering pump to 0.5 L / min, and pass in circulating water to control the temperature, and start dropping the mixed solution. Observe the temperature during the dropping process, adjust the inlet and outlet valves of the circulating water to keep the reaction temperature within the range of 20 - 40°C, and take samples at stages to detect the reaction progress. After the dropping is completed, continue the reaction for 4 hours, take samples for testing to confirm that the reaction no longer proceeds, and the residual propionitrile is <0.2%. Close the inlet and outlet valves of the circulating water, change to ice water cooling, cool down to about 0°C, and transfer the reaction material into the centrifuge. Start centrifugal discharging, and continuously add a small amount of the rinsing solvent MTBE during the discharging process until the solid material concentrated by centrifugation presents a dry powder state, indicating that the centrifugation is complete. Subsequently, collect the liquid phase material after centrifugation, perform atmospheric distillation to recover the solvent, and then perform vacuum distillation again to obtain 2,2-diisopropylpropionitrile. Finally, detect that the content of the finished product in the subsequent distillate material is ≥97%, start centralized collection, and the final amount of the obtained finished product is 101 kg, the content of the finished product is 99.6%, and the yield is 90%.

[0046] It should be noted that in this embodiment, the addition amount of the metal organic ligand Ni(CO)4 is 0.5% of the mass of sodium amide, and the dropping time is 7.5 h.

[0047] Example Two

[0048] Check the sealing of the 1000L stainless steel reactor, confirm that the inside of the reactor is dry and water-free, and confirm that the equipment is working properly. Charge 322 kg of MTBE and 68 kg of sodium amide into the reactor, start low-speed stirring, and add 0.2 kg of the metal organic ligand Ni(CO)4. Then adjust the stirring speed to 200 revolutions per minute and stir for 0.5 hours at a temperature of 20 - 35°C. Subsequently, start pumping 44 kg of propionitrile and 225 kg of 2-bromopropane into the dropping tank, adjust the flow rate of the metering pump to 0.75 L / min, and introduce circulating water for temperature control, and start dropping the mixed solution. Observe the temperature during the dropping process, adjust the inlet and outlet valves of the circulating water to keep the reaction temperature within the range of 20 - 40°C, and take samples at stages to detect the reaction progress. After the dropping is completed, continue the reaction for 4 hours, take samples for detection to confirm that the reaction no longer proceeds, and the residual propionitrile is <0.2%. Close the inlet and outlet valves of the circulating water, change to ice water for cooling, cool down to about 0°C, transfer the reaction material into the centrifuge, start centrifugal discharging, and continuously add a small amount of the rinsing solvent MTBE during the discharging process until the solid material concentrated by centrifugation presents a dry powder state, indicating complete centrifugation. Subsequently, collect the liquid phase material after centrifugation, perform atmospheric distillation to recover the solvent, and then perform vacuum distillation again to obtain 2,2-diisopropylpropionitrile. Finally, detect that the finished product content in the subsequent distillate material is ≥97%, start centralized collection, and the finally obtained finished product amount is 95 kg, the finished product content is 99.5%, and the yield is 85.4%.

[0049] It should be noted that in this embodiment, the addition amount of the metal organic ligand Ni(CO)4 is reduced, the addition amount of the metal organic ligand Ni(CO)4 is 0.3% of the mass of sodium amide, and the dropping speed of the mixture of propionitrile and 2-bromopropane is increased, and the dropping time is 5 h.

[0050] Example Three

[0051] Check the tightness of the 1000L stainless steel reactor, confirm that the inside of the reactor is dry and free of water, and confirm that the equipment is working properly. Charge 320 kg of MTBE and 68 kg of sodium amide (10% in excess) into the reactor. Start low-speed stirring and add 0.68 kg of metal-organic ligand Ni(CO)4. Then adjust the stirring speed to 200 revolutions per minute and stir for 0.5 hours at a temperature of 20 - 35 °C. Subsequently, start pumping 44 kg of propionitrile and 225 kg of 2-bromopropane into the dropping tank, adjust the flow rate of the metering pump to 0.75 L / min, and pass in circulating water for temperature control, then start dropping the mixed solution. Observe the temperature during the dropping process, adjust the inlet and outlet valves of the circulating water to keep the reaction temperature within the range of 20 - 40 °C, and take samples at intervals to detect the reaction progress. After the dropping is completed, continue the reaction for 4 hours, take samples to detect and confirm that the reaction no longer proceeds, and the residual propionitrile is <0.2%. Close the inlet and outlet valves of the circulating water, change to ice water for cooling, cool down to about 0 °C, transfer the reaction material into the centrifuge, start centrifugal discharging, and continuously add a small amount of rinsing solvent MTBE during the discharging process until the solid material concentrated by centrifugation presents a dry powder state, indicating complete centrifugation. Subsequently, collect the liquid phase material after centrifugation, carry out atmospheric distillation to recover the solvent, and then carry out vacuum distillation again to obtain 2,2-diisopropylpropionitrile. Finally, detect that the content of the finished product in the subsequent distillate material is ≥97%, start centralized collection, and the final amount of the obtained finished product is 103 kg, the content of the finished product is 99.65%, and the yield is 92.6%.

[0052] It should be noted that in this embodiment, the addition amount of the metal-organic ligand Ni(CO)4 is increased. The addition amount of the metal-organic ligand Ni(CO)4 is 1% of the mass of sodium amide. The dropping speed and dropping time of the propionitrile and 2-bromopropane mixture are the same as those in Example 2, and the yield is increased.

[0053] Example 4

[0054] Check the sealing of the 1000L stainless steel reactor, confirm that the inside of the reactor is dry and free of water, and confirm that the equipment is working properly. Charge 320 kg of MTBE and 68 kg of sodium amide (10% in excess) into the reactor, start low-speed stirring, and add 0.68 kg of the metal organic ligand Ni(CO)4. Then adjust the stirring speed to 200 revolutions per minute and stir for 0.5 hours at a temperature of 20 - 35°C. Subsequently, start pumping 44 kg of propionitrile and 225 kg of 2-bromopropane into the dropping tank, adjust the flow rate of the metering pump to 0.55 L / min, and pass in circulating water for temperature control, and start dropping the mixed solution. Observe the temperature during the dropping process, adjust the circulating water inlet and outlet valves to keep the reaction temperature within the range of 20 - 40°C, and take samples at intervals to detect the reaction progress. After the dropping is completed, continue the reaction for 4 hours, take samples for detection to confirm that the reaction no longer proceeds, and the residual propionitrile is <0.2%. Close the circulating water inlet and outlet valves, change to ice water for cooling, cool down to about 0°C, transfer the reaction material into the centrifuge, start centrifugal discharging, and continuously add a small amount of the rinsing solvent MTBE during the discharging process until the solid material concentrated by centrifugation presents a dry powder state, indicating complete centrifugation. Subsequently, collect the liquid phase material after centrifugation, perform atmospheric distillation to recover the solvent, and then perform vacuum distillation to obtain 2,2-diisopropylpropionitrile. Finally, detect that the content of the finished product in the subsequent distillate material is ≥97%, start centralized collection, and the final amount of the obtained finished product is 105 kg, the content of the finished product is 99.75%, and the yield is 94.4%.

[0055] It should be noted that in this embodiment, the addition amount of the metal organic ligand Ni(CO)4 is the same as that in Example 3, the dropping speed of the propionitrile and 2-bromopropane mixture is reduced, the dropping time is 7.5 h, and the yield increases.

[0056] Therefore, the present invention adopts the above-mentioned green and efficient method for preparing 2,2-diisopropylpropionitrile. A metal organic ligand catalyst is added to the raw materials, and the reaction is carried out under normal temperature conditions of 20 - 40°C. Samples can be taken at any time during the reaction process for detection, so as to control the progress of the reaction, maximize the reaction efficiency, and subsequent water addition is not required to dissolve the by-product sodium bromide, avoiding the generation of side reactions under high temperature conditions, thereby achieving the purpose of improving the production yield, reducing raw material consumption and energy consumption.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A green and efficient method for preparing 2,2-diisopropylpropionitrile, characterized in that, The raw material components include sodium amide, propionitrile, 2-bromopropane, an organic solvent, and a metal-organic ligand catalyst, abbreviated as catalyst M; the metal-organic ligand catalyst is Ni(CO)4, and the organic solvent is methyl tert-butyl ether MTBE; The preparation method of 2,2-diisopropylpropionitrile using the above raw material components includes the following steps: S1. Add the organic solvent to a stainless steel reactor, and add sodium amide and the metal-organic ligand catalyst to the stainless steel reactor under stirring. The reaction temperature range is 20~40°C. After stirring for half an hour, carry out a dropwise reaction; S2. Mix propionitrile and 2-bromopropane evenly, and then slowly add the evenly mixed solution to the stainless steel reactor, and control the dropping time of the mixed solution; S3. After the dropping is completed, continue the insulation reaction, and sample during the reaction to monitor the reaction end point by gas chromatography; S4. After the reaction in step S3 is completed, cool down and put the reaction solution into a centrifuge to separate the solid and liquid. Add the washing solvent to the centrifuge multiple times, and finally collect the organic phase uniformly. The organic phase is the crude material of 2,2-diisopropylpropionitrile; S5. Put the organic phase into a distillation kettle, first carry out desolvation at normal pressure, and then carry out vacuum rectification to obtain 2,2-diisopropylpropionitrile; Its chemical reaction formula is: 。 2. The method for preparing 2,2 - diisopropylpropionitrile as claimed in claim 1, wherein In step S4, during the process of adding the washing solvent to the centrifuge multiple times and collecting the organic phase uniformly, the centrifuge uses nitrogen replacement and real-time monitors the oxygen solubility, and is interlocked with the start and stop of the centrifuge.

3. A method for preparing 2,2 - diisopropylpropionitrile with high green efficiency according to claim 2, characterized in that, The washing solvent is the same solvent as the organic solvent in step S1, and is used to reduce the loss of reaction products.

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