CN113307746A - Two-step preparation method of 6-aminocapronitrile - Google Patents
Two-step preparation method of 6-aminocapronitrile Download PDFInfo
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Abstract
The invention relates to a two-step preparation method of 6-aminocapronitrile, which comprises the following steps: carrying out ammonolysis reaction on caprolactam and hot ammonia gas in an inert solvent or in a molten state to obtain 6-aminocaproamide; 6-aminocaproamide is dehydrated in the presence of a dehydrating agent to give 6-aminocapronitrile. The invention carries out ring-opening ammonolysis under anhydrous condition, effectively controls the polymerization of ammonolysis products and reduces the generation of byproducts; under the condition of no catalyst, the dehydrating agent is directly used for dehydration reaction, so that the problems of catalyst coking, short service life of the catalyst and the like in the catalytic dehydration process are effectively avoided.
Description
Technical Field
The invention relates to the technical field of synthesis of hexamethylene diamine, and particularly relates to a method for preparing a key intermediate 6-aminocapronitrile of hexamethylene diamine by a two-step method.
Background
1, 6-hexamethylene diamine is an important intermediate of high-performance materials such as nylon 66, nylon 610 and the like, is also used in the production of polyurethane such as 1, 6-Hexamethylene Diisocyanate (HDI), and can also be used as a curing agent of urea resin and epoxy resin.
The production method of hexamethylenediamine is mainly four according to different raw materials, namely a butadiene method, an acrylonitrile method, a adipic acid method and a caprolactam method.
The butadiene method generally adopts a complex of transition metals such as Rh, Ni, Ru and the like as a catalyst, introduces hydrocyanic acid of two molecules into butadiene, prepares adiponitrile through addition reaction, and prepares 1, 6-hexamethylene diamine through hydrogenation; the method has the advantages of low cost of raw materials for production, easy automatic control of equipment and good product quality; the disadvantages of using virulent hydrocyanic acid, having extremely high requirements on production equipment, operation and management, great occupational hazards, great difficulty in catalyst preparation technology and high construction investment.
The method for synthesizing adiponitrile by electrolytic dimerization of acrylonitrile uses propylene as a raw material, converts the propylene into acrylonitrile by using oxygen, ammonia gas and a catalyst, further electrolytically reduces the acrylonitrile into adiponitrile, and then obtains 1, 6-hexamethylene diamine by hydrogenation reduction and refining of the adiponitrile; the method has the advantages of simple process flow and high conversion rate; the defects are that the electrolysis process has more technical nodes, great control difficulty and high safety risk.
Adipic acid is aminated and dehydrated in a molten state to prepare adiponitrile by a adipic acid method, and 1, 6-hexamethylene diamine is obtained by hydrogenation reduction and refining; the method has the advantages that the technical route is relatively mature, the yield of the raw material adipic acid is excessive, and the manufacturing cost of the adiponitrile gradually has certain competitiveness along with the reduction of the manufacturing cost of the adipic acid; the disadvantages are high energy consumption, easy coking and corrosion of the reactor, low product yield and poor quality.
The caprolactam method is originated from 60 s in the 20 th century, and waste nylon is depolymerized to obtain caprolactam by a Nippon Dongli company, and the caprolactam is reacted with ammonia gas under the action of a catalyst to obtain 6-aminocapronitrile, and the 6-aminocapronitrile is further subjected to hydrogenation reduction and refining to obtain 1, 6-hexamethylenediamine. The process has high caprolactam raw material price and high product manufacturing cost, and cannot be popularized on a large scale, and the production of a Nippon Dongli device is stopped in 1989.
However, with the improvement of the caprolactam preparation process, particularly with the popularization and application of a new process, the total caprolactam yield in 2019 at home and abroad is 771 ten thousand tons/year, wherein the domestic capacity is 401 ten thousand tons/year, the foreign capacity is 370 ten thousand tons/year, the Chinese capacity accounts for up to 52%, and the domestic capacity in 2021 can reach 559 ten thousand tons; experts predict that caprolactam production will reach 1000 ten thousand tons in 2025; the process for preparing hexamethylenediamine by caprolactam is also more competitive with the reduction of the manufacturing cost of caprolactam.
The Chinese patent application with the application number of 201710943063.4 discloses a method and a device for preparing 6-aminocapronitrile by a one-step liquid phase method caprolactam liquid phase method, the process is to carry out ammonolysis dehydration on caprolactam and ammonia in a reaction kettle under the condition of taking phosphoric acid or phosphate as a catalyst to prepare 6-aminocapronitrile, but the caprolactam conversion rate in the process is only 50-60 percent, and the catalyst is difficult to recover, and the manufacturing cost is higher.
The Chinese patent application with the application number of 201710942344.8 discloses a method for preparing 6-aminocapronitrile by a caprolactam gas phase one-step method, which comprises the steps of heating and vaporizing caprolactam, mixing the caprolactam with hot ammonia gas, and contacting the caprolactam with a catalyst through a fixed bed reactor for ammoniation and dehydration reaction to prepare 6-aminocapronitrile, wherein the patent process describes that the reaction conversion rate is improved to 96%. However, caprolactam is easy to generate ring-opening self-polymerization in the processes of vaporization and reaction in the presence of a trace amount of water, which reduces the reaction selectivity, and the generated polymers are all attached to the surface of the catalyst and coked under the high-temperature condition, thereby influencing the stable operation of the device and the service life of the catalyst.
The Chinese patent application with the application number of 202010525804.9 discloses a method and a device for preparing 6-aminocapronitrile by a two-step method. As water is firstly used for hydrolytic ring opening in the first step of reaction, more energy is consumed to remove free water after the reaction is finished, the polymerization degree of caprolactam is increased due to the introduction of water, and polymers are easy to coke at high temperature after the subsequent catalytic ammoniation dehydration, so that the total yield of the reaction is unstable, and the quality of products is also influenced.
Disclosure of Invention
The invention mainly aims to provide a method for preparing 6-aminocapronitrile by a two-step method, which aims to solve the problems that the operation stability of a device is affected by easy coking and inactivation of a catalyst for preparing 6-aminocapronitrile by the one-step method in the prior art and the problems of increased energy consumption and increased polymer caused by hydrolysis and ammoniation in the original two-step method patent application and coking of the catalyst in catalytic ammoniation dehydration.
In order to achieve the above object, there is provided according to the present invention a two-step process for preparing 6-aminocapronitrile, comprising:
step S1, ammonolysis reaction is carried out on caprolactam and hot ammonia gas in an inert solvent or in a molten state to obtain 6-aminocaproamide;
the reaction equation is as follows:
step S2, dehydrating the 6-aminocaproamide in the presence of a dehydrating agent to obtain 6-aminocapronitrile,
the reaction equation is as follows:
further, in the above step S1, the inert solvent is a solvent that does not participate in the ammonolysis reaction, and may be, for example, one or more selected from benzene, toluene, xylene, chlorobenzene, chloroform, dichloromethane, dichloroethane, cyclohexane, acetonitrile, and the like, and is preferably one or more selected from toluene and acetonitrile, but is not limited thereto.
In step S1, the caprolactam is first dissolved in an inert solvent at a temperature of 0 to 200 ℃, preferably 30 to 120 ℃, for example, 40, 50, 60, 70, 80, 90, 100, 110 ℃, etc., but not limited thereto.
Further, in the step S1, the temperature of the hot ammonia gas may be 100-.
Further, in the step S1, the molar ratio of caprolactam to ammonia gas may be 1:1 to 100, preferably 1:5 to 20, such as 1:6, 1:7, 1:8, 1:10, 1:12, 1:15, 1:18, 1:19, but is not limited thereto.
Further, in the step S1, the mass percentage concentration of caprolactam in the inert solvent may be 0.1% to 99.9%, preferably 25% to 80%, for example, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, etc., but is not limited thereto.
Further, in the step S1, the reaction temperature of the ammonolysis may be 100 to 400 ℃, preferably 200 to 380 ℃, such as 210, 220, 230, 240, 250, 260, 280, 290, 300, 310, 320, 350, 360, 370 ℃, but is not limited thereto.
Further, in the above step S1, the reaction pressure of the ammonolysis may be 0.1 to 10MPa, for example, 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, 9.0MPa, etc., but is not limited thereto.
In addition, the above step S1 may further include a purification step to obtain high purity 6-aminocaproamide.
Further, in the above step S2, the dehydrating agent may be one or more selected from phosgene, triphosgene, thionyl chloride, phosphorus pentoxide, p-toluenesulfonyl chloride, Dicyclohexylcarbodiimide (DCC), phosphorous trichloride o-phenylene, titanium tetrachloride-tertiary amine, triphenylphosphine-carbon tetrachloride-triethylamine, trichloroacetyl chloride-triethylamine, trifluoromethanesulfonic anhydride-triethylamine, dibutyltin oxide, and the like, and preferably one or more selected from phosgene, triphosgene, and thionyl chloride.
Further, in the step S2, the reaction temperature for the dehydration may be 50-500 ℃, preferably 80-300 ℃, more preferably 110-250 ℃, such as 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240 ℃ and the like, but is not limited thereto.
Further, in the step S2, the reaction pressure for dehydration may be 0 to 10MPa, preferably 0.1 to 1.0MPa, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9MPa, or the like, but is not limited thereto.
Further, in the step S2, the molar ratio of the dehydrating agent to the 6-aminocaproamide may be 1 to 50:1, preferably 1 to 20:1, for example, 1.5:1, 2:1, 2.5:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 15:1, 18:1, 19:1, and the like, but is not limited thereto.
In addition, the step S2 may further include a vacuum distillation purification step to obtain high-purity 6-aminocapronitrile.
By applying the technical scheme of the invention, two steps are adopted, and step S1 is used for ring-opening ammonolysis of caprolactam under the solvent anhydrous condition, so that the hydrolytic polymerization of caprolactam is avoided under the anhydrous condition, and a crude product of 6-aminocaproamide is obtained; and adding a dehydrating agent into the crude product, and further dehydrating the 6-aminocaproamide under the condition of no catalyst to obtain a target product 6-aminocapronitrile.
According to the method, ring-opening ammonolysis is carried out under the anhydrous condition in the step S1, so that the polymerization of ammonolysis products is effectively controlled, and the generation of byproducts is reduced; in the step S2, the dehydrating agent is directly used for dehydration reaction without catalyst, thereby effectively avoiding the problems of catalyst coking, short service life of the catalyst and the like in the catalytic dehydration process.
The present invention has been described in detail hereinabove, but the above embodiments are merely illustrative in nature and are not intended to limit the present invention. Furthermore, there is no intention to be bound by any theory presented in the preceding prior art or the summary or the following examples.
Unless expressly stated otherwise, a numerical range throughout this specification includes any sub-range therein and any numerical value incremented by the smallest sub-unit within a given value. Unless expressly stated otherwise, numerical values throughout this specification represent approximate measures or limitations to the extent that such deviations from the given values, as well as embodiments having approximately the stated values and having the exact values stated, are included. Other than in the operating examples provided at the end of the detailed description, all numbers expressing quantities or conditions of parameters (e.g., quantities or conditions) used in the specification (including the appended claims) are to be understood as being modified in all instances by the term "about" whether or not "about" actually appears before the number. "about" means that the numerical value so stated is allowed to be somewhat imprecise (with some approach to exactness in that value; about or reasonably close to that value; approximately). As used herein, "about" refers to at least variations that can be produced by ordinary methods of measuring and using such parameters, provided that the imprecision provided by "about" is not otherwise understood in the art with this ordinary meaning. For example, "about" can include variations of less than or equal to 10%, less than or equal to 5%, less than or equal to 4%, less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, or less than or equal to 0.5%.
Drawings
FIG. 1 is a graph showing the carbon deposition of the catalyst and quartz sand in comparative example 1;
fig. 2 is a graph showing the carbon deposition of the catalyst in comparative example 2.
Detailed Description
The present invention is further illustrated by the following examples, which are provided for illustrative purposes only and are not to be construed as limiting the scope of the invention.
The experimental method comprises the following steps:
detection of polymerization by-products
The reaction by-product is mainly ring-opening polymerization of caprolactam under the action of a trace amount of water to form a small amount of polymerization, and the reaction equation is as follows:
the polymerization by-products were detected as follows:
for the determination of the content of 6-aminocaproic acid obtained by ring cleavage in the ammonolysis product, reference is made to the non-aqueous titration method of Lihexoic acid and its hydrochloride salt, Lihexoic acid, Lehailong, et al, Ningbo university school of Material science and chemical engineering.
The polymer detection method can be referred to CN201410769073.7 "a caprolactam hydrolytic polymer and its hydrolytic polymerization method".
Detection of coking
Coking was detected as follows:
for the coking condition in the catalytic ammoniation reaction, an element analyzer is adopted to detect the content of carbon element attached in the catalyst, thereby calculating the coking content. In the embodiment of the invention, no catalyst is used, and the coking condition of the catalyst does not need to be detected.
Caprolactam conversion and 6-aminocaproamide selectivity were calculated as follows:
metering of the total mass M of caprolactamStep 1And the number of moles R and the total mass M of the discharged sampleGo out 1(including sampling port samples and materials collected by a condensation recovery system), and testing the mass percentage content of the 6-aminocaproamide and the caprolactam of the discharged sample by a GC external standard method, thereby calculating the mole number G of the 6-aminocaproamide and the mole number H of the caprolactam of the discharged sample.
The 6-aminocaproamide conversion and 6-aminocapronitrile selectivity were calculated as follows:
metering of the total mass M of 6-aminocaproamideStep 2And the number of moles N and the total mass of the discharged sampleQuantity MGo out 2(including sampling port samples and materials collected by a condensation recovery system), and testing the mass percentage content of the 6-aminocapronitrile and the 6-aminocaproamide in the discharged sample by a GC external standard method, thereby calculating the mole number D of the 6-aminocapronitrile and the mole number E of the 6-aminocaproamide in the discharged sample.
Example 1
Weighing 22.63g (0.2mol) of caprolactam, adding the caprolactam into a 500ml pressure kettle, adding 34g of toluene, starting stirring, and heating to 60 +/-2 ℃ to dissolve. And (2) ammonia gas passes through the preheater, the temperature reaches 150 ℃, the ammonia gas is introduced into the pressure kettle, the temperature of the materials in the reaction kettle is continuously increased to 200-fold organic nitrogen 250 ℃, hot ammonia gas is continuously introduced, the back pressure is 2.5MPa, the temperature is reduced and the pressure is relieved after the stirring reaction is carried out for about 20 hours, 59g of toluene solution of the crude 6-aminocaproamide is obtained, and 20g of ammonia gas is consumed in the reaction process. Tests show that the mass percentage of the 6-aminocaproamide is 72.18%, the caprolactam conversion rate is 73.1%, and the selectivity of the 6-aminocaproamide is 95.3%. The results of the detection of the polymerization by-products are shown in Table 1 below.
Transferring the toluene solution of the crude 6-aminocaproamide into a pressure-resistant glass reaction kettle, adding 82.68g (0.28mol) of triphosgene into the reaction kettle, stirring and heating to 180 ℃, carrying out reaction for about 8 hours at the backpressure of 0.8MPa, cooling to obtain 63g of reaction liquid, and carrying out reduced pressure rectification and purification to obtain 12.88g (with the purity of 99.8%) of 6-aminocapronitrile, the conversion rate of 6-aminocaproamide is 85%, and the selectivity of 6-aminocapronitrile is 97%.
Example 2
Weighing 22.63g (0.2mol) of caprolactam, adding the caprolactam into a 500ml pressure kettle, adding 68g of acetonitrile, starting stirring, and heating to 30 +/-2 ℃ for dissolution. And ammonia gas passes through the preheater, the temperature reaches 250 ℃, the ammonia gas is introduced into the pressure kettle, the temperature of the materials in the reaction kettle is continuously increased to 300-350 ℃, hot ammonia gas is continuously introduced, the back pressure is 3.0MPa, the temperature is reduced and the pressure is relieved after the stirring reaction is carried out for about 20 hours, 89g of acetonitrile solution of the crude 6-aminocaproamide is obtained, and 31g of ammonia gas is consumed in the reaction process. Tests show that the mass percentage of the 6-aminocaproamide is 83.94%, the caprolactam conversion rate is 82.7%, and the selectivity of the 6-aminocaproamide is 97.1%. The results of the detection of the polymerization by-products are shown in Table 1 below.
Transferring the acetonitrile solution of the crude 6-aminocaproamide into a pressure-resistant glass reaction kettle, gradually adding 187g (1.57mol) of thionyl chloride into the reaction kettle, stirring and heating to 110 ℃, carrying out reaction for about 6 hours at the reaction kettle back pressure of 0.2MPa, cooling to obtain 246g of reaction liquid, and carrying out reduced pressure rectification and purification to obtain 15.4g (purity is 99.8%) of 6-aminocapronitrile, conversion rate of 6-aminocaproamide is 91%, and selectivity of 6-aminocapronitrile is 96%.
Example 3
Weighing 22.63g (0.2mol) of caprolactam, adding the caprolactam into a 500ml pressure kettle, adding 25g of chlorobenzene, starting stirring, and heating to 70 +/-2 ℃ for dissolution. And ammonia gas passes through the preheater, the temperature reaches 200 ℃, the ammonia gas is introduced into the pressure kettle, the temperature of materials in the reaction kettle is continuously increased to 300-350 ℃, hot ammonia gas is continuously introduced, the back pressure is 3.0MPa, the materials are stirred for reaction for about 13 hours, then the temperature is reduced and the pressure is relieved to obtain 46g of crude 6-aminocaproamide chlorobenzene solution, and 23g of ammonia gas is consumed in the reaction process. Tests show that the mass percentage of the 6-aminocaproamide is 75.51 percent, the caprolactam conversion rate is 76.5 percent, and the selectivity of the 6-aminocaproamide is 95.7 percent. The results of the detection of the polymerization by-products are shown in Table 1 below.
Transferring the acetonitrile solution of the crude 6-aminocaproamide into a pressure-resistant glass reaction kettle, gradually adding 166.2g (1.17mol) of phosphorus pentoxide into the reaction kettle, stirring and heating to 250 ℃, carrying out reaction for about 13 hours at the backpressure of 1.0MPa, cooling to obtain 209g of reaction liquid, and carrying out reduced pressure rectification and purification to obtain 14.97g (with the purity of 99.8%) of 6-aminocapronitrile, the conversion rate of 6-aminocaproamide of 93% and the selectivity of 6-aminocapronitrile of 98%.
Example 4
Weighing 22.63g (0.2mol) of caprolactam, adding the caprolactam into a 500ml pressure kettle, adding 60g of toluene, starting stirring, and heating to 40 +/-2 ℃ for dissolution. And (3) ammonia gas passes through a preheater, the temperature reaches 250 ℃, the ammonia gas is introduced into the pressure kettle, the temperature of materials in the reaction kettle is continuously raised to 350-. Tests show that the mass percentage of the 6-aminocaproamide is 74.21 percent, the caprolactam conversion rate is 75.3 percent, and the selectivity of the 6-aminocaproamide is 95.4 percent. The results of the detection of the polymerization by-products are shown in Table 1 below.
Transferring the toluene solution of the crude 6-aminocaproamide into a pressure-resistant glass reaction kettle, gradually adding 128g (0.43mol) of triphosgene into the reaction kettle, stirring and heating to 250 ℃, carrying out reaction for about 7 hours at the backpressure of 1.0MPa, cooling to obtain 202g of reaction liquid, and carrying out reduced pressure rectification and purification to obtain 13.75g (with the purity of 99.8%) of 6-aminocapronitrile, the conversion rate of 89% of 6-aminocaproamide and the selectivity of 95.9% of 6-aminocapronitrile.
Comparative example 1
According to the method disclosed in the Chinese patent application with the application number of 201710942344.8.
Specifically, 35g of catalyst is filled into a fixed bed reactor, caprolactam is melted at 80 ℃ and then is pumped into a preheater through a temperature control metering pump to be preheated together with ammonia gas, the mass ratio of the caprolactam to the ammonia gas is 1:3, the preheating temperature is 330 ℃, mixed steam enters the fixed bed reactor to be in contact reaction with the catalyst, the contact time is 0.2s, the reaction temperature is 350 ℃, the reaction pressure is 0.15MPa, and the catalyst is a modified silicon-aluminum molecular sieve. The caprolactam conversion was 55.3% and the 6-aminocapronitrile selectivity was 94.7%.
The coking conditions were as follows:
the generated polymerization byproducts are attached to the surface of the catalyst and are coked to form carbon deposit under the high-temperature condition. Because the whole device is used for continuously feeding and discharging materials, the catalyst and quartz sand are taken out after the equipment runs for 360 hours, the carbon deposition on the catalyst is detected by an element analyzer, the content of the carbon deposition in the catalyst is 11.69 percent, and the appearance state of the catalyst is shown in figure 1.
Comparative example 2
According to the method disclosed in the Chinese patent application with the application number of 202010525804.9.
Specifically, caprolactam and a hydrochloric acid aqueous solution are mixed and hydrolyzed in a reaction kettle, the mass ratio of the caprolactam to water to hydrogen chloride is 1:10:0.002, the mixture reacts for 24 hours at 140 ℃ and 0.6MPa, 80% of moisture is evaporated from the obtained product under reduced pressure, hot ammonia gas at 150 ℃ is continuously introduced into the reaction kettle, the ammonia gas flux is 3 times of the mass of the caprolactam per hour, and the amino caproamide crude product is obtained after 5 hours of continuous gas introduction.
The crude product is treated at a mass space velocity of 6h-1Pumping the mixture into a fixed bed reactor filled with an alumina catalyst by a temperature-controlled metering pump, and simultaneously introducing ammonia gas with the mass of 300 ℃ which is 7 times that of the crude aminocaproamide product, wherein the conversion per pass of the total caprolactam is 67.8 percent, and the highest selectivity of the aminocapronitrile is 94.8 percent.
The coking conditions were as follows:
the generated polymerization byproducts are attached to the surface of the catalyst and are coked to form carbon deposit under the high-temperature condition. The reaction in this step is continuous feeding and discharging, the catalyst is taken out after the device runs for 360 hours, carbon deposition on the catalyst is detected by an element analyzer, the content of the carbon deposition in the catalyst is 9.79 percent, and the appearance state of the catalyst is shown in figure 2.
TABLE 1 statistical table of the results of the ammonolysis polymerization by-product detection
| Examples | Measurement results of polymerization by-product |
| Example 1 | 0.08w％ |
| Example 2 | 0.06w％ |
| Example 3 | 0.07w％ |
| Example 4 | 0.08w％ |
| Comparative example 1 carbon deposition | 11.69％ |
| Comparative example 2 carbon deposition | 9.79％ |
As can be seen from table 1, the process of the present application effectively reduces the production of polymeric by-products (e.g. hydrolytic polymerization of caprolactam and polymerization of ammonolysis products) compared to the prior art.
In addition, the coking condition shows that the method effectively avoids the problems of catalyst coking, short service life of the catalyst and the like in the catalytic dehydration process.
Claims (10)
1. A two-step process for the preparation of 6-aminocapronitrile comprising:
step S1, ammonolysis reaction is carried out on caprolactam and hot ammonia gas in an inert solvent or in a molten state to obtain 6-aminocaproamide;
the reaction equation is as follows:
step S2, dehydrating the 6-aminocaproamide in the presence of a dehydrating agent to obtain 6-aminocapronitrile,
the reaction equation is as follows:
2. the method according to claim 1, wherein in step S1, the inert solvent is one or more selected from the group consisting of benzene, toluene, xylene, chlorobenzene, chloroform, dichloromethane, dichloroethane, cyclohexane and acetonitrile.
3. The method of claim 1, wherein in step S1, the inert solvent is one or more selected from toluene and acetonitrile.
4. The process of claim 1, wherein in step S1, the caprolactam is first dissolved in an inert solvent at a temperature of 0 to 200 ℃.
5. The method of claim 1, wherein, in step S1,
the temperature of the hot ammonia gas is 100-300 ℃;
the molar ratio of caprolactam to ammonia gas is 1: 1-100;
the mass percentage concentration of caprolactam in the inert solvent is 0.1-99.9%;
the reaction temperature of the ammonolysis is 100-400 ℃; and/or
The reaction pressure of the ammonolysis is 0.1-10 MPa.
6. The method of claim 1, wherein, in step S1,
the temperature of the hot ammonia gas is 150-250 ℃;
the molar ratio of caprolactam to ammonia gas is 1: 5-20;
the mass percentage concentration of caprolactam in the inert solvent is 25-80 percent; and/or
The reaction temperature of the ammonolysis is 200-380 ℃.
7. The method of claim 1, wherein in step S2, the dehydrating agent is one or more selected from the group consisting of phosgene, triphosgene, thionyl chloride, phosphorus pentoxide, p-toluenesulfonyl chloride, Dicyclohexylcarbodiimide (DCC), phosphorous trichloride o-phenylene, titanium tetrachloride-tertiary amine, triphenylphosphine-carbon tetrachloride-triethylamine, trichloroacetyl chloride-triethylamine, trifluoromethanesulfonic anhydride-triethylamine, and dibutyltin oxide.
8. The method according to claim 1, wherein in step S2, the dehydrating agent is one or more selected from phosgene, triphosgene and thionyl chloride.
9. The method of claim 1, wherein, in step S2,
the reaction temperature of dehydration is 50-500 ℃;
the reaction pressure of dehydration is 0-10 MPa; and/or
The molar ratio of the dehydrating agent to the 6-aminocaproamide is 1-50: 1.
10. The method of claim 1, wherein, in step S2,
the reaction temperature of dehydration is 80-300 ℃;
the reaction pressure of dehydration is 0.1-1.0 MPa; and/or
The molar ratio of the dehydrating agent to the 6-aminocaproamide is 1-20: 1.
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| CN114773224A (en) * | 2022-04-29 | 2022-07-22 | 河南新邦化工技术有限公司 | Method for synthesizing nitrile compound by amide dehydration |
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