CN112592302A - Method for preparing methylthio aminobutyronitrile by utilizing continuous ammoniation of cyanohydrin - Google Patents
Method for preparing methylthio aminobutyronitrile by utilizing continuous ammoniation of cyanohydrin Download PDFInfo
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- CN112592302A CN112592302A CN202011490390.7A CN202011490390A CN112592302A CN 112592302 A CN112592302 A CN 112592302A CN 202011490390 A CN202011490390 A CN 202011490390A CN 112592302 A CN112592302 A CN 112592302A
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- C07C319/00—Preparation of thiols, sulfides, hydropolysulfides or polysulfides
- C07C319/14—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of sulfides
- C07C319/20—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of sulfides by reactions not involving the formation of sulfide groups
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Abstract
The invention aims at the technical field of methylthio aminobutyronitrile, and particularly relates to a method for preparing methylthio aminobutyronitrile by utilizing continuous ammoniation of cyanohydrin; cyanhydrin and an ammonia source are carried out in a preheating mode according to a certain mass ratio in a high-efficiency mixing continuous reactor for ammoniation reaction to prepare methylthio aminobutyronitrile. The invention aims to provide a method for preparing methylthio aminobutyronitrile by utilizing continuous ammoniation of cyanohydrin, which improves the conversion rate of cyanohydrin and the selectivity of methylthio aminobutyronitrile, reduces the generation of dinitrile by-products and further improves the yield of methylthio aminobutyronitrile products by controlling the mass ratio of the cyanohydrin to an ammonia source, efficiently mixing the cyanohydrin with the ammonia source, optimizing ammoniation process parameters and other procedures.
Description
Technical Field
The invention aims at the technical field of methylthio aminobutyronitrile, and particularly relates to a method for preparing methylthio aminobutyronitrile by utilizing continuous ammoniation of cyanohydrin.
Background
2-amino-4-methylthiobutyronitrile is an important chemical intermediate and can be used for preparing antiepileptic drug levetiracetam, novel antibiotic acetylglucosamine deacetylase, immune biochemical preparation homocysteine and the like. The known chemical synthesis process route is that 2-hydroxy-4-methylthiobutyronitrile (abbreviated as 'cyanohydrin') is aminated to prepare 2-amino-4-methylthiobutyronitrile (abbreviated as 'methylthioaminobutyronitrile'), but the amination process generates dinitrile byproducts, and the chemical name of the dinitrile byproducts is as follows: 2, 2-bis- (2-methylthioethyl) iminodiacetonitrile, when the proportion relationship between cyanohydrin and ammonia source is not good, the concentration of ammonia source is small and the control of ammoniation condition is not good, the generation of dinitrile by-product (specifically DN related in CN 1103066A) is promoted, and the yield of methylthio aminobutyronitrile product is further influenced, therefore, the effect is realized by controlling the concentration, proportion and process condition of ammonia and cyanohydrin.
Chinese patent CN1400966A discloses a method for preparing 2-amino-4-methylthiobutanamide by contacting cyanohydrin with pure ammonia, contacting 2-hydroxy-4-methylthiobutyronitrile with ammonia or ammonium solution and water in the first step of reaction to generate a mixture containing 2-amino-4-methylthiobutyronitrile, removing excessive ammonia after the first step of reaction is finished, and then hydrolyzing in the presence of ketone and metal alkali hydroxide; the method lacks preheating and efficient mixing processes for contacting 2-hydroxy-4-methylthiobutyronitrile with ammonia or ammonium solution and water, and simultaneously, the mass ratio of the sum of cyanohydrin and ammonia to the solution is not determined, and dinitrile byproducts are not quantitatively analyzed, so that the yield of cyanohydrin is low, and more dinitrile byproducts are generated.
Chinese patent CN1103066A discloses a continuous process for the production of methionine or methionine derivatives by hydrolysis of methionine nitriles to methionine amides in the presence of ketones followed by saponification with alkali to produce methionine or a methionine salt, wherein DE-OS1643535 describes a reaction carried out at an excess pressure of 4.6-55 equivalents of NH3 based on MMP and a NH3 concentration of about 50% by weight at a temperature which can be as high as 60 ℃ maximum, preferably 15-40 ℃, whereas, especially for a continuous process, the residence time of 4.5-5.5 hours is too long and the process is accompanied by considerable by-product production (DN and DNMA) which is unacceptable for continuous large-scale production, the methionine yield after acid hydrolysis of the amino nitriles being 97-99% in MMP; this process discloses the formation of dinitrile by-products (DN) during the ammoniation process, but does not disclose a method for reducing the formation of dinitrile by-products.
In summary, the current preparation process of 2-amino-4-methylthiobutyronitrile has the main problems that: (1) in the ammoniation process, the ratio of the mass sum of the cyanohydrin and the ammonia source to the total mass ratio of the solution is not well controlled, dinitrile byproducts are easily generated, and the yield of methylthio aminobutyronitrile products is further influenced; (2) the ammoniation condition is not well controlled, the generation of dinitrile byproducts can be promoted, and the yield of methylthio aminobutyronitrile products is further influenced; (3) the cyanogen alcohol and the ammonia source are not fully mixed, the ammonification reaction rate is slow, the yield of the methylthio aminobutyronitrile product is low, and the method is not suitable for industrial production.
Therefore, a method for preparing methylthio aminobutyronitrile by utilizing cyanohydrin to carry out continuous ammoniation is provided.
Disclosure of Invention
The invention aims to provide a method for preparing methylthio aminobutyronitrile by utilizing continuous ammoniation of cyanohydrin, which is used for improving the ammoniation reaction rate, reducing the generation of dinitrile byproducts and further improving the yield of methylthio aminobutyronitrile products by optimizing ammoniation process parameters, controlling the mass relation between the cyanohydrin and an ammonia source and promoting the efficient mixing of the cyanohydrin and the ammonia source.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the method for preparing methylthio aminobutyronitrile by utilizing continuous ammoniation of cyanohydrin comprises the step of carrying out ammoniation reaction on cyanohydrin and an ammonia source in a high-efficiency mixing continuous reactor according to a certain mass ratio in a preheating mode to prepare methylthio aminobutyronitrile, wherein the ammonia source is ammonia gas or ammonia water.
Because of the problems of poor control of the proportion relationship between the cyanohydrin and the ammonia source and poor control of the mass ratio of the sum of the cyanohydrin and the ammonia source in the total solution mass ratio in the ammoniation process, the ammonia source is ammonia gas or ammonia water, wherein the molar ratio of the cyanohydrin and the ammonia source is 1:3-7, the concentration of the ammonia water is more than 25%, the concentration of the cyanohydrin is 50-100%, the mass ratio of the sum of the cyanohydrin and the ammonia source in the total mixed solution is not less than 33%, and preferably, the mass ratio of the sum of the cyanohydrin and the ammonia source in the total mixed solution is not less than 45%.
Through the ammoniation process control, the proportioning relation between the cyanhydrin and the ammonia source and the concentration of the ammonia source are further improved, the cyanhydrin can be subjected to ammoniation reaction in an environment with sufficient ammonia source, the generation of dinitrile byproducts can be reduced, the yield of methylthio aminobutyronitrile products can be further improved, and the yield of ammoniation reaction liquid is improved.
In order to further optimize the parameters of the ammoniation process to reduce the generation of dinitrile byproducts, the preheating mode in the method adopts one of a mode of preheating and then mixing the cyanohydrin and the ammonia source, a mode of mixing the cyanohydrin and the ammonia source and then preheating, and a mode of mixing and preheating the cyanohydrin and the ammonia source.
Through the optimization of the ammonification process parameters, the cyanhydrin and the ammonia source are preheated first, the subsequent reaction residence time is shortened, the reaction efficiency is improved, and the method is suitable for industrial production.
In order to further optimize the ammoniation process parameters to reduce the generation of dinitrile byproducts, in the method, the temperature of the ammoniation reaction is 50-100 ℃, the pressure of the ammoniation reaction is 0.2-0.9MPa, and the time of the ammoniation reaction is 2-20 min.
By optimizing the parameters of the ammoniation process, utilizing the synergistic effect of preheating treatment and ammoniation reaction condition control, the invention can greatly improve the reaction rate, reduce the generation of dinitrile by-products and further improve the yield of methylthio aminobutyronitrile products.
In order to further promote the high-efficiency mixing of the cyanohydrin and the ammonia source so as to improve the yield of the methylthio aminobutyronitrile product, in the method, the high-efficiency mixing continuous reactor comprises a high-efficiency mixing section and a high-efficiency reaction section, wherein the high-efficiency mixing section comprises one or more of a static mixing section, a dynamic mixing section and a large-flux micro-channel mixing section, and the high-efficiency mixing continuous reactor comprises one or more of a tubular reactor, a tower reactor and a kettle reactor.
Particularly, the continuous reactor is formed by connecting a plurality of micro-tubes in parallel, and has extremely large specific surface area, so that the basic advantages of extremely high heat exchange efficiency and mixing efficiency are achieved; the reaction temperature can be accurately controlled and the reaction materials can be instantly mixed according to the accurate proportion, thereby effectively improving the yield, the selectivity and the safety and improving the product quality.
Specifically, the method for preparing methylthio aminobutyronitrile by utilizing cyanohydrin continuous ammoniation comprises the following steps:
(1) preheating treatment: one of a mode of preheating and then mixing the cyanhydrin and the ammonia source, a mode of mixing and then preheating the cyanhydrin and the ammonia source, and a mode of mixing and preheating the cyanhydrin and the ammonia source;
(2) continuous ammoniation reaction: carrying out ammoniation reaction on cyanohydrin and ammonia source in a continuous reactor according to the molar ratio of 1:3-7, carrying out ammoniation reaction for 2-20min under the conditions of 50-100 ℃ and 0.2-0.9MPa, reacting to generate methylthio aminobutyronitrile, and judging the reaction end point by a central control.
Further, the invention relates to an ammoniation reaction which comprises the following steps:
the invention has the beneficial effects that:
(1) the invention provides a method for preparing methylthio aminobutyronitrile by utilizing continuous ammoniation of cyanohydrin, which uses cyanohydrin and an ammonia source as raw materials, and ensures that the cyanohydrin is always under the condition of sufficient ammonia source and is not easy to generate a dinitrile byproduct in the ammoniation reaction process by strictly controlling the concentration of the ammonia source and the proportion relation between the cyanohydrin and the ammonia source, thereby greatly improving the yield of methylthio aminobutyronitrile products, ensuring more thorough ammoniation and high conversion rate;
(2) the invention provides a method for preparing methylthio aminobutyronitrile by utilizing continuous ammoniation of cyanohydrin, which is characterized in that cyanohydrin and an ammonia source are subjected to preheating treatment, and ammoniation conditions between the cyanohydrin and the ammonia source are strictly controlled, so that dinitrile byproducts are not easily generated or less dinitrile byproducts are generated in the reaction process, the ammoniation time is short, the ammoniation rate is high, the yield of methylthio aminobutyronitrile products is high, and the economic benefit is obviously improved compared with the prior art;
(3) the invention provides a method for preparing methylthio aminobutyronitrile by utilizing continuous ammoniation of cyanohydrin, which is characterized in that cyanohydrin and an ammonia source are fed into a continuous reactor for reaction, so that the efficient mixing of the cyanohydrin and the ammonia source in the continuous reactor can be promoted, the cyanohydrin and the ammonia source can be continuously fed after the complete ammoniation reaction of the cyanohydrin and the ammonia source, and the yield of methylthio aminobutyronitrile products is improved;
(4) the preparation method is simple and suitable for industrial production.
Detailed Description
The present invention is described in detail below with reference to specific examples, which are given for the purpose of further illustrating the invention and are not to be construed as limiting the scope of the invention, and the invention may be modified and adapted by those skilled in the art in light of the above disclosure. Except for special description, the parts are parts by weight, the percentages are mass percentages, and the concentration is mass percentage concentration.
The invention relates to a method for preparing methylthio aminobutyronitrile by continuously ammoniating cyanohydrin, which comprises the following steps: the ammonification preparation of 2-amino-4-methylthiobutyronitrile from 2-hydroxy-4-methylthiobutyronitrile, the preparation of 2-amino-4-methylthiobutyronitrile is well known in the art and widely used industrially.
Example 1
In this example, the preheating mode, the proportion configuration and the ammoniation condition of the cyanohydrin and the ammonia source adopt the scheme in Table 1.
Example 2
In this example, the preheating mode, the proportion configuration and the ammoniation condition of the cyanohydrin and the ammonia source adopt the scheme in Table 1.
Example 3
In this example, the preheating mode, the proportion configuration and the ammoniation condition of the cyanohydrin and the ammonia source adopt the scheme in Table 1.
Example 4
In this example, the preheating mode, the proportion configuration and the ammoniation condition of the cyanohydrin and the ammonia source adopt the scheme in Table 1.
Example 5
In this example, the preheating mode, the proportion configuration and the ammoniation condition of the cyanohydrin and the ammonia source adopt the scheme in Table 1.
Example 6
In this example, the preheating mode, the proportion configuration and the ammoniation condition of the cyanohydrin and the ammonia source adopt the scheme in Table 1.
Example 7
In this example, the preheating mode, the proportion configuration and the ammoniation condition of the cyanohydrin and the ammonia source adopt the scheme in Table 1.
Example 8
In this example, the preheating mode, the proportion configuration and the ammoniation condition of the cyanohydrin and the ammonia source adopt the scheme in Table 1.
Example 9
In this example, the preheating mode, the proportion configuration and the ammoniation condition of the cyanohydrin and the ammonia source adopt the scheme in Table 1.
Example 10
In this example, the preheating mode, the proportion configuration and the ammoniation condition of the cyanohydrin and the ammonia source adopt the scheme in Table 1.
Example 11
In this example, the preheating mode, the proportion configuration and the ammoniation condition of the cyanohydrin and the ammonia source adopt the scheme in Table 1.
Comparative example 1
This comparative example is different from example 1 in that the preheating treatment of the cyanohydrin and ammonia gas is not performed in this comparative example.
Comparative example 2
This comparative example differs from example 1 in that the cyanhydrin and ammonia gas in a molar ratio of 1:2 in this comparative example were subjected to an amination reaction in a continuous reactor.
Comparative example 3
This comparative example differs from example 1 in that the cyanhydrin and ammonia gas in a molar ratio of 1:8 in this comparative example were subjected to an amination reaction in a continuous reactor.
Comparative example 4
The difference between the comparative example and the example 1 is that the comparative example adopts an intermittent driving mode, and the specific steps are that cyanohydrin and ammonia gas are placed in a reaction bottle, the ammoniation reaction condition is judged in sampling control, and the yield of the ammoniation reaction liquid is calculated.
Comparative example 5
The difference between the comparative example and the example 1 is that the ammoniation temperature is controlled to be 40 ℃, the ammoniation pressure is 0.1MPa, and the ammoniation reaction is carried out for 1 min.
Comparative example 6
The difference between the comparative example and the example 1 is that the ammoniation temperature is controlled to be 110 ℃, the ammoniation pressure is 1.0MPa, and the ammoniation reaction is carried out for 25 min.
The liquid phase method is adopted to detect the content of methylthio aminobutyronitrile, and the yield of the ammoniation reaction liquid is calculated, and the preheating modes, proportion configuration, ammoniation conditions and result analysis data of the embodiments 1 to 11 and the comparative examples 1 to 6 are shown in table 1.
TABLE 1 data for examples 1-11 and comparative examples 1-6
The method has the advantages that the concentration of the ammonia source, the proportioning relation between the cyanohydrin and the ammonia source are strictly controlled, the cyanohydrin and the ammonia source are subjected to preheating treatment, the ammoniation condition between the cyanohydrin and the ammonia source is strictly controlled, and continuous ammoniation reaction is carried out, so that dinitrile byproducts are not easily generated or less are generated in the reaction process, the ammoniation time is short, the ammoniation speed is high, the yield of methylthio aminobutyronitrile products is high, the economic benefit is obviously improved compared with the prior art, and the preparation method is simple and is suitable for industrial production.
Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.
Claims (9)
1. The method for preparing methylthio aminobutyronitrile by utilizing continuous ammoniation of cyanohydrin is characterized in that cyanohydrin and an ammonia source are subjected to ammoniation reaction in a high-efficiency mixing continuous reactor in a preheating mode according to a certain mass ratio to prepare methylthio aminobutyronitrile, wherein the ammonia source is ammonia gas or ammonia water.
2. The process for the continuous ammonification of methylthio aminobutyronitrile using cyanohydrin according to claim 1, wherein the molar ratio of the cyanohydrin to the ammonia source is 1:3 to 7.
3. The method for preparing methylthio aminobutyronitrile by continuous ammoniation with cyanohydrin as claimed in claim 1, wherein the sum of the mass of the cyanohydrin and the mass of the ammonia source is not less than 33% by mass of the total mixed solution.
4. The method according to claim 3, wherein the mass ratio of the sum of the mass of the cyanohydrin and the mass of the ammonia source to the total mixed solution is preferably not less than 45%.
5. The method for preparing methylthio aminobutyronitrile by continuous ammoniation with cyanohydrin as claimed in claim 1, wherein the concentration of the aqueous ammonia is 25% or more.
6. The process for the continuous ammonification of methylthio aminobutyronitrile using cyanohydrin as claimed in claim 1, wherein the concentration of the cyanohydrin is 50 to 100%.
7. The method for preparing methylthio aminobutyronitrile by continuously ammoniating cyanohydrin as claimed in claim 1, wherein the high-efficiency mixing continuous reactor comprises a high-efficiency mixing section and a high-efficiency reaction section, wherein the high-efficiency mixing section comprises one or more of a static mixing section, a dynamic mixing section and a large-flux microchannel mixing section, and the high-efficiency mixing continuous reactor comprises one or more of a tubular reactor, a tower reactor and a kettle reactor.
8. The method for preparing methylthio aminobutyronitrile by continuously ammonifying with cyanohydrin as claimed in claim 1, wherein the preheating is performed by one of preheating and mixing the cyanohydrin and the ammonia source, mixing and preheating the cyanohydrin and the ammonia source, and mixing and preheating the cyanohydrin and the ammonia source.
9. The method for preparing methylthio aminobutyronitrile by continuously ammonifying with cyanohydrin as claimed in claim 1, wherein the temperature of the ammonification reaction is 50-100 ℃, the pressure of the ammonification reaction is 0.2-0.9MPa, and the residence time of the ammonification reaction is 2-20 min.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113336684A (en) * | 2021-06-09 | 2021-09-03 | 天宝动物营养科技股份有限公司 | Production process and production system of methionine and methionine hydroxy analogue |
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| CN110088085A (en) * | 2016-12-21 | 2019-08-02 | 赢创德固赛有限公司 | The method for preparing methionine |
| EP3689851A1 (en) * | 2019-02-04 | 2020-08-05 | Evonik Operations GmbH | Salt-free production of methionine from methionine nitrile |
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| US4064159A (en) * | 1975-10-10 | 1977-12-20 | Produits Chimiques Du Bearn | Process for preparing alpha-amino-gamma-methylmercaptobutyronitrile |
| CN103641758A (en) * | 2013-11-19 | 2014-03-19 | 重庆紫光化工股份有限公司 | Cheap preparation method for high purity D,L-methionine |
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