CN112979515A - Method for preparing 2-amino-4-methylthiobutanamide - Google Patents
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Abstract
The invention provides a method for preparing 2-amino-4-methylthiobutanamide, which comprises the steps of taking 2-hydroxy-4-methylthiobutyronitrile as a raw material, preparing 2-amino-4-methylthiobutyronitrile, maintaining 2-10% of ammonia in a hydrolysis system, and then performing catalytic hydrolysis at a relatively low temperature to prepare the 2-amino-4-methylthiobutanamide. The invention uses solid catalyst in the hydrolysis process, and prepares the 2-amino-4-methylthiobutanamide by hydrolysis at relatively low temperature, the catalyst and the hydrolysate are easy to separate, so that the catalyst can be recycled, and the service life of the catalyst is greatly prolonged. The invention uses cerium dioxide as a catalyst to carry out low-temperature catalytic hydrolysis reaction, and the activity is still kept higher after the cerium dioxide is circularly used for 20 times, so that the economic benefit is obviously improved compared with the prior art.
Description
Technical Field
The invention relates to a method for preparing 2-amino-4-methylthiobutanamide, and belongs to the technical field of fine chemical engineering.
Background
2-amino-4-methylthiobutanamide, also known as methionine amide, 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. At present, the production method of 2-amino-4-methylthiobutanamide mainly comprises a chemical synthesis method, a biological fermentation method and an enzyme catalysis method, wherein the chemical synthesis method is the most common. The known chemical synthesis process route is that 2-amino-4-methylthiobutyronitrile (abbreviated as 'aminobutyronitrile') is catalyzed and hydrolyzed to prepare 2-amino-4-methylthiobutyramide. Because 2-hydroxy-4-methylthiobutyronitrile (cyanohydrin for short) and aminobutyronitrile have amino or hydroxyl at alpha position, the amino or hydroxyl is electron-withdrawing group, has larger influence on adjacent nitrile group, and has obvious difference with other nitrile compounds in property, the conventional catalyst is difficult to catalyze the hydrolysis of aminobutyronitrile. In the hydrolysis of organic nitriles, it has been reported in many known documents that the corresponding amides can be formed or the corresponding carboxylic acids can be directly formed by controlling the hydrolysis conditions.
Chinese patent CN1400966A discloses a method for preparing 2-amino-4-methylthiobutanamide by contacting cyanohydrin with pure ammonia, removing excessive ammonia after the first-step reaction is finished, and hydrolyzing in the presence of ketone and metal alkali hydroxide; the method adopts ketone as a catalyst, and the catalyst is difficult to separate and recover because the catalyst and reaction materials are mutually soluble; the metal alkali hydroxide causes final acidification to form salt, the yield of amide is low, and meanwhile, the catalytic effect of the catalyst is poor, so that the method is not suitable for industrial production.
Chinese patent CN1211360C discloses a method for preparing 2-amino-4-methylthiobutanamide by contacting with hydroxide ion exchange resin in the presence of ketone after preparing aminobutyronitrile with cyanohydrin; the method requires that in an aminonitrile hydrolysis system, 0.1-1.5 mol of ammonia is remained in each mol of aminonitrile, the reaction efficiency is influenced because the aminonitrile as a raw material is unstable due to the excessively low ammonia content in the system, and meanwhile, the problem of difficult separation and recovery of the catalyst exists because the ketone is adopted as the catalyst and is mutually soluble with reaction materials; the hydroxide radical ion exchange resin needs to be added with alkali to regenerate salt, the catalyst has poor catalytic effect and low yield, and the amide is only 82.3 percent and is not suitable for industrial production.
Chinese patent CN107108487A discloses a one-pot method for preparing methionine by hydrolyzing aminobutyronitrile in the presence of cerium oxide catalyst. The method has the problems that the hydrolysis temperature is too high, nitrile polymerization is generated in the hydrolysis process, and colored substances are formed, so that the color of the hydrolysis liquid is dark, and the service life of the catalyst is short; and excessive hydrolysis to D, L-methionine makes it difficult to obtain 2-amino-4-methylthiobutanamide.
In summary, the current preparation process of 2-amino-4-methylthiobutanamide has the following main problems: (1) the raw material of the aminobutyronitrile is unstable and is inconvenient to store; (2) the catalyst has low catalytic efficiency, poor hydrolysis selectivity and low yield, and is not suitable for industrial production; (3) nitrile polymerization is generated in the hydrolysis process, and colored substances are formed to cause the color of hydrolysate to be dark, so that the product quality is influenced; (4) the catalyst is quick in inactivation, the cycle times are few, and the process cost is high; (5) the hydrolysis conditions are not well controlled and carboxylic acid is directly produced.
Disclosure of Invention
In order to solve the problem that nitrile is easy to polymerize in the hydrolysis process, the invention provides a method for preparing 2-amino-4-methylthiobutanamide.
The invention uses cyanohydrin to react with ammonia source to prepare aminobutyronitrile, and then hydrolyzes to generate 2-amino-4-methylthiobutanamide. In the research process, the hydrolysis temperature has an important influence on the yield and the quality of a target product, and once the control is not good, the polymerization of nitrile is accelerated to deepen the color of hydrolysate, so that the product quality is influenced. In addition, the yield and the quality of a target product can be influenced by the content of ammonia in the hydrolysate, and when the content of ammonia is too low, the stability of the raw material is poor, the polymerization of nitrile is accelerated, the color of the hydrolysate is deepened, and the quality of the product is influenced; too high an ammonia content is detrimental to the subsequent hydrolysis. After a lot of experiments, the method maintains 2-10% of ammonia (referring to free NH in the system) in a hydrolysis system at 20-50 DEG C3) And the reaction is facilitated.
The purpose of the invention is realized as follows:
a process for preparing 2-amino-4-methylthiobutanamide, characterized by: the cyanhydrin reacts with an ammonia source to prepare the aminobutyronitrile, and the aminobutyronitrile is catalyzed and hydrolyzed at the temperature of 20-50 ℃ and in the presence of 2-10% ammonia to generate the 2-amino-4-methylthiobutanamide.
In the method, cyanhydrin reacts with an ammonia source to prepare ammoniated liquid containing the aminobutyronitrile, the ammoniated liquid containing the aminobutyronitrile is subjected to flash evaporation to remove excessive ammonia under the conditions of normal temperature and normal pressure, the content of the ammonia in the ammoniated liquid is maintained to be 2-10%, and the aminobutyronitrile is subjected to catalytic hydrolysis reaction under the condition of 20-50 ℃ to generate the 2-amino-4-methylthiobutyramide.
In order to take the catalytic efficiency of the reaction and the recycling of the catalyst into consideration, in the method, the catalyst for catalyzing hydrolysis is a solid catalyst; the solid catalyst is selected from molybdenum trioxide (MoO)3) Lanthanum oxide (La)2O3) Cerium oxide (CeO)2) Manganese dioxide (MnO)2) One or a combination of several of them. In the production process, the cerium dioxide is found to be the best experimental effect when being used as the catalyst, so the solid catalyst is preferably the cerium dioxide.
In order to further reduce the polymerization of nitrile in the hydrolysis process and improve the quality of products, in the method, the ammonia content of ammoniated liquor after excessive ammonia is removed by flash evaporation is preferably 5-7%;
in order to further reduce the polymerization of nitrile during hydrolysis to improve the quality of the product, the hydrolysis temperature is preferably 30 to 40 ℃ in the above method.
Since aminobutyronitrile is unstable and not favorable for storage, and cyanohydrin is relatively stable, the present invention uses cyanohydrin as a starting material for the reaction. In the above process, cyanhydrin is reacted with an ammonia source at 10-50 deg.C, preferably 20-30 deg.C to produce aminobutyronitrile, wherein the mole number of ammonia is 2.5-5 times, preferably 3-4 times that of cyanhydrin.
In the method, the ammonia source is selected from ammonia gas or ammonia water, and the ammonia water is preferably concentrated ammonia water with the concentration of 22-25%.
The invention discloses a method for preparing 2-amino-4-methylthiobutanamide, which comprises the following steps: reacting cyanhydrin with ammonia gas or ammonia water at 20-30 deg.C and 0.3-0.4MPa to obtain aminobutyronitrile, wherein the mol number of ammonia is 3-4 times of that of cyanhydrin, and then flashing the aminobutyronitrile-containing ammoniation solution at normal temperature and normal pressure to remove excessive ammonia, and maintaining the ammonia content in the ammoniation solution at 5-7%; adding the flash evaporated ammoniated liquid containing the aminobutyronitrile, a solid catalyst and water into a reaction device, hydrolyzing at 30-40 ℃ for 1-2h, and reacting to generate the 2-amino-4-methylthiobutyramide.
In the method, after hydrolysis is finished, water is added into the reaction device, standing and layering are carried out, hydrolysate is taken out to separate target products, and the catalyst in the reaction device is mechanically applied to the next hydrolysis reaction.
Specifically, the method for preparing the 2-amino-4-methylthiobutanamide comprises the following steps:
(1) ammoniation reaction: reacting cyanhydrin with ammonia gas or ammonia water at 20-30 deg.C and 0.3-0.4MPa to obtain aminobutyronitrile, wherein the mol number of ammonia is 3-4 times of that of cyanhydrin, and then flashing the aminobutyronitrile-containing ammoniation solution at normal temperature and normal pressure to remove excessive ammonia, and maintaining the ammonia content in the ammoniation solution at 5-7%;
(2) and (3) hydrolysis reaction: adding the flash evaporated ammoniated liquid containing the aminobutyronitrile and a solid catalyst into a reaction device, hydrolyzing at 30-40 ℃ for 1-2h to generate 2-amino-4-methylthiobutanamide, and determining the reaction end point by central control;
(3) and (3) recycling: and (3) adding water into the reaction device in the step (2), standing for layering, taking out the upper layer of clear hydrolysate, separating a target product, and mechanically applying the catalyst in the reaction device to the next batch of hydrolysis reaction.
The ammonia recovered by the flash evaporation of the ammoniated solution can be applied to the step of cyanhydrin ammoniation reaction, and the ammonia released by the hydrolysis reaction can be circularly applied to the ammoniation reaction.
Has the advantages that:
the invention provides a method for preparing 2-amino-4-methylthiobutanamide, which comprises the steps of firstly preparing aminobutyronitrile by using cyanohydrin as a raw material, and then preparing a target product, namely 2-amino-4-methylthiobutanamide through hydrolysis. The invention maintains 2-10% of ammonia in a hydrolysis system before the aminobutyronitrile is hydrolyzed, and strictly controls the hydrolysis temperature to carry out low-temperature hydrolysis, so that nitrile is relatively stable in the reaction process, is not easy to polymerize, is hydrolyzed more thoroughly, and has high conversion rate. The invention uses solid catalyst in the hydrolysis process, and prepares the 2-amino-4-methylthiobutanamide by hydrolysis at relatively low temperature, the catalyst and the hydrolysate are easy to separate, so that the catalyst is regenerated for recycling, and the service life of the catalyst is greatly prolonged. The method uses cerium dioxide as a catalyst to carry out low-temperature catalytic hydrolysis reaction, can still maintain higher activity after being recycled for 20 times, has short hydrolysis time and high yield, and has stable product quality after feed liquid recycling and obviously improved economic benefit compared with the prior art. The invention adopts 2-hydroxy-4-methylthiobutyronitrile as the initial raw material, which is more beneficial to the storage of the raw material; meanwhile, no inorganic salt is generated in the preparation process, and the method is suitable for the complete cycle of ammonia, distilled water, mother liquor and catalyst, has less three wastes, and is economic and environment-friendly. The preparation method is simple and suitable for industrial production.
Drawings
FIG. 1 is a process flow diagram for preparing 2-amino-4-methylthiobutanamide.
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 preparation method of the 2-amino-4-methylthiobutanamide of the invention refers to the operation of the process flow of the 2-amino-4-methylthiobutanamide of figure 1. Cyanidation reaction: under the condition of basic catalyst, the methylthio propionaldehyde reacts with gaseous hydrocyanic acid or liquid hydrocyanic acid to obtain cyanohydrin, and the preparation of cyanohydrin is well known in the industry and widely applied in industrialization.
(first) use of the Experimental examples
Example 1 (Ceria as catalyst, 1 st batch)
Putting cyanohydrin (60g, 77.9 percent and 0.356mol) into a stainless steel high-pressure reaction kettle provided with a magnetic stirrer and a jacket, introducing ammonia gas under the condition of heating to 30 ℃, controlling the pressure to be 0.3-0.4MPa, stirring for 3 hours at 30 ℃, wherein the ammonia consumption is 3.5 times of the mole number of the cyanohydrin, and removing excessive ammonia from the obtained ammoniacal butyronitrile-containing ammoniated liquid by flash evaporation, and the ammonia content is 6.3 percent. Adding 56.7g of ammoniated liquid containing aminobutyronitrile after deamination and 35g of solid catalyst cerium dioxide into a reaction device, maintaining the temperature at 40 ℃ for hydrolysis reaction to generate 2-amino-4-methylthiobutanamide, and hydrolyzing for 1 h. After the reaction is finished, 390g of water is added, the mixture is kept at the temperature and is kept stand for layering for 0.5h, the catalyst at the bottom of the reaction device is mechanically applied to the next batch of hydrolysis reaction, the mass of the aminobutanamide hydrolysate is 409.5g, the chroma value of the hydrolysate is 20 degrees (the chroma is detected according to a platinum-cobalt standard colorimetric method GBT 5750.4-2006), the content of the liquid phase is 12.6 percent, and the yield of the 2-amino-4-methylthiobutanamide is 97.7 percent.
Example 2 (Ceria catalyst, catalyst set 1)
Putting cyanohydrin (60g, 77.9 percent and 0.356mol) into a stainless steel high-pressure reaction kettle provided with a magnetic stirrer and a jacket, introducing ammonia gas under the condition of heating to 30 ℃, controlling the pressure to be 0.3-0.4MPa, stirring for 3 hours at 30 ℃, wherein the ammonia consumption is 3.5 times of the mole number of the cyanohydrin, and removing excessive ammonia from the obtained ammoniacal butyronitrile-containing ammoniated liquid by flash evaporation, and the ammonia content is 5.8 percent. Adding deaminated 56.6g of ammoniated liquid containing aminobutyronitrile into a reaction device containing a cerium dioxide catalyst, maintaining the temperature at 40 ℃ for hydrolysis reaction to generate 2-amino-4-methylthiobutyramide, and hydrolyzing for 1 h. After the reaction is finished, 390g of water is added, the mixture is kept at the temperature and is kept stand for layering for 0.5h, the catalyst at the bottom of the reaction device is mechanically applied to the next batch of hydrolysis reaction, 421.8g of the upper layer of clear aminobutanamide hydrolysate is taken out, the chromatic value of the hydrolysate is 20 degrees, the content of liquid phase analysis is 12.3 percent, and the yield of 2-amino-4-methylthiobutanamide is 98.2 percent.
Example 3 (Ceria catalyst, catalyst set 2)
Putting cyanohydrin (60g77.9 percent, 0.356mol) into a stainless steel high-pressure reaction kettle provided with a magnetic stirrer and a jacket, introducing ammonia gas under the condition of heating to 30 ℃, controlling the pressure to be 0.3-0.4MPa, stirring for 3 hours at 30 ℃, wherein the ammonia consumption is 3.5 times of the mole number of the cyanohydrin, and removing excessive ammonia from the obtained ammoniacal butyronitrile ammoniated liquid by flash evaporation, and the ammonia content is 5.9 percent. Adding 57.2g of ammoniated liquid containing aminobutyronitrile after deamination into a reaction device containing a cerium dioxide catalyst, maintaining the temperature at 40 ℃ for hydrolysis reaction to generate 2-amino-4-methylthiobutyramide, and hydrolyzing for 1 h. After the reaction is finished, 390g of water is added, the mixture is kept at the temperature and is kept stand for layering for 0.5h, the catalyst at the bottom of the reaction device is mechanically applied to the next batch of hydrolysis reaction, 420.7g of the upper layer of clear aminobutanamide hydrolysate is taken out, the chromatic value of the hydrolysate is 20 degrees, the content of liquid phase analysis is 12.3 percent, and the yield of 2-amino-4-methylthiobutanamide is 98.0 percent.
Examples 4-10 (Ceria as catalyst, catalyst set from batches 3-9)
Aminobutanamide was prepared using the same charge and reaction conditions as in example 3 above, and cyanohydrin was reacted with ammonia to give aminobutyronitrile. Deaminating the aminobutyronitrile, adding the deaminated aminobutyronitrile into a reaction device containing a cerium dioxide catalyst, performing amidation reaction, supplementing water, standing and layering to obtain 2-amino-4-methylthiobutanamide hydrolysate.
Referring to example 3, the 10 th to 18 th batches of the cycle production were carried out.
Example 11 (Ceria catalyst, catalyst application No. 19)
Putting cyanohydrin (60g, 77.9 percent and 0.356mol) into a stainless steel high-pressure reaction kettle provided with a magnetic stirrer and a jacket, introducing ammonia gas under the condition of heating to 30 ℃, controlling the pressure to be 0.3-0.4MPa, stirring for 3 hours at 30 ℃, wherein the ammonia consumption is 3.5 times of the mole number of the cyanohydrin, and removing excessive ammonia from the obtained ammoniacal butyronitrile-containing ammoniated liquid by flash evaporation, and the ammonia content is 6.3 percent. Adding 57.5g of ammoniated liquid containing aminobutyronitrile after deamination into a reaction device containing a cerium dioxide catalyst, maintaining the temperature at 40 ℃ for hydrolysis reaction to generate 2-amino-4-methylthiobutyramide, and hydrolyzing for 1 h. After the reaction is finished, 390g of water is added, the mixture is kept at the temperature and is kept stand for layering for 0.5h, the catalyst at the bottom of the reaction device is mechanically applied to the next batch of hydrolysis reaction, 424.5g of the upper layer of clear aminobutanamide hydrolysate is taken out, the chromatic value of the hydrolysate is 20 degrees, the content of liquid phase analysis is 12.3 percent, and the yield of 2-amino-4-methylthiobutanamide is 98.9 percent.
Example 12 (Ceria catalyst, catalyst set 20)
Putting cyanohydrin (60g77.9 percent, 0.356mol) into a stainless steel high-pressure reaction kettle provided with a magnetic stirrer and a jacket, introducing ammonia gas under the condition of heating to 30 ℃, controlling the pressure to be 0.3-0.4MPa, stirring for 3 hours at 30 ℃, wherein the ammonia consumption is 3.5 times of the mole number of the cyanohydrin, and removing excessive ammonia from the obtained ammoniacal butyronitrile ammoniated liquid by flash evaporation, and the ammonia content is 5.9 percent. Adding 57.6g of ammoniated liquid containing aminobutyronitrile after deamination into a reaction device containing a cerium dioxide catalyst, maintaining the temperature at 40 ℃ for hydrolysis reaction to generate 2-amino-4-methylthiobutyramide, and hydrolyzing for 1 h. After the reaction is finished, 390g of water is added, the mixture is kept at the temperature and is kept stand for layering for 0.5h, the catalyst at the bottom of the reaction device is mechanically applied to the next batch of hydrolysis reaction, 419.6g of the upper layer of clear aminobutanamide hydrolysate is taken out, the chromatic value of the hydrolysate is 30 degrees, the content of liquid phase analysis is 12.4 percent, and the yield of 2-amino-4-methylthiobutanamide is 98.5 percent.
The results of examples 1 to 12 of the present invention are shown in Table 1.
TABLE 1 apply example data
The nitrile in the hydrolysis reaction process is relatively stable and is not easy to polymerize, the color of the hydrolysate is determined to be 20 degrees according to the detection of a platinum-cobalt standard colorimetric method GBT5750.4-2006, and the yield and the conversion rate are high. The method uses cerium dioxide as a catalyst to carry out low-temperature catalytic hydrolysis reaction, the high activity is still kept after 20 times of cyclic application, the secondary product quality is stable after the feed liquid is circulated, the catalyst is still kept at high hydrolytic activity without being supplemented within 20 times of cyclic application in industrial application, and the economic benefit is obviously improved compared with the prior art. The invention adopts the cyanohydrin as the initial raw material, which is more beneficial to the storage of the raw material; meanwhile, no inorganic salt is generated in the preparation process, ammonia, distilled water, mother liquor and a catalyst are completely recycled, the 'three wastes' are less, and the method is economical, environment-friendly and suitable for industrial production.
(II) other embodiments
Example 13 (manganese dioxide as catalyst)
60g (77.9 percent, 0.356mol) of cyanhydrin is put into a stainless steel high-pressure reaction kettle provided with a magnetic stirrer and a jacket, ammonia gas is introduced under the condition of heating to 30 ℃, the pressure is controlled to be 0.3-0.4MPa, the mixture is stirred for 3 hours at 30 ℃, the ammonia consumption is 3.5 times of the mole number of the cyanhydrin, and the obtained ammoniacal butyronitrile ammoniacal liquid is subjected to flash evaporation to remove excessive ammonia, wherein the ammonia content is 5.8 percent.
Adding 57.1g of ammoniated liquid containing aminobutyronitrile after deamination and 35g of solid catalyst manganese dioxide into a reaction device, maintaining the temperature at 40 ℃ for hydrolysis reaction to generate 2-amino-4-methylthiobutanamide, and hydrolyzing for 1 h. After the reaction is finished, 390g of water is added, the mixture is kept warm and kept stand for layering for 0.5h, the upper layer of clear aminobutanamide hydrolysate is taken out, the mass is 405.9g, the chromatic value of the hydrolysate is 50 degrees, the content of liquid phase analysis is 5.5 percent, and the yield of the 2-amino-4-methylthiobutanamide is 42.3 percent.
Example 14 (molybdenum trioxide as catalyst)
60g (77.9 percent, 0.356mol) of cyanhydrin is put into a stainless steel high-pressure reaction kettle provided with a magnetic stirrer and a jacket, ammonia gas is introduced under the condition of heating to 30 ℃, the pressure is controlled to be 0.3-0.4MPa, the mixture is stirred for 3 hours at 30 ℃, the ammonia consumption is 3.5 times of the mole number of the cyanhydrin, and the obtained ammoniacal butyronitrile ammoniacal liquid is subjected to flash evaporation to remove excessive ammonia, wherein the ammonia content is 5.9 percent.
Adding 56.8g of ammoniated liquid containing aminobutyronitrile after deamination and 35g of molybdenum trioxide as a solid catalyst into a reaction device, maintaining the temperature at 40 ℃ for hydrolysis reaction to generate 2-amino-4-methylthiobutanamide, wherein the hydrolysis time is 1 h. After the reaction is finished, 390g of water is added, the mixture is kept warm and kept stand for layering for 0.5h, the upper layer of clear aminobutanamide hydrolysate is taken out, the mass is 405.6g, the chromatic value of the hydrolysate is 30 degrees, the content of liquid phase analysis is 8.3 percent, and the yield of the 2-amino-4-methylthiobutanamide is 63.7 percent.
Example 15 (lanthanum oxide as catalyst)
60g (77.9 percent, 0.356mol) of cyanhydrin is put into a stainless steel high-pressure reaction kettle provided with a magnetic stirrer and a jacket, ammonia gas is introduced under the condition of heating to 30 ℃, the pressure is controlled to be 0.3-0.4MPa, the mixture is stirred for 3 hours at 30 ℃, the ammonia consumption is 3.5 times of the mole number of the cyanhydrin, and the obtained ammoniacal butyronitrile ammoniacal liquid is subjected to flash evaporation to remove excessive ammonia, wherein the ammonia content is 5.5 percent.
Adding 56.5g of ammoniated liquid containing aminobutyronitrile after deamination and 35g of solid catalyst lanthanum oxide into a reaction device, maintaining the temperature at 40 ℃ for hydrolysis reaction to generate 2-amino-4-methylthiobutyramide, and hydrolyzing for 1 h. After the reaction is finished, 390g of water is added, the mixture is kept warm and kept stand for layering for 0.5h, the upper layer of clear aminobutanamide hydrolysate is taken out, the mass is 406.2g, the chromatic value of the hydrolysate is 30 degrees, the content of liquid phase analysis is 11.4 percent, and the yield of the 2-amino-4-methylthiobutanamide is 87.7 percent.
Example 16 (cerium oxide as catalyst)
60g (77.9 percent, 0.356mol) of cyanhydrin is put into a stainless steel high-pressure reaction kettle provided with a magnetic stirrer and a jacket, ammonia gas is introduced under the condition of heating to 30 ℃, the pressure is controlled to be 0.3-0.4MPa, the mixture is stirred for 3 hours at 30 ℃, the ammonia consumption is 3.5 times of the mole number of the cyanhydrin, and the obtained ammoniacal butyronitrile ammoniacal liquid is subjected to flash evaporation to remove excessive ammonia, wherein the ammonia content is 5.6 percent.
Adding 56.2g of ammoniated liquid containing aminobutyronitrile after deamination and 35g of solid catalyst cerium dioxide into a reaction device, maintaining the temperature at 40 ℃ for hydrolysis reaction to generate 2-amino-4-methylthiobutanamide, and hydrolyzing for 1 h. After the reaction is finished, 390g of water is added, the mixture is kept warm and kept stand for layering for 0.5h, the upper layer of clear aminobutanamide hydrolysate is taken out, the mass is 408.3g, the chroma value of the hydrolysate is 20 degrees (the chroma is detected according to a platinum-cobalt standard colorimetric method GBT 5750.4-2006), the content of liquid phase analysis is 12.6 percent, and the yield of the 2-amino-4-methylthiobutanamide is 97.4 percent.
The results of examples 13 to 16 of the present invention are shown in Table 2.
TABLE 2 data for examples 13-16
Through comparative analysis, the molybdenum trioxide, lanthanum trioxide, cerium oxide and manganese dioxide as catalysts can be subjected to low-temperature catalytic hydrolysis to prepare the 2-amino-4-methylthiobutanamide, wherein the cerium dioxide as the catalyst has the best experimental effect.
Claims (10)
1. A process for preparing 2-amino-4-methylthiobutanamide, characterized by: the cyanhydrin reacts with an ammonia source to prepare the aminobutyronitrile, and the aminobutyronitrile is catalyzed and hydrolyzed at the temperature of 20-50 ℃ and in the presence of 2-10% ammonia to generate the 2-amino-4-methylthiobutanamide.
2. The method of claim 1, wherein: the cyanhydrin reacts with an ammonia source to prepare ammoniated liquid containing the aminobutyronitrile, and the ammoniated liquid containing the aminobutyronitrile is subjected to flash evaporation under the conditions of normal temperature and normal pressure to remove excessive ammonia.
3. The method of claim 1 or 2, wherein: the catalyst for catalyzing hydrolysis is a solid catalyst.
4. The method of claim 3, wherein: the solid catalyst is selected from one or a combination of more of molybdenum trioxide, lanthanum oxide, cerium dioxide and manganese dioxide.
5. The method of claim 4, wherein: the solid catalyst is cerium dioxide.
6. The method of any one of claims 1-5, wherein: the ammonia content is 5-7%.
7. The method of any one of claims 1-6, wherein: the hydrolysis temperature is 30-40 deg.C.
8. The method of any one of claims 1-7, wherein: the cyanhydrin reacts with an ammonia source at the temperature of 10-50 ℃ to prepare the aminobutyronitrile, wherein the mol number of ammonia is 2.5-5 times of that of the cyanhydrin.
9. The method of any one of claims 1-8, wherein: the ammonia source is selected from ammonia gas or ammonia water.
10. The method of any one of claims 1-8, wherein: after hydrolysis is finished, adding water into the reaction device, standing for layering, and taking out hydrolysate to separate a target product; the catalyst in the reaction device is mechanically applied to the next batch of hydrolysis reaction.
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| CN115925565A (en) * | 2022-12-22 | 2023-04-07 | 浙江卓浩生物科技有限公司 | Food-grade glycine and continuous preparation method thereof |
Citations (4)
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| CN1325383A (en) * | 1998-11-06 | 2001-12-05 | 阿方蒂动物营养素股份有限公司 | Method for preparing methionine |
| CN1400966A (en) * | 2000-02-15 | 2003-03-05 | 阿方蒂动物营养素股份有限公司 | Process for the production of methionine |
| CN103641759A (en) * | 2013-11-19 | 2014-03-19 | 重庆紫光化工股份有限公司 | Environmentally-friendly preparation method of highly-pure D,L-2-hydroxy-4-methylthiobutyramide |
| CN107108487A (en) * | 2014-09-26 | 2017-08-29 | 住友化学株式会社 | The manufacture method of methionine |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115925565A (en) * | 2022-12-22 | 2023-04-07 | 浙江卓浩生物科技有限公司 | Food-grade glycine and continuous preparation method thereof |
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