Treatment method and application of 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis mother liquor

Abstract

The invention provides a method for treating a synthetic mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine and its application, and relates to the technical field of organic synthesis, comprising the following steps: acetamidine in the synthetic mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine is thermally decomposed into acetonitrile and ammonia, and acetonitrile, ammonia and the synthetic mother liquor are separated by distillation to obtain acetonitrile, ammonia and the separated synthetic mother liquor. The invention solves the technical problem that a large amount of free acetamidine in the synthetic mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine in the existing process is not effectively recycled, resulting in waste of resources, and achieves the technical effects of effectively recycling acetonitrile and ammonia produced by thermal decomposition of acetamidine in the synthetic mother liquor, effectively separating acetamidine from by-product o-chloroaniline, and greatly reducing the discharge of sewage ammonia nitrogen and COD in the subsequent treatment process.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, in particular to a method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis mother liquor and an application thereof. Background Art

[0002] In order to ensure the yield of the main reaction, the existing 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis process uses a large amount of acetamidine hydrochloride, and the molar ratio of acetamidine hydrochloride to the main raw material α-(o-chloroaniline)-methyl-β-formylaminopropionitrile (enamine) reaches 1:1.5. A large amount of excess acetamidine hydrochloride is freed as acetamidine, which exists excessively in the synthesis mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine.

[0003] The high price of acetamidine hydrochloride leads to high synthesis cost of 2-methyl-4-amino-5-formylaminomethylpyrimidine. In order to reduce its production cost, a method for recovering excess acetamidine in mother liquor and comprehensively utilizing it is urgently needed.

[0004] The reaction formula of acetamidine hydrochloride free to acetamidine:

[0005]

[0006] The synthetic reaction formula of 2-methyl-4-amino-5-formylaminomethylpyrimidine (formylpyrimidine):

[0007]

[0008] In view of this, the present invention is proposed. Summary of the invention

[0009] One of the purposes of the present invention is to provide a method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis mother liquor, which can effectively recover acetonitrile and ammonia produced by thermal decomposition of acetylamino in the synthesis mother liquor, and effectively separate acetylamino from the by-product o-chloroaniline, thereby reducing the production cost and improving the economic benefit of the synthesis process.

[0010] The second object of the present invention is to provide an application of a method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis mother liquor, which can make resource utilization of excess acetamidine and reduce the discharge of ammonia nitrogen and COD in sewage.

[0011] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0012] In a first aspect, a method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis mother liquor comprises the following steps:

[0013] The acetonitrile in the synthesis mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine is decomposed into acetonitrile and ammonia by heat, and the acetonitrile and ammonia are separated from the synthesis mother liquor by distillation to obtain acetonitrile, ammonia and the separated synthesis mother liquor.

[0014] Furthermore, the temperature of thermal decomposition of the acetylamide is 100-120°C.

[0015] Further, the distillation comprises the following steps:

[0016] First, ammonia is distilled off at the top of the distillation tower, and then acetonitrile is distilled off at the top of the distillation tower to obtain acetonitrile and ammonia.

[0017] Furthermore, the method for collecting the evaporated ammonia includes collecting it by absorption with alcohol.

[0018] Further, the alcohol includes methanol;

[0019] Preferably, the temperature of the methanol is 0-5°C.

[0020] Furthermore, the method for collecting the distilled acetonitrile includes collecting it through a condenser.

[0021] Furthermore, the gas phase temperature during the distillation of acetonitrile is below 81°C.

[0022] Furthermore, the processing method further comprises the following steps:

[0023] The separated synthetic mother liquor is subjected to reduced pressure distillation to obtain o-chloroaniline.

[0024] In a second aspect, a treatment method as described in any one of the above items is used for preparing 2-methyl-4-amino-5-formylaminomethylpyrimidine.

[0025] Furthermore, the reaction raw materials for preparing 2-methyl-4-amino-5-formylaminomethylpyrimidine include α-(o-chloroaniline)methyl-β-formylaminopropionitrile and ethylamine hydrochloride.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] The method for treating the synthetic mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine provided by the present invention can reduce the production cost and improve the economic benefit of the synthetic process. A large amount of acetamidine in the synthetic mother liquor is firstly decomposed into acetonitrile and ammonia by heat, and then the acetonitrile and ammonia are separated from the synthetic mother liquor by a distillation method, so that not only the product after the thermal decomposition of acetamidine is effectively recovered, but also acetamidine is effectively separated from the synthetic mother liquor, thereby avoiding the problem of high ammonia nitrogen content in the wastewater caused by a large amount of ammonia generated by the decomposition of a large amount of acetamidine in the form of non-condensable gas being discharged by a vacuum pump to a pickling tower for absorption and then discharged to dilute wastewater in the subsequent process of recovering o-chloroaniline by vacuum distillation, and the problem of low o-chloroaniline content in the vacuum distillation product caused by a large amount of acetonitrile generated by the decomposition being mixed in the o-chloroaniline collected by condensation (when the recovered o-chloroaniline is used to synthesize enamine, a large amount of acetonitrile is mixed in the synthetic mother liquor and then discharged to wastewater for treatment, which increases the COD amount of the wastewater).

[0028] The application of the method for treating the 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis mother liquor provided by the present invention can make resource utilization of excess acetamidine in the synthesis mother liquor, and can also reduce the discharge of ammonia nitrogen and COD in sewage. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] According to a first aspect of the present invention, there is provided a method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis mother liquor, comprising the following steps:

[0031] The acetonitrile in the synthesis mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine is decomposed into acetonitrile and ammonia by heat, and the acetonitrile and ammonia are separated from the synthesis mother liquor by distillation to obtain acetonitrile, ammonia and the separated synthesis mother liquor.

[0032] The method for treating the synthetic mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine provided by the present invention can reduce the production cost and improve the economic benefit of the synthetic process. A large amount of acetamidine in the synthetic mother liquor is firstly decomposed into acetonitrile and ammonia by heat, and then the acetonitrile and ammonia are separated from the synthetic mother liquor by a distillation method, so that not only the product after the thermal decomposition of acetamidine is effectively recovered, but also acetamidine is effectively separated from the synthetic mother liquor, thereby avoiding the problem of high ammonia nitrogen content in the wastewater caused by a large amount of ammonia generated by the decomposition of a large amount of acetamidine in the form of non-condensable gas being discharged by a vacuum pump to a pickling tower for absorption and then discharged to dilute wastewater in the subsequent process of recovering o-chloroaniline by vacuum distillation, and the problem of low o-chloroaniline content in the vacuum distillation product caused by a large amount of acetonitrile generated by the decomposition being mixed in the o-chloroaniline collected by condensation (when the recovered o-chloroaniline is used to synthesize enamine, a large amount of acetonitrile is mixed in the synthetic mother liquor and then discharged to wastewater for treatment, which increases the COD amount of the wastewater).

[0033] In a preferred embodiment, the temperature of thermal decomposition of acetonitrile in the present invention can be above 100°C, and can be further preferably 100-120°C, for example, 100°C, 102°C, 104°C, 106°C, 108°C, 110°C, 112°C, 114°C, 116°C, 118°C, 120°C, but not limited thereto, which is more conducive to fully thermally decomposing acetonitrile into acetonitrile and ammonia.

[0034] The reaction formula for the thermal decomposition of acetonitrile into acetonitrile and ammonia is as follows:

[0035]

[0036] In a preferred embodiment, the distillation in the present invention comprises the following steps:

[0037] The acetylamine in the mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis is first decomposed into acetonitrile and ammonia by heat in a distillation tower, and then the ammonia is evaporated at the top of the distillation tower, and then the acetonitrile is distilled at the top of the distillation tower to obtain acetonitrile and ammonia.

[0038] The synthesis mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine is first heated to above 100°C in a distillation tower, and the property of acetamidine that it is easily decomposed by heat is utilized to thermally decompose acetamidine into acetonitrile and ammonia, and then the ammonia generated by the thermal decomposition is evaporated from the top of the distillation tower. After the ammonia drive is completed, the acetonitrile generated by the thermal decomposition is distilled and collected from the top of the distillation tower to obtain acetonitrile and ammonia, thereby achieving the purpose of effectively recovering the thermal decomposition products of acetamidine and effectively separating acetamidine from the synthesis mother liquor.

[0039] In a preferred embodiment, the method for collecting the acetonitrile distilled during the distillation process includes but is not limited to collecting it through a condenser. The acetonitrile can be condensed and collected through a condenser, which is more conducive to collecting acetonitrile.

[0040] In a preferred embodiment, the gas phase temperature when acetonitrile is distilled off during the distillation process may be below 81°C, for example, 81°C or 80°C, but not limited thereto, which is more conducive to improving the distillation effect of acetonitrile.

[0041] The acetonitrile recovered in the present invention can be used to synthesize acetamidine, and the reaction formula is as follows:

[0042]

[0043] In a preferred embodiment, the method for collecting ammonia evaporated during the distillation process includes but is not limited to collecting it through absorption by alcohol, and the alcohol includes but is not limited to methanol. The ammonia methanol obtained after methanol absorbs ammonia can be further used for the amination of acetamidine to synthesize acetamidine hydrochloride, thereby achieving effective utilization of ammonia.

[0044] In the present invention, the ammonia methanol after methanol absorbs ammonia can be used for the amination of acetamidine to synthesize acetamidine hydrochloride, and the amination reaction formula is as follows:

[0045]

[0046] The side reaction of amination (reaction of ammonia with hydrogen chloride) is as follows:

[0047]

[0048] The side reaction of amination (reaction of acetamidine with methanol) has the following reaction formula:

[0049]

[0050] In a preferred embodiment, the methanol used to absorb ammonia in the present invention can be refrigerated methanol. For example, the temperature of the methanol can be 0-5°C, and its typical but non-limiting temperatures are, for example, 0°C, 1°C, 2°C, 3°C, 4°C, and 5°C.

[0051] In a preferred embodiment, the processing method of the present invention further comprises the following steps:

[0052] The separated synthetic mother liquor is distilled under reduced pressure to obtain o-chloroaniline.

[0053] The synthetic mother liquor after separation of acetylamino is transferred to a vacuum distillation system for vacuum distillation to recover o-chloroaniline therein. Since acetylamino has been effectively separated, the content of o-chloroaniline in the vacuum distillation product is increased, and the discharge of ammonia nitrogen and COD in the subsequent treatment process is also greatly reduced.

[0054] A typical method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis mother liquor comprises the following steps:

[0055] The synthesis mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine is first heated to above 100°C in a distillation tower and fully refluxed for more than 1.5 hours, and a large amount of acetamidine in the synthesis mother liquor is thermally decomposed into acetonitrile and ammonia by utilizing the property that acetamidine is easily decomposed by heat;

[0056] The ammonia produced by thermal decomposition is evaporated from the top of the distillation tower, and the ammonia is washed and absorbed with refrigerated methanol (the temperature of the methanol can be 0-5°C) in the scrubber to obtain ammonia methanol, which can be used as a raw material for the subsequent synthesis of acetamidine hydrochloride;

[0057] After the ammonia drive is completed, the gas phase temperature at the top of the distillation tower is controlled to be ≤81°C, and the acetonitrile is collected from the top of the distillation tower through a condenser for distillation, which can be used as a raw material for the subsequent synthesis of acetamidine hydrochloride, thereby realizing the comprehensive utilization of acetonitrile and ammonia;

[0058] The bottoms of the distillation tower (i.e., the synthetic mother liquor after separation of acetamidine) are transferred to the o-chloroaniline distillation kettle for vacuum distillation to recover o-chloroaniline for standby use, and can be used as a raw material for synthesizing α-(o-chloroaniline)-methyl-β-formylaminopropionitrile (enamine).

[0059] The treatment method provided by the present invention comprises the following steps: firstly decomposing acetamidine in a synthetic mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine into acetonitrile and ammonia by heat in a distillation tower, then firstly distilling off ammonia at the top of the distillation tower, then distilling off acetonitrile at the top of the distillation tower through a condenser, and then transferring the still residue of the distillation tower into a vacuum distillation system for vacuum distillation to recover o-chloroaniline, thereby solving the technical problem that a large amount of free acetamidine in the synthetic mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine in the prior art is not effectively recycled and utilized, resulting in waste of resources, and achieving the technical effects of effectively recovering acetonitrile and ammonia produced by thermal decomposition of acetamidine in the synthetic mother liquor, effectively separating acetamidine from by-product o-chloroaniline, and greatly reducing the discharge of ammonia nitrogen and COD in sewage in the subsequent treatment process.

[0060] According to a second aspect of the present invention, there is provided use of any one of the above-mentioned treatment methods in the preparation of 2-methyl-4-amino-5-formylaminomethylpyrimidine.

[0061] The reaction raw materials for preparing 2-methyl-4-amino-5-formylaminomethylpyrimidine include α-(o-chloroaniline)-methyl-β-formylaminopropionitrile and ethylamine hydrochloride.

[0062] The application of the method for treating the 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis mother liquor provided by the present invention can make resource utilization of excess acetamidine in the synthesis mother liquor, and can also reduce the discharge of ammonia nitrogen and COD in sewage.

[0063] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0064] Example 1

[0065] A method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine (formylpyrimidine) synthesis mother liquor comprises the following steps:

[0066] Recovery of ammonia and acetonitrile from synthetic mother liquor:

[0067] Set up a distillation experimental table, add 1400g of formylpyrimidine mother liquor into a distillation flask, then heat the formylpyrimidine mother liquor in the flask to 100°C, stir and heat for 2 hours, pass cooling water into the junction of the distillation tower, perform total reflux operation, vent the top of the tower and use a rubber hose to connect it to a flask filled with 250g of methanol, stir and cool to 0-5°C to absorb ammonia, observe the generation of bubbles in the flask, and after the bubbling in the flask stops, weigh the absorption flask to measure the amount of ammonia absorbed to be 37g, and obtain ammonia methanol solution (ammonia methanol);

[0068] The top of the tower was vented and switched to the acetonitrile collection condenser and the receiving bottle, the cooling water of the distillation tower was turned off, the temperature at the bottom of the distillation tower was slowly increased, and the gas phase temperature was controlled to be ≤81°C to steadily collect acetonitrile until no acetonitrile was distilled out, and the amount of acetonitrile recovered by weighing was 84g;

[0069] The remaining material in the distillation tower is transferred to the o-chloroaniline distillation flask to recover the o-chloroaniline through reduced pressure distillation.

[0070] The ammonia and acetonitrile recovered by the above method are used to synthesize acetamidine hydrochloride, and the method is as follows:

[0071] Addition reaction: according to the amount of acetonitrile recovered in the above method, prepare 220g of acid methanol with a mass fraction of 46%, then add the acid methanol into the reaction flask and stir and cool to 0°C, then drop the recovered acetonitrile into the reaction flask, control the reaction temperature at 0-8°C, dropwise add for about 4 hours, then slowly heat to 15-20°C and keep warm for 6 hours to obtain ethylene amidine;

[0072] Amination reaction of acetamidine: 287g of frozen ammonia methanol recovered by the above method is further prepared into 296g of ammonia methanol with an ammonia mass content of about 15.5%, which is then added to an amination reaction flask with a reflux condenser. Under stirring, the obtained acetamidine is controlled to be added to the ammonia methanol within about 15 to 20 minutes to obtain a reaction solution, and the temperature of the reaction solution is controlled to be about 50°C and kept warm for 1 hour. The reaction solution is then cooled to 10°C, and the ammonium chloride in the reaction solution is separated using a centrifuge, and then 50g of methanol is used for washing, and 37g of ammonium chloride is dried by centrifugal filtration. The washing methanol and the centrifuged filtered solution are combined and concentrated to obtain acetamidine hydrochloride solid, and 187g of acetamidine hydrochloride crude product is obtained. The content of acetamidine hydrochloride detected is 92.6%.

[0073] Example 2

[0074] A method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine (formylpyrimidine) synthesis mother liquor comprises the following steps:

[0075] Recovery of ammonia and acetonitrile from synthetic mother liquor:

[0076] Set up a distillation experimental table, add 1400g of formylpyrimidine mother liquor into a distillation flask, then heat the formylpyrimidine mother liquor in the flask to 105°C, stir and heat for 1.5 hours, pass cooling water into the casing of the distillation tower, perform total reflux operation, vent the top of the tower and use a rubber hose to connect it to a flask filled with 250g of methanol, stir and cool to 0-5°C to absorb ammonia, observe the generation of bubbles in the flask, and after the bubbling in the flask stops, weigh the absorption flask to measure the amount of ammonia absorbed to be 37.8g, and obtain ammonia methanol solution (ammonia methanol);

[0077] The top of the tower was vented and switched to the acetonitrile collection condenser and the receiving bottle, the cooling water of the distillation tower was turned off, the temperature at the bottom of the distillation tower was slowly increased, and the gas phase temperature was controlled to be ≤81°C to steadily collect acetonitrile until no acetonitrile was distilled out, and the amount of recovered acetonitrile was 86g by weight;

[0078] The remaining material in the distillation tower is transferred to the o-chloroaniline distillation flask to recover the o-chloroaniline through reduced pressure distillation.

[0079] The ammonia and acetonitrile recovered by the above method are used to synthesize acetamidine hydrochloride, and the method is as follows:

[0080] Addition reaction: according to the amount of acetonitrile recovered in the above method, prepare 225g of acid methanol with a mass fraction of 46%, then add the acid methanol into the reaction flask and stir and cool to 0°C, then drop the recovered acetonitrile into the reaction flask, control the reaction temperature at 0-8°C, dropwise add for about 4 hours, then slowly heat to 15-20°C and keep warm for 6 hours to obtain ethylene amidine;

[0081] Amination reaction of acetamidine: 287.8g of frozen ammonia methanol recovered by the above method is supplemented with 6.1g of methanol to prepare 303g of ammonia methanol with an ammonia mass content of about 15.5%, which is then added to an ammonia reaction flask with a reflux condenser. Under stirring, the obtained acetamidine is controlled to be added to the ammonia methanol within about 15 to 20 minutes to obtain a reaction solution, and the temperature of the reaction solution is controlled to be about 50°C and kept warm for 1 hour. The reaction solution is then cooled to 10°C, and the ammonium chloride in the reaction solution is separated by a centrifuge, and then 50g of methanol is used for washing. 38.2g of ammonium chloride is dried by centrifugal filtration, and the washing methanol and the centrifuged filtered solution are combined and concentrated to obtain acetamidine hydrochloride solid, and 191.3g of acetamidine hydrochloride crude product is obtained. The content of acetamidine hydrochloride detected is 92.8%.

[0082] Example 3

[0083] A method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine (formylpyrimidine) synthesis mother liquor comprises the following steps:

[0084] Recovery of ammonia and acetonitrile from synthetic mother liquor:

[0085] Set up a distillation experimental table, add 1400g of formylpyrimidine mother liquor into a distillation flask, then heat the formylpyrimidine mother liquor in the flask to 110°C, stir and heat for 2 hours, pass cooling water into the junction of the distillation tower, perform total reflux operation, vent the top of the tower and use a rubber hose to connect it to a flask filled with 250g of methanol, stir and cool to 0-5°C to absorb ammonia, observe the generation of bubbles in the flask, and after the bubbling in the flask stops, weigh the absorption flask to measure the amount of ammonia absorbed to be 39.3g, and obtain ammonia methanol solution (ammonia methanol);

[0086] The top of the tower was vented and switched to the acetonitrile collection condenser and the receiving bottle, the cooling water of the distillation tower was turned off, the temperature at the bottom of the distillation tower was slowly increased, and the gas phase temperature was controlled to be ≤81°C to steadily collect acetonitrile until no acetonitrile was distilled out, and the amount of recovered acetonitrile was 89.5g by weight;

[0087] The remaining material in the distillation tower is transferred to the o-chloroaniline distillation flask to recover the o-chloroaniline through reduced pressure distillation.

[0088] The ammonia and acetonitrile recovered by the above method are used to synthesize acetamidine hydrochloride, and the method is as follows:

[0089] Addition reaction: according to the amount of acetonitrile recovered in the above method, prepare 234g of acid methanol with a mass fraction of 46%, then add the acid methanol into the reaction flask and stir and cool to 0°C, then drop the recovered acetonitrile into the reaction flask, control the reaction temperature at 0-8°C, dropwise add for about 4 hours, then slowly heat to 15-20°C and keep warm for 6 hours to obtain ethylene amidine;

[0090] Amination reaction of acetamidine: 289.3g of frozen ammonia methanol recovered by the above method is supplemented with 16.5g of methanol to prepare 315g of ammonia methanol with an ammonia mass content of about 15.5%, which is then added to an ammonia reaction flask with a reflux condenser. Under stirring, the obtained acetamidine is controlled to be added to the ammonia methanol within 15 to 20 minutes to obtain a reaction solution, and the temperature of the reaction solution is controlled to be about 50°C and kept warm for 1 hour. The reaction solution is then cooled to 10°C, and the ammonium chloride in the reaction solution is separated by a centrifuge, and then 50g of methanol is used for washing. 40.2g of ammonium chloride is dried by centrifugal filtration, and the washing methanol and the centrifuged filtered solution are combined and concentrated to obtain acetamidine hydrochloride solid, and 198g of acetamidine hydrochloride crude product is obtained. The content of acetamidine hydrochloride detected is 93.1%.

[0091] Example 4

[0092] A method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine (formylpyrimidine) synthesis mother liquor comprises the following steps:

[0093] Recovery of ammonia and acetonitrile from synthetic mother liquor:

[0094] Set up a distillation experimental table, add 1400g of formylpyrimidine mother liquor into a distillation flask, then heat the formylpyrimidine mother liquor in the flask to 115°C, stir and heat for 2 hours, pass cooling water into the knot of the distillation tower, perform total reflux operation, vent the top of the tower using a rubber hose to connect to a flask filled with 250g of methanol, stir and cool to 0-5°C to absorb ammonia, observe the generation of bubbles in the flask, and after the bubbling in the flask stops, weigh the absorption flask to measure the amount of ammonia absorbed to be 39.5g, and obtain ammonia methanol solution (ammonia methanol);

[0095] The top of the tower was vented and switched to the acetonitrile collection condenser and the receiving bottle, the cooling water of the distillation tower was turned off, the temperature of the bottom of the distillation tower was slowly increased, and the gas phase temperature was controlled to be ≤81°C to steadily collect acetonitrile until no acetonitrile was distilled out, and the amount of acetonitrile recovered by weighing was 90g;

[0096] The remaining material in the distillation tower is transferred to the o-chloroaniline distillation flask to recover the o-chloroaniline through reduced pressure distillation.

[0097] The ammonia and acetonitrile recovered by the above method are used to synthesize acetamidine hydrochloride, and the method is as follows:

[0098] Addition reaction: according to the amount of acetonitrile recovered in the above method, prepare 236g of acid methanol with a mass fraction of 46%, then add the acid methanol into the reaction flask and stir and cool to 0°C, then drop the recovered acetonitrile into the reaction flask, control the reaction temperature at 0-8°C, dropwise add for about 4 hours, then slowly heat to 15-20°C and keep warm for 6 hours to obtain ethylene amidine;

[0099] Amination reaction of acetamidine: 289.5g of frozen ammonia methanol recovered by the above method is supplemented with 18g of methanol to prepare 317g of ammonia methanol with an ammonia mass content of about 15.5%, which is then added to an ammonia reaction flask with a reflux condenser. Under stirring, the obtained acetamidine is controlled to be added to the ammonia methanol within 15 to 20 minutes to obtain a reaction solution, and the temperature of the reaction solution is controlled to be about 50°C and kept warm for 1 hour. The reaction solution is then cooled to 10°C, and the ammonium chloride in the reaction solution is separated by a centrifuge, and then 50g of methanol is used for washing. 39.8g of ammonium chloride is dried by centrifugal filtration, and the washing methanol and the centrifuged filtered solution are combined and concentrated to obtain acetamidine hydrochloride solid, and 200g of acetamidine hydrochloride crude product is obtained. The content of acetamidine hydrochloride detected is 92.7%.

[0100] Example 5

[0101] A method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine (formylpyrimidine) synthesis mother liquor comprises the following steps:

[0102] Recovery of ammonia and acetonitrile from synthetic mother liquor:

[0103] Set up a distillation experimental table, add 1400g of formylpyrimidine mother liquor into a distillation flask, then heat the formylpyrimidine mother liquor in the flask to 120°C, stir and heat for 3 hours, pass cooling water into the casing of the distillation tower, perform total reflux operation, vent the top of the tower using a rubber hose to connect to a flask filled with 250g of methanol, stir and cool to 0-5°C to absorb ammonia, observe the generation of bubbles in the flask, and after the bubbling in the flask stops, weigh the absorption flask to measure the amount of ammonia absorbed to be 41.6g, and obtain ammonia methanol solution (ammonia methanol);

[0104] The top of the tower was vented and switched to the acetonitrile collection condenser and the receiving bottle, the cooling water of the distillation tower was turned off, the temperature of the bottom of the distillation tower was slowly increased, and the gas phase temperature was controlled to be ≤81°C to steadily collect acetonitrile until no acetonitrile was distilled out, and the amount of acetonitrile recovered by weighing was 95g;

[0105] The remaining material in the distillation tower is transferred to the o-chloroaniline distillation flask to recover the o-chloroaniline through reduced pressure distillation.

[0106] The ammonia and acetonitrile recovered by the above method are used to synthesize acetamidine hydrochloride, and the method is as follows:

[0107] Addition reaction: According to the amount of acetonitrile recovered in the above method, 249g of acid methanol with a mass fraction of 46% is prepared, and then the acid methanol is added to the reaction flask and stirred to cool to 0°C, and then the recovered acetonitrile is added dropwise to the reaction flask, and the reaction temperature is controlled at 0-8°C, and the addition is carried out dropwise for about 4 hours, and then the temperature is slowly raised to 15-20°C and kept warm for 6 hours to obtain ethylene amidine;

[0108] Amination reaction of acetamidine: 291.6 g of frozen ammonia methanol recovered by the above method is supplemented with 32.9 g of methanol to prepare 335 g of ammonia methanol with an ammonia mass content of about 15.5%, which is then added to an ammonia reaction flask with a reflux condenser. Under stirring, the obtained acetamidine is controlled to be added to the ammonia methanol within about 15 to 20 minutes to obtain a reaction solution, the temperature of the reaction solution is controlled to be about 50° C., and the reaction solution is kept warm for 1 hour. The reaction solution is then cooled to 10° C., and the ammonium chloride in the reaction solution is separated by a centrifuge, and then 50 g of methanol is used for washing. 43.4 g of ammonium chloride is dried by centrifugal filtration, and the washing methanol and the centrifuged filtered solution are combined and concentrated to obtain acetamidine hydrochloride solid, and 216.3 g of acetamidine hydrochloride crude product is obtained. The content of acetamidine hydrochloride detected is 92.9%.

[0109] The parameters of each step process and product recovery in Examples 1-5 are shown in Table 1.

[0110] Table 1

[0111]

[0112] Comparative Example 1

[0113] In the prior art, the method for treating the synthetic mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine is to directly perform vacuum distillation on the synthetic mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine to recover o-chloroaniline, which causes the ammonia decomposed by acetamidine in the synthetic mother liquor to be discharged to the acid washing tower for absorption by a vacuum pump in the form of non-condensable gas during the vacuum distillation, and then discharged to the dilute wastewater, thereby increasing the discharge of ammonia nitrogen in the sewage. At the same time, the acetonitrile decomposed by acetamidine will be mixed with o-chloroaniline for condensation and collection, which causes the content of o-chloroaniline in the vacuum distillation product to be only about 90-92%. Then, when it is used to synthesize α-(o-chloroaniline)-methyl-β-formylaminopropionitrile (enamine), a large amount of acetonitrile is mixed into the enamine synthetic mother liquor and then discharged to the wastewater for treatment, thereby increasing the COD discharge in the wastewater.

[0114] In summary, the treatment method of the present invention heats and decomposes a large amount of excess acetamidine in the synthesis mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine into acetonitrile and ammonia, and then distills and separates ammonia, acetonitrile and o-chloroaniline in the synthesis mother liquor, and the obtained acetonitrile and ammonia can be used to synthesize acetamidine hydrochloride (reused for the synthesis of 2-methyl-4-amino-5-formylaminomethylpyrimidine), thereby achieving effective resource utilization of the recovered acetonitrile, reducing production costs, and improving the core competitiveness of the product, while greatly reducing the discharge of ammonia nitrogen and COD in sewage.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for treating a 2-methyl-4-amino-5-formylaminomethylpyrimidine synthesis mother liquor, characterized in that: The following steps are involved: The acetamidine in the synthesis mother liquor of 2-methyl-4-amino-5-formylaminomethylpyrimidine is decomposed into acetonitrile and ammonia by heat, and the acetonitrile and ammonia are separated from the synthesis mother liquor by distillation to obtain acetonitrile, ammonia and the separated synthesis mother liquor; The temperature of thermal decomposition of the acetamidine is 100-120°C.

2. The processing method according to claim 1, characterized in that: The distillation comprises the following steps: First, ammonia is distilled off at the top of the distillation tower, and then acetonitrile is distilled off at the top of the distillation tower to obtain acetonitrile and ammonia.

3. The processing method according to claim 2, characterized in that: The evaporated ammonia is collected by absorption with alcohol.

4. The processing method according to claim 3, characterized in that: The alcohol is methanol; The temperature of the methanol is 0-5°C.

5. The processing method according to claim 2, characterized in that: The distilled acetonitrile is collected by a condenser.

6. The processing method according to claim 2, characterized in that: The gas phase temperature during the distillation of acetonitrile is below 81°C.

7. The processing method according to any one of claims 1 to 6, characterized in that: The processing method further comprises the following steps: The separated synthetic mother liquor is subjected to reduced pressure distillation to obtain o-chloroaniline.

8. Use of the treatment method according to any one of claims 1 to 7 in the preparation of 2-methyl-4-amino-5-formylaminomethylpyrimidine.

9. The use according to claim 8, characterized in that: The reaction raw materials for preparing 2-methyl-4-amino-5-formylaminomethylpyrimidine include α-(o-chloroaniline)methyl-β-formylaminopropionitrile and acetamidine hydrochloride.

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