Method for co-producing methyl formate by using free acetamidine hydrochloride from aminopyrimidine mother liquor

Abstract

The present invention provides a method for utilizing free acetamidine hydrochloride from aminopyrimidine mother liquor and co-producing methyl formate, and relates to the technical field of compound preparation. In the above method, aminopyrimidine mother liquor and acetamidine hydrochloride are first subjected to free reaction in a reactor, and the products are separated to obtain acetamidine and a formic acid-containing solution; then the formic acid-containing solution is esterified with methanol to obtain methyl formate. The above method utilizes sodium formate free acetamidine hydrochloride in aminopyrimidine mother liquor to achieve separation of acetamidine and formic acid-containing solution, and simultaneously utilizes the separated formic acid-containing solution and methanol for esterification synthesis to co-produce methyl formate, thereby eliminating the use of relatively expensive raw and auxiliary materials such as liquid sodium methoxide and formic acid in the production process of acetamidine and methyl formate, thereby greatly reducing the production cost.

Description

Technical Field

[0001] The invention relates to the technical field of compound preparation, in particular to a method for co-producing methyl formate by utilizing free acetamidine hydrochloride from aminopyrimidine mother liquor. Background Art

[0002] In the existing production process of vitamin B1, formyl pyrimidine needs to be hydrolyzed to prepare amino pyrimidine, and a large amount of sodium formate will be produced in the mother liquor after hydrolysis.

[0003] The existing process for treating the mother liquor after the hydrolysis and separation of formylpyrimidine to obtain aminopyrimidine is to directly enter the triple-effect evaporation, so the sodium formate contained in the aminopyrimidine mother liquor after hydrolysis cannot be used as a resource. In addition, the existing acetamidine hydrochloride freeing process uses 30% liquid sodium methoxide for freeing, and the esterification synthesis process of methyl formate uses 85% formic acid as raw material for production, and the production costs of both are very high.

[0004] Therefore, it is necessary and urgent to study and develop a method for co-producing methyl formate by utilizing free acetamidine hydrochloride in aminopyrimidine mother liquor in order to reduce production cost and improve production efficiency.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] On the one hand, in the production process of vitamin B1, the aminopyrimidine mother liquor after the hydrolysis of formylpyrimidine usually enters the triple-effect evaporation system directly, and the sodium formate in the mother liquor cannot be utilized as a resource.

[0007] The existing route for the hydrolysis of formylpyrimidine is:

[0008]

[0009] On the other hand, the alkali substance consumed in the existing acetamidine hydrochloride free process is 30% liquid sodium methoxide, and the production cost of sodium methoxide is very high as an expensive auxiliary material. Taking our company as an example, the annual consumption of sodium methoxide is 2,380 tons, and the direct production cost = 2,380*3,795 / 10,000 = 9,032,100 yuan;

[0010] The existing process route for freeing acetamidine hydrochloride using sodium methoxide is:

[0011]

[0012] In addition, the existing esterification synthesis process of methyl formate uses 85% formic acid as raw material, and the cost of esterification synthesis using formic acid is also very high. Taking our company as an example, the annual usage of formic acid is 715 tons, and the direct production cost = 715*3502 / 10000 = 2.5 million yuan.

[0013] The existing process route for producing methyl formate by esterification synthesis using formic acid is:

[0014] HCOOH+CH3OH→HCOOCH3+H2O

[0015] In view of this, the object of the present invention is to provide a method for utilizing free acetamidine hydrochloride in aminopyrimidine mother liquor and co-producing methyl formate, so as to reduce the production cost of free acetamidine hydrochloride and methyl formate, and at the same time turn waste into treasure and make resource use of sodium formate in aminopyrimidine mother liquor.

[0016] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0017] The present invention provides a method for co-producing methyl formate by using free acetamidine hydrochloride from aminopyrimidine mother liquor, the method comprising:

[0018] The aminopyrimidine mother liquor and acetamidine hydrochloride are subjected to a free reaction in a reactor, and the products are separated to obtain acetamidine and a formic acid-containing solution;

[0019] The formic acid-containing solution is esterified with methanol to obtain methyl formate.

[0020] Further, the free reaction comprises the following steps:

[0021] Acetamidine hydrochloride is added into the reactor, and then the aminopyrimidine mother liquor is added dropwise into the acetamidine hydrochloride to carry out a dissociation reaction.

[0022] Furthermore, the mass ratio of the aminopyrimidine mother solution to acetamidine hydrochloride is 170-190:77.5-86.6;

[0023] Preferably, the mass ratio of the aminopyrimidine mother liquor to acetamidine hydrochloride is 130:77.5.

[0024] Furthermore, the temperature of the free reaction is 0 to 25°C, preferably 5 to 10°C.

[0025] Furthermore, the separation of the free reaction product is carried out by utilizing the difference in specific gravity between acetamidine and the formic acid-containing solution.

[0026] Furthermore, the separation method comprises: after the aminopyrimidine mother liquor is freed from acetamidine hydrochloride, the mother liquor is allowed to stand for stratification by utilizing the difference in specific gravity;

[0027] The lower layer is the acetamidine layer, and the upper layer is the water layer containing the formic acid solution.

[0028] Further, the esterification synthesis is carried out in a distillation device;

[0029] During the esterification synthesis process, the top temperature of the distillation unit is 30-33°C.

[0030] Furthermore, the mass ratio of the aminopyrimidine mother solution, acetamidine hydrochloride and methanol is 170-190:77.5-86.6:26.4-29.5;

[0031] Preferably, the mass ratio of the aminopyrimidine mother liquor, acetamidine hydrochloride and methanol is 130:77.5:26.4.

[0032] Further, the esterification synthesis comprises the following steps:

[0033] adding the formic acid solution and methanol into a distillation device for distillation to obtain methyl formate;

[0034] Furthermore, the esterification synthesis also includes the step of: introducing the residual liquid after distillation into a triple-effect evaporation system for evaporation and salt removal.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention provides a method for co-producing methyl formate by utilizing free acetamidine hydrochloride from aminopyrimidine mother liquor. The method firstly allows aminopyrimidine mother liquor and acetamidine hydrochloride to undergo a free reaction in a reactor, and the products are separated to obtain acetamidine and a formic acid-containing solution; then the formic acid-containing solution is esterified with methanol to obtain methyl formate. The above method utilizes sodium formate free acetamidine hydrochloride in aminopyrimidine mother liquor to achieve separation of acetamidine and formic acid-containing solution, and simultaneously utilizes formic acid and methanol for esterification synthesis to co-produce methyl formate, thereby eliminating the use of relatively expensive raw and auxiliary materials such as liquid sodium methoxide and formic acid in the production process of acetamidine and methyl formate, thereby greatly reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 This is a schematic flow chart of a method for co-producing methyl formate by freeing acetamidine hydrochloride from aminopyrimidine mother liquor, as provided in Example 1 of the present application. DETAILED DESCRIPTION

[0039] 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.

[0040] According to one aspect of the present invention, a method for co-producing methyl formate by freeing acetamidine hydrochloride from aminopyrimidine mother liquor comprises:

[0041] The aminopyrimidine mother liquor and acetamidine hydrochloride are subjected to a free reaction in a reactor, and the products are separated to obtain acetamidine and a formic acid-containing solution;

[0042] The formic acid-containing solution is esterified with methanol to obtain methyl formate.

[0043] The present invention provides a method for co-producing methyl formate by utilizing free acetamidine hydrochloride from aminopyrimidine mother liquor. The method firstly allows aminopyrimidine mother liquor and acetamidine hydrochloride to undergo a free reaction in a reactor, and the products are separated to obtain acetamidine and a formic acid-containing solution; then the formic acid-containing solution is esterified with methanol to obtain methyl formate. The above method utilizes sodium formate free acetamidine hydrochloride in aminopyrimidine mother liquor to achieve separation of acetamidine and formic acid-containing solution, and simultaneously utilizes formic acid and methanol for esterification synthesis to co-produce methyl formate, thereby eliminating the use of relatively expensive raw and auxiliary materials such as liquid sodium methoxide and formic acid in the production process of acetamidine and methyl formate, thereby greatly reducing production costs.

[0044] In a preferred embodiment of the present invention, the freeing reaction comprises the following steps:

[0045] Acetamidine hydrochloride is added into the reactor, and then the aminopyrimidine mother liquor is added dropwise into the acetamidine hydrochloride to carry out a dissociation reaction.

[0046] It should be noted that the present application adopts a dropwise addition method to add the aminopyrimidine mother solution into acetamidine hydrochloride for free reaction, which makes the reaction temperature more stable and also reduces the destruction of acetamidine hydrochloride.

[0047] In a preferred embodiment of the present invention, the mass ratio of the aminopyrimidine mother solution to acetamidine hydrochloride is 170-190:77.5-86.6;

[0048] Preferably, the mass ratio of the aminopyrimidine mother liquor to acetamidine hydrochloride is 130:77.5.

[0049] In a preferred embodiment of the present invention, the temperature of the free reaction is 0 to 25°C, preferably 5 to 10°C.

[0050] In a preferred embodiment of the present invention, the separation of the free reaction product is carried out by utilizing the difference in specific gravity between acetamidine and the formic acid-containing solution.

[0051] In the above preferred embodiment, the separation method comprises: after the aminopyrimidine mother liquor is freed from acetamidine hydrochloride, static stratification is performed using the difference in specific gravity;

[0052] The lower layer is the acetamidine layer, and the upper layer is the water layer containing the formic acid solution.

[0053] In a preferred embodiment of the present invention, the esterification synthesis is carried out in a distillation device;

[0054] During the esterification synthesis process, the top temperature of the distillation unit is 30-33°C.

[0055] As a preferred embodiment, the top temperature of the distillation device in the above-mentioned esterification synthesis process can well realize the preparation of methyl formate. If the top temperature is too high, the recovered methyl formate has many impurities. If the top temperature is low, the yield of methyl formate is low.

[0056] In a preferred embodiment of the present invention, the mass ratio of the aminopyrimidine mother solution, acetamidine hydrochloride and methanol is 170-190:77.5-86.6:26.4-29.5;

[0057] Preferably, the mass ratio of the aminopyrimidine mother liquor, acetamidine hydrochloride and methanol is 130:77.5:26.4.

[0058] In a preferred embodiment of the present invention, the esterification synthesis comprises the following steps:

[0059] adding the formic acid solution and methanol into a distillation device for distillation to obtain methyl formate;

[0060] In a preferred embodiment of the present invention, the esterification synthesis further comprises: the residual liquid after distillation enters a triple-effect evaporation system for evaporation and salt removal.

[0061] As a preferred embodiment, the present invention obtains methyl formate as a by-product after distillation, and the distillation residue containing water and sodium chloride enters a triple-effect system for evaporation and salt removal, thereby realizing a new process for the co-production of methyl formate from aminopyrimidine mother liquor free acetamidine hydrochloride.

[0062] The specific process route of the method for co-producing methyl formate by using aminopyrimidine mother liquor to free acetamidine hydrochloride is as follows:

[0063] (I) Formylpyrimidine hydrolysis:

[0064]

[0065] (ii) Sodium formate free acetamidine hydrochloride:

[0066]

[0067] (III) Esterification synthesis:

[0068] HCOOH+CH3OH→HCOOCH3+H2O

[0069] The technical solution of the present invention will be further described below in conjunction with embodiments.

[0070] Example 1

[0071] Figure 1 The figure is a schematic flow chart of the method for co-producing methyl formate by freeing acetamidine hydrochloride from aminopyrimidine mother liquor in this embodiment.

[0072] See also Figure 1 , a method for utilizing free acetamidine hydrochloride from aminopyrimidine mother liquor and co-producing methyl formate, the method comprising:

[0073] 1. Provide aminopyrimidine mother liquor (sodium formate content 30%, water 70%) after hydrolysis of formylpyrimidine, then add 77.5g of acetamidine hydrochloride (content 91%) into the reaction device, control the temperature at 20-25°C, and drop 170g of aminopyrimidine mother liquor (sodium formate content 30%, water 70%) to carry out free reaction;

[0074] 2. After the free reaction is completed, the mixture is allowed to stand for 2 hours and the layers are separated. The lower layer is 37 g of acetamidine solution. The acetamidine content detected by meteorological GC is 95.4%;

[0075] 3. Add 26.4 g of methanol to the upper water layer, and perform esterification synthesis in a distillation device. Control the top temperature of the distillation device within 33° C. The esterification synthesis distillation produces 46.75 g of methyl formate with a content of 94.3%;

[0076] According to calculation, the free yield of this embodiment is 81.48%, and the esterification synthesis yield is 97.9%.

[0077] Example 2

[0078] A method for utilizing free acetamidine hydrochloride from aminopyrimidine mother liquor and co-producing methyl formate, the method comprising:

[0079] 1. Provide aminopyrimidine mother liquor (sodium formate content 30%, water 70%) after hydrolysis of formylpyrimidine, then add 77.5g of acetamidine hydrochloride (content 91%) into the reaction device, control the temperature at 10-15°C, and drop 170g of aminopyrimidine mother liquor (sodium formate content 30%, water 70%) to carry out free reaction;

[0080] 2. After the free reaction is completed, the mixture is allowed to stand for 2 hours and the layers are separated. The lower layer is 41.3 g of acetamidine solution. The acetamidine content detected by meteorological GC is 96.2%;

[0081] 3. Add 26.4 g of methanol to the upper water layer, and perform esterification synthesis in a distillation device. Control the top temperature of the distillation device within 33° C. The esterification synthesis distillation produces 45.65 g of methyl formate with a content of 96.3%;

[0082] According to calculation, the free yield of this embodiment is 91.7%, and the esterification synthesis yield is 97.7%.

[0083] Example 3

[0084] A method for utilizing free acetamidine hydrochloride from aminopyrimidine mother liquor and co-producing methyl formate, the method comprising:

[0085] 1. Provide aminopyrimidine mother liquor (sodium formate content 30%, water 70%) after hydrolysis of formylpyrimidine, then add 77.5g of acetamidine hydrochloride (content 91%) into the reaction device, control the temperature at 5-10°C, and drop 170g of aminopyrimidine mother liquor (sodium formate content 30%, water 70%) to carry out free reaction;

[0086] 2. After the free reaction is completed, the mixture is allowed to stand for 2 hours and the layers are separated. The lower layer is 43.7 g of acetamidine solution. The acetamidine content detected by meteorological GC is 98.3%;

[0087] 3. Add 26.4 g of methanol to the upper water layer, and perform esterification synthesis in a distillation device. Control the top temperature of the distillation device within 33° C. The esterification synthesis distillation produces 45.95 g of methyl formate with a content of 96.1%;

[0088] According to calculation, the free yield of this embodiment is 99.1%, and the esterification synthesis yield is 98.1%.

[0089] Example 4

[0090] A method for utilizing free acetamidine hydrochloride from aminopyrimidine mother liquor and co-producing methyl formate, the method comprising:

[0091] 1. Provide aminopyrimidine mother liquor (sodium formate content 30%, water 70%) after hydrolysis of formylpyrimidine, then add 77.5g of acetamidine hydrochloride (content 91%) into the reaction device, control the temperature at 0-5°C, and drop 170g of aminopyrimidine mother liquor (sodium formate content 30%, water 70%) to carry out free reaction;

[0092] 2. After the free reaction is completed, the mixture is allowed to stand for 2 hours and the layers are separated. The lower layer is 44 g of acetamidine solution. The acetamidine content is 97.8% as determined by meteorological GC.

[0093] 3. Add 26.4 g of methanol to the upper water layer, and perform esterification synthesis in a distillation device. Control the top temperature of the distillation device within 33° C. The esterification synthesis distillation produces 46.25 g of methyl formate with a content of 95.1%;

[0094] According to calculation, the free yield of this embodiment is 99.3%, and the esterification synthesis yield is 97.7%.

[0095] In order to make the comparative analysis clearer, the applicant summarizes the above-mentioned embodiments 1 to 4 as follows:

[0096]

[0097] As can be seen from the above, the method of utilizing aminopyrimidine mother liquor to free acetamidine hydrochloride and co-produce methyl formate not only realizes the coupled free reaction of aminopyrimidine mother liquor and acetamidine hydrochloride, eliminates the use of intermediate raw materials liquid sodium methoxide and formic acid, but also makes resource utilization of sodium formate in aminopyrimidine mother liquor, and the formic acid generated by the reaction co-produces methyl formate, turning waste into treasure and reducing production costs.

[0098] 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 co-producing methyl formate by using free acetamidine hydrochloride from aminopyrimidine mother liquor, characterized in that: The method comprises: Providing an aminopyrimidine mother liquor after hydrolysis of formylpyrimidine, wherein the aminopyrimidine mother liquor contains 30% sodium formate and 70% water; The aminopyrimidine mother liquor and acetamidine hydrochloride are subjected to a free reaction in a reactor, and the free reaction product is separated to obtain acetamidine and a formic acid-containing solution; The formic acid-containing solution is subjected to esterification with methanol to obtain methyl formate; The dissociation reaction comprises the following steps: adding acetamidine hydrochloride into a reactor, and then dropping aminopyrimidine mother solution into acetamidine hydrochloride for dissociation reaction; The mass ratio of aminopyrimidine mother liquor to acetamidine hydrochloride in the free reaction is 130:77.5; The temperature of the free reaction is 5-10°C; The separation of the free reaction product is carried out by utilizing the difference in specific gravity between acetamidine and the formic acid solution. The separation method comprises: after the aminopyrimidine mother liquor is freed from acetamidine hydrochloride, the separation is carried out by utilizing the difference in specific gravity; the lower layer is the acetamidine layer, and the upper layer is the water layer containing the formic acid solution.

2. The method according to claim 1, characterized in that The esterification synthesis is carried out in a distillation device; During the esterification synthesis process, the top temperature of the distillation unit is 30~33℃.

3. The method according to claim 1, characterized in that The mass ratio of the aminopyrimidine mother liquor, acetamidine hydrochloride and methanol is 130:77.5:26.4-29.

5.

4. The method according to claim 1, characterized in that: The esterification synthesis comprises the following steps: The formic acid solution and methanol are added into a distillation device for distillation to obtain methyl formate.

5. The method according to claim 4, characterized in that The esterification synthesis further comprises the step of: introducing the residual liquid after distillation into a triple-effect evaporation system for evaporation and salt removal.

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