Method for synthesizing 1, 1, 3, 3-tetramethylguanidine

Abstract

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a method for synthesizing 1, 1, 3, 3-tetramethylguanidine, which comprises the following steps: step 1, adding dimethylamine into a reaction flask, starting stirring, then controlling the temperature at 20-50 DEG C, introducing chlorine gas into the reaction liquid while adding hydrocyanic acid for 1-4 hours, reacting to generate dimethylamino nitrile and dimethylamine hydrochloride, and then adding the dimethylamine hydrochloride into the reaction flask to obtain dimethylamine hydrochloride; the method comprises the following steps: 1, preparing a reaction solution, 2, heating the reaction solution to carry out a condensation reaction so as to generate tetramethylguanidine hydrochloride, and 3, adding liquid caustic soda into the reaction solution to carry out alkalization so as to generate tetramethylguanidine, and sequentially carrying out dimethylamine recovery, solvent extraction, solvent concentration and rectification on the reaction solution so as to finally obtain tetramethylguanidine. The method is simple in technological process, mild in reaction condition, free of high-temperature and high-pressure operation, low in production risk and beneficial to large-scale production.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, and specifically to a method for synthesizing 1,1,3,3-tetramethylguanidine. Background Technology

[0002] 1,1,3,3-Tetramethylguanidine, abbreviated as TMG, is a colorless, oily liquid and a strong organic base. It is widely used in the synthesis of various chemical products. In pharmaceuticals, it is primarily used as a cosolvent in the production of cephalosporin antibiotics. In polymer materials, it can be used as a catalyst in polyurethane foam. It is also used as a leveling agent for nylon, wool, and other proteins.

[0003] Currently, two processes are commonly used: one is the sodium cyanide-chlorine method, where sodium cyanide reacts with chlorine and dimethylamine to first produce dimethylaminonitrile and dimethylamine hydrochloride. Then, the two undergo a condensation reaction at a higher temperature to obtain tetramethylguanidine hydrochloride. Finally, after post-processing, tetramethylguanidine is obtained. The other process is the cyanide-cyanate method, where cyanide-cyanate reacts directly with dimethylamine to produce dimethylaminonitrile and dimethylamine hydrochloride. Subsequent operations are the same as the sodium cyanide-chlorine method, ultimately yielding tetramethylguanidine.

[0004] The two methods for generating tetramethylguanidine described above have the following main drawbacks: The main disadvantages of the first sodium cyanide-chlorine method are: firstly, it produces a large volume of wastewater with high cyanide content, resulting in high treatment costs; secondly, the reaction system is complex, producing numerous byproducts that are difficult to purify and have a low yield.

[0005] The main disadvantages of the second cyanogen chloride method are: Cyanogen chloride is a low-boiling-point, highly toxic substance, and its synthesis requires stringent equipment conditions. It involves the reaction of sodium cyanide or hydrogen cyanide with chlorine gas for purification. When only hydrogen cyanide and chlorine gas are used, the reaction not only needs to be carried out under specific high-temperature conditions but also requires a high degree of airtightness in the production equipment. Due to the high-temperature conditions and airtightness requirements during the reaction, the production process is quite dangerous and not conducive to large-scale industrial production. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for synthesizing 1,1,3,3-tetramethylguanidine.

[0007] This invention is achieved by providing a method for synthesizing 1,1,3,3-tetramethylguanidine, comprising the following steps: Step 1: Add dimethylamine to the reaction flask, start stirring, and then control the temperature at 20-50℃. While adding hydrogen cyanide to the reaction solution, simultaneously introduce chlorine gas over 1-4 hours. The reaction produces dimethylaminonitrile and dimethylamine hydrochloride. ; Step 2: The reaction solution is heated to carry out a condensation reaction, generating tetramethylguanidine hydrochloride: ; Step 3: Add liquid alkali to the reaction solution for alkalization to generate tetramethylguanidine. Then, sequentially perform dimethylamine recovery, solvent extraction, solvent concentration, and distillation on the reaction solution to finally obtain tetramethylguanidine. .

[0008] Preferably, in step 1, the reaction temperature when adding hydrogen cyanide and chlorine to the reaction solution is 30-40°C.

[0009] Preferably, in step 1, the hydrogen cyanide and chlorine are added over a period of 2.5 hours.

[0010] Preferably, in step 1, the dimethylamine is an aqueous solution with a concentration of 40%.

[0011] Preferably, in step 1, the hydrogen cyanide is in liquid or gaseous state.

[0012] Preferably, in step 1, the molar ratio of hydrogen cyanide to chlorine is hydrogen cyanide:chlorine = 1:1-1.1.

[0013] Preferably, in step 1, the molar ratio of hydrogen cyanide to chlorine is hydrogen cyanide:chlorine = 1:1.04-1.06.

[0014] Preferably, in step 1, the molar ratio of hydrogen cyanide and dimethylamine is hydrogen cyanide:dimethylamine = 1:3-3.3.

[0015] Preferably, in step 1, the molar ratio of hydrogen cyanide and dimethylamine is hydrogen cyanide:dimethylamine = 1:3.1-3.2.

[0016] Preferably, the specific process of step 2 is as follows: the reaction solution after adding hydrogen cyanide and chlorine is heated to 90-100°C and kept at this temperature for 3 hours.

[0017] Compared with the prior art, the beneficial effects of the present invention are: No large amounts of cyanide-containing waste brine are generated during the synthesis process; It produces fewer byproducts and has a high crude product content. Through a single distillation, the content can usually reach over 99.2%, which can effectively reduce production costs. The product yield is high, with molar yields generally exceeding 88%, and the quality is better. The process is simple, the reaction conditions are mild, and it does not involve high temperature and high pressure operations, which reduces the risk of production and facilitates large-scale production. Detailed Implementation

[0018] The present invention will be further explained below with reference to specific implementation schemes, but this is not intended to limit the scope of protection of the present invention.

[0019] Example 1

[0020] Step 1: Add 1800g (16mol) of 40% dimethylamine to a 3000mL reaction flask (the reaction flask must be a sealed reaction vessel) and start stirring; While maintaining the temperature at 30-40℃, add 135g (5mol) of liquid hydrogen cyanide to the reaction flask, and simultaneously introduce 377g (5.3mol) of chlorine gas into the reaction solution over a period of 2.5 hours.

[0021] Compared with the traditional method of purifying hydrogen cyanide and chlorine by reacting two reactants, adding dimethylamine to the reaction flask can effectively reduce the high temperature and high pressure required for the purification of hydrogen cyanide and chlorine. The reaction process can be completed in a normal closed reaction vessel, which effectively reduces the danger in the production process and is conducive to large-scale production.

[0022] Step 2: After adding hydrogen cyanide and chlorine, heat the reaction flask and slowly raise the temperature to 90-100℃, then maintain the temperature for 3 hours.

[0023] Step 3: Cool the reaction solution to room temperature, then add liquid alkali to the reaction flask for alkalization; The reaction solution is then subjected to the following steps in sequence: recovery of dimethylamine, solvent extraction, solvent concentration, and distillation. Finally, 551.7 g of colorless liquid tetramethylguanidine was obtained, with a purity of 99.7% and a molar yield of 95.8%.

[0024] Example 2 The difference between this embodiment and Example 1 is that 135g (5mol) of hydrogen cyanide gas and 377g (5.3mol) of chlorine gas were simultaneously introduced into the reaction solution, and finally 520.0g of colorless liquid tetramethylguanidine was obtained, with a content of 99.5% and a molar yield of 90.3%.

[0025] Example 3 The difference between this embodiment and Example 1 is that: while adding 135g (5mol) of liquid hydrogen cyanide to the reaction solution, 355g (5mol) of chlorine gas is introduced into the reaction solution, and finally 536.2g of colorless liquid tetramethylguanidine is obtained, with a content of 99.5% and a molar yield of 93.1%.

[0026] Example 4 The difference between this embodiment and Example 1 is that: while adding 135g (5mol) of liquid hydrogen cyanide to the reaction solution, 391g (5.5mol) of chlorine gas was introduced into the reaction solution, and finally 533.9g of colorless liquid tetramethylguanidine was obtained, with a content of 99.6% and a molar yield of 92.7%.

[0027] Example 5 The difference between this embodiment and Example 1 is that 1690g (15mol) of 40% dimethylamine was added to a 3000mL reaction flask, and 540.8g of colorless liquid tetramethylguanidine was finally obtained, with a purity of 99.4% and a molar yield of 93.9%.

[0028] Example 6 The difference between this embodiment and Example 1 is that 1860g (16.5mol) of 40% dimethylamine was added to a 3000mL reaction flask, and 543.6g of colorless liquid tetramethylguanidine was finally obtained, with a purity of 99.5% and a molar yield of 94.4%.

[0029] Example 7 The difference between this embodiment and Example 1 is that after adding 1800g (16mol) of 40% dimethylamine, the temperature was controlled at 20-30℃ for the reaction, and finally 543.6g of colorless liquid tetramethylguanidine was obtained, with a content of 99.3% and a molar yield of 94.4%.

[0030] Example 8 The difference between this embodiment and Example 1 is that after adding 1800g (16mol) of 40% dimethylamine, the temperature was controlled at 40-50℃ for the reaction, and finally 524.6g of colorless liquid tetramethylguanidine was obtained, with a content of 99.2% and a molar yield of 91.1%.

[0031] Example 9 The difference between this embodiment and Example 1 is that after adding 1800g (16mol) of 40% dimethylamine, the temperature was controlled at 30-40℃ for the reaction, and the hydrogen cyanide and chlorine were added for 1 hour. Finally, 526.9g of colorless liquid tetramethylguanidine was obtained, with a content of 99.6% and a molar yield of 91.5%.

[0032] Example 10 The difference between this embodiment and Example 1 is that after adding 1800g (16mol) of 40% dimethylamine, the temperature was controlled at 30-40℃ and stirred. Hydrogen cyanide and chlorine were added over 4 hours, and finally 547.7g of colorless liquid tetramethylguanidine was obtained with a content of 99.7% and a molar yield of 95.1%.

[0033] Example 11 The difference between this embodiment and Example 1 is that 7200g (16mol) of 10% dimethylamine was added to a 10000mL reaction flask, and 507.9g of colorless liquid tetramethylguanidine was finally obtained, with a purity of 99.7% and a molar yield of 88.2%.

Claims

1. A method for synthesizing 1,1,3,3-tetramethylguanidine, characterized in that, Includes the following steps: Step 1: Add dimethylamine to the reaction flask, start stirring, and then control the temperature at 20-50℃. While adding hydrogen cyanide to the reaction solution, simultaneously introduce chlorine gas over 1-4 hours. The reaction produces dimethylaminonitrile and dimethylamine hydrochloride. ； Step 2: The reaction solution is heated to carry out a condensation reaction, generating tetramethylguanidine hydrochloride: ； Step 3: Add liquid alkali to the reaction solution for alkalization to generate tetramethylguanidine. Then, sequentially perform dimethylamine recovery, solvent extraction, solvent concentration, and distillation on the reaction solution to finally obtain tetramethylguanidine. 。 2. The method for synthesizing 1,1,3,3-tetramethylguanidine according to claim 1, characterized in that: In step 1, the reaction temperature when adding hydrogen cyanide and chlorine to the reaction solution is 30-40℃.

3. The method for synthesizing 1,1,3,3-tetramethylguanidine according to claim 1, characterized in that: In step 1, the hydrogen cyanide and chlorine are added over a period of 2.5 hours.

4. The method for synthesizing 1,1,3,3-tetramethylguanidine according to claim 1, characterized in that: In step 1, dimethylamine is an aqueous solution with a concentration of 40%.

5. The method for synthesizing 1,1,3,3-tetramethylguanidine according to claim 1, characterized in that: In step 1, the hydrogen cyanide is in liquid or gaseous state.

6. The method for synthesizing 1,1,3,3-tetramethylguanidine according to claim 1, characterized in that: In step 1, the molar ratio of hydrogen cyanide to chlorine is hydrogen cyanide:chlorine = 1:1-1.

1.

7. The method for synthesizing 1,1,3,3-tetramethylguanidine according to claim 6, characterized in that: In step 1, the molar ratio of hydrogen cyanide to chlorine is hydrogen cyanide:chlorine = 1:1.04-1.

06.

8. The method for synthesizing 1,1,3,3-tetramethylguanidine according to claim 1, characterized in that: In step 1, the molar ratio of hydrogen cyanide and dimethylamine is hydrogen cyanide:dimethylamine = 1:3-3.

3.

9. The method for synthesizing 1,1,3,3-tetramethylguanidine according to claim 8, characterized in that: In step 1, the molar ratio of hydrogen cyanide and dimethylamine is hydrogen cyanide:dimethylamine = 1:3.1-3.

2.

10. The method for synthesizing 1,1,3,3-tetramethylguanidine according to claim 1, characterized in that: The specific process of step 2 is as follows: the reaction solution after adding hydrogen cyanide and chlorine is heated to 90-100℃ and kept at this temperature for 3 hours.

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