Synthesis method of 2-methyl-3-butyne-2-amine

Abstract

The invention relates to the technical field of synthesis of fine chemical products, in particular to a synthesis method of 2-methyl-3-butyne-2-amine, which comprises the following steps: S1, mixing methyl butynol and a catalyst, dropwise adding thionyl chloride at the temperature of-10-5 DEG C for chlorination, carrying out heat preservation reaction for 1-2 hours, adding a saturated sodium chloride solution at the temperature of 5 DEG C for washing, and carrying out vacuum drying to obtain 2-methyl-3-butyne-2-amine; after liquid separation, taking out methyl butyne chloride of an organic phase for later use; and S2, adding the methyl butyne chloride obtained in the S1, a composite catalyst containing 8-hydroxyquinolinone and a polymerization inhibitor into a reaction kettle, after gas replacement is qualified, slowly introducing liquid ammonia at 0-20 DEG C for ammonolysis, keeping the pressure at 0.4-0.8 MPa, after ammonia introduction is finished, carrying out heat preservation reaction at 20-25 DEG C for 8-12 hours, after the reaction is finished, relieving the pressure, expelling ammonia by nitrogen, adding water and rectifying to obtain the 2-methyl-3-butyne-2-amine. According to the method, black waste acid in the methyl butynol chlorination process can be reduced, the increasingly serious chemical pollution problem is solved, meanwhile, silver noble metal catalyst substitutes in the ammonolysis process are developed, and the production cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemical product synthesis, and particularly relates to a method for synthesizing 2-methyl-3-butyn-2-amine. Background Art

[0002] 2-Methyl-3-butyn-2-amine is a raw material for synthesizing highly efficient and low-toxic pesticides, and is a representative product of the excellent-performance fourth-generation nickel plating brightener. Even containing milligram-level 2-methyl-3-butyn-2-amine per liter of plating solution has a significant brightening effect.

[0003] Currently, the main synthesis methods at home and abroad are both prepared from methyl butynol through two steps of chlorination and ammonolysis. The chlorination method and the ammonolysis method are the key factors affecting cost, product quality, environment and safety. Therefore, the selection of the process method is crucial. Currently, the chlorination reagents used in industrial production are mainly the co-chlorination method of concentrated hydrochloric acid and calcium chloride or hydrogen chloride. Most chlorination processes use copper chloride, cuprous chloride, copper powder or copper oxide as catalysts. After the reaction, a large amount of black waste acid will be generated, and there is still a certain amount of tar in the waste acid, which is difficult to treat, resulting in serious environmental pollution. Moreover, the purity of methyl butynyl chloride obtained after chlorination is only 80%-95%. The ammonolysis of methyl butynyl chloride is mostly carried out in a liquid ammonia medium, while in Patent CN101613287 and EP 834498, ammonia water is used for ammonolysis. However, the ammonolysis yield using ammonia water is much lower than that using liquid ammonia, and the method used in the literature is carried out at a temperature below -33°C, and the production conditions are harsh and not suitable for industrial production. Currently, the main ammonolysis methods in industry are to introduce ammonia gas and liquid ammonia into the reaction kettle, using silver-based noble metal catalysts such as silver nitrate or silver sulfate. The catalysts are difficult to recycle and reuse, resulting in high production costs of products and other problems. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a method for synthesizing 2-methyl-3-butyn-2-amine, which solves the problem that the black waste acid in existing industrial production is difficult to treat, and uses an 8-hydroxyquinolinone composite catalyst and a polymerization inhibitor to replace silver-based noble metal catalysts such as silver sulfate and silver nitrate, reducing production costs, improving product purity and yield, and having important significance for industrial production.

[0005] The present invention is realized through the following technical solutions:

[0006] A method for synthesizing 2-methyl-3-butyn-2-amine is provided, comprising the following steps:

[0007] S1. Mix methyl butynol with a catalyst, and dropwise add thionyl chloride for chlorination thereto at a temperature of -10 to 5 °C. After the dropping is completed, keep the temperature for reaction for 1 to 2 h, then add saturated sodium chloride solution at 5 °C for washing, and take out the organic phase of methyl butynyl chloride for standby after liquid separation; wherein: the catalyst is one or more of DMAP, N,N-dimethylaniline, 3-methylpyridine, DMF, 2-methyl-5-ethylpyridine, and hexamethylphosphoramide;

[0008] S2. Add the methyl butynyl chloride obtained in S1, a composite catalyst containing 8-hydroxyquinolinone, and an inhibitor to a reaction kettle. After sequentially performing gas displacement with nitrogen and ammonia to be qualified, slowly introduce liquid ammonia for ammonolysis at 0 to 20 °C, keep the pressure at 0.4 to 0.8 MPa, keep the temperature for reaction at 20 to 25 °C for 8 to 12 h after the ammonia introduction is completed. After the reaction is completed, relieve the pressure, drive away ammonia with nitrogen, and add water for rectification to obtain 2-methyl-3-butyn-2-amine.

[0009] The process reaction in this scheme includes the following several stages, specifically as follows:

[0010] 1. Chlorination reaction stage:

[0011] Methyl butynol reacts with thionyl chloride (SOCl 2 ), and the hydroxyl group (-OH) is replaced by chlorine (-Cl) to generate methyl butynyl chloride. SOCl 2 should be added dropwise slowly to control heat release and avoid local overheating. The temperature of -10 °C to 5 °C can balance the reaction rate and side reactions. Low temperature slows down side reactions such as over-chlorination. The catalyst is a Lewis base, which can accelerate the activation of SOCl 2 .

[0012] 2. Washing and liquid separation:

[0013] The purpose is to remove unreacted SOCl 2 , generated HCl and by-products (such as dichloride). The role of saturated sodium chloride solution is to reduce the solubility in the aqueous phase and promote layering. The waste gas (HCl, SO 2 ) generated during the process is treated by absorption with an alkali solution, and the wastewater is neutralized and discharged.

[0014] 3. Ammonolysis reaction stage:

[0015] The chlorine atom in methyl butynyl chloride is replaced by ammonia (NH 3 ) to generate an amino compound. The high-pressure condition of 0.4 to 0.8 MPa can increase the solubility of NH 3 and accelerate the reaction. The composite catalyst of 8-hydroxyquinolinone directionally activates Cl - through coordination, improves selectivity, and reduces by-products such as hydrolysis products or polymers; the inhibitor can effectively prevent the polymerization of alkynes at high temperature.

[0016] First, control the reaction rate at a low temperature of 0 - 20°C, and then raise the temperature to 20 - 25°C to promote the equilibrium conversion.

[0017] 4. Post-treatment and rectification:

[0018] Using nitrogen to drive off ammonia is for two purposes: one is to improve the rectification effect later, and the other is for operational safety; the boiling point of the product 2-methyl-3-butyn-2-amine is 80°C. The main purpose of adding water is to reduce the impact on rectification in the presence of ammonium chloride in the system. Vacuum distillation or molecular distillation can also be used to improve the purity.

[0019] Further, in step S1, the mass ratio of methyl butynol to thionyl chloride and the catalyst is 1:1.4 - 1.7:0.002 - 0.05.

[0020] Preferably, the mass ratio of methyl butynol to thionyl chloride and the catalyst is 1:1.5 - 1.6:0.005 - 0.01.

[0021] Preferably, the catalyst is one or more of DMAP, 2-methyl-5-ethylpyridine, and hexamethylphosphoramide.

[0022] Further, in step S2, the mass ratio of methyl butynyl chloride to liquid ammonia, the composite catalyst, and the inhibitor is 1:0.4 - 1:0.005 - 0.015:0.001 - 0.005.

[0023] The mass ratio of methyl butynyl chloride to liquid ammonia, the composite catalyst, and the inhibitor is 1:0.6 - 0.8:0.008 - 0.012:0.002 - 0.003.

[0024] Further, the composite catalyst is a mixture of component A and component B, where component A is 8-hydroxyquinolinone, and component B is one of benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium hydroxide, 18-crown-6, and cyclodextrin. The mass ratio of component A to component B is 1:0.2 - 0.5.

[0025] Preferably, component B is one of tetrabutylammonium bromide or 18-crown-6.

[0026] Further, the inhibitor is one or more of chloranil, 1,4-naphthoquinone, copper naphthenate, hydroquinone, p-tert-butylcatechol, and ZM-701.

[0027] Preferably, the inhibitor is chloranil and p-tert-butylcatechol.

[0028] The beneficial effects of the present invention:

[0029] The present invention uses methylbutynol as a raw material, and under the action of a catalyst, it is chlorinated with thionyl chloride to obtain methylbutynyl chloride. The low-temperature control in the chlorination stage effectively inhibits side reactions such as over-chlorination or oxidation of alkynes. At the same time, the high reactivity of SOCl 2 ensures the efficient substitution of hydroxyl groups, and the product yield is relatively high. In the ammonolysis stage, high pressure significantly increases the solubility of NH 3 , accelerating the amination reaction; the composite catalyst containing 8-hydroxyquinolinone directionally activates Cl - through coordination, improving selectivity and reducing by-products such as hydrolysis products or polymers; at the same time, using a composite catalyst of 8-hydroxyquinolinone and a polymerization inhibitor to replace silver-based noble metal catalysts such as silver sulfate and silver nitrate reduces production costs, improves product purity and yield, and is of great significance for industrial production. The addition of a polymerization inhibitor prevents the polymerization of alkynes at high temperatures, ensuring the smooth progress of the reaction and further improving the selectivity of the target product; washing with saturated NaCl solution can efficiently remove unreacted SOCl 2 , HCl and by-products (such as dichlorides), solving the problem of difficult treatment of black waste acid in existing industrial production, and the problem that the purity of methylbutynyl chloride obtained after chlorination is low, 80% - 95%.

[0030] In the present invention, the raw materials are easily available. Methylbutynol, SOCl 2 , liquid ammonia, etc. are all bulk chemicals with stable supply and low cost. The chlorination reaction can be controlled at low temperature. In the ammonolysis stage, high pressure is achieved by the self-evaporation pressurization of liquid ammonia, which can increase the reaction rate and equilibrium conversion rate or selectivity, reducing the external energy demand. The catalyst used in the present invention has a significantly lower price compared to silver-based noble metal catalysts, effectively controlling costs. This process has the core advantages of high selectivity, environmental friendliness, safe operation and economic efficiency, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 For the 13 C-NMR spectrum of the sample product obtained in Example 1 of the present invention.

[0032] Figure 2 For the gas chromatogram of the sample product obtained in Example 1 of the present invention.

[0033] Figure 3 For the graph of product yield and purity results of the comparison between Example 1, Example 2 of the present invention and the traditional calcium chloride chlorination method.

[0034] Figure 4 For the graph of product yield and purity results corresponding to the ratio and combination type of the composite catalyst in Example 3 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] To clearly illustrate the technical features of this solution, the following will elaborate on this solution through specific implementation manners.

[0036] The test materials used in the embodiments of the present invention are all conventional test materials in the art and can be obtained through commercial channels.

[0037] Example 1:

[0038] A method for synthesizing 2-methyl-3-butyn-2-amine, comprising the following steps:

[0039] S1. Charge 500 Kg of methyl butynol and 3 kg of catalyst DMAP into the reaction kettle, start dropping 720 Kg of thionyl chloride at -10°C. The temperature will rise during the dropping process. Pay attention to controlling the temperature of the reaction solution not to exceed 5°C. After the dropping is completed, keep the reaction for 1.5 h at a constant temperature, then add 300 kg of saturated sodium chloride solution at 5°C, wash and separate the liquid to obtain 589 kg of methyl butynyl chloride with a purity of 98.3%.

[0040] S2. Add the methyl butynyl chloride obtained in S1, 3 kg of composite catalyst, and 600 g of tetrachlorobenzoquinone inhibitor to the reaction kettle. Among them, the composite catalyst includes 8-hydroxyquinolinone and 18-crown-6, and the mass ratio of the two is 2:1. After three replacements with nitrogen and two replacements with ammonia are qualified, slowly introduce liquid ammonia for ammonolysis at 0 - 20°C, keep the pressure at 0.5 - 0.7 MPa. The temperature rises violently during the addition of liquid ammonia. Use circulating cooling liquid to control the temperature of the reaction kettle. After the ammonia introduction is completed, keep the reaction at a constant temperature of 20 - 25°C for 10 h. After the reaction is completed, release the pressure, drive away ammonia with nitrogen, and add water for rectification to obtain 2-methyl-3-butyn-2-amine.

[0041] Analyze the mixture after the reaction by GC. Based on methyl butynol, calculate the yield of 2-methyl-3-butyn-2-amine to be 91.3% and the purity to be 99.2%.

[0042] Take the sample product obtained in Example 1 for NMR testing and gas chromatography analysis. The test results are respectively as Figure 1 and Figure 2 shown.

[0043] 13 The test conditions for 13CNMR are 400 MHz, with the solvent CDCl 3 , and TMS as the reference. The alkyl carbon is SP3 hybridized. At the chemical shift value of 31.25 ppm, there are two methyl carbons, and at 44.56 ppm, there is the carbon connected to the amine group; the alkyne carbon is SP hybridized. At the chemical shift value of 67.82 ppm, there is the terminal alkyne carbon, and at 91.78 ppm, there is the alkyne carbon not connected to hydrogen; the triplet at 77 ppm is the solvent peak of CDCl 3 .

[0044] Example 2:

[0045] A synthetic method of 2-methyl-3-butyn-2-amine, comprising the following steps:

[0046] S1. Charge 500 Kg of methyl butynol and 3 kg of catalyst 2-methyl-5-ethylpyridine into the reaction kettle. Start dropping 720 Kg of thionyl chloride at -10°C. The temperature will rise during the dropping process. Pay attention to controlling the temperature of the reaction solution not to exceed 5°C. After the dropping is completed, keep the temperature for reaction for 1.5 h. Then add 300 kg of saturated sodium chloride solution at 5°C, wash and separate the liquid to obtain 597 kg of methyl butynyl chloride with a purity of 97.8%.

[0047] S2. Add the above-mentioned methyl butynyl chloride, 3 kg of composite catalyst, and 600 g of tetrachlorobenzoquinone inhibitor to the reaction kettle. The composite catalyst includes 8-hydroxyquinolinone and tetrabutylammonium bromide, and the mass ratio of the two is 2:1. After three replacements with nitrogen and two replacements with ammonia are qualified, slowly introduce liquid ammonia for ammonolysis at 0-20°C, keep the pressure at 0.5-0.7 MPa. The temperature rises violently during the addition of liquid ammonia. Use circulating cooling liquid to control the temperature of the reaction kettle. After the ammonia introduction is completed, keep the temperature for reaction at 20-25°C for 10 h. After the reaction is completed, relieve the pressure and drive out ammonia with nitrogen, and add water for rectification to obtain 2-methyl-3-butyn-2-amine.

[0048] Based on methyl butynol, the yield of the obtained 2-methyl-3-butyn-2-amine is 92.1%, and the purity is 99.3%.

[0049] Compare Example 1 and Example 2 of the synthesis method of the present invention with the traditional calcium chloride chlorination method in terms of yield and purity. As Figure 3 shown, it can be seen that the SOCl 2 method provided by the present invention is superior to the traditional calcium chloride chlorination method in both the yield and purity of 2-methyl-3-butyn-2-amine. The synthesis method of the present invention has high yield and high selectivity.

[0050] Example 3:

[0051] In this example, the operation steps and feeding amounts are the same as those in Example 1, only changing the proportion and cooperation type of the 8-hydroxyquinolinone composite catalyst during ammonolysis. The obtained results are as Figure 4 shown.

[0052] Of course, the above description is not limited to the above examples. The technical features not described in the present invention can be realized by or adopted the existing technology, and will not be elaborated here; the above examples and drawings are only used to illustrate the technical solutions of the present invention and are not limitations to the present invention. The present invention has been described in detail with reference to the preferred embodiments. Those of ordinary skill in the art should understand that the changes, modifications, additions or substitutions made by those of ordinary skill in the art within the scope of the essence of the present invention do not depart from the purpose of the present invention and should also fall within the scope of the claims of the present invention.

Claims

1. A method for synthesizing 2-methyl-3-butyn-2-amine, characterized in that: The following steps are involved: S1, methylbutynol and a catalyst are mixed, thionyl chloride is added dropwise at -10 to 5°C for chlorination, and the mixture is kept warm for 1 to 2 hours after the addition is complete, and then a 5°C saturated sodium chloride solution is added for washing, and the methylbutynyl chloride in the organic phase is taken out for standby use after separation; wherein: the catalyst is one or more of DMAP, N,N-dimethylaniline, 3-methylpyridine, DMF, 2-methyl-5-ethylpyridine, and hexamethylphosphoramide; S2. Add the methylbutynyl chloride and the composite catalyst containing 8-hydroxyquinolinone and the polymerization inhibitor obtained in S1 into the reactor, use nitrogen and ammonia to replace the gases in turn. After passing the gas replacement, slowly introduce liquid ammonia at 0-20°C for ammonolysis, maintain the pressure at 0.4-0.8MPa, and after the ammonia is passed, keep the temperature at 20-25°C for 8-12h. After the reaction is completed, release the pressure, drive out the ammonia with nitrogen, and add water for rectification to obtain 2-methyl-3-butyn-2-amine.

2. The method for synthesizing 2-methyl-3-butyn-2-amine according to claim 1, characterized in that: In step S1, the mass ratio of methylbutynol to thionyl chloride and catalyst is 1:1.4-1.7:0.002-0.

05.

3. The method for synthesizing 2-methyl-3-butyn-2-amine according to claim 2, characterized in that: The mass ratio of methylbutynol to thionyl chloride and catalyst is 1:1.5-1.6:0.005-0.

01.

4. The method for synthesizing 2-methyl-3-butyn-2-amine according to claim 1, 2 or 3, characterized in that: The catalyst is one or more of DMAP, 2-methyl-5-ethylpyridine and hexamethylphosphoramide.

5. The method for synthesizing 2-methyl-3-butyn-2-amine according to claim 1, characterized in that: In step S2, the mass ratio of methylbutyne chloride to liquid ammonia, composite catalyst and polymerization inhibitor is 1:0.4-1:0.005-0.015:0.001-0.

005.

6. The method for synthesizing 2-methyl-3-butyn-2-amine according to claim 5, characterized in that: The mass ratio of methylbutyne chloride to liquid ammonia, composite catalyst and inhibitor is 1: 0.6-0.8: 0.008-0.012: 0.002-0.

003.

7. The method for synthesizing 2-methyl-3-butyn-2-amine according to claim 5 or 6, characterized in that: The composite catalyst is a mixture of component A and component B, wherein component A is 8-hydroxyquinolinone, component B is one of benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium hydroxide, 18-crown-6, and cyclodextrin, and the mass ratio of component A to component B is 1:0.2-0.

5.

8. The method for synthesizing 2-methyl-3-butyn-2-amine according to claim 7, characterized in that: Component B is one of tetrabutylammonium bromide or 18-crown-6.

9. The method for synthesizing 2-methyl-3-butyn-2-amine according to claim 5 or 6, characterized in that: The polymerization inhibitor is one or more of tetrachlorobenzoquinone, 1,4-naphthoquinone, copper cyclohexaneate, hydroquinone, p-tert-butylcatechol, and ZM-701.

10. The method for synthesizing 2-methyl-3-butyn-2-amine according to claim 9, characterized in that: The inhibitors are chloranil and p-tert-butylcatechol.

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