A kind of synthetic method of 2-methyl-3-butyn-2-amine

Abstract

The present invention relates to the technical field of fine chemical product synthesis, and in particular to a kind of synthetic method of 2-methyl-3-butyn-2-amine, comprising the following steps: S1, methylbutynol and catalyst are mixed, thionyl chloride is added dropwise thereto at a temperature of 10-5 DEG C, insulation reaction 1-2h, 5 DEG C of saturated sodium chloride solution is added for washing, and the methylbutynyl chloride of organic phase is taken out for standby use after liquid separation; S2, the methylbutynyl chloride obtained by S1 and the composite catalyst and polymerization inhibitor containing 8-hydroxyquinolinone are added into reactor, after gas replacement is qualified, 0-20 DEG C of liquid ammonia is slowly passed into ammonia solution, maintaining a pressure of 0.4-0.8MPa, after the completion of ammonia, 20-25 DEG C of insulation reaction 8-12h, reaction is complete, pressure relief, nitrogen catches up with ammonia, and water distillation is performed to obtain 2-methyl-3-butyn-2-amine. The present invention can reduce black waste acid in methylbutynol chlorination process, to solve the increasingly serious chemical pollution problem, while developing ammonia solution process silver-based precious metal catalyst substitutes, to reduce production costs.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemical product synthesis, and in particular 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 high-efficiency, low-toxic pesticides. It is a representative product of the fourth generation of nickel plating brighteners with excellent performance. Even milligram-level 2-methyl-3-butyn-2-amine per liter of plating solution can produce a significant brightening effect.

[0003] At present, the main synthesis methods at home and abroad all use methylbutynol as raw material and produce it through a two-step reaction of chlorination and ammonolysis. The chlorination method and ammonolysis method are key factors affecting cost, product quality, environment and safety, so the selection of process methods is crucial. The chlorination reagent currently used in industrial production is mainly concentrated hydrochloric acid and calcium chloride or hydrogen chloride co-chlorination method. The chlorination process mostly uses cupric chloride, cuprous chloride, copper powder or cupric oxide as catalyst. After the reaction, a large amount of black waste acid is generated. The waste acid also contains a certain amount of tar, which is difficult to handle and causes serious environmental pollution. In addition, the purity of the methylbutynyl chloride obtained after chlorination is low, 80%-95%. The ammonolysis of methylbutynyl chloride is mostly carried out in liquid ammonia medium, while in patents CN101613287 and EP 834498, it is carried out with aqueous ammonia. The yield of ammonolysis with aqueous ammonia is much lower than that with liquid ammonia. Moreover, the method used in the literature is carried out at below -33°C, and the production conditions are harsh and unsuitable for industrial production. Currently, industrial ammonia decomposition mainly involves two methods: introducing ammonia gas or liquid ammonia into the reactor, using silver-based precious metal catalysts such as silver nitrate or silver sulfate. The catalysts are difficult to recycle and reuse, resulting in high product production costs. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for synthesizing 2-methyl-3-butyn-2-amine, which solves the problem of difficult treatment of black waste acid in existing industrial production. An 8-hydroxyquinolinone composite catalyst and a polymerization inhibitor are used to replace silver-based precious metal catalysts such as silver sulfate and silver nitrate, thereby reducing production costs and improving product purity and yield, which is of great significance to industrial production.

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

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

[0007] S1, methylbutynol and a catalyst are mixed, thionyl chloride is added dropwise thereto at a temperature of -10 to 5 ° C for chlorination, and the reaction is kept warm for 1 to 2 hours after the addition is complete, and then a saturated sodium chloride solution of 5 ° C is added for washing. After separation, the methylbutynyl chloride of the organic phase is taken out for standby use; wherein: the catalyst is one or more of DMAP, N, N-dimethylaniline, 3-picoline, DMF, 2-methyl-5-ethylpyridine, and hexamethylphosphoramide;

[0008] S2. Add the methylbutynyl chloride, 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, and after passing the gas replacement, slowly introduce liquid ammonia at 0-20°C for aminolysis, maintaining the pressure at 0.4-0.8 MPa. After the ammonia is introduced, keep the temperature at 20-25°C for 8-12 hours. 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.

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

[0010] 1. Chlorination reaction stage:

[0011] Methylbutynol reacts with thionyl chloride (SOCl2), replacing the hydroxyl group (-OH) with chlorine (-Cl) to produce methylbutynyl chloride. SOCl2 should be added slowly dropwise to control the exotherm and avoid local overheating. A temperature between -10°C and 5°C can balance the reaction rate and side reactions. Low temperatures slow side reactions, such as overchlorination. A Lewis base catalyst can accelerate the activation of SOCl2.

[0012] 2. Washing and separation:

[0013] The purpose is to remove unreacted SOCl2, generated HCl, and byproducts (such as dichlorides). The role of the saturated sodium chloride solution is to reduce the solubility of the aqueous phase and promote stratification. The waste gases (HCl and SO2) generated in the process are absorbed and treated with alkaline solution and then discharged after neutralization in wastewater.

[0014] 3. Ammonolysis reaction stage:

[0015] The chlorine atoms in methylbutyne chloride are replaced by ammonia (NH3) to generate amino compounds. The high pressure condition of 0.4-0.8 MPa can increase the solubility of NH3 and accelerate the reaction. The composite catalyst of 8-hydroxyquinolinone activates Cl by coordination. - , improve selectivity, reduce by-products such as hydrolysis products or polymers; inhibitors can effectively prevent alkyne polymerization at high temperatures.

[0016] First, the reaction rate is controlled at a low temperature of 0-20°C, and then the temperature is raised to 20-25°C to promote balanced conversion.

[0017] 4. Post-processing and distillation:

[0018] Nitrogen is used to drive out ammonia in order to improve the subsequent distillation effect and ensure operational safety. The product 2-methyl-3-butyn-2-amine has a boiling point of 80°C. The main purpose of adding water is to reduce the impact on distillation when ammonium chloride is in the system. Vacuum distillation or molecular distillation can also be used to increase purity.

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

[0020] Preferably, the mass ratio of methylbutynol to thionyl chloride and 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] Furthermore, 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.

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

[0024] Furthermore, the composite catalyst is a mixture of component A and component B, wherein component A is 8-hydroxyquinolinone, and 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.

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

[0026] Furthermore, the polymerization inhibitor is one or more of chlorobenzoquinone, 1,4-naphthoquinone, copper cyclohexane, hydroquinone, 4-tert-butylcatechol, and ZM-701.

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

[0028] Beneficial effects of the present invention:

[0029] The invention uses methylbutynol as a raw material and uses thionyl chloride to chlorinate under the action of a catalyst to obtain methylbutynyl chloride. Low temperature control in the chlorination stage effectively suppresses side reactions such as over-chlorination or alkyne oxidation. At the same time, the high reactivity of SOCl2 ensures efficient replacement of hydroxyl groups, resulting in a high product yield. High pressure in the ammonolysis stage significantly increases the solubility of NH3 and accelerates the amination reaction. The composite catalyst containing 8-hydroxyquinolinone directionally activates Cl through coordination. - , improve selectivity, reduce by-products such as hydrolysis products or polymers; at the same time, 8-hydroxyquinolinone composite catalyst and inhibitor are used to replace silver sulfate, silver nitrate and other silver-based precious metal catalysts, reducing production costs, improving product purity and yield, and having important significance for industrial production. The addition of inhibitors prevents the polymerization of alkynes at high temperatures, ensuring a smooth reaction and further improving the selectivity of the target product; washing with saturated NaCl solution can effectively remove unreacted SOCl2, 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 methylbutyne chloride obtained after chlorination is as low as 80% to 95%.

[0030] The raw materials used in the present invention are readily available, and methylbutynol, SOCl2, liquid ammonia, etc. are all bulk chemicals with stable supply and low cost. The chlorination reaction is controllable at low temperature, and the high pressure in the ammonolysis stage is pressurized by evaporation of the liquid ammonia itself, which can increase the reaction rate and equilibrium conversion rate or selectivity and reduce the demand for external energy. The catalyst used in the present invention is significantly cheaper than silver-based precious metal catalysts, effectively controlling costs. The process has the core advantages of high selectivity, environmental friendliness, safe operation, and economical and efficient operation, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 To obtain the sample product of Example 1 of the present invention 13 C-NMR spectrum.

[0032] Figure 2 A gas chromatogram of a sample product was obtained for Example 1 of the present invention.

[0033] Figure 3 The figure shows the product yield and purity results of Example 1 and Example 2 of the present invention compared with the traditional calcium chloride chlorination method.

[0034] Figure 4 This is a graph showing the product yield and purity corresponding to the ratio and coordination type of the composite catalyst in Example 3 of the present invention. DETAILED DESCRIPTION

[0035] In order to clearly illustrate the technical features of this solution, this solution is described below through specific implementation methods.

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

[0037] Example 1:

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

[0039] S1. Add 500 kg of methylbutynol and 3 kg of DMAP catalyst to a reactor, and begin to add 720 kg of thionyl chloride dropwise at -10 ° C. The temperature will rise during the addition. Pay attention to control the reaction liquid temperature not to exceed 5 ° C. After the addition is complete, keep the reaction warm for 1.5 hours, then add 300 kg of 5 ° C saturated sodium chloride solution, wash and separate the liquid to obtain 589 kg of methylbutynyl chloride with a purity of 98.3%.

[0040] S2. Add the methylbutyne chloride obtained in S1, 3 kg of composite catalyst, and 600 g of tetrachlorobenzoquinone polymerization inhibitor into the reactor, wherein the composite catalyst includes 8-hydroxyquinolinone and 18-crown-6, and the mass ratio of the two is 2:1; after three nitrogen and two ammonia replacements are qualified, slowly introduce liquid ammonia at 0-20°C for ammonia solution, and maintain the pressure at 0.5-0.7 MPa. The temperature rises sharply during the addition of liquid ammonia, and the reactor is temperature-controlled by using circulating coolant. After the ammonia is passed, the reactor is kept at 20-25°C for 10 hours for reaction. After the reaction is completed, the pressure is released, the ammonia is driven out by nitrogen, and water is added for distillation to obtain 2-methyl-3-butyn-2-amine.

[0041] The reaction mixture was analyzed by GC. The yield of 2-methyl-3-butyn-2-amine was calculated to be 91.3% based on methylbutynol, and the purity was 99.2%.

[0042] The sample product obtained in Example 1 was subjected to NMR test and gas chromatography analysis, and the test results were as follows: Figure 1 and Figure 2 shown.

[0043] 13 CNMR measurements were conducted at 400 MHz, using CDCl₃ as the solvent and TMS as the reference. The alkyl carbons were sp⁃ hybridized, with the chemical shift at 31.25 ppm representing two methyl carbons and 44.56 ppm representing the carbon connected to the amine group. The alkyne carbons were sp⁃ hybridized, with the chemical shift at 67.82 ppm representing the terminal alkyne carbon and 91.78 ppm representing the alkyne carbon not connected to hydrogen. The triplet peak at 77 ppm was the CDCl⁃ solvent peak.

[0044] Example 2:

[0045] A method for synthesizing 2-methyl-3-butyn-2-amine comprises the following steps:

[0046] S1. Add 500 kg of methylbutynol and 3 kg of catalyst 2-methyl-5-ethylpyridine into a reactor, and start adding 720 kg of thionyl chloride dropwise at -10 ° C. The temperature will rise during the addition. Pay attention to control the reaction liquid temperature not to exceed 5 ° C. After the addition is complete, keep the reaction warm for 1.5 hours, then add 300 kg of 5 ° C saturated sodium chloride solution, wash and separate the liquid to obtain 597 kg of methylbutynyl chloride with a purity of 97.8%.

[0047] S2. Add the methylbutynyl chloride and 3kg composite catalyst and 600g tetrachlorobenzoquinone polymerization inhibitor from the previous step into the reactor, wherein the composite catalyst includes 8-hydroxyquinolinone and tetrabutylammonium bromide, and the mass ratio of the two is 2:1; after three nitrogen and two ammonia replacements are qualified, slowly introduce liquid ammonia at 0-20℃ for aminolysis, and maintain the pressure at 0.5-0.7MPa. The temperature rises sharply during the addition of liquid ammonia, and the reactor is temperature-controlled by using circulating coolant. After the ammonia is passed, the reactor is kept warm at 20-25℃ for 10h. After the reaction is completed, the pressure is released, the ammonia is driven out by nitrogen, and water is added for distillation to obtain 2-methyl-3-butyn-2-amine.

[0048] The yield of the obtained 2-methyl-3-butyn-2-amine was 92.1% based on methylbutynol, and the purity was 99.3%.

[0049] The yield and purity of Example 1 and Example 2 of the synthesis method of the present invention were compared with those of the traditional calcium chloride chlorination method. Figure 3 As shown, it can be seen that the SOCl2 method provided by the present invention is superior to the traditional calcium chloride chlorination method in terms of yield and purity of 2-methyl-3-butyn-2-amine, and the synthesis method of the present invention has high yield and high selectivity.

[0050] Example 3:

[0051] In this embodiment, the operation steps and feeding amount are the same as those in Example 1, and only the ratio and coordination type of the 8-hydroxyquinolinone composite catalyst in the ammonolysis process are changed. The results are as follows Figure 4 shown.

[0052] Of course, the above description is not limited to the above examples. Technical features not described in the present invention can be achieved by or by adopting existing technologies, which will not be described here. The above embodiments and drawings are only used to illustrate the technical solutions of the present invention and are not limitations of the present invention. The present invention is described in detail with reference to the preferred implementation methods. Ordinary technicians in this field should understand that changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention do not depart from the purpose of the present invention and should also fall within the scope of protection 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 thereto at a temperature of -10~5°C for chlorination, the reaction is kept warm for 1~2h after the addition is complete, and then a saturated sodium chloride solution of 5°C is added for washing. After separation, the methylbutynyl chloride of the organic phase is taken out for standby use; wherein: the catalyst is one or more of DMAP, N,N-dimethylaniline, 3-picoline, DMF, 2-methyl-5-ethylpyridine, and hexamethylphosphoramide; S2. Add the methylbutynyl chloride obtained in S1 and the composite catalyst containing 8-hydroxyquinolinone and the polymerization inhibitor into the reactor, use nitrogen and ammonia to replace the gases in turn, and after passing the gas replacement, slowly introduce liquid ammonia at 0-20℃ for aminolysis, maintain the pressure at 0.4-0.8MPa, and after the ammonia is passed, keep the temperature at 20-25℃ 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; the composite catalyst is a mixture of component A and component B, wherein component A is 8-hydroxyquinolinone, and 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; the polymerization inhibitor is one or more of tetrachlorobenzoquinone, 1,4-naphthoquinone, copper cyclohexane, hydroquinone, 4-tert-butylcatechol, and ZM-701.

2. The method for synthesizing 2-methyl-3-butyn-2-amine according to claim 1, wherein: In step S1, the mass ratio of methylbutynol to thionyl chloride to 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, wherein: 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, wherein: 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, wherein: The mass ratio of methylbutyne chloride to liquid ammonia, composite catalyst and polymerization 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 1, wherein: Component B is one of tetrabutylammonium bromide or 18-crown-6.

8. The method for synthesizing 2-methyl-3-butyn-2-amine according to claim 1, wherein: The polymerization inhibitors are chloranil and p-tert-butylcatechol.

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