Method for preparing aminoacetonitrile and N,N-dimethylcyanamide from methane and ammonia gas through plasma synthesis

Abstract

The invention relates to a method for synthesizing aminoacetonitrile and N,N-dimethylcyanamide by using methane and ammonia gas as raw materials, which is characterized by comprising the following steps: performing non-equilibrium plasma activation on methane and ammonia gas to generate carbon-containing and nitrogen-containing free radical active species, and performing one-step spontaneous reaction on the species to generate the target products. The method belongs to a one-step direct synthesis process, has the advantages of simplicity and cheap raw materials, does not use solvent and causes no pollution. Besides, the method is also applicable to synthesis of organic compounds from various C1-5 alkane, olefin and alkyne and ammonia gas. Moreover, in addition to the aminoacetonitrile and N,N-dimethylcyanamide, acetonitrile, ethylenediamine, 4,5-dihydro-5-methylpyrazole, aminopyrazole and other products can be also obtained through the plasma synthesis method.

Description

technical field

[0001] The invention belongs to the technical field of plasma chemical synthesis, and relates to a method for synthesizing aminoacetonitrile and N,N-dimethylcyanamide by using methane and ammonia as raw materials. Background technique

[0002] Aminoacetonitrile is an important fine chemical and pharmaceutical intermediate, which can be used to synthesize N-containing drug molecules such as timolol. Patent CN102531960A (application date: 2012-01-13) discloses a preparation method of aminoacetonitrile. The synthesis reaction of aminoacetonitrile is CH 2 = NCH 2 CN+H 2 SO 4 →NH 2 CH 2 CN. The synthetic overall reaction of the used raw material methylene amino acetonitrile of this reaction process is: NaCN+HCHO+NH 4 Cl+CH 3 COOH(anhydrous)→CH 2 = NCH 2 CN+NaCl+H 2 O+CO 2 (the yield is about 60%), its synthetic process uses highly toxic NaCN, and produces a large amount of waste water and other solid wastes, and is expensive.

[0003] N,N-Dimethylcya...

Examples

Embodiment 1

[0059] Example 1: Single dielectric barrier discharge --- wire barrel reactor

[0060] Under the pressure of 0.1MPa, methane and ammonia are passed into the discharge reactor at a molar ratio of 1:2 (the flow rate of methane is 20ml / min, and the flow rate of ammonia is 40ml / min). After the gas flow is stable, the plasma power supply is turned on. Dielectric barrier discharge. The reactor adopts a wire cylinder electrode structure, and a cylindrical reactor is made of a hard glass tube with an outer diameter of 9mm and an inner diameter of 6mm (also used as a barrier medium). The central electrode is a stainless steel electrode with a diameter of 3mm, and the ground electrode has a cylindrical wall thickness of 1mm. Shaped iron foil (close to the outer wall of the glass tube), the pole spacing is 3mm, and the effective discharge length of the reactor is 100mm.

[0061] The discharge parameters of the reactor are: voltage 12kV, frequency 12kHz; other reaction conditions of the ...

Embodiment 2

[0063] Repeat Example 1, but change the pressure to 0.05MPa, and keep the other parameters unchanged. The result of the reaction is: the methane conversion rate is 10%, there is carbon deposition, the selectivity of aminoacetonitrile is 10%, and the selectivity of N,N-dimethylcyanamide is 15%.

Embodiment 3

[0065] Repeat Example 1, but change the molar ratio of methane and ammonia to 1:3 (wherein the methane flow rate is 15ml / min, the ammonia flow rate is 45ml / min), and the remaining parameters are unchanged. The reaction results are: the methane conversion rate is 7%, the aminoacetonitrile selectivity is 35%, and the N,N-dimethylcyanamide selectivity is 43%.

technical field

[0001] The invention belongs to the technical field of plasma chemical synthesis, and relates to a method for synthesizing aminoacetonitrile and N,N-dimethylcyanamide by using methane and ammonia as raw materials. Background technique

[0002] Aminoacetonitrile is an important fine chemical and pharmaceutical intermediate, which can be used to synthesize N-containing drug molecules such as timolol. Patent CN102531960A (application date: 2012-01-13) discloses a preparation method of aminoacetonitrile. The synthesis reaction of aminoacetonitrile is CH 2 = NCH 2 CN+H 2 SO 4 →NH 2 CH 2 CN. The synthetic overall reaction of the used raw material methylene amino acetonitrile of this reaction process is: NaCN+HCHO+NH 4 Cl+CH 3 COOH(anhydrous)→CH 2 = NCH 2 CN+NaCl+H 2 O+CO 2 (the yield is about 60%), its synthetic process uses highly toxic NaCN, and produces a large amount of waste water and other solid wastes, and is expensive.

[0003] N,N-Dimethylcya...

Examples

Embodiment 1

[0059] Example 1: Single dielectric barrier discharge --- wire barrel reactor

[0060] Under the pressure of 0.1MPa, methane and ammonia are passed into the discharge reactor at a molar ratio of 1:2 (the flow rate of methane is 20ml / min, and the flow rate of ammonia is 40ml / min). After the gas flow is stable, the plasma power supply is turned on. Dielectric barrier discharge. The reactor adopts a wire cylinder electrode structure, and a cylindrical reactor is made of a hard glass tube with an outer diameter of 9mm and an inner diameter of 6mm (also used as a barrier medium). The central electrode is a stainless steel electrode with a diameter of 3mm, and the ground electrode has a cylindrical wall thickness of 1mm. Shaped iron foil (close to the outer wall of the glass tube), the pole spacing is 3mm, and the effective discharge length of the reactor is 100mm.

[0061] The discharge parameters of the reactor are: voltage 12kV, frequency 12kHz; other reaction conditions of the ...

Embodiment 2

[0063] Repeat Example 1, but change the pressure to 0.05MPa, and keep the other parameters unchanged. The result of the reaction is: the methane conversion rate is 10%, there is carbon deposition, the selectivity of aminoacetonitrile is 10%, and the selectivity of N,N-dimethylcyanamide is 15%.

Embodiment 3

[0065] Repeat Example 1, but change the molar ratio of methane and ammonia to 1:3 (wherein the methane flow rate is 15ml / min, the ammonia flow rate is 45ml / min), and the remaining parameters are unchanged. The reaction results are: the methane conversion rate is 7%, the aminoacetonitrile selectivity is 35%, and the N,N-dimethylcyanamide selectivity is 43%.

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