Process for synthesizing ethenylamidine hydrochloride by one-step method

Abstract

The process of synthesizing ethyl amidine hydrochloride includes: setting acidyl methoxide into synthesizing kettle, dropping acetonitrile, maintaining at 15-30 deg.c for 4-6 hr before lowering the temperature to -5 deg.c to 20 deg.c, adding amido alcohol, stirring to react, cooling after reaction and discharging, solid-liquid separation, concentrating and centrifugally separating to obtain ethyl amidine hydrochloride. The synthesizing kettle is provided with a valve in the discharge port for measuring temperature, and the concentrating kettle is provided with a stirrer for favoring heat transfer and mass transfer. The present invention has optimized aminating condition, less reaction step, simplified reaction apparatus, high yield and high product quality.

Description

technical field [0001] The invention belongs to the manufacturing method of fine chemical products-medicine intermediates, in particular to the synthesis process of acetamidine hydrochloride. Background technique [0002] Acetamidine hydrochloride is made from acetonitrile, hydrogen chloride, methanol and ammonia through addition ammoniation, and its reaction formula is as follows: [0003] [0004] [0005] HCL+NH 3 →NH 4 CL [0006] The process is: [0007] ① Preparation of raw materials: dry HCL is absorbed with methanol to make 45%-48% acid methanol for later use. Dried ammonia is absorbed with methanol to make 12%-14% ammonia methanol for later use. [0008] ②Synthesis: Put 45-48% acid methanol into the imidine synthesis kettle at one time, start stirring, cool down, add acetonitrile dropwise into the imidine synthesis kettle at 8-15°C, and finish adding dropwise in about 4-6 hours . Keep warm at 18-24°C for 4-6 hours, depending on the reaction state of the...

AI Technical Summary

Problems solved by technology

If in a large reaction kettle, the material is only at the bottom of the kettle, the thermometer cannot be inserted into the material at all, and the temperature of the material cannot be truly measured, which will bring great difficulties to the operation.

During the ammoniation, the volume of the material increases three times, and the small kettle cannot hold it. In order to solve this problem, the existing technology adopts the synthesis of imidine in the small kettle, and the ammoniation in the large kettle is used to synthesize the acetamidine hydrochloride, so that the synthesis of the acetamidine hydrochloride is divided into two steps. Multi-purpose equipment and multi-purpose personnel also limit the production capacity of acetamidine hydrochloride

[0011] The concentration kettle in the prior art has an unreasonable design and cannot meet the requirements for the concentration of acetamidine hydrochloride. Without stirring, it is not conducive to the mass and heat transfer. It is difficult for the material in the center of the kettle to obtain the required heat, because The distance of heat and mass transfer is relatively long

In order to obtain the required heat, it is necessary to increase the external heat supply, especially in the later stage of concentration, when the material thickens and appears solid, heat transfer is more difficult. The result of increasing the external heat supply will inevitably cause local overheating of the material. Partially decompose the material, polymerize and form hard lumps, which seriously reduces the product quality (appearance and internal), and also reduces the yield of the product

[0012] There are two methods of ammoniation in the prior art: low-temperature ammoniation and high-temperature ammoniation. Low-temperature ammoniation needs to cool the temperature of the material to -5°C, and it must also be cooled during the ammoniation process. After the reaction, the temperature of the material rises to 35-37°C. This is beneficial to reduce the evaporation of methanol and reduce the loss of methanol, but the process takes a long time and consumes a lot of energy

Although the high-temperature method starts at a high temperature (10-15°C), the ammonia alcohol is pumped into the ammoniation kettle in about 3 minutes under cooling conditions. The reaction is intense, and the material temperature can automatically rise to 66-70°C. The pressure is too high to be safe. Large methanol evaporation, high loss, and poor operating environment

[0013] As can be seen from the above analysis, there are many deficiencies in the process and equipment in the prior art

① Synthesis of acetamidine hydrochloride: The synthesis of imidine and ammoniation are carried out in two reaction kettles in two steps, which requires unloading, which takes up more equipment and manpower, and the amount of single-batch feed is small, which limits the production capacity

②The design of the concentration kettle is unreasonable, and the lack of stirring seriously hinders the mass transfer and heat transfer. Therefore, it cannot be enlarged. It can only be produced by small kettle group equipment. The material is prone to local overheating, resulting in decomposition and polymerization, which reduces the quality and efficiency of the product.

③High-temperature or low-temperature ammoniation is unreasonable, and there is no methanol recovery condenser on the ammoniation kettle, resulting in a large loss of methanol and polluting the environment

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