Imidazole ring is an important component of many commonly used chemical substances. Imidazoles have significant application value in various fields such as heterocyclic chemistry, medicinal chemistry, biochemistry, etc. In particular, simple imidazole substances including imidazole, 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, etc. are more important due to their extensive use in drug production.

　　Microchannel continuous flow reactorCompared to traditional operational processes, it has significant advantages in heat and mass transfer, regulation of reaction conditions, process efficiency, and safety control.

For example, due to the difficulty in precise control of process parameters in kettle reactors, the reaction residence time and temperature distribution range are wide, while in continuous flow reactors, the reaction residence time and temperature distribution are more uniform, which is conducive to process optimization operations. In addition, continuous flow reactors can significantly shorten the time required from research and development to industrial production due to their continuous operation and ease of parallel scaling up.

This article focuses on constructing a continuous flow reactor system for the Radziszewski reaction and conducting research on the synthesis process behavior of simple imidazole. A back pressure valve is introduced in the system to increase system pressure, thereby eliminating the problem of limited boiling point of system materials in traditional atmospheric pressure reaction processes and significantly improving the process reaction rate.

This article specifically investigates the effects of residence time, reaction temperature, raw material ratio, concentration of acetaldehyde, and type of catalyst on imidazole yield to obtain an optimized process route. Meanwhile, the continuous synthesis of 2-methylimidazole, 2-ethylimidazole, and 2-isopropylimidazole by Radziszewski reaction was studied using a microchannel continuous flow reactor.

By constructing a continuous flow reactor system, the Radziszewski reaction for preparing imidazole can be continuously carried out in a controllable state, thereby improving the traditional kettle type imidazole preparation process.

The effects of residence time, reaction temperature, formaldehyde/glyoxal molar ratio, ammonium acetate/glyoxal molar ratio, glyoxal concentration, and different ammonia sources on imidazole yield were investigated in a microchannel continuous flow reactor, and the process route for imidazole synthesis was optimized.