Homogeneous continuous-flow nitration of O-methylisouronium sulfate and its optimization by kinetic modeling

Submitting author affiliation:
Zhejiang University of Technology, Hangzhou, China

Beilstein Arch. 2024, 202439. https://doi.org/10.3762/bxiv.2024.39.v1

Published 11 Jun 2024

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Nitration of O-methylisouronium sulfate under mixed acid conditions gives O-methyl-N-nitroisourea, a key intermediate of neonicotinoid insecticides with high application value. The reaction is a fast and highly exothermic process with a high mass transfer resistance, making its control difficult and risky. In this paper, a homogeneous continuous-flow microreactor system was developed for the nitration of O-methylisouronium sulfate under high concentrations of mixed acids, with a homemade static mixer eliminating the mass transfer resistance. In addition, the kinetic modeling of this reaction was performed based on the theory of NO2+ attack, with the activation energy and pre-exponential factor determined. Finally, based on the response surface generated by the kinetic model, the reaction was optimized with a conversion of 87.4 % under a sulfuric acid mass fraction of 94 %, initial reactant concentration of 0.5 mol/L, reaction temperature of 40 °C, molar ratio of reactants at 4.4:1, and residence time of 12.36 minutes.

Keywords: Nitration; Continuous flow; Static mixer; Kinetic modeling; Reaction optimization

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Guo, J.; Su, W.; Su, A. Beilstein Arch. 2024, 202439. doi:10.3762/bxiv.2024.39.v1

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