Continuous synthesis of tetraethyl thiuram disulfide with CO2 as acid agent in a gas-liquid microdispersion system

Herein, a continuous synthetic method of tetraethyl thiuram disulfide (TETD) with CO2 as a weak acid reagent in a gas-liquid microdispersion reaction system has been described. A microdispersion reaction system comprising two microreactors for CO2 absorption and diethyldithiocarbamate acid subsequent oxidation reaction was developed. In the first step, the main products of absorption and oxidation reactions were identified. Next, the yield of TETD and selectivity of sodium diethyldithiocarbamate under different flow rates of raw materials, amount of CO2, aging effect, and pressure in the microreaction system were determined. The yield reached 89.03% based on 60% H2O2 dosage and the selectivity was 92.86% in less than 3 min of residence time, which was more than 30 min in the batch process. The space time yield in the microreaction system was similar to 20 times of that achieved in the batch process. The study provides a new successful reference for replacing batch synthesis by a continuous process using a microreaction system.