Microfluidic electrosynthesis of thiuram disulfides

• Published in: Green chemistry : an international journal and green chemistry resource : GC Vol. 23; no. 1; pp. 582 - 591
• Main Authors: Zheng, Siyuan, Wang, Kai, Luo, Guangsheng
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 18.01.2021
• Subjects: Amines; Carbon disulfide; Disulfides; Electrochemical analysis; Electrolysis; electrosynthesis; Enlargement; Free radicals; Green chemistry; High-performance liquid chromatography; industry; Microchannels; Microfluidics; Oxidation; Packed beds; Reactors; Salts; Sodium; surface area; Synthesis; Taylor flow
• ISSN: 1463-9262; 1463-9270; 1463-9270
• DOI: 10.1039/d0gc03336g

An electrolytic approach to sodium dithiocarbamates based on a microfluidic reactor is proposed for the green synthesis of thiuram disulfides, which are versatile free radical initiators. The electro-oxidation reactions avoid the over-oxidation of sodium dithiocarbamates and the generation of waste salts, which have perplexed the industry for a long time. This microfluidic electrolysis method prevents solid deposition by introducing liquid-liquid Taylor flow into the microchannel, and promotes the synthesis efficiency of thiuram disulfides with the enlargement of the electrode-specific surface area. The highest yield of thiuram disulfide was 88% in the experiment without any oxidation by-products. The Faraday efficiencies of most reactions are higher than 96%, showing the excellent electronic utilization. In addition to improving the environmental friendliness of sodium dithiocarbamate oxidation, the electrosynthesis method helps to create a cyclic technology of thiuram disulfide synthesis via the combination of sodium dithiocarbamate generation in a packed bed reactor. The cyclic technology finally achieved >99% atom utilization in thiuram disulfide synthesis from secondary amines and carbon disulfide. A microfluidic electrosynthesis method, which works with high efficiency in a flow chemistry system, for thiuram disulfides is proposed in order to avoid the generation of over-oxidation by-products and waste salts.