1,2-Dipyridiniumditribromide-ethane (DPTBE) as a New Oxidizing Agent for the Chemoselective Oxidation of Sulfides to the Sulfoxides

Mechanistic reaction model for oxidation of sulfur mustard simulant by a catalytic system of nitrate and tribromide

A new metal-free catalytic reaction system is developed to selectively oxidize 2-chloroethyl ethyl sulfide (CEES), a surrogate of sulfur mustard. The combination of two catalytic precursors, tribromide and nitrate, allows a rapid sulfoxidation of CEES even at ambient conditions. The kinetic behaviours at various reaction conditions are investigated to identify the most probable reaction pathways of the development of catalytic loop and the overall reaction steps of CEES sulfoxidation. The mechanistic study demonstrates that the catalytic loop does not require an addition of mineral acid or water, which is common in most other reaction systems. Incomplete catalytic systems with one precursor are also examined to uncover the complex network of sulfoxidation in the catalytic reaction system. The results reveal that the complex between CEES and bromine is a reactive intermediate, bromosulfonium, which can be further catalysed and converted into sulfoxide by nitrate. Based on the proposed reaction mechanism, a predictive kinetic model fully describing most reaction behaviours is developed.

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Bromination is one of the most important transformations in organic synthesis and can be carried out using bromine and many other bromo compounds. Use of molecular bromine in organic synthesis is well-known. However, due to the hazardous nature of bromine, enormous growth has been witnessed in the past several decades for the development of solid bromine carriers. This review outlines the use of bromine and different bromo-organic compounds in organic synthesis. The applications of bromine, a total of 107 bromo-organic compounds, 11 other brominating agents, and a few natural bromine sources were incorporated. The scope of these reagents for various organic transformations such as bromination, cohalogenation, oxidation, cyclization, ring-opening reactions, substitution, rearrangement, hydrolysis, catalysis, etc. has been described briefly to highlight important aspects of the bromo-organic compounds in organic synthesis.