Transition Metal Mediated Hydrolysis of C-S Bonds: An Overview of a New Reaction Strategy.

Desulfurization of organosulfur substrates is highly important due to its relation with the industrial hydrodesulfurization (HDS) process of fossil fuels, which helps to eliminate the sulfur-containing impurities such as thiols, sulfide, thiophenes, etc. from crude oil for the production of easily processed and more cleanly combusted fuel with very low sulfur content. While the HDS process involves a hydrogenolysis reaction under a high pressure of hydrogen gas at high temperature, the hydrolysis of C-S bonds of organosulfur substrates at ambient conditions may very well be considered as a potential alternative for model desulfurization reactions. However, unlike the availability of an appreciable number of reports on base, acid, and metal ion mediated hydrolysis of thioesters in the literature, reports on the hydrolysis of more difficult substrates such as thiolates, sulfides, and other organosulfur substrates remained unavailable until 2017. The very recent discovery of a transition metal mediated hydrolysis reaction of C-S bonds at ambient conditions, however, has rapidly filled in this gap within the past few years. Development of this new stoichiometric reaction allowed the desulfurization of a large number of organosulfur substrates, including aliphatic and aromatic thiols, thiocarboxylic acids, sulfides, disulfides, thiophenes, and dibenzothiophene, at ambient conditions and was subsequently converted to a catalytic process for the hydrolysis of thiols. A brief overview of this new reaction strategy, a proposed reaction mechanism, a critical analysis of the efficiency, and future prospects are presented.