Formation of Organic Sulfur Compounds through SO₂ Initiated Photochemistry of PAHs and DMSO at the Air-Water Interface

The presence of organic sulfur compounds (OSs) at the water surface, acting as organic surfactants, may influence the air-water interaction and contribute to new particle formation in the atmosphere. However, the impact of ubiquitous anthropogenic pollutant emissions, such as SO2 and polycyclic aromatic hydrocarbons (PAHs) on the formation of OSs at the air-water interface still remains unknown. Here, we observe large amounts of OSs formation in presence of SO2, upon irradiation of aqueous solutions containing typical PAHs such as pyrene (PYR), fluoranthene (FLA), and phenanthrene (PHE), as well as dimethylsulfoxide (DMSO). We observe rapid formation of several gaseous OSs from light-induced heterogeneous reactions of SO2 with either DMSO or a mixture of PAHs/DMSO, and some of these OSs (e.g. methanesulfonic acid) are well established secondary organic aerosol (SOA) precursors. A myriad of OSs and unsaturated compounds are produced and detected in the aqueous phase. The tentative reaction pathways are supported by theoretical calculations of the reaction Gibbs energies. Our findings provide new insights into potential sources and formation pathways of OSs occurring at the water (sea, lake, river) surface, that should be considered in future model studies to better represent the air-water interaction and SOA formation processes.

9 Anodic Arylation Reactions

The arylation of organic compounds is a tremendously important tool in organic synthesis, since substituted (het)arenes are essential moieties in many applications ranging from organic intermediates to natural products, pharmaceuticals, and materials. Therefore, an effective, sustainable, and economic synthetic accesses to such compounds is of great demand. This chapter covers the arylation of carbon and heteroatom compounds via an electrooxidative pathway. Direct dehydrogenative methods without the application of a metal catalyst as well as constant-current electrolyses are emphasized. The electrochemical synthesis of biaryl compounds, arylalkanes and arylalkenes, as well as arylated nitrogen, oxygen, and sulfur compounds are described in detail. Additionally, the synthesis of heterocycles through anodic arylation reactions is discussed.