Photolysis and Study of Reactive Carbene Intermediates from Diazo and Sulfonium Ylide Precursor Molecules

Abstract

Carbenes are reactive intermediates comprised of a carbon atom with a lone pair of electrons. Carbenes can be found in interstellar space and their study helps inform our understanding of the formation of early complex molecules that may have contributed to life. This study focused on the photolysis of dibenzyl sulfonium ylide malonate and dibenzyl diazo malonate, two carbene precursors. When these molecules are irradiated, a bond is broken and the carbene intermediate is formed. The unstable carbene reacts immediately with a trapping agent, in this case, methanol, which also serves as the solvent for the reaction. These trapping experiments yield stable products that can be studied and analyzed for evidence of carbene intermediate formation. Carbene intermediates can exist in either a singlet or triplet electronic state, with the latter suspected to be favored. Analysis by 1H NMR and GC-MS spectroscopies suggests that a malonate product was formed, indicating a triplet carbene intermediate