Main article. The selective and controlled C-H functionalization of sp -hybridized carbons is arguably one of the most challenging goals in contemporary synthetic organic chemistry. Despite decades of research, the current state of the art in C-H activation still struggles to achieve selective C-H functionalization of saturated hydrocarbons. This is due to several factors, including the low reactivity of C-H bonds, the difficulty in achieving selective reactions in the absence of directing groups, and the presence of more reactive functional groups that can interfere with the reaction. These difficulties become even more pronounced when gaseous components are involved, either as the starting material or as the reactant, exacerbating the challenges already present due to limitations in gas-liquid mass transfer.