High pressure chemistry of red phosphorus by photo-activated simple molecules

High pressure (HP) is very effective in reducing intermolecular distances andinducing unexpected chemical reactions. In addition the photo-activation of the reactants inHP conditions can lead to very efficient and selective processes. The chemistry of phosphorus iscurrently based on the white molecular form. The red polymeric allotrope, despite more stableand much less toxic, has not attracted much attention so far. However, switching from thewhite to the red form would benefit any industrial procedure, especially from an environmentalpoint of view. On the other side, water and ethanol are renewable, environmental friendly andlargely available molecules, usable as reactants and photo-activators in HP conditions. Here wereport a study on the HP photo-induced reactivity of red phosphorus with water and ethanol,showing the possibility of very efficient and selective processes, leading to molecular hydrogenand valuable phosphorus compounds. The reactions have been studied by means of FTIR andRaman spectroscopy and pressure has been generated using membrane Diamond (DAC) andSapphire (SAC) anvil cells. HP reactivity has been activated by the two-photon absorption ofnear-UV wavelengths and occurred in total absence of solvents, catalysts and radical initiators,at room T and mild pressure conditions (0.2-1.5 GPa).