Porphyrin synthesis using mechanochemistry: Sustainability assessment

Looking tor sustainable synthetic methodologies, mechanochemistry as a new tool for one-step and two-step approaches for the synthesis of meso-substituted porphyrins was explored. The best results were obtained in a two-step procedure, under liquid-assisted grinding in the oxidation step using 2-methyltetrahydrofuran, an environmentally acceptable solvent, and MnO2 as a heterogeneous oxidant. The sustainability was assessed using two sustainability metrics, E-factor and EcoScale, which allow comparison between procedures and methods.