A synthetic toolbox for sustainable methods in porphyrin chemistry

Abstract

Greener synthesis for red dyes. As the days of chlorinated organic solvents are numbered, we propose a sustainable synthetic protocol for porphyrin synthesis to facilitate the transition into a more viable, safer and greener lab. Here we present a facile flow-assisted method for the sustainable synthesis of 40 meso-substituted planar porphyrins of the A4-, A2-, and trans-A2B2-type, including 10 examples of dodecasubstituted nonplanar porphyrins. We set forth a sustainable approach towards porphyrin synthesis, saving up to 90% of chlorinated solvents and drastically limiting waste generation by merging a flow synthesis process via a continuous stirred tank reactor (CSTR) with a traditional batch oxidation method.