Controlled multistep oxidation of alcohols and aldehydes to carboxylic acids using air, sunlight and a robust metalloporphyrin sensitizer with a pH-switchable photoreactivity

A homogeneous photocatalytic reaction cascade for the stepwise biomimetic oxidation of alcohols to form either aldehydes or alternatively carboxylic acids is presented. The system is based on robust and abundant materials and efficiently utilizes dioxygen as a clean and sustainable oxidant. Photoassisted substrate transformation occurs upon exposure to visible light (<620 nm) or sunlight. The pH-dependent photoredox mechanism of the sensitizer can be reversibly switched between two different selectivity patterns to control the desired product formation.