The intermolecular photodecarboxylation of arylacetic acids 3–5 in water by use of stoichiometric amounts of N-alkylated phthalimides 1a,b was investigated by NMR and online pH- and CO2-release sensing. Decreasing the electron donor capability of the arylacetic acids by 4-fluoro and trifluoromethyl substitution alters the efficiency of the photodecarboxylation and selectivity of the secondary reaction. A remarkable switch in reaction channel (A to B) was observed for perfluoropropionic acid.
