Photooxygenation of alkenes by molecular oxygen in the presence of porphyrins and chlorin sensitizers under visible light irradiation

Photooxidation of alkenes by molecular oxygen and visible light in the presence of tetraphenylporphyrin (H2TPP), tetramesitylporphyrin (H2TMP), tetrakis pentafluorophenylporphyrin (H2TPFPP) and tetrakis(2,3-dimetoxyphenyl)porphyrin T(2,3-OMeP)P and metalloporphyrins such as ClFeTPP, ClMnTMP, ClMnTPP, ClMnTPFPP, ClCoTPP and ZnTPP has been performed. Photooxidation of alkenes with tetraphenylchlorin (H2TPC) as the sensitizer with visible light has also been studied. The conversion rates for alkene oxidation were in the order of free-base porphyrins > chlorin > metalloporphyrins. In the presence of NaN3/Na2SO3 the yield of oxidation products and conversion percentage is considerably reduced, confirming involvement of O-1(2) in the mechanism.