Photoacoustic studies on radical kinetics and enthalpy change for photolysis of methylcobalamin

摘要

In the present work, photolytic radical kinetics 'of MeCbl was investigated by using time-resolved photoacoustic calorimetry. Two consequent steps were observed for photolysis of MeCbl in the presence of radical trap, Tempo. The first process corresponds to photo-induced Co-C bond homolysis forming a Co(Ⅱ) species and a methyl radical. The second represents the formation of Me-Tempo. The radical trapping rate constant of (2.9 +- 0.3) X10~9M~(-1)s~(-1) was obtained from a Stern-Volmer plot.