The oxidation reaction of o-phenylenediamine (PDA) to 2,3-diaminophenazine (DAP) initiated by 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) has been investigated in methanol at ambient temperature. The oxidation of PDA was followed by electronic spectroscopy and the rate constants were determined according to the rate law -d[PDA]/dt = kobs[PDA][TEMPO]. The rate constant, activation enthalpy and entropy at 323 K are as follows: kobs (dm3 mol-1 s-1) = (3.60±0.13) × 10-6, Ea (kJ mol-1) = 76±11, ΔH‡ (kJ mol-1) = 74±10, ΔS‡ (J mol-1 K-1) = -122±31.
- O-Phenylenediamine oxidation
- Phenoxazinone synthase
- TEMPO catalysis
ASJC Scopus subject areas
- Physical and Theoretical Chemistry