Abstract To identify the chemical species involved in a unique, vanadium-based chemical oscillator reaction, products derived from indole in the oscillation solution were isolated and characterized. NMR and mass spectra showed that 3, 3-dichloro-2-oxoindole and isatin were formed during the oscillation process. The formation of these two compounds suggests that peroxo species such as CHCl 2 OO· and CHCl 2 OOH play a key role in the ...