The first ESR observation of radical species in subcritical water

Triphenylmethanol was treated in subcritical and supercritical water. A radical species, triphenylmethyl radical, was directly generated from triphenylmethanol in subcritical and supercritical water without using any radical initiator. The radical formation was confirmed by direct electron spin resonance (ESR) measurement in high-temperature and high-pressure subcritical water and by capturing the radical intermediate using hydrogen donors in supercritical water.