The role of organic solvent radical cations in separations ligand degradation

The dodecane radical cation reaction rate constant with CMPO was measured using ps electron pulse radiolysis/absorption spectroscopy as k = (1.30 ± 0.11) × 1010 M−1s−1 in dodecane/0.10 M CH2Cl2 solution. No reactivity increase occurred when these solutions were pre-contacted with nitric acid, similar to the behavior observed for TODGA. To corroborate these kinetic data with steady-state radiolysis measurements, where acid pre-contacted CMPO showed significantly less degradation, it is proposed that the dodecane radical cation always reacts directly with TODGA, but for CMPO the charge-transfer occurs with the CMPO·HNO3 complex formed in the acid contacted solvent.