Stability of [MeBu3N][Tf2N] under gamma irradiation

The stability of the ionic liquid [MeBu3N][Tf2N], dry or after contact with water (where [MeBu3N](+) is the methyltributylammonium cation and [Tf2N](-) is the bistriflimide anion), was studied under Cs-137 gamma irradiation in argon and in air. In a quantitative study with an absorbed dose of 2 MGy this ionic liquid was highly stable regardless of the radiolysis conditions. The radiolytic disappearance yields determined by ESI-MS were -0.38 and -0.25 mu mol J(-1) for the cation and anion, respectively. ESI-MS, NMR, and liquid chromatography coupled with ESI-MS identified a large number of degradation products in very small quantities for the same dose. The cation radicals were formed by the loss of a Bu-lozenge group, the Me-lozenge group, or two H-lozenge atoms to form a double bond with the butyl chain. Radiolysis of the anion produced mainly F-lozenge and CF3 lozenge radicals. The anion radicals recombined with the cation to form a wide range of secondary degradation products regardless of the radiolysis conditions.