Hydrolysis and Radiation Stability of m-Xylylene Bis-diglycolamide: Synthesis and Quantitative Study of Degradation Products by HPLC-APCI+

For nuclear hydrometallurgical separation process development, it is necessary to demonstrate the stability of the extracting systems, since it is well known that radio- and hydrolytic degradation leads to undesirable effects, such as a decrease in selectivity, poorer phase separation and third-phase formation. Recently, we have developed a new family of bis-diglycolamide (bis-DGA) molecules with high distribution coefficients (D) for Eu-III over Am-III. One of these bis-DGA extractants, namely, compound 1, showed high distribution coefficients even under gamma irradiation at 1000 kGy with external Co-60 sources. We report herein a detailed account on the stability of 1 against radio- and hydrolysis. We have also identified and quantified the sub-products formed during the irradiation process. Qualitative and quantitative analyses of irradiated 1 were performed by HPLC-MS, indicating the presence of seventeen degradation compounds. All fragments (2-18) were identified and synthesized independently. To complete this study, the An(III) and Ln(III) extraction properties of these fragments were assessed under the same experimental conditions as those used to evaluate the An(III) and Ln(III) extraction by irradiated 1. Despite the significance of a decrease in the concentration of 1, Am/Eu D values are still quite high. This means that at least some degradation products also act as efficient extractants. It is relevant to remark that two of the major degradation products (compounds 3 and 11) are stable to radiation and showed high D values for Am-III and Eu-III extraction.