FULL PAPER DOI: 10.1002/ejoc.201100443 Hydrolysis and Radiation Stability of m-Xylylene Bis-diglycolamide: Synthesis and Quantitative Study of Degradation Products by HPLC–APCI + Hitos Galán, [a] María Teresa Murillo, [a] Rosa Sedano, [b] Ana Núñez, [c] Javier de Mendoza, [d] Amparo González-Espartero, [c] and Pilar Prados* [a] Keywords: Bis-diglycolamides / Lanthanides / Actinides / Radiochemistry / Nuclear waste For nuclear hydrometallurgical separation process develop- ment, it is necessary to demonstrate the stability of the ex- tracting systems, since it is well known that radio- and hydro- lytic degradation leads to undesirable effects, such as a de- crease 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 60 Co 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 dur- ing the irradiation process. Qualitative and quantitative Introduction One of the strategies used for spent nuclear fuel manage- ment is the hydrometallurgical treatment of high level-li- quid waste (HLLW), coming from the PUREX process, in two steps. [1] The first one consists of co-extraction of tri- valent actinides (An III ) and trivalent lanthanides (Ln III ) by the DIAMEX process (DIAMide EXtraction), which re- moves part of the nitric acid and most of the fission prod- ucts. [2] The second step, called the SANEX process (Selec- tive ActiNide EXtraction), separates the An III /Ln III group. [3] In these processes, organic ligands are used as cat- ion extractants in apolar solvents. Since the system is in contact with highly radioactive solutions, for process devel- opment it is not only necessary to demonstrate high extrac- [a] Departamento de Química Orgánica (C-I), Facultad de Ciencias, Universidad Autónoma de Madrid Carretera de Colmenar Viejo 15.3 km, 28049 Madrid, Spain Fax: +34-91-4973966 E-mail: pilar.prados@uam.es [b] Servicio Interdepartamental de Investigación (SIDI), Facultad de Ciencias, Universidad Autónoma de Madrid Carretera de Colmenar Viejo 15.3 km, 28049 Madrid, Spain [c] Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Avda. Complutense 22, 28040 Madrid, Spain [d] Institute of Chemical Research of Catalonia (ICIQ), 43007 Tarragona, Spain Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/ejoc.201100443. Eur. J. Org. Chem. 2011, 3959–3969 © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 3959 analyses of irradiated 1 were performed by HPLC–MS, indi- cating the presence of seventeen degradation compounds. All fragments (2–18) were identified and synthesized inde- pendently. To complete this study, the An III and Ln III extrac- tion 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 signifi- cance of a decrease in the concentration of 1, Am/Eu D val- ues are still quite high. This means that at least some degra- dation products also act as efficient extractants. It is relevant to remark that two of the major degradation products (com- pounds 3 and 11) are stable to radiation and showed high D values for Am III and Eu III extraction. tion coefficients (D) for An III and Ln III , but also to demon- strate the stability of the extractant. It is well known that radio- and hydrolytic degradation during the extraction process leads to undesirable effects, such as a decrease of selectivity, poorer phase separation and third-phase forma- tion. Most often, the new species generated have extracting properties that markedly differ from those of the original ligands. [4] Although several technologies have been used to determine the degradation process, [5] a study to assess the structure of these compounds has not been performed yet. Previously, we have described a family of bis-DGA ex- tractants containing either rigid spacers or flexible alkyl chains that co-extract An III and Ln III . Specifically, com- pound 1 with a m-xylylene spacer between the di- glycolamide subunits showed higher selectivity than simple diglycolamides for Eu III over Am III extraction from 3  solutions of nitric acid in a mixture (95:5 vol.-%) of hydro- genated tetrapropylene (HTP)/1-octanol (Figure 1). [6] To evaluate the effect of hydrolysis and extended irradia- tion on the distribution coefficients, we have studied the degradation products of 1 by HPLC–APCI + and fragments 2–18 were identified (Figure 1). These compounds have been synthesized and their extraction properties have been assessed separately. Finally, quantification of 1 and its de- gradation products has been performed by HPLC–APCI + after irradiation of 1 under different experimental condi- tions and pretreatments of the organic solutions.