Bis-crown calix [4]arenes, their preparation process and their u

Details Bis-crown calix [4]arenes, their preparation process and their u Bis-crown calix [4]arenes, their preparation process and their u

1995-05-17

1997-03-04

Spear, Frank

Liquid purification or separation

Processes

Liquid/liquid solvent or colloidal extraction or diffusing...

210643, 423 9, B01D 6138

Patent

active

056075910

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to bis-crown calix[4]arenes, their preparation process and their use for the selective extraction of cesium and actinides.
More specifically, it relates to bis-crown calix[4]arenes able to selectively extract the cesium and actinides present in the state of traces in acid solutions which may or may not have high cation concentrations, such as aqueous effluents from irradiated nuclear fuel reprocessing installations or irradiated fuel dissolving solutions. In such effluents, cesium 137 is one of the most noxious fission products as a result of its long half-life (thirty years). It is therefore of interest to selectively eliminate it from the liquid effluents from reprocessing plants, particularly the concentrates of evaporators and acid solutions which may or may not have a high salinity due to the presence of sodium nitrate.
In view of the very similar chemical properties of sodium and cesium, it is extremely difficult to selectively extract the cesium present in these effluents, at a concentration generally below 10.sup.-6 mole/l, whereas the sodium concentration is approximately 4 mole/l. In order to solve this problem consideration has been given to the extraction of cesium by means of macrocyclic ligands such as para-tert.-butyl calixarenes, as described in U.S. Pat. No. 4,477,377. The para-tert.-butyl calixarenes used are the tetramer, hexamer and oxtamer and the best results are obtained with the hexamer and octamer, the tetramer not having a very good selectivity for separating cesium from potassium. This cesium extraction procedure is of interest, but suffers from the main disadvantage of only being applicable to the treatment of basic aqueous solutions, whereas most effluents resulting from reprocessing are acid solutions.
Other macrocyclic ligands such as crown ethers have also been used for this purpose, as is described by Dozol et al in report EUR 13887 FR of the Commission of the European Union (1992), but they have a low selectivity with respect to cesium.
The present invention isdirected at novel calixarenes making it possible to selectively extract cesium from acid solutions and separate it from sodium with a good efficiency.
According to the invention, the calixarenes are bis-crown calix[4]arenes of formula: ##STR2## in which R.sup.1 represents X (C.sub.2 H.sub.4 X).sub.m with X representing O, NH and/or N (CH.sub.3) and m being equal to 3, 4, 5 or 6, and/or N(CH.sub.3) and n being equal to 3, 4, 5 or 6, or H.sub.4 X).sub.p/2 with X representing O, NH and/or N(CH.sub.3), p being equal to 2 or 4 and Y representing a cycloalkylene or arylene group and
In the above formula, the term "cycloalkylene" group is understood to mean a divalent group derived from a cyclic hydrocarbon by removing a hydrogen atom from each of the two carbon atoms of the cycle. As an example of such a group reference can be made to the cyclohexylene group.
The term "arylene" group is understood to mean a divalent group derived from an aromatic or heterocyclic nucleus by removing a hydrogen atom from each of the two carbon atoms of the cycle. Examples of such groups are phenylene, naphthylene, pyridylene and thiophenylene groups.
In the R.sup.1 and/or R.sup.2 links, the X can represent hydrogen atoms, which can be partly or totally replaced by NH or N(CH.sub.3). Generally m and n are identical and are preferably equal to 4 or 5.
These calixarenes are very different from the calixarenes used in U.S. Pat. No. 4,477,377. Thus, in the latter document, use was made of calixarenes having on each benzene nucleus a phenol group or a tert.-butyl group, said calixarenes only having a single macrocycle.
However, in the case of the calixarenes according to the invention, there are three cycles respectively constituted by a first cycle corresponding to all the benzene nuclei linked by CH.sub.2 groups, a second cycle formed by a crown ether bridge between the benzene nuclei in the 1 and 3 positions and a third cycle of the crown ether type between the benzene nuclei in the 2 and 4 positions.
As a result o

REFERENCES:
patent: 4477377 (1984-10-01), Izatt et al.
patent: 4906376 (1990-03-01), Fyles
Journal of the American Chemical Society, vol. 112, No. 19, 12 Sep. 1990, Gaston, PA, U.S., pp. 6979-6985, Eleonora Ghidini et al.: Complexation of Alkali Metal Cations by Conformationally Rigid, Stereoisomeric Calix[4]Arene Crown Ethers: A Quantitative evaluation of Preorganization.

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