Abstract
Calix[n]arene-based uranophiles bearing hydroxamic groups on the lower rim (2n; n = 4 and 6) have been synthesized and the extractability (Ex%) and the selectivity towards uranyl ion (UO22+) estimated in a two-phase (water-chloroform) solvent-extraction system. Ex% for 2 4 and 26 increases from pH 2 and saturation is reached at around pH 5 where 100% extractability occurs. Since the pKa values for hydroxamic acids are 8-9, the apparent pKa shift caused by the UO22+-complexation amounts to 6-7 pK units. Extraction of UO22+ from aqueous carbonate solution established that 26 in the organic phase can compete efficiently with CO 32- ions in the aqueous phase for UO2 2+ whereas in 24 and a calix[6]arene-based uranophile bearing six carboxy groups (16) UO22+ is reextracted to the aqueous phase. The difference indicates that 26, which has the hexacoordination geometry preorganized for the binding of UO 22+, is superior to 24 as a uranophile. We also found that the selectivity of 26 is superior to 16: the Ex% values for 26 is scarcely affected by the addition of competing metal cations (except Fe3+). These results show that 26 serves as an excellent UO22+-selective extraction reagent.
| Original language | English |
|---|---|
| Pages (from-to) | 1063-1066 |
| Number of pages | 4 |
| Journal | Journal of the Chemical Society, Perkin Transactions 2 |
| Issue number | 7 |
| Publication status | Published - 1991 |
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All Science Journal Classification (ASJC) codes
- Chemistry(all)
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Synthesis and solvent extraction studies of novel calixarene-based uranophiles bearing hydroxamic groups. / Nagasaki, Takeshi; Shinkai, Seiji.
In: Journal of the Chemical Society, Perkin Transactions 2, No. 7, 1991, p. 1063-1066.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Synthesis and solvent extraction studies of novel calixarene-based uranophiles bearing hydroxamic groups
AU - Nagasaki, Takeshi
AU - Shinkai, Seiji
PY - 1991
Y1 - 1991
N2 - Calix[n]arene-based uranophiles bearing hydroxamic groups on the lower rim (2n; n = 4 and 6) have been synthesized and the extractability (Ex%) and the selectivity towards uranyl ion (UO22+) estimated in a two-phase (water-chloroform) solvent-extraction system. Ex% for 2 4 and 26 increases from pH 2 and saturation is reached at around pH 5 where 100% extractability occurs. Since the pKa values for hydroxamic acids are 8-9, the apparent pKa shift caused by the UO22+-complexation amounts to 6-7 pK units. Extraction of UO22+ from aqueous carbonate solution established that 26 in the organic phase can compete efficiently with CO 32- ions in the aqueous phase for UO2 2+ whereas in 24 and a calix[6]arene-based uranophile bearing six carboxy groups (16) UO22+ is reextracted to the aqueous phase. The difference indicates that 26, which has the hexacoordination geometry preorganized for the binding of UO 22+, is superior to 24 as a uranophile. We also found that the selectivity of 26 is superior to 16: the Ex% values for 26 is scarcely affected by the addition of competing metal cations (except Fe3+). These results show that 26 serves as an excellent UO22+-selective extraction reagent.
AB - Calix[n]arene-based uranophiles bearing hydroxamic groups on the lower rim (2n; n = 4 and 6) have been synthesized and the extractability (Ex%) and the selectivity towards uranyl ion (UO22+) estimated in a two-phase (water-chloroform) solvent-extraction system. Ex% for 2 4 and 26 increases from pH 2 and saturation is reached at around pH 5 where 100% extractability occurs. Since the pKa values for hydroxamic acids are 8-9, the apparent pKa shift caused by the UO22+-complexation amounts to 6-7 pK units. Extraction of UO22+ from aqueous carbonate solution established that 26 in the organic phase can compete efficiently with CO 32- ions in the aqueous phase for UO2 2+ whereas in 24 and a calix[6]arene-based uranophile bearing six carboxy groups (16) UO22+ is reextracted to the aqueous phase. The difference indicates that 26, which has the hexacoordination geometry preorganized for the binding of UO 22+, is superior to 24 as a uranophile. We also found that the selectivity of 26 is superior to 16: the Ex% values for 26 is scarcely affected by the addition of competing metal cations (except Fe3+). These results show that 26 serves as an excellent UO22+-selective extraction reagent.
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UR - http://www.scopus.com/inward/citedby.url?scp=37049082940&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:37049082940
SP - 1063
EP - 1066
JO - Journal of the Chemical Society, Perkin Transactions 2
JF - Journal of the Chemical Society, Perkin Transactions 2
SN - 1470-1820
IS - 7
ER -