Chemistry Reference
In-Depth Information
tAbLe 4.38
selectivity Americium over Lanthanides from Aqueous solutions 3M Hno
3
into a nPHe solution of CPw23-CPw28 (10
−
3
M)
CPw24
D
La
D
Ce
D
Nd
D
Sm
D
Eu
D
Am
4.3
4.0
1.85
0.88
0.60
2.30
D
Am/La
D
Am/Ce
D
Am/Nd
D
Am/Sm
D
Am/Eu
D
Am/Am
0.53
0.57
1.23
2.59
3.84
1
CPw25
D
La
D
Ce
D
Nd
D
Sm
D
Eu
D
Am
0.67
0.64
0.32
0.18
0.12
0.43
D
Am/La
D
Am/Ce
D
Am/Nd
D
Am/Sm
D
Am/Eu
D
Am /Am
0.65
0.68
1.35
2.35
3.7
1
CPw26
D
La
D
Ce
D
Nd
D
Sm
D
Eu
D
Am
97
79
28
7.5
3.7
36
D
Am/La
D
Am/Ce
D
Am/Nd
D
Am/Sm
D
Am/Eu
D
Am /Am
0.37
0.45
1.27
4.77
9.8
1
D
La
D
Ce
D
Nd
D
Sm
D
Eu
D
Am
CPw27 (10
−3
M)
10.5
9.05
3.45
1.14
0.69
4.15
D
Am/La
D
Am/Ce
D
Am/Nd
D
Am/Sm
D
Am/Eu
D
Am /Am
0.39
0.46
1.19
3.60
5.98
1
D
La
D
Ce
D
Nd
D
Sm
D
Eu
D
Am
CPw28 (10
−3
M)
16.5
14.1
5.3
1.6
0.83
6.55
D
Am/La
D
Am/Ce
D
Am/Nd
D
Am/Sm
D
Am/Eu
D
Am /Am
0.40
0.47
1.24
4.14
7.94
1
softer picolinamide-binding groups. CPw29,
which
bears three CMPO and one
picolinamide groups at the wide rim of pentoxy-calix[4]arene, displays lower
D
Eu
and
D
Am
than its analogue bearing four CMPO moieties CPw3, without improv-
ing the selectivity
S
Am/Eu
. It seems that the arm bearing the picolinamide residue
hinders the extraction of cations without enhancing the discrimination between
actinides and lanthanides
18
(see Section 4.7).
Parma University
workers also synthesized CPn16
bearing three CMPO and one
picolinamide residue at the narrow rim of
p-tert-
butylcalix[4]arene. They also syn-
thesized CPn17 and CPn18, bearing two CMPO and two thiopicolinamide residues
linked to the phenolic oxygen atom by spacers of different length. As for their wide-
rim counterpart, the picolinamide groups do not modify the selectivity of these com-
pounds (Table 4.39).
In order to find compounds able to perform an efficient lanthanide/actinide sepa-
ration, the Twente group prepared two cavitands (Cv1 and Cv2) functionalized with
CMPO groups and two cavitands (Cv3 and Cv4) with carbamoylmethylphosphonate
(CMP) groups
192,193
(see Section 4.7). Distribution ratios displayed by CMPO cav-
itands are much lower than those found for the calixarene counterpart. This impor-
tant decrease of extracting ability of cavitand is probably due to the presence of a
carbon atom between the benzene unit and the nitrogen atom, causing N-protonation
below pH 2. Furthermore, the Am/Eu selectivity is less than that of CMPO-calix[4]
