Synergistic extraction of calcium and strontium into nitrobenzene by using hydrogen dicarbollylcobaltate and n,n´-dimethyl-n,n´-diphenyl-2,6-dipicolinamide.

Extraction of microamounts of calcium and strontium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H+B-) in the presence of N,N´-dimethyl-N,N´-diphenyl-2,6-dipicolinamide (MePhDPA, L) has been investigated. The equilibrium data have been explained assuming that the species HL+, HL+2, ML2+2 and ML2+3 (M2+ = Ca2+, Sr2+) are extracted into the organic phase. The values of extraction and stability constants of the cationic complex species in nitrobenzene saturated with water have been determined.

N,N'-Diethyl-N,N'-diphenyl-pyridine-2,6-dicarboxamide.

The asymmetric unit of the title compound, C(23)H(23)N(3)O(2), contains two mol-ecules in both of which, one amide N atom is in a syn position with respect to the pyridine N atom, while the other amide N atom is in an anti position (the syn--anti conformation). There are minor conformational differences between the two mol-ecules, as reflected in the N(pyridine)-C-C-N(amide) torsion angles of -44.9 (3) and 136.0 (2)° for one mol-ecule and 43.5 (3) and -131.1 (2)° for the other mol-ecule. However, the two mol-ecules show significant differences in the orientation of an ethyl group, with corresponding C-C-N-C torsion angles of 86.6 (3)° for one mol-ecule and 79.6 (3)° for the other mol-ecule. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming a three-dimensional supra-molecular network.

N,N,N',N'-Tetra-isobutyl-pyridine-2,6-dicarboxamide.

In the title compound, C(23)H(39)N(3)O(2), the amide O atoms are displaced by 1.020 (1) and 1.211 (1) Šfrom the mean plane of the central pyridine ring. In the crystal, mol-ecules are connected by weak C-H⋯O hydrogen bonds between methyl-ene groups in the isobutyl substituents and the amide O atoms.

N,N,N',N'-Tetra-ethyl-pyridine-2,6-dicarboxamide.

The title compound, C(15)H(23)N(3)O(2), crystallizes with two mol-ecules in the asymmetric unit which are linked by a C-H⋯N hydrogen bond. In the crystal, mol-ecules are connected via weak C-H⋯O and C-H⋯N hydrogen bonds between the amide O atoms and ethyl chains and between pyridine N atoms and aromatic H atoms in para positions. C-H⋯π inter-actions also occur.

Stability of Different BTBP and BTPhen Extracting or Masking Compounds against γ Radiation.

The radiolytic stability of hydrophobic extracting compounds CyMe4-BTBP and CyMe4-BTPhen and a hydrophilic masking agent (PhSO3H)2-BTPhen, widely employed for trivalent minor actinoid and lanthanoid separation, against γ radiation was tested. Even though the solvent with a promising fluorinated diluent BK-1 provides better extraction properties compared to octan-1-ol, its radiation stability is much lower, and no extraction was observed already after an absorbed dose of 150 kGy (CyMe4-BTBP) or 200 kGy (CyMe4-BTPhen). For the (PhSO3H)2-BTPhen hydrophilic masking agent, the results showed that the rate of radiolytic degradation was significantly higher in 0.25 M HNO3 than in 0.5 M HNO3. For both the hydrophobic and hydrophilic agents, degradation was slower in the presence of both organic and aqueous phases during irradiation.