TRI-n-OCTYLPHOSPHINE OXIDE AND TRIS(2-ETHYLHEXYL)PHOSPHINE OXIDE COMPLEXES OF URANYL NITRATE
The nature of the species resulting from uranyl nitrateR/sub 3/PO (R = alkyl group) interaction was investigated. The two phosphine oxides selected for the study were: tri-noctylphosphine oxide (TOPO) and tris(2-ethylhexyl)phosphine oxide (TEHPO). By extraction experiments, the solvation number of U(VI) by TOPO was found to be two. Extraction experiments also established that one U atom is present per formula unit of the complex. The result of the continuous variations experiment was consistent with a 1: 2 stoichiometry for U(VI): TOPO. The effect of nitric acid on the extraction of U(VI) was investigated. Temperature dependence studies for the extraction of uranyl nitrate were carried out to arrive at approximate values of DELTA H and DELTA S. The complex was found to be highly stable. However, U-233 exchange experiments showed that the complex is labile. Precipitation of the uranyl nitrate-TOPO complex from ethanol by addition of excess water was studied quantitatively. This study together with the study of the infrared spectrum of the complex showed that the formula of the complex could be written as UO/sub 2/(NO/sub 3/)/sub 2/TOPO)/sub 2/. The nitrate groups are coordinated to the central atom. The complex does not contain water. A decrease in the P---0 absorption frequency by about 70 cm/sup -1/ was observed as a result of complex formation. Spectra in the visible light region showed absorption bands at 436 and 450 m mu for the complex. Cryoscopic molecular weight of the complex (prepared by reacting uranyl nitrate and TOPO in a 1; 2 mole ratio in ethanol, followed by evaporation of the solvent) was found to be significantly different in the two solvents cyclohexane and benzene. A dipole moment value of about 8 Debyes was obtained for the complex. Concerning the nitric acid-TOPO interaction, a 1: 1 stoichiometry, was obtained at low HNO/sub 3/ concentrations. Sufficient evidence was obtained that in the case of uranyl nitrate-TEHPO a 1: 2 complex is also formed. The uranyl nitrate-TEHPO complex could be precipitated like the corresponding TOPO complex. The TEHPO complex was found to be less stable compared to the TOPO complex. U-233 exchange studies established the lability of the UTEHPO complex. A study of the infrared spectra showed that: the complex does not contain water; the P---O frequency is lowered by about 58 cm/sup -1/ on complex formation; and the nitrate groups in the complex are coordinated to the uranium atom. In the visible light region, absorption bands at 438 and 455 m mu were attributed to the complex. (TCO)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-18-003790
- OSTI ID:
- 4130035
- Resource Relation:
- Other Information: Thesis. Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ABSORPTION
ALKYL RADICALS
BENZENE
CRYOSCOPY
CYCLOALKANES
DIPOLE MOMENTS
DIPOLES
EFFICIENCY
ELECTRIC MOMENTS
ENTHALPY
ENTROPY
ETHANOL
ETHYL RADICALS
HEXANE
HEXYL RADICALS
INFRARED RADIATION
ISOTOPIC EXCHANGE
LIGHT
MAGNETIC MOMENTS
NITRIC ACID
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHORUS COMPOUNDS
PRECIPITATION
SOLVENT EXTRACTION
SPECTROSCOPY
STABILITY
TEHPO
TEMPERATURE
THERMODYNAMICS
TOPO
URANIUM 233
URANYL NITRATES
WATER
WEIGHT