Uranyl oxalate

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Uranyl oxalate
U Oxalate Trihydrate.tif
Other names
Uranyl oxalate trihydrate; uranyl oxalate hydrate
3D model (JSmol)
PubChem CID
  • InChI=1S/C2H2O4.2O.U/c3-1(4)2(5)6;;;/h(H,3,4)(H,5,6);;;/q;;;+2/p-2
  • C(=O)(C(=O)[O-])[O-].O=[U+2]=O
Molar mass 358 g/mole (412 g/mol as trihydrate)
AppearancePale yellow powder
Partially soluble
Related compounds
Related uranium oxides
Uranyl peroxide
Triuranium octoxide
Uranium dioxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Uranyl oxalate (UO2C2O4) is a pale yellow powdered uranyl compound. It is often encountered in industrial nuclear processes at both the front and back-end of the nuclear fuel cycle. Due to its hygroscopicity, uranyl oxalate rarely exists in the dehydrated state and is usually instead found in the trihydrate form (UO2C2O4·3H2O) at room temperature. [1] At room temperature, the powder exhibits a monoclinic crystal structure in the P21/c space group. [2]


Uranyl oxalate trihydrate can be produced by the reaction of uranyl nitrate hexahydrate with oxalic acid. [3]

Uranyl oxalate has been used in actinometers. [4]

Related Research Articles

Uranium hexafluoride Chemical compound

Uranium hexafluoride (UF
), (sometimes called "hex") is an inorganic compound with the formula UF6. Uranium hexafluoride is a volatile white solid that reacts with water, releasing corrosive hydrofluoric acid. The compound reacts mildly with aluminium, forming a thin surface layer of AlF3 that resists any further reaction from the compound. UF6 is used in the process of enriching uranium, which produces fuel for nuclear reactors and nuclear weapons.

PUREX Spent fuel reprocessing process for plutonium and uranium recovery

PUREX is a chemical method used to purify fuel for nuclear reactors or nuclear weapons. PUREX is the de facto standard aqueous nuclear reprocessing method for the recovery of uranium and plutonium from used nuclear fuel. It is based on liquid–liquid extraction ion-exchange.

Uranyl Oxycation of uranium

The uranyl ion is an oxycation of uranium in the oxidation state +6, with the chemical formula UO2+
. It has a linear structure with short U–O bonds, indicative of the presence of multiple bonds between uranium and oxygen. Four or more ligands may be bound to the uranyl ion in an equatorial plane around the uranium atom. The uranyl ion forms many complexes, particularly with ligands that have oxygen donor atoms. Complexes of the uranyl ion are important in the extraction of uranium from its ores and in nuclear fuel reprocessing.

Uranium trioxide Chemical compound

Uranium trioxide (UO3), also called uranyl oxide, uranium(VI) oxide, and uranic oxide, is the hexavalent oxide of uranium. The solid may be obtained by heating uranyl nitrate to 400 °C. Its most commonly encountered polymorph, γ-UO3, is a yellow-orange powder.

Uranyl acetate Chemical compound

Uranyl acetate is the acetate salt of uranium oxide, a toxic yellow-green powder useful in certain laboratory tests. Structurally, it is a coordination polymer with formula UO2(CH3CO2)2(H2O)·H2O.

Uranyl peroxide Chemical compound

Uranyl peroxide or uranium peroxide hydrate (UO4·nH2O) is a pale-yellow, soluble peroxide of uranium. It is found to be present at one stage of the enriched uranium fuel cycle and in yellowcake prepared via the in situ leaching and resin ion exchange system. This compound, also expressed as UO3·(H2O2)·(H2O), is very similar to uranium trioxide hydrate UO3·nH2O. The dissolution behaviour of both compounds are very sensitive to the hydration state (n can vary between 0 and 4). One main characteristic of uranium peroxide is that it consists of small needles with an average AMAD of about 1.1 μm.

Uranyl chloride Chemical compound

Uranyl chloride refers to inorganic compounds with the formula UO2Cl2(H2O)n where n = 0, 1, or 3. These are yellow-colored solids.


A uranate is a ternary oxide involving the element uranium in one of the oxidation states 4, 5 or 6. A typical chemical formula is MxUyOz, where M represents a cation. The uranium atom in uranates(VI) has two short collinear U–O bonds and either four or six more next nearest oxygen atoms. The structures are infinite lattice structures with the uranium atoms linked by bridging oxygen atoms.

Ammonium uranyl carbonate Chemical compound

Ammonium uranyl carbonate (UO2CO3·2(NH4)2CO3) is known in the uranium processing industry as AUC and is also called uranyl ammonium carbonate. This compound is important as a component in the conversion process of uranium hexafluoride (UF6) to uranium dioxide (UO2). The ammonium uranyl carbonate is combined with steam and hydrogen at 500–600 °C to yield UO2. In another process aqueous uranyl nitrate, known as uranyl nitrate liquor (UNL) is treated with ammonium bicarbonate to form ammonium uranyl carbonate as a solid precipitate. This is separated from the solution, dried with methanol and then calcinated with hydrogen directly to UO2 to obtain a sinterable grade powder. The ex-AUC uranium dioxide powder is free-flowing, relatively coarse (10 µ) and porous with specific surface area in the range of 5 m2/g and suitable for direct pelletisation, avoiding the granulation step. Conversion to UO2 is often performed as the first stage of nuclear fuel fabrication.

Uranium nitrides Chemical compound

Uranium nitrides is any of a family of several ceramic materials: uranium mononitride (UN), uranium sesquinitride (U2N3) and uranium dinitride (UN2). The word nitride refers to the −3 oxidation state of the nitrogen bound to the uranium.

Potassium ferrioxalate Chemical compound

Potassium ferrioxalate, also called potassium trisoxalatoferrate or potassium tris(oxalato)ferrate(III) is a chemical compound with the formula K
]. It often occurs as the trihydrate K3[Fe(C2O4)3]·3H2O. Both are crystalline compounds, lime green in colour.

Tantalum boride

Tantalum borides are compounds of tantalum and boron most remarkable for their extreme hardness.

Paulscherrerite, UO2(OH)2, is a newly named mineral of the schoepite subgroup of hexavalent uranium hydrate/hydroxides. It is monoclinic, but no space group has been determined because no single-crystal study has been done. Paulscherrerite occurs as a canary yellow microcrystalline powdery product with a length of ~500 nm. It forms by the weathering and ultimate pseudomorphism of uranium-lead bearing minerals such as metaschoepite. The type locality for paulscherrerite is the Number 2 Workings, Radium Ridge near Mount Painter, North Flinders Ranges, South Australia, an area where radiogenic heat has driven hydrothermal activity for millions of years. It is named for Swiss physicist Paul Scherrer, co-inventor of the Debye-Scherrer X-ray powder diffraction camera. Study of paulscherrerite and related minerals is important for understanding the mobility of uranium around mining sites, as well as designing successful strategies for the storage of nuclear weapons and the containment of nuclear waste.

Chromium(III) boride Chemical compound

Chromium(III) boride, also known as chromium monoboride (CrB), is an inorganic compound with the chemical formula CrB. It is one of the six stable binary borides of chromium, which also include Cr2B,Cr5B3, Cr3B4, CrB2, and CrB4. Like many other transition metal borides, it is extremely hard (21-23 GPa), has high strength (690 MPa bending strength), conducts heat and electricity as well as many metallic alloys, and has a high melting point (~2100 °C). Unlike pure chromium, CrB is known to be a paramagnetic, with a magnetic susceptibility that is only weakly dependent on temperature. Due to these properties, among others, CrB has been considered as a candidate material for wear resistant coatings and high-temperature diffusion barriers.

Caesium oxalate (standard IUPAC spelling) dicesium oxalate, or cesium oxalate (American spelling) is the oxalate of caesium. Caesium oxalate has the chemical formula of Cs2C2O4.

Amorphous uranium(VI) oxide Chemical compound

Amorphous uranium(VI) oxide(am-U2O7) is an orange diuranyl compound, most commonly obtained from the thermal decomposition of uranyl peroxide tetrahydrate at temperatures between 150 and 500 °C. It exists at room temperature as a powder. Am-U2O7 does not comprise a regular, long-range atomic structure, as demonstrated by its characteristic diffuse scattering pattern obtained by X-ray diffraction. As a result, the molecular structure of this material is little understood, although experimental and computational attempts to elucidate a local atomic environment have yielded some success.

Yttrium oxalate Chemical compound

Yttrium oxalate is an inorganic compound, a salt of yttrium and oxalic acid with the chemical formula Y2(C2O4)3. The compound does not dissolve in water and forms crystalline hydrates—colorless crystals.

The carbonate oxalates are mixed anion compounds that contain both carbonate (CO3) and oxalate (C2O4) anions. Most compounds incorporate large trivalent metal ions, such as the rare earth elements. Some carbonate oxalate compounds of variable composition are formed by heating oxalates.

Manganese oxalate is a chemical compound, a salt of manganese and oxalic acid with the chemical formula MnC
. The compound creates light pink crystals, does not dissolve in water, and forms crystalline hydrates. It occurs naturally as the mineral Lindbergite.

A selenate selenite is a chemical compound or salt that contains selenite and selenate anions (SeO32- and SeO42-). These are mixed anion compounds. Some have third anions.


  1. Thompson, Nathan B. A.; Stennett, Martin C.; Gilbert, Matthew R.; Hyatt, Neil C. (2021-01-06). "Nuclear forensic signatures and structural analysis of uranyl oxalate, its products of thermal decomposition and Fe impurity dopant". Journal of Radioanalytical and Nuclear Chemistry. 327 (2): 957–973. doi: 10.1007/s10967-020-07538-2 . ISSN   0236-5731.
  2. Jayadevan, N. C.; Chackraburtty, D. M. (1972-11-15). "The crystal and molecular structure of uranyl oxalate trihydrate". Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry. 28 (11): 3178–3182. doi:10.1107/s0567740872007691. ISSN   0567-7408.
  3. Tel, H; Bülbül, M; Eral, M; Altaş, Y (November 1999). "Preparation and characterization of uranyl oxalate powders". Journal of Nuclear Materials. 275 (2): 146–150. Bibcode:1999JNuM..275..146T. doi:10.1016/s0022-3115(99)00119-1. ISSN   0022-3115.
  4. Bryce-Smith, D. (1971). Photochemistry. Royal Society of Chemistry. p. 279. ISBN   978-0-85186-015-2.