Uranium IV acetate

Submitted by R. C. Radi, J, S. Ghbtba, and M. S. Bains Checked by Henry R. HoekstraI 

Tripathy, Sahoo, and Patnaik have reduced alcoholic solutions of uranyl compounds photochemically, but the photolytic reduction is not complete in a reasonable time, and the products are partially hydrolyzed and/or hydrated. A large amount of acetic anhydride is required for complete conversion of the oxide acetate into the desired product and subsequent recovery. Oxide oxalate and oxalate can, however, be prepared by the addition of oxalic acid to the reduced aqueous solutions. The method reported below is unique in the sense that reduction is complete in a fairly short time and the yield is almost quantitative. Two alternative procedures are outlined. 

A solution of uranyl acetate (5 g.) in 50 ml. of glacial acetic acid is heated at reflux, with stirring, with amalgamated zinc. On completion of the reduction, the slurry of Zn[U(OOCCH3)6] in acetic acid is separated from the amalgamated zinc by decantation. The complex is precipitated completely by refluxing the decantate with an excess of acetic anhydride (20 ml.). The solid is filtered on a sintered-glass crucible and washed twice with ether. 

The precipitate is refluxed with a solution made up of 20 ml. of glacial acetic acid, 20 ml. of acetic anhydride, and 3.0 ml. of concentrated hydrochloric acid. Zinc chloride, being soluble in acetic acid, goes into solution, and the ura-nium(IV) acetate precipitates. The product is recovered and freed from the solvent as described under Part A. The yield is 5.2 g. (90%). 

An infrared spectrum of the product provides a quick check on the presence of U(VI). The uranyl ion in incompletely reduced samples exhibits a strong peak at 930 cm. , while the nearest acetate band is at 965 cm.  

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See also Uranium(IV) acetate, synthesis 11 Metal iron (III) oxides, synthesis 40 Salts of dinitrodiglycinatocobaltate(III), synthesis 46... 

Uranium(IV) acetate is stable in dry air, but it is slowly attacked by atmospheric moisture at room temperature. It is insoluble in benzene, alcohol, and ether and is completely hydrolyzed by water. Thermogravimetric studies show that thermal decomposition is complete at 320°. 

CbH,2Cl208Re2, Tetrakis(/x2"acetato)dichlorodirhenium, 46B, 1012 C8Hi2CrMo08, Chromiumdl) molybdenum(II) tetraacetate, 42B, 783 CBH12CU2O10, Copper(II) formate dioxan complex, 31B, 406 C8H12MO2O8, Dimolybdenum tetraacetate, 40B, 864 CbHi208U, Uranium(IV) acetate, 29, 458... 

Synonyms UN2977 uranium fluoride (fissle) Uranium (IV) chloride Uranium oxyfluoride uranium fluoride oxide bis(Acetate-B) dioxouranium bis(Nitrate-O) dioxouranium hexahydrate... 

We noted earlier that the principle uranyl (VI) species extracted from acetic acid by TOA-xylene is different from that extracted by TOA-chloroform (JO). To explore the effect of the solvent further we have now measured the spectra of uranium (VI) extracted with solutions of TOA in different solvents. In these experiments a O.IOM uranyl acetate solution in IV acetic acid was extracted with an equal volume of O.IOM TOA in each of the several solvents, and the spectra of both phases were measured. In most cases the extracted uranium was found to be a mixture of tri- and tetraacetato complexes. Some examples of these spectra are shown in Figure 6. 

Uranium(IV) oxalate has been prepared by the reaction of uranium(IV) chloride,sulfate, and hydroxide with a saturated solution of oxalic acid, or by the reduction of a water-soluble uranyl compound with copper, zinc, or sodium dithionite (Na2S204), followed by treatment with oxalic acid. It is prepared conveniently by the reduction of the readily available uranyl acetate 2-hydrate with sodium dithionite. 

Five grams (0.012 mol) of powdered uranyl acetate 2-hydrate is dissolved in 100 ml. of warm (80°) dilute hydrochloric acid (10 ml. of concentrated hydrochloric acid and 90 ml. of water). Five grams (0.024 mol) of powdered sodium dithionite 2-hydrate is added in small amounts while the solution is stirred. As the dithionite comes in contact with the solution a brown material is formed that quickly changes to a whitish-green precipitate. Five milliliters of concentrated hydrochloric acid is added and the mixture is then heated on a steam bath for at least 10 minutes mtil solution has been effected. The solution is usually cloudy due to the formation and presence of a small amount of free sulfur. The latter is easily removed by filtration, yielding a filtrate that possesses the characteristic dark green color of the uranium(IV) ion. 

The oxidizing action of Geobacter has another beneficial effect. Tests show that uranium salts can replace iron(III) oxide as the electron acceptor. Thus, by adding acetate ions and the bacteria to the groundwater contaminated with uranium, it is possible to reduce the soluble uranium(VI) salts to the insoluble uranium(IV) salts, which can be readily removed before the water ends up in households and farmlands. 

The solutions in acetic acid contain scarcely dissociated ion-pairs owing to its low dielectric constant. Some reactions lead to solvolysis products, such as FeCl(RCOO)2. Partial hydrolysis is found to occur with ferric and aluminium chloride, titanium(IV), niobium(V) and tantalum(V)-chlorides, while halides of arsenic(III), zirconium(IV), thorium(IV) and uranium(IV) are completely solvo-lysed. The high reactivity is undoubtedly due to the presence of acetate ions, and ethylacetate gives many more adducts with acceptor molecules than does acetic acid. 

Anthranlllc acid. Uranium (IV) Is precipitated from a solution of the reagent buffered with ammonium acetate. The reagent added to a O.IMUC (N0 )2 solution foms a heavy... 

Uranium compounds include acetates, carbonates, halides, nitrates, oxalates, oxides, phosphates, and sulfates. In broad terms uranyl (hexavalent, VI) compounds, which exist primarily as the U02 complex ion, tend to be the most soluble. The uranous (tetravalent, IV) compounds, such as UF4, are less soluble. Uranium oxides are the least soluble [3]. 

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