Chemical compound From Wikipedia, the free encyclopedia
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.
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UO2(H2O)2+[CH3CO−2]2 Hydrated crystal structure | |
| Names | |
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| IUPAC name
Uranium bis((acetato)-O)dioxo-dihydrate | |
| Other names
Uranyl ethanoate; Uranyl acetate dihydrate | |
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3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.007.971 |
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CompTox Dashboard (EPA) |
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| Properties | |
| UO2(CH3COO)2 (anhydrous) UO2(CH3COO)2·2H2O (dihydrate) | |
| Molar mass | 424.146 g/mol (dihydrate) |
| Appearance | yellow-green crystals (dihydrate) |
| Density | 2.89 g/cm3 (dihydrate) |
| Melting point | decomposes at 80 °C (dihydrate) |
| 7-8 g/100 ml | |
| Solubility | slightly soluble in ethanol[1] |
| Hazards | |
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| Danger | |
| H300, H330, H373, H411 | |
| P260, P264, P270, P271, P273, P284, P301+P310, P304+P340, P310, P314, P320, P321, P330, P391, P403+P233, P405, P501 | |
| Safety data sheet (SDS) | External MSDS |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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In the polymer, uranyl (UO22+) centers are bridged by acetate ligands. The remainder of each (heptacoordinate) coordination sphere is provided by an aquo ligand and a bidentate acetate ligand. One water of crystallization occupies the lattice.[2]
Uranyl carboxylates are known for diverse carboxylic acids (formate, butyrate, acrylate).[3]
Uranyl acetate is extensively used as a negative stain in electron microscopy.[4] Most procedures in electron microscopy for biology require the use of uranyl acetate. Negative staining protocols typically treat the sample with 1% to 5% aqueous solution. Uranyl acetate staining is simple and quick to perform and one can examine the sample within a few minutes after staining. Some biological samples are not amenable to uranyl acetate staining and, in these cases, alternative staining techniques and or low-voltage electron microscopy technique may be more suitable.[citation needed]
1% and 2% uranyl acetate solutions are used as an indicator, and a titrant in stronger concentrations in analytical chemistry, as it forms an insoluble salt with sodium (the vast majority of sodium salts are water-soluble). Uranyl acetate solutions show evidence of being sensitive to light, especially UV, and will precipitate if exposed.[citation needed]
Uranyl acetate is also used in a standard test—American Association of State Highway and Transportation Officials (AASHTO) Designation T 299—for alkali-silica reactivity in aggregates (crushed stone or gravel) being considered for use in cement concrete.[citation needed]
Uranyl acetate dihydrate has been used as a starting reagent in experimental inorganic chemistry.[5]
The compound can be prepared by treating uranium trioxide]] with acetic acid:
The acetate ligands of uranyl acetate can be replaced to give a variety of uranyl complexes.[6] Uranyl acetate can also be reduced by zinc to give the uranium(IV) acetate (U(OAc)4).[7]
In general, uranium salts exhibit nephrotoxicity. Normal commercial stocks from depleted uranium have typical specific activity 0.37–0.51 microcuries per gram (14–19 kBq/g), too weak to harm from outside the body. However, uranyl acetate is very toxic if ingested, inhaled as dust, or absorbed through cut or abraded skin.[citation needed]
Microbiologists have developed a number of alternative stains:[8] neodymium acetate,[9][10] platinum blue,[11] hafnium chloride,[12] and oolong tea extracts.[13][14]
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