uranyl acetate
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 431952998
| Name = Uranyl acetate
| ImageFile = Uranyl_Acetate_10_3_07.jpg
| ImageName = Uranyl acetate
| ImageFile1 =
| ImageCaption1 = Hydrated crystal structure
| IUPACName = Uranium bis((acetato)-O)dioxo-dihydrate
| OtherNames = Uranyl ethanoate; Uranyl acetate dihydrate
| Section1 = {{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 541-09-3
| index_label = (anhydrous)
| CASNo1_Ref = {{cascite|correct|CAS}}
| CASNo1 = 6159-44-0
| index1_label = (dihydrate)
| ChemSpiderID = 10468551
| ChemSpiderID1 = 11567664
| EC_number = 208-767-5
| PubChem = 10915
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 285PN2K1AO
| UNII1_Ref = {{fdacite|correct|FDA}}
| UNII1 = KJF3TEU4G6
| InChI=1S/2C2H4O2.2O.U/c2*1-2(3)4;;;/h2*1H3,(H,3,4);;;
| InChIKey = IXSMFXMQHOBORU-UHFFFAOYSA-N
| InChI1=1S/2C2H4O2.2H2O.2O.U/c2*1-2(3)4;;;;;/h2*1H3,(H,3,4);2*1H2;;;/q;;;;;;+2/p-2
| InChIKey1 = VVAHPLNXWRLLIG-UHFFFAOYSA-L
| SMILES = O=C(C)[O-].[O+]#[U]#[O+].O=C(C)[O-]
| SMILES_Comment = ionic form (anhydrate)
| SMILES1 = CC(=O)[O-].CC(=O)[O-].O.O.O=[U+2]=O
| SMILES3 = O0[C-](C)O[U+6]01(=[O-2])(=[O-2])O[C-](C)O[U+6]0(O[C-](C)O0)(=[O-2])(=[O-2])O[C-](C)O1
| SMILES3_Comment = coordination dimer (anhydrous)
| SMILES2 = O0[C-](C)O[U+6]01(=[O-2])(=[O-2])([OH2])O[C-](C)O[U+6]2(O[C-](C)O2)(=[O-2])(=[O-2])([OH2])O[C-](C)O1
| SMILES2_Comment = coordination dimer (hydrate)
}}
| Section2 = {{Chembox Properties
| Formula = UO2(CH3COO)2 (anhydrous)
UO2(CH3COO)2·2H2O (dihydrate)
| MolarMass = 424.146 g/mol (dihydrate)
| Appearance = yellow-green crystals (dihydrate)
| Density = 2.89 g/cm3 (dihydrate)
| MeltingPt = decomposes at 80 °C (dihydrate)
| BoilingPt =
| Solubility = 7-8 g/100 ml
| SolubleOther = slightly soluble in ethanol
{{Citation
| last = Lide
| first = David R.
| year = 1998
| title = Handbook of Chemistry and Physics
| edition = 87
| publication-place = Boca Raton, FL
| publisher = CRC Press
| isbn = 0-8493-0594-2
| pages = 3–566
}}
}}
| Section7 = {{Chembox Hazards
| GHSPictograms = {{GHS06}}{{GHS08}}{{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|300|330|373|411}}
| PPhrases = {{P-phrases|260|264|270|271|273|284|301+310|304+340|310|314|320|321|330|391|403+233|405|501}}
| ExternalSDS = [https://web.archive.org/web/20080515160616/http://www.laddresearch.com/wsmsds/23620.htm External MSDS]}}
}}
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.
Structure
image:Uranyl-acetate-dihydrate-chain-from-xtal-3D-bs-17.png) of uranyl acetate dihydrate. Color code: red = O, gray = C, blue = U.]]
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.{{cite journal |doi=10.1016/0022-1902(75)80918-3|title=Crystal and molecular structure of uranyl acetate dihydrate|year=1975|last1=Howatson|first1=J.|last2=Grev|first2=D.M.|last3=Morosin|first3=B.|journal=Journal of Inorganic and Nuclear Chemistry|volume=37|issue=9|pages=1933–1935}}
Uranyl carboxylates are known for diverse carboxylic acids (formate, butyrate, acrylate).{{cite journal |doi=10.1039/C5CE01957E|title=Structural diversity of uranyl acrylates|year=2016|last1=Klepov|first1=Vladislav V.|last2=Vologzhanina|first2=Anna V.|last3=Alekseev|first3=Evgeny V.|last4=Pushkin|first4=Denis V.|last5=Serezhkina|first5=Larisa B.|last6=Sergeeva|first6=Olga A.|last7=Knyazev|first7=Aleksandr V.|last8=Serezhkin|first8=Viktor N.|journal=CrystEngComm|volume=18|issue=10|pages=1723–1731|bibcode=2016CEG....18.1723K }}
Uses
Uranyl acetate is extensively used as a negative stain in electron microscopy.[http://web.path.ox.ac.uk/~bioimaging/bitm/instructions_and_information/EM/neg_stain.pdf "Negative Staining"] University of Oxford 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.{{cn|date=January 2025}}
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.{{cn|date=January 2025}}
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.{{cn|date=January 2025}}
Uranyl acetate dihydrate has been used as a starting reagent in experimental inorganic chemistry.{{cite journal|doi=10.1002/1521-3773(20010202)40:3<591::AID-ANIE591>3.0.CO;2-0|title=Hexaphyrin(1.0.1.0.0.0): An Expanded Porphyrin Ligand for the Actinide Cations Uranyl (UO22+) and Neptunyl (NpO2+)|year=2001|last1=Sessler|first1=Jonathan L.|last2=Seidel|first2=Daniel|last3=Vivian|first3=Anne E.|last4=Lynch|first4=Vincent|last5=Scott|first5=Brian L.|last6=Keogh|first6=D. Webster|journal=Angewandte Chemie International Edition|volume=40|issue=3|pages=591–594}}
Preparation and reactions
The compound can be prepared by treating uranium trioxide]] with acetic acid:
:{{chem2|UO3 + 2 CH3COOH + H2O -> UO2(CH3COO)2*2H2O}}
The acetate ligands of uranyl acetate can be replaced to give a variety of uranyl complexes.{{cite book |doi=10.1002/9780470132357.ch35 |chapter=Bis(8-quinolinolo)dioxouranium(VI) and its Addition Compound with 8-Quinolinol |title=Inorganic Syntheses |date=1953 |last1=Moeller |first1=Therald |last2=Wilkins |first2=Donald H. |last3=Merritt |first3=Lynne L. |volume=4 |pages=101–103 |isbn=978-0-470-13163-3 }} Uranyl acetate can also be reduced by zinc to give the uranium(IV) acetate (U(OAc)4).{{cite book |doi=10.1002/9780470132401.ch12 |chapter=Uranium(IV) Acetate |title=Inorganic Syntheses |date=1967 |last1=Paul |first1=R. C. |last2=Ghetra |first2=J. S. |last3=Bains |first3=M. S. |last4=Hoekstra |first4=Henry R. |volume=9 |pages=41–43 |isbn=978-0-470-13168-8 }}
Safety
In general, uranium salts exhibit nephrotoxicity. Normal commercial stocks from depleted uranium have typical specific activity {{convert|0.37|-|0.51|μCi/g|kBq/g}}, too weak to harm from outside the body.[https://www.monash.edu/hsw/info-docs/chemical-management/uranyl-acetate-and-uranyl-nitrate "Health Safety & Wellbeing. Uranyl acetate and uranyl nitrate"] Monash University However, uranyl acetate is very toxic if ingested, inhaled as dust, or absorbed through cut or abraded skin.{{cn|date=June 2022}}
Microbiologists have developed a number of alternative stains:Yamaguchi K, Suzuki K, Tanaka K (2010) Examination of electron stains as a substitute for uranyl acetate for the ultrathin sections of bacterial cells. J Electron Microsc (Tokyo) 59:113–118 neodymium acetate,{{cite journal |last1=Kuipers |first1=Jeroen |last2=Giepmans |first2=Ben N. G. |title=Neodymium as an alternative contrast for uranium in electron microscopy |journal=Histochemistry and Cell Biology |date=1 April 2020 |volume=153 |issue=4 |pages=271–277 |doi=10.1007/s00418-020-01846-0 |pmid=32008069 |pmc=7160090 |language=en |issn=1432-119X}}Hosogi N, Nishioka H, Nakakoshi M (2015) Evaluation of lanthanide salts as alternative stains to uranyl acetate. Microscopy (Oxf) 64:429–435 platinum blue,Inaga S, Katsumoto T, Tanaka K, Kameie T, Nakane H, Naguro T (2007) Platinum blue as an alternative to uranyl acetate for staining in transmission electron microscopy. Arch Histol Cytol 70:43–49 hafnium chloride,Ikeda K, Inoue K, Kanematsu S, Horiuchi Y, Park P (2011) Enhanced effects of nonisotopic hafnium chloride in methanol as a substitute for uranyl acetate in TEM contrast of ultrastructure of fungal and plant cells. Microsc Res Tech 74:825–830 and oolong tea extracts.Sato S, Adachi A, Sasaki Y, Ghazizadeh M (2008) Oolong tea extract as a substitute for uranyl acetate in staining of ultrathin sections. J Microsc 229:17–20He X, Liu B (2017) Oolong tea extract as a substitute for uranyl acetate in staining of ultrathin sections based on examples of animal tissues for transmission electron microscopy. J Microsc 267:27–33