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Mercury(II) sulfate
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| Names | |
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| Other names
Mercuric sulfate, Mercurypersulfate, Mercury Bisulfate[1]
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.029.083 |
| EC Number |
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PubChem CID
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| RTECS number |
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| UNII | |
| UN number | 1645 |
CompTox Dashboard (EPA)
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| Properties | |
| HgSO4 | |
| Molar mass | 296.653 g/mol |
| Appearance | white monoclinic crystals |
| Odor | odorless |
| Density | 6.47 g/cm3, solid |
| 450 °C (dec.)[2] | |
| Decomposes in water to yellow mercuric subsulfate and sulfuric acid | |
| Solubility | soluble in hot H2SO4, NaCl solution insoluble in ethanol, acetone, ammonia |
| −78.1·10−6 cm3/mol | |
| Structure | |
| rhombic | |
| Thermochemistry | |
Std enthalpy of
formation (ΔfH⦵298) |
−707.5 kJ mol−1[3] |
| Hazards | |
| GHS labelling:[4] | |
| Danger | |
| H300, H310, H330, H373, H410 | |
| P260, P262, P264, P270, P271, P273, P280, P284, P301+P316, P302+P352, P304+P340, P316, P319, P320, P321, P330, P361+P364, P391, P403+P233, P405, P501 | |
| NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Mercury(II) sulfate, commonly called mercuric sulfate, is the chemical compound HgSO4. It is an odorless salt that forms white granules or crystalline powder. In water, it separates into an insoluble basic sulfate with a yellow color and sulfuric acid.[3]
Structure
[edit]
The anhydrous compound features Hg2+ in a highly distorted tetrahedral HgO4 environment. Two Hg-O distances are 2.22 Å and the others are 2.28 and 2.42 Å.[5] In the monohydrate, Hg2+ adopts a linear coordination geometry with Hg-O (sulfate) and Hg-O (water) bond lengths of 2.179 and 2.228 Å, respectively. Four weaker bonds are also observed with Hg---O distances >2.5 Å.[6]
History
[edit]In 1932, the Japanese chemical company Chisso Corporation began using mercury sulfate as the catalyst for the production of acetaldehyde from acetylene and water. Though it was unknown at the time, methylmercury is formed as a side product of this reaction. Exposure and consumption of the mercury waste products, including methylmercury, that were dumped into Minamata Bay by Chisso are believed to be the cause of Minamata disease in Minamata, Japan.[7]
Production
[edit]Mercury sulfate can be produced by treating mercury with hot concentrated sulfuric acid:[8]
- Hg + 2 H2SO4 → HgSO4 + SO2 + 2 H2O
Alternatively yellow mercuric oxide reacts also with concentrated sulfuric acid.[9]
Uses
[edit]Denigés' reagent
[edit]An acidic solution of mercury sulfate is known as Denigés' reagent. It was commonly used throughout the 20th century as a qualitative analysis reagent. If Denigés' reagent is added to a solution containing compounds that have tertiary alcohols, a yellow or red precipitate will form.[10]
Hydration reactions
[edit]
Mercury sulfate, as well as other mercury(II) compounds, are commonly used as catalysts in oxymercuration-demercuration, a type of electrophilic addition reaction that results in hydration of an unsaturated compound. The hydration of an alkene gives an alcohol. The regioselectivity is that predicted by Markovnikov's rule. For an alkyne, the result is an enol, which tautomerizes to give the carbonyl.[11] At one time, this chemistry was employed commercially for the preparation of acetaldehyde from acetylene:[12]
- C2H2 + H2O → CH3CHO
A related and specialized example is the conversion of 2,5-dimethylhexyne-2,5-diol to 2,2,5,5-tetramethyltetrahydrofuran using aqueous mercury sulfate without the addition of acid.[13]
Health issues
[edit]Inhalation of HgSO4 can result in acute poisoning: causing tightness in the chest, difficulties breathing, coughing and pain. Exposure of HgSO4 to the eyes can cause ulceration of conjunctiva and cornea. If mercury sulfate is exposed to the skin it may cause sensitization dermatitis. Lastly, ingestion of mercury sulfate will cause necrosis, pain, vomiting, and severe purging. Ingestion can result in death within a few hours due to peripheral vascular collapse.[1]
It was used in the late 19th century to induce vomiting for medical reasons.[14]
Further reading
[edit]- Vogt, R; Nieuwland, J (September 1921). "The role of mercury salts in the catalytic transformation of acetylene into acetaldehyde, and a new commercial process for manufacture of paraaldehyde". J. Am. Chem. Soc. 43 (9): 2071–81. doi:10.1021/ja01442a010.
References
[edit]- ^ a b "Chemicalbook". Retrieved 2 May 2011.
- ^ Wu, Shengji; Uddin, Md. Azhar; Nagano, Saori; Ozaki, Masaki; Sasaoka, Eiji (2011). "Fundamental Study on Decomposition Characteristics of Mercury Compounds over Solid Powder by Temperature-Programmed Decomposition Desorption Mass Spectrometry". Energy & Fuels. 25 (1): 144–153. doi:10.1021/ef1009499.
- ^ a b Lide, David R. (1998). Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. pp. 5–19. ISBN 0-8493-0594-2.
- ^ "Mercuric sulfate". pubchem.ncbi.nlm.nih.gov.
- ^ Aurivillius, Karin; Stålhandske, Claes (1980). "A Reinvestigation of the Crystal Structures of HgSO4 and CdSO4". Zeitschrift für Kristallographie - Crystalline Materials. 153 (1–2): 121–129. Bibcode:1980ZK....153..121A. doi:10.1524/zkri.1980.0011.
- ^ Stålhandske, C. (1980). "An X-ray and Neutron Diffraction Study of Mercury(II) Sulphate Monohydrate". Acta Crystallographica Section B: Structural Crystallography and Crystal Chemistry. 36: 23–26. doi:10.1107/s0567740880002361.
- ^ Minamata Disease Archived 13 November 2019 at the Wayback Machine. Boston University. Retrieved 2016-11-10.
- ^ Simon, Matthias; Jönk, Peter; Wühl-Couturier, Gabriele; Halbach, Stefan (2006). "Mercury, Mercury Alloys, and Mercury Compounds". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a16_269.pub2. ISBN 3527306730.
- ^ Robey, R. F.; Robertson, N. C. (May 1947). "Test for tert-Butyl and Isopropyl Alcohols with Deniges Reagent". Analytical Chemistry. 19 (5): 310–311. doi:10.1021/ac60005a007.
- ^ Marks, E.M.; Lipkin, D. (1939). "Reaction of Aliphatic Ethers with Denigés' Reagent". J. Org. Chem. 3 (6): 598–602. doi:10.1021/jo01223a008.
- ^ Clayden, Jonathan; Greeves, Nick; Warren, Stuart (2012). Organic chemistry (2nd ed.). Oxford: Oxford university press. pp. 444–445. ISBN 978-0-19-927029-3.
- ^ Eckert, Marc; Fleischmann, Gerald; Jira, Reinhard; Bolt, Hermann M.; Golka, Klaus (2006). "Acetaldehyde". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a01_031.pub2. ISBN 978-3-527-30385-4.
- ^ Wasacz, J. P.; Badding, V. G. (1982). "A hydration of an alkyne illustrating steam and vacuum distillation". Journal of Chemical Education. 59 (8): 694. Bibcode:1982JChEd..59..694W. doi:10.1021/ed059p694.
- ^ Hubbard (24 June 1846). "On the Effects of the Sub-Sulphate of Mercury, (Turpeth Mineral,) As An Emetic". BMJ. s1-10 (25): 288–289. doi:10.1136/bmj.s1-10.25.288. ISSN 0959-8138. PMC 2559525. PMID 20794001.
External links
[edit]Mercury(II) sulfate
View on GrokipediaMercury(II) sulfate is an inorganic compound with the chemical formula HgSO4, appearing as an odorless white crystalline powder or granules denser than water.[1][2] Its molecular weight is 296.66 g/mol, and it decomposes upon heating rather than melting.[1] The compound exhibits low solubility in water but dissolves in concentrated sulfuric acid and dilute nitric acid, forming acidic solutions useful in specific chemical analyses.[2] Primarily employed as a catalyst in organic synthesis, such as the hydration of alkynes to produce ketones and the industrial production of acetaldehyde from acetylene, it also serves as an analytical reagent to precipitate chloride ions and in processes for extracting gold and silver.[1][3] However, mercury(II) sulfate is highly toxic, causing fatal outcomes via ingestion, inhalation, or skin absorption, with additional risks of severe respiratory irritation, organ damage, and long-term environmental persistence that renders it hazardous to aquatic life.[1][4][5]
Properties
Molecular structure and bonding
Mercury(II) sulfate, HgSO₄, is an ionic compound comprising Hg²⁺ cations and SO₄²⁻ anions.[1] In the solid state, it forms a crystalline lattice where the mercury(II) ions exhibit coordination to oxygen atoms provided by the sulfate anions.[6] The crystal structure is orthorhombic, belonging to the space group Pmn2₁, and is isomorphous with cadmium(II) sulfate. The Hg²⁺ cation adopts an irregular eight-coordinate geometry, bonded to eight O²⁻ atoms with Hg–O bond distances spanning 2.23–2.93 Å, reflecting the hemidirected bonding characteristic of d¹⁰ mercury(II) centers due to relativistic effects and lone pair repulsion.[6] This coordination results in a three-dimensional network framework linking [HgO₈] polyhedra with [SO₄] tetrahedra via corner-sharing.[7] The sulfate tetrahedra maintain nearly regular geometry, with S–O bond lengths typical for SO₄²⁻ (approximately 1.47–1.49 Å). The bonding nature is predominantly ionic, arising from the electrostatic attraction between the highly charged, polarizable Hg²⁺ (a soft Lewis acid) and the SO₄²⁻ anions, though significant covalent character is present in the Hg–O interactions owing to orbital overlap and charge transfer from oxygen lone pairs.[8] This hybrid bonding aligns with Pearson's HSAB theory, where soft-soft interactions stabilize the structure despite the formal ionic formulation.[1] Experimental refinements confirm the lattice parameters and atomic positions, with reliability factors indicating high structural accuracy (R ≈ 0.033 for HgSO₄).Physical and thermodynamic properties
Mercury(II) sulfate appears as an odorless white crystalline powder or granules. Its molecular formula is HgSO₄, with a molar mass of 296.65 g/mol.[9] The compound has a density of 6.47 g/cm³ at standard conditions.[9][10] The solid decomposes upon heating at approximately 450 °C, releasing mercury vapor, sulfur dioxide, and oxygen without exhibiting a distinct melting or boiling point.[11] This thermal instability limits practical measurements of higher-temperature properties. Limited thermodynamic data are available; the standard enthalpy of formation is reported as -707.5 kJ/mol, though direct experimental verification in peer-reviewed thermochemical compilations is sparse due to the compound's reactivity and toxicity. No standard values for heat capacity or entropy at 298 K are widely documented in accessible databases, reflecting challenges in handling mercury compounds for calorimetry.| Property | Value | Conditions |
|---|---|---|
| Density | 6.47 g/cm³ | Solid, room temp. |
| Decomposition temp. | ~450 °C | Heating |
| Molar mass | 296.65 g/mol | - |
| Appearance | White crystalline powder | - |
Solubility and stability
Mercury(II) sulfate exhibits limited solubility in water, undergoing hydrolysis rather than true dissolution to yield sulfuric acid and a yellow basic mercuric sulfate precipitate, such as HgSO₄·2HgO.[1][9] It dissolves in concentrated hydrochloric acid, nitric acid, hot dilute sulfuric acid, and concentrated sodium chloride solutions, forming soluble complexes.[1][9] The compound is insoluble in organic solvents including alcohol, acetone, and ammonia.[1] Under standard ambient conditions, mercury(II) sulfate maintains chemical stability, showing no significant reactivity with air or moisture in the absence of hydrolysis triggers.[13] Thermally, it decomposes in a single step between 450°C and 750°C, releasing toxic mercury vapors and sulfur oxides without forming stable intermediates.[11][14] Hydrolytic instability in aqueous media limits its use in neutral or basic solutions, favoring acidic environments for handling.[9]Historical development
Early discovery and characterization
Mercury(II) sulfate was prepared through the oxidation of elemental mercury by hot concentrated sulfuric acid, yielding the white crystalline solid, sulfur dioxide gas, and water. This straightforward synthesis, feasible after the production of concentrated sulfuric acid in the 16th century, positioned the compound as a known reagent in early modern chemical practice by the late 17th century. German chemist Johann Kunckel von Löwenstern documented its utility in producing mercuric chloride via sublimation of a mixture with sodium chloride, underscoring its role as an established intermediate for mercury salt synthesis.[15][16] Initial characterizations described mercury(II) sulfate as an odorless white powder or granules denser than water, with noted toxicity via ingestion or inhalation, reflecting empirical observations from handling rather than quantitative analysis. Its insolubility in water but reactivity in forming basic sulfates upon heating or dilution was observed, though systematic compositional verification awaited 19th-century gravimetric methods and stoichiometry.[17]Key industrial milestones
In 1932, Chisso Corporation in Japan initiated industrial-scale production of acetaldehyde from acetylene using mercury(II) sulfate as a catalyst in sulfuric acid solution, implementing the Kucherov hydration process on a commercial basis for the first time.67944-0/fulltext)[18] This marked a pivotal advancement, with initial output of 210 metric tons of acetaldehyde that year, enabling efficient Markovnikov addition of water to acetylene under mild conditions (typically 60–80°C and 1–2 atm).[19] The process converted acetylene (C₂H₂) to acetaldehyde (CH₃CHO) via vinyl mercurinium intermediates, yielding up to 90% selectivity when optimized.[20] By 1951, Chisso's capacity had expanded to 6,000 metric tons annually, reflecting broader adoption of the technology amid post-World War II demand for acetaldehyde-derived products such as acetic acid, ethyl acetate, and early plastics.[19] Mercury(II) sulfate concentrations of 0.1–0.5% in 10–20% sulfuric acid proved optimal for catalyst longevity and reaction rates, though mercury losses necessitated continuous replenishment.[20] This route dominated acetaldehyde synthesis globally until the 1960s, when cheaper ethylene oxidation via the Wacker process supplanted it due to petroleum feedstock availability and reduced toxicity concerns.[20] Other industrial applications emerged concurrently, including mercury(II) sulfate's use as an electrolyte in primary mercury batteries and in gold/silver extraction from pyritic ores, but these lacked the scale of acetaldehyde production until environmental regulations curtailed mercury use post-1970. The Chisso implementation highlighted both the compound's catalytic efficacy—stemming from mercury's soft Lewis acid coordination to alkyne π-bonds—and eventual drawbacks from effluent mercury accumulation.[21]Synthesis and production
Laboratory synthesis
Mercury(II) sulfate is commonly prepared in the laboratory by heating elemental mercury with an excess of hot concentrated sulfuric acid, which oxidizes the mercury and yields the product along with sulfur dioxide gas and water:Hg + 2 H₂SO₄ → HgSO₄ + SO₂ + 2 H₂O.[9][12] This method requires careful control of temperature to ensure complete reaction, typically around 200–250 °C, and the product forms as white crystals that can be isolated by filtration after cooling and dilution.[22] An alternative procedure involves dissolving yellow mercury(II) oxide in concentrated sulfuric acid, followed by evaporation to concentrate the solution, cooling to induce crystallization, and filtration to recover the solid.[9] This approach avoids the production of sulfur dioxide gas and is suitable for smaller-scale preparations, though it presupposes access to mercury(II) oxide. Both methods produce anhydrous HgSO₄, which is sparingly soluble in water and must be handled under fume hood conditions due to the toxicity of mercury compounds and reaction byproducts.[22]
Industrial-scale production
Mercury(II) sulfate is produced on an industrial scale primarily by the direct oxidation of elemental mercury with excess hot concentrated sulfuric acid, yielding the product alongside sulfur dioxide and water:Hg + 2 H₂SO₄ → HgSO₄ + SO₂ + 2 H₂O.[2][1] This exothermic reaction requires careful control of temperature and acid concentration to ensure complete conversion and minimize side products, with the mercury sulfate precipitating as white crystals that are filtered, washed, and dried.[2] Historically, this method supported the preparation of mercury(II) sulfate as a catalyst for the large-scale hydration of acetylene to acetaldehyde, a key process in early 20th-century chemical manufacturing, such as operations by the Chisso Corporation starting in 1932.[21] The catalyst was typically generated in situ or batch-processed in acidic media for direct use in reactors, enabling acetaldehyde yields essential for downstream production of acetic acid and other organics before ethylene-based alternatives dominated post-World War II.[21] Contemporary industrial production is minimal due to stringent regulations under the Minamata Convention on Mercury, which mandated phase-out of mercury catalysts in acetaldehyde processes by 2018, driven by bioaccumulation risks and environmental persistence.[23] Residual output occurs via recycling from spent catalysts, involving distillation of mercury from waste followed by re-oxidation with hypochlorite or acid treatments to regenerate HgSO₄, as detailed in recovery patents.[24] Such approaches prioritize waste minimization but do not support broad commercial volumes, with global mercury supply now constrained to essential uses.[23]

