Mercury(II) perchlorate
Chemical compound
From Wikipedia, the free encyclopedia
Mercury(II) perchlorate is an inorganic chemical compound with the formula Hg(ClO4)2·nH2O, where n can range from 0 to 6. The anhydrous and hydrates are all toxic, water-soluble, and hygroscopic white solids.[2][1]
| Names | |
|---|---|
Other names
| |
| Identifiers | |
3D model (JSmol) |
|
| ECHA InfoCard | 100.028.659 |
| EC Number |
|
PubChem CID |
|
CompTox Dashboard (EPA) |
|
| |
| |
| Properties | |
| Hg(ClO4)2 | |
| Molar mass | 399.49 g/mol (anhydrous) |
| Appearance | White solid |
| Density | 2.84 g/cm3 (hexahydrate)[1] |
| Melting point | 170 °C (338 °F; 443 K)[2] (anhydrous) |
| Boiling point | 250 °C (482 °F; 523 K)[2] (decomposition, anhydrous) |
| Soluble | |
| Structure[1] | |
| Trigonal (hexahydrate) | |
| P3m1 (hexahydrate) | |
a = 8.01 Å, b = 8.01 Å, c = 5.34 Å α = 90°, β = 90°, γ = 120° (hexahydrate) | |
| Hazards | |
| GHS labelling: | |
   | |
| NFPA 704 (fire diamond) | |
Threshold limit value (TLV) |
0.05 mg/m3 (TWA), 0.1 mg/m3 (C) |
| NIOSH (US health exposure limits): | |
IDLH (Immediate danger) |
10 mg/m3 |
| Related compounds | |
Other cations |
Cadmium perchlorate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Preparation and reactions
Hydrates of mercury(II) perchlorate are most commonly prepared by the reaction of mercury(II) oxide and concentrated perchloric acid:[1]
- HgO + 2 HClO4 → Hg(ClO4)2 + H2O
Evaporation of the resulting solution results in the formation of the hexahydrate, Hg(ClO4)2·6H2O, which can be converted to lower hydrates, such as the dihydrate, by heating to 30 °C in a vacuum. Further heating does not produce the anhydrous form, but instead forms a basic mercury perchlorate.[2][1]
The anhydrous form is produced by dehydrating the dihydrate with anhydrous perchloric acid or dichlorine hexoxide.[2][3]
Solutions of mercury(II) perchlorate in water reacts with aqueous ammonia to produce tetraamminemercury(II) perchlorate, [Hg(NH3)4](ClO4)2. Heating of the tetraammine complex results in the diammine complex.[4]
Mercury(II) perchlorate also reacts with elemental mercury to form mercury(I) perchlorate:[2][5]
- Hg(ClO4)2 + Hg → Hg2(ClO4)2
Structure
The solid hexahydrate, Hg(ClO4)2·6H2O, has a trigonal crystal structure and consists of octahedral [Hg(H2O)6]2+ centers and ClO4– ions.[1]
The anhydrous form was probed by IR spectroscopy and was found to consist of monodendate perchlorate ions.[3]
Applications
Mercury(II) perchlorate finds limited applications in organic synthesis, such as in the hydrolysis of vinyl halides and the allylation of isatins and isatin ketoimines.[6][7]