Osmium tetroxide

(Redirected from Osmic acid)

**Properties**
General
Name	Osmium tetroxide
Chemical formula	OsO₄
Appearance	colourless or pale-yellow solid
Physical
Formula weight	254.2
Melting point	42 °C
Boiling point	129.7 °C
Density	4.9 × 10³ kg/m³
Crystal structure
Solubility	6 g/100 ml water
Thermochemistry
Δ_fH⁰_gas	kJ/mol
Δ_fH⁰_liquid	kJ/mol
Δ_fH⁰_solid	kJ/mol
S⁰_{gas, 1 bar}	J/mol·K
S⁰_{liquid, 1 bar}	J/mol·K
S⁰_solid	J/mol·K
Safety
Ingestion	Causes nausea and abdominal pain, possibly fatal.
Inhalation	Severe irritation and burning sensation with coughing and shortness of breath. Possible delayed lung edema and bronchopneumonia.
Skin	Irritation and possible burns.
Eyes	Tearing, pain, and burning sensation, leading to corneal staining and possible complete loss of sight.
More info	Hazardous Chemical Database
SI units were used where possible. Unless otherwise stated, standard conditions were used. Disclaimer and references

The chemical compound osmium tetroxide (OsO₄) is an oxide of the element osmium, in which it attains its highest oxidation number of 8.

Osmium tetroxide sublimates at room temperature and is readily formed when powdered osmium is exposed to air. In fact it explains the name of the element, derived from a Greek word for stench. The oxide is a powerful staining agent in regular use in transmission electron microscopy (TEM) to provide contrast to the image. It also stains the human cornea, which can lead to blindness if proper safety precautions are not observed.

In organic synthesis it is sometimes used to oxidise alkenes to the dialcohols. One catalytic reaction with osmium tetroxide is the Sharpless bishydroxylation named after K. Barry Sharpless.

Osmium tetroxide is highly poisonous, even at very low exposure levels, and must be handled with appropriate precautions. In particular, inhalation at concentrations well below those at which a smell can be perceived can lead to edema of the lungs, and subsequent death. Noticeable symptoms can take hours to appear after exposure.

On the 6th April 2004 the American news organisation ABC News reported that British intelligence sources believed they had foiled a plot to detonate a bomb involving the chemical due to its poisonous properties.

External links

Categories: Oxides