Osmium Tetroxide is slightly soluble in water, soluble in ethanol, ether, carbon tetrachloride, ammonia. Osmium tetroxide has been reported to cause reproductive toxicity in animals. Molecular weight: 254.20. Osmium tetroxide is a colorless to pale yellow crystalline solid with an odor that has been described as pungent or chlorine-like (odor threshold 0.0019 ppm). Concentrations of vapor that do not cause immediate irritation can have an insidious cumulative effect; symptoms may not be noted until several hours after exposure. No specific detection systems exist; samples may be analyzed for the presence of the agent using standard analytical techniques. this substance has not been shown to be carcinogenic or to show reproductive or developmental toxicity in humans. OsO4 is a widely used staining agent used in transmission electron microscopy (TEM) to provide contrast to the image.
In organic synthesis OsO4 is widely used to oxidise alkenes to the vicinal diols, adding two hydroxyl groups at the same side (syn addition). See reaction and mechanism above. This reaction has been made both catalytic (Upjohn dihydroxylation) and asymmetric (Sharpless asymmetric dihydroxylation).
Osmium tetroxide is also used in catalytic amount in the Sharpless oxyamination to give vicinal amino-alcohols. Osmium tetroxide has an important, if limited, part in fixation for light microscopy as it is the only fixing agent known which completely and easily fixes fats.
Chronic exposure to osmium tetroxide can result in an accumulation of osmium compounds in the liver and kidney and damage to these organs. It is used as a redox catalyst in organic synthesis. Osmium tetroxide is regarded as a substance with poor warning properties. Molecular formula: OsO4. There are two solid allotropes, each with its own physical properties. Unfortunately osmium tetroxide has two very serious drawbacks. It is quite toxic and it is very expensive. For those reasons it is usual to use it only in circumstances in which other fixing agents are not suitable. Usually this is the fixation of fat for paraffin sectioning, as it is the only fixing agent that allows this to be done, although it also has value for fixation of lipid membranes and structures such as mitochondria. Osmium tetroxide acts as a corrosive chemical, producing rapid injury. Onset may be rapid or delayed, but is usually rapid at all but very low concentrations.
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