Osmium tetroxide (CAS 20816-12-0)

Osmium tetroxide, with the CAS number 20816-12-0, is a highly volatile and toxic chemical compound that finds extensive use in research, particularly in the fields of materials science and electron microscopy. As a heavy metal oxide, it consists of one osmium atom bonded to four oxygen atoms, forming a tetrahedral structure. In research, osmium tetroxide acts primarily as a staining agent due to its ability to add contrast to organic tissues when viewed under an electron microscope. This is achieved through its mechanism of action, which involves the fixation and staining of lipid-rich tissues. Osmium tetroxide reacts with unsaturated lipids, forming a black osmium lipid complex that enhances electron density and thus, visibility under electron beams. This property makes it invaluable for detailed cellular and subcellular imaging, allowing scientists to observe fine structures within biological samples with high resolution. Beyond biological applications, osmium tetroxide is used in materials science for the synthesis of osmium-containing compounds and the catalysis of certain chemical reactions, such as dihydroxylation in organic synthesis, where it adds two hydroxyl groups across carbon-carbon double bonds, modifying molecular structures and altering physical and chemical properties. Its use in research must be handled with extreme caution due to its volatile and toxic nature, necessitating stringent safety protocols to mitigate risks associated with exposure.