DEVELOPMENT OF NEW METHODS FOR THE SYNTHESIS OF ORGANIC COMPOUNDS USING SELENIUM DIOXIDE

Abstract

Selenium is a member of the group 16 elements (O, S, Se, Te and radioactive Po), collectively known as chalcogens. Selenium is a non-metal with the symbol Se and has an atomic number 34. It was discovered in 1817 by J. J. Berzelius in the reddish deposits that were formed in the lead chambers at his sulfuric acid plant at Gripsholm in Sweden. He named the element selenium in the honour of Greek Goddess Selene, meaning moon. The physical and chemical properties of selenium are intermediate between those of sulfur and tellurium. Elemental selenium exists in various allotropic forms, of which three are generally known, namely two red allotropes of puckered Se8 rings which changed on heating to the more stable grey or black trigonal selenium, which is made up of helical Sen chains.