1. Performance Chemicals

• Oxidation of Alkenes: Selenium dioxide is a key reagent for oxidizing alkenes to allylic alcohols or ketones. This process often involves an ene reaction followed by a-sigmatropic rearrangement. The reaction conditions are generally mild, making it a useful method for introducing oxygen-containing functional groups. 
• Oxidation of Carbonyl Compounds: Selenium dioxide can oxidize the α-methylene group adjacent to a carbonyl group to form a 1,2-dicarbonyl compound. This reaction is useful for synthesizing compounds with adjacent carbonyl groups, which are important building blocks in organic synthesis. 
• Desulfurization: Selenium dioxide can replace sulfur atoms in organic compounds with oxygen, a process called desulfurization. This is useful for synthesizing sulfur-free organic compounds. 
• Synthesis of Selenium Compounds: Selenium dioxide serves as a precursor in the production of various selenium-based chemicals like selenates and selenides. These compounds have applications in both industrial and laboratory settings.
• Reagent: Selenium dioxide (SeO2) is a versatile reagent in organic synthesis, particularly for oxidizing benzylic and allylic positions to carbonyl compounds. 
• Benzylic oxidation: It's used in benzylic oxidation to convert a methylene group (CH2) adjacent to an aromatic ring into a carbonyl group (C=O), often forming aldehydes or ketones. 
• Allylic oxidations: In allylic oxidations, Selenium dioxide converts alkenes to allylic alcohols, which can be further oxidized to conjugated aldehydes or ketones.

2. Pharmaceuticals

• Precursor: Selenium dioxide serves as a precursor for synthesizing various selenium compounds used in pharmaceuticals, including selenium-containing drugs and intermediates.