Common peroxide formers include: THF (Tetrahydrofuran) Diethyl ether Peroxide-forming chemicals are a class of compounds that have the ability to form shock-sensitive explosive peroxide crystals. If not managed properly they can cause serious chemical incidents. As a result, extensive precautions have to be implemented to ensure that these chemicals can be disposed of properly. Common peroxide formers include: THF (Tetrahydrofuran) Diethyl ether Dioxane Azides Perchlorates Picrates https://www.ehs.harvard.edu/sites/ehs.harvard.edu/files/chemical_l ist_potentially_unstable.pdf Peroxide-forming chemicals react with oxygen – even at low concentrations – to form peroxy compounds. The risk associated with peroxide formation increases if the peroxide crystallizes or becomes concentrated by evaporation or distillation. Factors that affect rate of peroxide formation include exposure to air, light and heat, moisture, and contamination from metals. http://www.sfasu.edu/safety/documents/Reactive_Materials_Guidance_Document.pdf

http://ccc.chem.pitt.edu/wipf/web/16340.pdf

Safe Handling Procedures Purchase small quantities at time. Whenever possible purchase chemicals with peroxide inhibitors (ie BHT). Store away from light and heat, cap tightly. Use the Peroxide Forming Label to track peroxides. Check containers frequently for precipitation/stratification, crystal formation (in the liquid or around the cap),and any other irregularities that could indicate the material has become unstable. Dispose of chemicals after 6 months if opened, and 1 year if unopened. Manufacturers may add an inhibitor to peroxide forming chemicals to counter peroxide formation. For many peroxide-forming solvents, butylated hydroxy toluene (BHT) is commonly added. BHT ‘scavenges’ oxygen in the solvent and prevents it from reacting with the solvent to form peroxides. Over time, BHT or other inhibitor in the solvent can become exhausted allowing peroxides to form. Distilling the solvent can completely remove the BHT and make the solvent immediately susceptible to peroxide formation. http://www.sfasu.edu/safety/documents/Reactive_Materials_Guidance_Document.pdf

Always, always, always use:

Contact EH&S If: If an old container of peroxide-forming material is found (past expiration date). If the container is compromised (damaged, rusty, or bulging). If the container is not labeled and is suspected to be a peroxide. Any indication of peroxide crystals. Never move a chemical suspected of having formed peroxide crystals https://www.ehs.harvard.edu/sites/ehs.harvard.edu/files/peroxidizable_mat erials_lab_safety_guideline_0.pdf

Questions and Resources EHS Lab Safety Advisors (LSAs) Hazardous Waste Service Request https://www.ehs.harvard.edu/Chemical- Waste-Pickup-Form