Tetrahydrofuran, dangers from peroxides

Ethers are relatively stable and unreactivc in many respects, but some ethers react slowly with the oxygen in air to give peroxides, compounds that contain an 0-0 bond. The peroxides from low-molecular-weight ethers such as diisopropyl ether and tetrahydrofuran arc explosive and extremely dangerous, even in tiny amounts. Ethers are very useful as solvents in the laboratory, but they must always be used cautiously and should not be stored for long periods of time. 

Alkoxyalkyl Hydroperoxides. These compounds (1, X — OR R — H) have been prepared by the ozonization of certain unsaturated compounds in alcohol solvents. Alkoxyalkyl hydroperoxides are more commonly called ether hydroperoxides. They form readily by the autoxidation of most ethers containing cr-hydrogens, e.g., dioxane. tetrahydrofuran, diethyl ether, diisopropyl ether, di-n-butyl ether, and diisoamyl ether. From certain ethers, e.g., diethyl ether, the initially formed ether hydroperoxide can yield alcohol on standing, or with acid treatment form dangerously shock-sensitive and explosive polymeric peroxides. 

Tetrahydrofuran is best dried according to the procedure described in Org. Syntheses, 46, 105 (1966). (Caution Note warning of danger in drying tetrahydrofuran containing peroxides.) The checkers employed a peroxide-free grade of anhydrous tetrahydrofuran which is available from Fisher Scientific Co. 

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