Peroxides and peroxide-forming compounds

Inorganic and organic peroxides, because of their exceptional reactivity and oxidative potential are widely used in research laboratories. This review is intended to serve as a guide to the hazards and safety issues associated with the laboratory use, handling, and storage of inorganic and organic peroxy-compounds and peroxide-forming compounds. The relatively weak oxygen-oxygen linkage (bond-dissociation energy of 20 to 50 kcal mole) is the characteristic structure of organic and inorganic peroxide molecules, and is the basis for their reactivity and tendency for spontaneous decomposition. The unusual weakness of the -O-Obond is probably a consequence of the molecular and electronic structure of peroxide molecules and of the relatively high electronegative character of the oxygen atoms. As a class, peroxides are exceptionally prone to violent decomposition that can be initiated by heat, mechanical shock, or friction, especially in the presence of certain catalysts and promoters. The hazards of inorganic and organic peroxides and peroxide-forming chemicals have been long recognized so that most relevant information is now found in text books on organic chemistry and laboratory safety. A comprehensive three-volume series on the chemistry of organic peroxides includes a chapter on safety issues associated with these materials. Bretherick included a discussion of organic peroxide in a chapter on highly reactive and unstable compounds and used “oxygen balance” to predict the stability of individual compounds and to assess the hazard potential of an oxidative reaction. Jackson et al. addressed the use of peroxidizable chemicals in the research laboratory and published recommendations for maximum storage time for common peroxide-forming laboratory solvents. Several solvents, (e.g., diethyl ether) commonly used in the laboratory can form explosive reaction products through a relatively slow oxidation process in the presence of atmospheric oxygen. The risk of explosion can be greatly reduced by following storage and handling practices that are compatible with the properties of these materials. More recently, Kelly reviewed the chemistry and safe handling of peroxideforming chemicals and included procedures on detection and removal of peroxides from laboratory solvents. Safety awareness, prudent handling and proper storage are essential when working with these compounds.