Acetone peroxides are unwanted by-products of some oxidation reactions such as those used in phenol syntheses. Due to their explosive nature, their presence in chemical processes and chemical samples creates potential hazardous situations. Accidental occurrence at illicit MDMA laboratories is possible. Numerous methods are used to reduce their appearance, including shifting pH to more alkaline, adjusting reaction temperature, or adding inhibitors of their production. For example, triacetone peroxide is the major contaminant found in diisopropyl ether as a result of photochemical oxidation in air.