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Cumene hydroperoxide is a colourless to (pale) yellow organic liquid at 1013 hPa and 20°C with a characteristic odor. The melting point of cumene hydroperoxide is -9°C and the boiling point 53°C at 0.13 hPa. Cumene hydroperoxide decomposes at temperatures > 80°C and environmental conditions. The relative density is reported to be 1.0619 at 20°C. According to REACH Regulation (Annex VII, 7.14, column II), the study on granulometry does not need to be done if the substance is used or marketed in a non granular or non solid form. The experimentally determined vapor pressure is stated to be 0.00327 mm Hg (0.0044 hPa) at 25°C. The n-octanol/water partition coefficient log Kow was experimentally determined to be 1.6 at 25°C. Cumene hydroperoxide can be classified as very soluble in water (water solubility: 13900 mg/L at 25°C). The substance under investigation is readily soluble in alcohol, acetone, esters, hydrocarbons, and chlorinated hydrocarbons. The surface tension of cumene hydroperoxide (pure substance) is reported to be 28 mN/m at -9°C. According to REACH Regulation (Annex VII, 7.6, column II), the study on surface tension needs only to be done if based on the structure surface-active properties are to be expected or predicted or surface-activity is a desired property of the material. Cumene hydroperoxide does not contain any functional groups indicating surface-active properties. Cumene hydroperoxide has a flash point of 79°C (closed cup). According to REACH Regulation (Annex XI, 2.), a study does not need to be done if testing is not feasible. Cumene hydroperoxide has a self-accelerating decomposition temperature of ca. 80°C. Therefore cumene hydroperoxide will decompose under the test conditions which have to be applied for the determination of the self-ignition temperature (reference SADT: CLP regulations 2.15.2.3 and UN Recommendations on the transport of Dangerous Goods, Manual of Tests and Criteria, sub-sections 28.1, 28.2, 28.3, and Table 28.3). According to REACH Regulation (Annex XI, 1.), a study does not need to be done if based on the available data a risk assessment is possible. Cumene hyroperoxide is a liquid under standard conditions. For such substances the flash point and not flammability is the relevant endpoint for the assessment. The substance has no explosive properties because it is not classified as Organic Peroxide Type B (reference CLP regulations 2.15.2.2 and UN Recommendations on the Transport of Dangerous Goods, 16th revised edition, Section 2.5.3.2.4). See also ECHA guidance on the application of the CLP criteria, section 2.14. Cumene hydroperoxide is classified as organic peroxide TYPE E and belongs to the class of substances which, in laboratory testing, neither detonate nor deflagrate at all and show low or no effect when heated under confinement. Cumene hydroperoxide is a strong oxidant. Cumene hydroperoxide is stable in saturated hydrocarbon solvents up to 130 -140°C. At higher temperatures cumene hydroperoxide decomposes to an alkoxy and a hydroxy radical. Cumene hydroperoxide must be stored cool and dry in an area without drain or sewer access and separated from combustible and reducing substances, mineral acids, food and feedstuffs. Cumene hydroperoxide must be stored and transported at a temperature significantly below the SADT (self-accelerating decomposition temperature). For cumene hydroperoxide the SADT is reported to be 80°C. Cumene hydroperoxide may explode on heating at about 150°C. At 158°C cumene hydroperoxide has a half-life of 10 h. The substance is a strong oxidant and reacts violently with combustible and reducing materials causing fire and explosion hazard. Contact with cobalt, copper or lead alloys and mineral acids may lead to violent decomposition. Cumene hydroperoxide has a dissociation constant (pKa) of 12.6 at 20°C.