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Octane has the potential to volatilize to air, based on a relatively high vapor pressure, where it is subject to atmospheric oxidation. In air, octane can react with photosensitized oxygen in the form of hydroxyl radicals (OH-).

According to Atkinson (1985) the half-life of octane, normalized to a 12-hour day, is 3.7 days, based on 12-hour light / 12-hour dark periods and an OH- concentration of 5E5. The half-life is normalized to a 12-hour day because atmospheric oxidation reactions only take place in the presence of sunlight.

Estimation with the APOWIN model (HSPA Consortium 2009) resulted in a test substance half-life, as mediated by hydroxyl radical (OH-) attack, of 15.493 hours based on a 12-hour day (the 12-hour day half-life value normalizes degradation to a standard day light period during which hydroxyl radicals needed for degradation are generated). The half-life was calculated based on an OH- reaction rate constant of 8.2844 E-12 cm3/molecule-sec and an OH- concentration of 1.5E6 OH/cm3.

Octane as well as other constituent chemicals of the C7-C9 aliphatic hydrocarbon solvents category are composed of carbon and hydrogen and are not amenable to hydrolysis because of their molecular structure and the chemical reaction required for this type of transformation to occur.