Propylene

CAS RN: 115-07-1

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 22(SRC), determined from a structure estimation method(2), indicates that propylene is expected to have very high mobility in soil(SRC). Volatilization of propylene from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 0.196 atm-cu m/mole(3). Propylene is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 8690 mm Hg at 25 deg C(4). Biodegradation data in soil were not available(SRC, 2017). However, propylene was biodegraded to propylene oxide using acclimated cell free extracts(5).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 22(SRC), determined from a structure estimation method(2), indicates that propylene is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon a Henry's Law constant of 0.196 atm-cu m/mole(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 2 hrs and 3 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 7(SRC), from its log Kow of 1.77(6) and a regression-derived equation(2), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data in water were not available(SRC, 2017). However, propylene was biodegraded to propylene oxide using acclimated cell free extracts(7).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), propylene, which has a vapor pressure of 8690 mm Hg at 25 deg C(2), is expected to exist solely as a gas in the ambient atmosphere. Gas-phase propylene is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 15 hrs(SRC), calculated from its rate constant of 2.9X10-11 cu cm/molecule-sec at 25 deg C(3). Gas-phase propylene is degraded in the atmosphere by reaction with ozone(SRC); the half-life for this reaction in air is estimated to be 23 hrs(4), calculated from its rate constant of 1.2X10-17 cu cm/molecule-sec at 25 deg C(5). Propylene does not contain chromophores that absorb at wavelengths >290 nm(6) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).
ATMOSPHERIC FATE: The atmospheric fate and photochemical reactions of propylene ... indicate that the principal reactant is the hydroxyl radical. Reactions of propylene with ozone occur predominantly in the evening, while reactions of propylene with atomic oxygen or sulfur dioxide (SO2) are reported to be insignificant ... because of their relatively low /atmospheric/ concentration. ... The atmospheric half-life of propylene was 7.7 hr (calc).
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