1,3-Pentadiene

CAS RN: 504-60-9

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 500(SRC), determined from a log Kow of 2.44(2) and a regression-derived equation(3), indicates that 1,3-pentadiene is expected to have low mobility in soil(SRC). Volatilization of 1,3-pentadiene from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 0.069 atm-cu m/mole(SRC), using a fragment constant estimation method(4). The potential for volatilization of 1,3-pentadiene from dry soil surfaces may exist based upon a vapor pressure of 405 mm Hg(5).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 500(SRC), determined from a log Kow of 2.44(2) and a regression-derived equation(3), indicates that 1,3-pentadiene is expected to adsorb to suspended solids and sediment in water(SRC). Volatilization from water surfaces is expected to be an important fate process(3) based upon an estimated Henry's Law constant of 0.069 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 1 and 78 hrs, respectively(SRC). According to a classification scheme(5), an estimated BCF of 15(SRC), from its log Kow(2) and a regression-derived equation(6), suggests the potential for bioconcentration in aquatic organisms is low. No biodegradation data were located for 1,3-pentadiene(SRC), but the biodegradation half-life of 1,3-butadiene has been reported as 7 days in aerobic water and 28 days in anaerobic water(7). These data suggest that 1,3-pentadiene will also be biodegraded in aquatic systems(SRC).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 1,3-pentadiene, which has a vapor pressure of 405 mm Hg at 25 deg C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase 1,3-pentadiene is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals and ozone molecules(SRC). The half-life for the reaction in air with hydroxyl radicals is estimated to be 3.7 hours(SRC), calculated from its rate constant of 1.01X10-10 cu cm/molecule-sec at 24 deg C(3). The half-life for the reaction in air with ozone is estimated to be 5 hours(SRC), calculated from its rate constant of 5.26X10-17 cu cm/molecule-sec(SRC), estimated with a structure estimation method(4). The vapor phase reaction of 1,3-pentadiene with nitrate radicals may be an important atmospheric removal process in urban areas at night(5), but the rate of this reaction is not known.
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