Mesityl Oxide

CAS RN:141-79-7

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 15(SRC), determined from a water solubility of 28,900 mg/L(2) and a regression-derived equation(3), indicates that mesityl oxide is expected to have very high mobility in soil(SRC). Volatilization of mesityl oxide from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 3.67X10-5 atm-cu m/mole(SRC), derived from its vapor pressure, 8.21 mm Hg(4), and water solubility(2). Mesityl oxide is expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(4). Theoretical %BOD values of 74(5) and 30(6) from studies done with sewage inoculum suggest that biodegradation may be an important environmental fate process in soil(SRC).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 15(SRC), determined from a water solubility of 28,900 mg/L(2) and a regression-derived equation(3), indicates that mesityl oxide is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 3.67X10-5 atm-cu m/mole(SRC), derived from its vapor pressure, 8.21 mm Hg(4), and its water solubility(2). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 17 hours and 11 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 1.9(SRC), using a water solubility of 28,900 mg/L(2) and a regression-derived equation(6), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Theoretical %BOD values of 74(7) and 30(8) from studies done with sewage inoculum suggest that biodegradation may be an important environmental fate process in water(SRC).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), mesityl oxide, which has a vapor pressure of 8.21 mm Hg at 25 deg C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase mesityl oxide 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 4.9 hours(SRC), calculated from its rate constant of 7.86X10-11 cu cm/molecule-sec at 25 deg C(SRC) that was derived using a structure estimation method(3). The rate constant for the vapor-phase reaction of mesityl oxide with ozone has been estimated as 2X10-16 cu cm/molecule-sec at 25 deg C(SRC) that was derived using a structure estimation method(3). This corresponds to an atmospheric half-life of about 1.4 hours at an atmospheric concentration of 7X10+11 ozone molecules per cu cm(4). The rate constant for the vapor-phase reaction of mesityl oxide with nitrate has been estimated as 2.04X10-13 cu cm/molecule-sec at 25 deg C(5). This corresponds to an atmospheric half-life of about 3.9 hours at an atmospheric concentration of 2.4X10+8 nitrate molecules per cu cm(6). Vapor-phase mesityl oxide undergoes direct photolysis with an experimental half-life and rate constant of 76.8 hrs and 8.75X10-3/hr, respectively(7).
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