Isopropanol

CAS RN: 67-63-0

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 1.5(SRC), determined from a structure estimation method(2), indicates that isopropanol is expected to have very high mobility in soil(SRC). Volatilization of isopropanol from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 8.10X10-6 atm-cu m/mole(3). Isopropanol is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 45.4 mm Hg at 25 deg C(4). Isopropanol is reported to be readily degraded in both aerobic and anaerobic conditions(5). Isopropanol was readily degraded in a variety of microbial degradation tests(6-10). Utilizing the Japanese MITI test, 86% of the Theoretical BOD was reached in 2 weeks indicating that biodegradation is an important environmental fate process(10). Acetone has been identified as a metabolite in anaerobic degradation in sludge(11).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 1.5(SRC), determined from a structure estimation method(2), indicates that isopropanol 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 8.10X10-6 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 86 hours and 29 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 3(SRC), from a log Kow(2) and a regression-derived equation(6), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Isopropanol is reported to be readily degraded under both aerobic and anaerobic conditions(7). Isopropanol was readily degraded in a variety of microbial degradation tests(8-12). Utilizing the Japanese MITI test, 86% of the Theoretical BOD was reached in 2 weeks indicating that biodegradation is an important environmental fate process(12). Acetone has been identified as a metabolite in anaerobic degradation(13). Isopropanol is not expected to undergo hydrolysis in the environment due to the lack of hydrolyzable functional groups(3).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), isopropanol, which has a vapor pressure of 45.4 mm Hg at 25 deg C(2), is expected to exist solely as a vapor in the ambient atmosphere(SRC). Vapor-phase isopropanol 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 3.2 days(SRC), calculated from its rate constant of 5.07X10-12 cu cm/molecule-sec at 25 deg C(3).
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