Nitromethane

CAS RN:75-52-5

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 10(SRC), determined from a structure estimation method(2), indicates that nitromethane is expected to have very high mobility in soil(SRC). Volatilization of nitromethane from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 2.86X10-5 atm-cu m/mole(3). Nitromethane is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 35.8 mm Hg(4). Nitromethane was readily degradable in a solid surface photomineralization test with 4.4% mineralization to CO2 in 17 hr(5); therefore, direct photolysis is expected to occur on soil surfaces exposed to sunlight(SRC). Utilizing a soil microcosm test, 5.1 and 2.3% conversion to CO2 in aerobic and anerobic soil, respectively, after 35 days(6) indicates that biodegradation may be important environmental fate process in soil(SRC).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 10(SRC), determined from a structure estimation method(2), indicates that nitromethane 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 2.86X10-5 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 27 hours and 10 days, respectively(SRC). According to a classification scheme(5), a BCF of 1.4 measured for fish (Golden ide)(6) suggests the potential for bioconcentration in aquatic organisms is low(SRC). Direct photolysis in water exposed to sunlight is expected to occur(SRC) based on an observed photodegradation of 64.8% in 24 hours(7). Hydrolysis is not expected to occur in water(7). Biodegradation studies utilizing aqueous media give conflicting results(6,7).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), nitromethane, which has a vapor pressure of 35.8 mm Hg at 25 deg C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase nitromethane 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 123 days(SRC), calculated from its rate constant of 1.30X10-13 cu cm/molecule-sec at 25 deg C(3). Nitromethane is expected to undergo direct photolysis in the atmosphere based on 83% degradation within 24 hours, and a half-life of 4.3 hours measured during tests for photodegradation(4,5).
Find more information on this substance at: Hazardous Substances Data Bank , TOXNET , PubMed