Dicyclohexyldisulfid

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 7.3X10+4(SRC), determined from an estimated log Kow of 6.41(2,SRC) and a regression-derived equation(3), indicates that dicyclohexyl disulfide is expected to be immobile in soil(SRC). Volatilization of dicyclohexyl disulfide from moist soil surfaces may be important(SRC) given an estimated Henry's Law constant of 4.0X10-3 atm-cu m/mole(SRC), using a fragment constant estimation method(4). However, volatilization from moist soil surfaces is expected to be attenuated by adsorption to organic matter(SRC). Dicyclohexyl disulfide is not expected to volatilize from dry soil surfaces based on an estimated vapor pressure of 5.5X10-4 mm Hg(SRC), determined from a fragment constant method(5). Biodegradation data were not available for dicyclohexyl disulfide(SRC).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 7.3X10+4(SRC), determined from an estimated log Kow of 6.41(2,SRC) and a regression-derived equation(3), indicates that dicyclohexyl disulfide is expected to adsorb to suspended solids and sediment in water(SRC). Dicyclohexyl disulfide is expected to volatilize from water surfaces(3,SRC) based on an estimated Henry's Law constant of 4.0X10-3 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). Estimated volatilization half-lives for a model river and model lake are 4.8 hours and 6.1 days, respectively(3,SRC). However, adsorption to suspended solids and sediment in the water column is expected to attenuate this process(SRC). The volatilization half-life from a model pond 2 m deep is estimated to be about 2.3 days ignoring adsorption(5); when considering maximum adsorption, the volatilization half-life increases to approximately 23 years(5). According to a classification scheme(6), an estimated BCF of 4.4X10+4(3,SRC), from an estimated log Kow(2,SRC), suggests the potential for bioconcentration in aquatic organisms is very high(SRC). Biodegradation data were not available for dicyclohexyl disulfide(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), dicyclohexyl disulfide, which has an estimated vapor pressure of 5.5X10-4 mm Hg at 25 °C(2,SRC), is expected to exist solely as a will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase dicyclohexyl disulfide 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 1.4 hours(3,SRC). Particulate-phase dicyclohexyl disulfide may be physically removed from the air by wet and dry deposition(SRC).

The Koc of dicyclohexyl disulfide is estimated as approximately 7.3X10+4(SRC), using an log Kow of 6.41(1) and a regression-derived equation(2,SRC). According to a classification scheme(3), this estimated Koc value suggests that dicyclohexyl disulfide is expected to be immobile in soil(SRC).

An estimated BCF of 4.4X10+4 was calculated for dicyclohexyl disulfide(SRC), using an estimated log Kow of 6.41(1,SRC) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is very high(SRC).

The Henry's Law constant for dicyclohexyl disulfide is estimated as 4.0X10-3 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that dicyclohexyl disulfide is expected to volatilize rapidly from water surfaces(2,SRC). Based on this Henry's Law constant, the estimated volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec) is approximately 4.8 hours(2,SRC). The estimated volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec) is approximately 6.1 days(2,SRC). The volatilization half-life from a model pond 2 m deep is estimated to be about 2.3 days ignoring adsorption(3); when considering maximum adsorption, the volatilization half-life increases to about 23 years(3). Dicyclohexyl disulfide's Henry's Law constant(1,SRC) indicates that volatilization from moist soil surfaces may occur(SRC). Dicyclohexyl disulfide is not expected to volatilize from dry soil surfaces based on an estimated vapor pressure of 5.5X10-4 mm Hg(SRC), determined from a fragment constant method(4).

The rate constant for the vapor-phase reaction of dicyclohexyl disulfide with photochemically-produced hydroxyl radicals has been estimated as 2.8X10-10 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1,SRC). This corresponds to an atmospheric half-life of about 1.4 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1,SRC).

Dicyclohexyl disulfide does not appear to have any commercial uses that could result in its release to the environment. If dicyclohexyl disulfide is released to air, an estimated vapor pressure of 5.5X10-4 mm Hg at 25 °C indicates it will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase dicyclohexyl disulfide will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 1.4 hours. Particulate-phase dicyclohexyl disulfide will be physically removed from the atmosphere by wet and dry deposition. If released to soil, dicyclohexyl disulfide is expected to be immobile based upon an estimated Koc of 7.3X10+4. Volatilization from moist soil surfaces may occur based upon an estimated Henry's Law constant of 4.0X10-3 atm-cu m/mole. However, adsorption to organic matter is expected to attenuate this process. If released into water, dicyclohexyl disulfide is expected to adsorb to suspended solids and sediment in water based on the estimated Koc. Volatilization from water surfaces may be an important fate process based upon the estimated Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 4.8 hours and 6.1 days, respectively. However, adsorption to suspended solids and sediment in the water column is expected to attenuate this process. An estimated BCF of 4.4X10+4 suggests the potential for bioconcentration in aquatic organisms is very high. Biodegradation data were not available for dicyclohexyl disulfide. (SRC)