Dibenzylsulfid

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 5400(SRC), determined from an estimated log Kow of 4.33(2,SRC) and a regression-derived equation(3), indicates that benzyl sulfide is expected to be immobile in soil(SRC). Volatilization of benzyl sulfide from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 5.1X10-6 atm-cu m/mole(SRC), using a fragment constant estimation method(4). Benzyl sulfide is not expected to volatilize from dry soil surfaces based on an estimated vapor pressure of 2.9X10-4 mm Hg(SRC), determined from a fragment constant method(5). Limited biodegradation data indicate benzyl sulfide is amenable to aerobic biodegradation with formation of benzylmercaptoacetic acid; under anaerobic conditions benzyl mercaptan, toluene, and hydrogen sulfide have been identified as metabolites(6).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 5400(SRC), determined from an estimated log Kow of 4.33(2,SRC) and a regression-derived equation(3), indicates that benzyl sulfide is expected to adsorb to suspended solids and sediment in water(SRC). Benzyl sulfide is expected to volatilize slowly from water surfaces(3,SRC) based on an estimated Henry's Law constant of 5.1X10-6 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 11 and 82 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 120 days ignoring adsorption(5); when considering maximum adsorption, the volatilization half-life increases to about 6 years(5). According to a classification scheme(6), an estimated BCF of 1200(3,SRC), from the estimated log Kow(2,SRC), suggests the potential for bioconcentration in aquatic organisms is very high(SRC). Limited biodegradation data indicate benzyl sulfide is amenable to aerobic biodegradation with formation of benzylmercaptoacetic acid; under anaerobic conditions benzyl mercaptan, toluene, and hydrogen sulfide have been identified as metabolites(7).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), benzyl sulfide, which has an estimated vapor pressure of 2.9X10-4 mm Hg at 25 °C(2,SRC), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase benzyl sulfide 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 15 hours(3,SRC). Particulate-phase benzyl sulfide may be physically removed from the air by wet and dry deposition(SRC).

The Koc of benzyl sulfide is estimated as approximately 5400(SRC), using a log Kow of 4.33(1,SRC) and a regression-derived equation(2,SRC). According to a classification scheme(3), this estimated Koc value suggests that benzyl sulfide is expected to be immobile in soil(SRC).

Benzylmercaptoacetic acid was identified as a metabolite following incubation with a mixed population of aerobic bacteria; toluene, benzyl mercaptan, and hydrogen sulfide were identified as metabolites following anaerobic incubation with a strain of Desulfovibrio(1).

An estimated BCF of 1200 was calculated for benzyl sulfide(SRC), using an estimated log Kow of 4.33(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 benzyl sulfide is estimated as 5.1X10-6 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that benzyl sulfide is expected to volatilize slowly 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 11 days(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 82 days(2,SRC). The volatilization half-life from a model pond 2 m deep is estimated to be about 120 days ignoring adsorption(3); when considering maximum adsorption, the volatilization half-life increases to about 6 years(3). Benzyl sulfide's Henry's Law constant(1,SRC) indicates that volatilization from moist soil surfaces may occur(SRC). Benzyl sulfide is not expected to volatilize from dry soil surfaces based on an estimated vapor pressure of 2.9X10-4 mm Hg(SRC), determined from a fragment constant method(3).

The rate constant for the vapor-phase reaction of benzyl sulfide with photochemically-produced hydroxyl radicals has been estimated as 2.6X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1,SRC). This corresponds to an atmospheric half-life of about 15 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1,SRC).

Benzyl sulfide's use in organic synthesis may result in its release to the environment through various waste streams. If released to air, an estimated vapor pressure of 2.9X10-4 mm Hg at 25 °C indicates benzyl sulfide will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase benzyl sulfide 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 15 hours. Particulate-phase benzyl sulfide will be physically removed from the atmosphere by wet and dry deposition. If released to soil, benzyl sulfide is expected to be immobile based upon an estimated Koc of 5400. Volatilization from moist soil surfaces is not expected to be an important fate process based upon an estimated Henry's Law constant of 5.1X10-6 atm-cu m/mole and this compound's estimated Koc. Benzyl sulfide is expected to be amenable to microbial degradation under aerobic conditions yielding benzylmercaptoacetic acid; under anaerobic conditions toluene, benzyl mercaptan, and hydrogen sulfide are formed. If released into water, benzyl sulfide is expected to adsorb to suspended solids and sediment in the water column based upon its estimated Koc. Volatilization from water surfaces may occur based upon the estimated Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 11 and 82 days, respectively. However, this process is expected to be attenuated by adsorption to suspended solids and sediment in the water column. An estimated BCF of 1200 suggests the potential for bioconcentration in aquatic organisms is very high. Occupational exposure to benzyl sulfide may occur through inhalation of dust particles and dermal contact with this compound at workplaces where benzyl sulfide is produced or used. (SRC)