Chloressigsäureanhydrid

TERRESTRIAL FATE: A base-catalyzed second-order hydrolysis rate constant of 1.9X10+5 L/mole-sec(SRC) estimated using a structure estimation method(2); corresponding to half-lives of 37 and 4 seconds at pH values of 7 and 8, respectively(1). Therefore, chloroacetic anhydride will not adsorb to soil nor volatilize from moist soil due to this rapid reaction with water. Chloroacetic anhydride is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 3.72X10-2 mm Hg(2).

AQUATIC FATE: A base-catalyzed second-order hydrolysis rate constant of 1.9X10+5 L/mole-sec(SRC) was estimated using a structure estimation method(1); this corresponds to half-lives of 37 and 4 seconds at pH values of 7 and 8, respectively(1). This hydrolysis rate indicates that chloroacetic anhydride will react rapidly with water and will not adsorb to suspended solids or sediment, volatilize, or bioconcentrate(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), chloroacetic anhydride, which has a vapor pressure of 3.72X10-2 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase chloroacetic anhydride 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 73 days(SRC), calculated from its rate constant of 2.2X10-11 cu cm/molecule-sec at 25 °C(3) determined using a structure estimation method(3).

Using a structure estimation method based on molecular connectivity indices(1), the Koc for chloroacetic anhydride can be estimated to be 3(SRC). According to a classification scheme(2), this estimated Koc value suggests that chloroacetic anhydride is expected to have very high mobility. An estimated base-catalyzed second-order hydrolysis rate constant of 1.9X10+5 L/mole-sec(SRC) which corresponds to half-lives of 37 and 4 seconds at pH values of 7 and 8, respectively(3) will make it unlikely for chloroacetic anhydride to be mobile.

Chloroacetic anhydride (CAS# 541-88-8) was evaluated for acute dermal toxicity in six guinea pigs at a dose range of 0.1 to 1.0 g/kg. The test substance was applied as a solid moistened with water on the cuff. Toxic signs with 24-hours included moderate edema and an entire patch area necrotic with hemorrhagic ban at periphery. After 1-week there was a depressed eschar over the entire patch area with moderate erythema at periphery. After 2-weeks, a secondary eschar appeared on one rabbit and another rabbit had one depressed, and a third had scarring. Time of death was between 4 and 24 hours. The test substance was determined to be a severe skin irritant with evidence of percutaneous absorption. The LD50 was determined to be between 0/1 and 0/2 g/kg.

An estimated BCF of 3 was calculated for chloroacetic anhydride(SRC), using an estimated log Kow of -0.07(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 low. Bioconcentration is unlikely to occur due to an estimated base-catalyzed second-order hydrolysis rate constant of 1.9X10+5 L/mole-sec(SRC) which corresponds to half-lives of 37 and 4 seconds at pH values of 7 and 8, respectively(4).

The Henry's Law constant for chloroacetic anhydride is estimated as 4.42X10-6 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that chloroacetic anhydride could volatilize from water surfaces(2) if it did not hydrolyze. A base-catalyzed second-order hydrolysis rate constant of 1.9X10+5 L/mole-sec(SRC) which corresponds to half-lives of 37 and 4 seconds at pH values of 7 and 8, respectively(4), makes chloroacetic anhydride very susceptible to hydrolysis. Chloroacetic anhydride is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 3.72X10-2 mm Hg(3).

The rate constant for the vapor-phase reaction of chloroacetic anhydride with photochemically-produced hydroxyl radicals has been estimated as 2.2X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 73 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). A base-catalyzed second-order hydrolysis rate constant of 1.9X10+5 L/mole-sec(SRC) was estimated using a structure estimation method(2); this corresponds to half-lives of 37 and 4 seconds at pH values of 7 and 8, respectively(2).

Chloroacetic anhydride's production and use as an intermediate for cellulose chloroacetate may result in its release to the environment through various waste streams. If released to air, a vapor pressure of 3.72X10-2 mm Hg at 25 °C indicates chloroacetic anhydride will exist solely as a vapor in the ambient atmosphere. Vapor-phase chloroacetic anhydride 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 73 days. If released to soil, chloroacetic anhydride will rapidly react with water; an estimated base-catalyzed second-order hydrolysis rate constant of 1.9X10+5 L/mole-sec corresponds to half-lives of 37 and 4 seconds at pH values of 7 and 8, respectively. Chloroacetic anhydride is not expected to volatilize from dry soil surfaces based upon its vapor pressure. If released into water, chloroacetic anhydride will react rapidly with water and will not adsorb to suspended solids or sediment, volatilize or bioconcentrate. Occupational exposure to chloroacetic anhydride may occur through inhalation and dermal contact with this compound at workplaces where chloroacetic anhydride is produced or used. (SRC)