3,4,4-トリメチル-2-ペンテン

Using a structure estimation method based on molecular connectivity indices(1), the Koc for 3,4,4-trimethyl-2-pentene can be estimated to be about 298(SRC). According to a classification scheme(2), this estimated Koc value suggests that 3,4,4-trimethyl-2-pentene is expected to have moderate mobility in soil.

An estimated BCF of 240 was calculated for 3,4,4-trimethyl-2-pentene(SRC), using an estimated log Kow of 4(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 high.

The Henry's Law constant for 3,4,4-trimethyl-2-pentene is estimated as 0.881 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that 3,4,4-trimethyl-2-pentene is expected to volatilize rapidly from water surfaces(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as approximately 3.1 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as approximately 101 hrs(SRC). 3,4,4-Trimethyl-2-pentene's Henry's Law constant(1) indicates that volatilization from moist soil surfaces may occur(SRC). 3,4,4-Trimethyl-2-pentene is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 9.88X10-2 mm Hg(SRC), determined from a fragment constant method(3).

The rate constant for the vapor-phase reaction of 3,4,4-trimethyl-2-pentene with photochemically-produced hydroxyl radicals has been estimated as 8.77X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 4.39 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). The rate constant for the vapor-phase reaction of 3,4,4-trimethyl-2-pentene with ozone is estimated to be 7.4X10-17 cu cm/molec sec(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of 3.7 hrs at an atmospheric concn of 7X10+11 molec/cu cm for ozone(2). 3,4,4-Trimethyl-2-pentene is not expected to undergo hydrolysis in the environment due to the lack of hydrolyzable functional groups(3) nor to directly photolyze due to the lack of absorption in the environmental UV spectrum.

3,4,4-Trimethyl-2-pentene's production and use in octene mixtures and gasoline blending may result in its release to the environment through various waste streams. If released to air, an estimated vapor pressure of 9.88X10-2 mm Hg at 25 °C indicates 3,4,4-trimethyl-2-pentene will exist solely in the vapor phase in the ambient atmosphere. Vapor-phase 3,4,4-trimethyl-2-pentene will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals and ozone; the half-life for these reaction in air is estimated to be 4.4 and 3.7 hrs, respectively. If released to soil, 3,4,4-trimethyl-2-pentene is expected to have moderate mobility based upon an estimated Koc of 298. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 0.881 atm-cu m/mole. 3,4,4-Trimethyl-2-pentene is not expected to volatilize from dry soil surfaces based upon its vapor pressure. If released into water, 3,4,4-trimethyl-2-pentene is expected to slightly adsorb to suspended solids and sediment in the water column based upon the estimated Koc. Volatilization from water surfaces is expected to be an important fate process based upon this compound's estimated Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 3.1 and 101 hrs, respectively. An estimated BCF of 240 suggests the potential for bioconcentration in aquatic organisms is high. Occupational exposure to 3,4,4-trimethyl-2-pentene may occur through inhalation and dermal contact with this compound at workplaces where 3,4,4-trimethyl-2-pentene is produced or used. (SRC)