りん酸ジフェニル=オクチル

Based on an experimentally derived water solubility(1) and a regression-derived equation, the Koc of diphenyl octyl phosphate was estimated as 13000(2,SRC). Using an estimated Kow of 6.37(3), the Koc for octyl diphenyl phosphate was estimated as 70000(2). According to a suggested classification scheme(4), these Koc values indicate that diphenyl octyl phosphate will be immobile in soil(SRC). Hydrolysis of diphenyl octyl phosphate may occur while this compound is bound to the soil(5).

Based on an estimated log Kow of 6.37(1,SRC), the BCF of diphenyl octyl phosphate is estimated as 41000 from a regression-derived equation(2,SRC). Using an experimental water solubility of 0.14 mg/L(3), a BCF of 1900 is calculated for diphenyl octyl phosphate(2,SRC). These BCF values indicate that bioconcentration of this compound in aquatic organisms is an important fate process for diphenyl octyl phosphate(SRC). However, depuration of many phosphate esters is rapid due to metabolism at the ester functionality; thus, these BCF values may not reflect what is seen in the environment(4,SRC).

The Henry's Law constant for diphenyl octyl phosphate is estimated as 2.5X10-7 atm-cu m/mole using a structure estimation method(1,SRC). This value indicates that from water surfaces and moist soil diphenyl octyl phosphate is essentially non-volatile(2,SRC).

The rate constant for the vapor phase reaction of diphenyl octyl phosphate with photochemically produced hydroxyl radicals has been estimated as 3.74X10-11 cu cm/molecule-sec at 25 °C(1). This corresponds to an atmospheric half-life of about 10 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1,SRC). Hydrolysis of diphenyl octyl phosphate may occur(SRC). Hydrolysis of phosphate esters is generally promoted by alkaline conditions as the phosphate ester undergoes second order nucleophilic reactions due to the hydroxide ion involving cleavage of the O-P bond; C-O cleavage is dominant for those compounds which can undergo either acid or water promoted hydrolyses of esters(2).

SURFACE WATER: Water samples were taken from the Inner Harbor Navigation Canal of Lake Pontchartrain in New Orleans, LA at depths of 1.5 and 10.0 m during both ebb and flood tides. Diphenyl octyl phosphate was found, using GC/MS, at 0.04 ppb at depths of 1.5 and 10 m during the flood tide June 23, 1980. It was not detected during the ebb tide sampling on May 6, 1980(1); this may reflect that flood tide samples were concentrated considerably prior to analysis while ebb tide samples were not(1). Diphenyl octyl phosphate was detected in water and sediment samples taken in the vicinity of a specialty chemicals manufacturing plant at unreported concentrations and at unreported locations during 1976-1977(2).

Diphenyl octyl phosphate's production and use as a flame retardant plasticizer may result in its release to the environment. If released to the atmosphere, diphenyl octyl phosphate will exist in both the vapor phase and in the particulate phase based on an estimated vapor pressure of 1.24X10-7 mm Hg. In the vapor phase diphenyl octyl phosphate will be degraded by hydroxyl radicals with an estimated half-life of 10.3 hours. Particulate phase diphenyl octyl phosphate may be removed physically from air by wet and dry deposition. In soil, diphenyl octyl phosphate is expected to be immobile. Hydrolysis of diphenyl octyl phosphate may be an important fate process, particularly under alkaline soil conditions. In water, hydrolysis is expected to be a major fate process for diphenyl octyl phosphate despite its low water solubility, especially if the water is alkaline. An estimated Henry's Law constant of 2.5X10-7 atm-cu m/mole indicates that this compound will not volatilize from water surfaces. BCF values of 1900 and 41000 suggest that diphenyl octyl phosphate may bioconcentrate in aquatic organisms. However, rapid depuration rates have been reported for phosphate esters. (SRC)