Octyl (R)-2-(4-chloro-2-methylphenoxy)propionate

Endpoint summary

Additional information

It has been demonstrated in mammals, plant and soil environments that hydrolysis of structural analoges - racemic Mecoprop isooctyl ester (MCPP IOE) and Mecoprop-P 2-ethylhexyl ester (MCPP-P 2-EHE) is rapid. Following this initial degradation step the studies available for Mecoprop-P acid (MCPP-P acid) predict the behaviour of the material in the environment.

The structure analog Mecoprop-P 2-ethylhexyl ester (MCPP-P 2-EHE) has been shown to degrade to the parent Mecoprop-P acid (MCPP-P acid) by a process of hydrolysis. In sterile buffered water this process is very slow, but in naturally occurring water, for example river water the hydrolysis is very rapid with a DT50 of approximately 4 hours. In practical situations the low solubility of Mecoprop-P n-octyl ester (<0.1 mg/l) will mean that the ester will bind to inorganic and organic matter and be released only very slowly as the reservoir of dissolved material is depleted due to hydrolysis. In practical terms this will limit the mobility of Mecoprop-P n-octyl ester in aquatic systems.

For the atmospheric oxidation the estimated half-life of Mecoprop-P n-octyl ester is 17.6 hours. Considering this result a potential for long-range transport of Mecoprop-P n-octyl ester itself is not given.

Mecoprop-P n-octyl ester is of very low water solubility and under the conditions of sterile buffer solution Mecoprop-P n-octyl ester is stable to hydrolysis at environmental temperatures and pH values. Data on structural analoges, racemic Mecoprop isooctyl ester (MCPP IOE) and Mecoprop-P 2-ethylhexyl ester (MCPP-P 2-EHE), showed that it is stable under sterile buffer but degrades rapidly in natural water due to hydrolysis forming Mecoprop-P acid (MCPP-P acid) with a DT50 of 4.34 hours, respectively. An investigation on Mecoprop-P acid (MCPP-P acid) showed no further degradation within 31 days depending on hydrolysis.

Mecoprop-P n-octyl ester is not readily biodegradable and not inherently biodegradable. However, the hydrolysis product Mecoprop-P acid (MCPP-P acid) is readily biodegradable with a degradation rate of 85 % within 28 days.

The estimated BCF of Mecoprop-P n-octyl ester was 487.6 L/kg. However, since Mecoprop-P n-octyl ester rapidly hydrolyses in natural water this is only of theoretical interest. Additionally the determined BCF of 5.5 and 3.0 (non-edible and whole fish) for the hydrolysis product Mecoprop-P acid (MCPP-P acid) showed no potential for bioaccumulation. Therefore, Mecoprop-P n-octyl ester is considered as not being bioaccumulative in the environment.

 

Mecoprop-P n-octyl ester hydrolyses rapidly in natural water. Therefore, the hydrolysis product Mecoprop-P acid (MCPP-P acid) was used for further assessment of Mecoprop-P n-octyl ester with respect to its potential for adsorption on soil.

Determined in 3 sandy soils the Koc of Mecoprop-P acid (MCPP-P acid) was in the range of 135 – 167 indicating that Mecoprop-P acid (MCPP-P acid) has a low sorption potential to soil and sediment, and a moderate migration potential to groundwater.

 

Mecoprop-P acid (MCPP-P acid), the hydrolysis product of Mecoprop-P n-octyl ester, is considered nonvolatile from the aqueous phase with a Henry’s Law constant of 5.74 E-05 Pa*m3/mol at 20°C.