Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Stability

Parent compound: In contact with water, the substance will hydrolyse rapidly (t1/2 < 9.5 h) (BASF AG, 2006; Report No. 06E02795).

Hydrolysis product: Stearic acid: According to structural properties hydrolysis is not expected.

In air, stearic chloride is expected to be photodegraded by OH-radicals with a half-life of 15.9 h (BASF SE, 2009).

This estimation refers to dry air. In mist, rain, droplets and aerosols hydrolysis will be the major fate process in air due to the short half-life in aqueous solutions.

Hydrolysis product: Stearic acid: A half-life of 17.1 h was calculated for the degradation in the atmosphere by OH-radicals (BASF SE, 2009). No data are available on phototransformation in water or in soil.

 

 

Biodegradation

Due to rapid hydrolysis, stearoyl chloride will not be present in the environment for a significant time.

The biodegradability of its hydrolysis product stearic acid was assessed via a weight of evidence approach. Based on the available test data and QSAR models, stearic acid is readily biodegradable.

 

Bioaccumulation

Stearoyl chloride has an estimated log Kow of 7.39 (BASF SE, 2009). The corresponding BCF estimate is 2181 (BASF SE, 2009), therefore accumulation in organisms is possible. However the test substance rapidly hydrolyses and forms stearic acid. Hence, the BCF-estimate may be of low relevance.

The hydrolysis product stearic acid has an experimentally determined log Kow of 8.23 (Sangster, 1993). Therefore based on log Kow accumulation in organisms is possible. However, the BCF was estimated to be 10 (BASF SE, 2009) and ca. 20 (BASF SE, 2010) using EPIWINv4.00 and Catabol - BCF base-line model (v01.04), respectively. Based on these BCF-estimates, significant accumulation in organisms is not expected.

 

 

Transport and Distribution

Due to rapid hydrolysis, stearoyl chloride will not be present in the environment for a significant time. Therefore the fate in the environment is mainly based on the hydrolysis product stearic acid.

 

Adsorption potential

The log Koc of stearyol chloride was calculated to be between 4.1 and 4.8 (Koc = 12250 to 60740; BASF SE, 2009).

Therefore adsorption to soil and sediment is expected. However, stearoyl chloride is expected to hydrolyse rapidly and to form stearic acid.

The hydrolysis product stearic acid has a calculated log Koc of 4.1 to 4.7 (uncharged molecule; BASF SE, 2009).

The pH-corrected values for the charged molecule show that with a log Koc of 3.74 at pH 7 adsorption to solid soil phase is expected (BASF SE, 2010). However, the hydrolysis product is readily biodegradable.

 

 

Henry’s Law Constant

A Henry law constant (HLC) of 6.27E3 Pa*m³/mol was calculated by SRC HENRYWIN v3.20 (BASF SE, 2009).

This indicates a volatile character of the test substance. However, stearoyl chloride is expected to rapidly hydrolyse and to form stearic acid.Therefore, this model calculation may be of low relevance.

Stearic acid has a HLC of 0.0904 Pa*m³/mol, which was calculated based on experimental data on vapour pressure and water solubility (BASF SE, 2009). Additionally, most of the stearic acid molecules will be present in dissociated form under environmental relevant pH conditions (pKa = 4.75).

Therefore it may be concluded, that due to rapid hydrolysis, stearoyl chloride will only exist for a short time in water and the hydrolysis product does not evaporate into air.

 

Distribution

Based on the results of the Mackay Level 1 calculation, the substance will over time preferentially distribute into the compartments sediment (43.2%) and soil (42.8%).

 

Stearoyl chloride (CAS 112 -76 -5) rapidly decomposes in water and forms HCl(CAS 7647-01-0) and stearic acid CAS 57 -11 -4). Therefore, the model calculation may be of low relevance.

 

The Mackay Level 1 calculation for the hydrolysis product stearic acid indicates that the substance will over time preferentially distribute into the compartments sediment (50.1%) and soil (49.5%).

The data refer to the uncharged molecule (calculated pKa value: 4.75). However, the model does not consider the ionic structure of the molecule at environmentally relevant pH conditions (pH 5 to pH 9). The model may underestimate the distribution into water.