Registration Dossier
Registration Dossier
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EC number: 203-996-7 | CAS number: 112-67-4
Adsorption / desorption
Administrative data
Link to relevant study record(s)
Description of key information
Parent compound palmitoyl chloride: no data.
Hydrolysis product palmitic acid: Adsorption to solid soil phase is expected. However, the substance is readily biodegradable.
Key value for chemical safety assessment
Additional information
QSAR-disclaimer
In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.
According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.
For the assessment of the hydrolysis product palmitic acid (CAS 57 -10 -3) (Q)SAR results were used for adsorption / desorption. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.
Therefore, further experimental studies on the adsorption potential are not provided.
Assessment
Palmitoyl chloride (CAS 112 -67 -4) rapidly hydrolyses in contact with water to form palmitic acid (CAS 57 -10 -3) and hydrogen chloride (CAS 7647-01-0, see IUCLID Ch. 5.1.2). Due to this rapid hydrolysis, the assessment of the adsorption potential of the parent compound is considered to be of low relevance. Therefore, the assessment of adsorption potential is based solely on the data available for palmitic acid.
According to Regulation (EC) No 1907/2006, Annex VIII, Section 9.3.1, Column 2, the study on adsorption/desorption screening does not need to be conducted if based on the physicochemical properties the substance can be expected to have a low potential for adsorption (e.g. the substance has a low octanol water partition coefficient), or the substance and its relevant degradation products decompose rapidly. Palmitoyl chloride hydrolyses very quickly to palmitic acid (CAS 57 -10 -3) and HCl (CAS 7647 -01 -0) (t1/2 < 5 min, see IUCLID Ch. 5.1.2) .The hydrolysis product palmitic acid is readily biodegradable (BODIS Test, BASF AG, 1994; see IUCLID Ch. 5.2.1). Therefore, a study does not need to be conducted.
No experimental data on the adsorption potential of palmitic acid (CAS 57 -10 -3) exist. Therefore, the Koc value was estimated using a QSAR model. However, the substance is not competely within the applicability domain of the model as its log Kow is slightly outside the range. At environmentally relevant conditions, palmitic acid will be present in its ionised form (pKa = 4.75; at 25 °C, SPARC On-line Calculator, BASF SE, 2020, see IUCLID Ch. 4.21). Therefore, the adsorption coefficient was calculated according to Franco & Trapp (2008, 2009, 2010) to correct for the charged molecule at pH 5, 7, and 8. This pH range is representative for 98% of the European soils. The substance is not within the applicability domain of the model. The Koc values of the Franco & Trapp method give a good indication on the adsorption potential of a substance depending on the pH conditions of soil. The method is based on the dissociation constant pKa and the log Kow for the uncharged molecule. The resulting Koc and log Koc values are presented in the following table:
| LogKoc | Koc [L/kg] |
pH 5 | 4.82 | 66353 |
pH 7 | 3.36 | 2308 |
pH 8 | 2.63 | 427 |
The Koc values for palmitic acid decrease with increasing pH.
It can be concluded, that adsorption to solid soil phase is expected at environmentally relevant conditions. However, the substance is readily biodegradable.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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