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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to the solid soil phase is not expected based on the estimated Koc.

Key value for chemical safety assessment

Koc at 20 °C:
25

Additional information

QSAR-disclaimer

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 the1,8 -diazabicyclo(5.4.0)undec-7-ene (CAS 6674 -22-2)(Q)SAR results were used for the estimation of the adsorption potential. 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

In order to assess the adsorption potential of the substance, the Koc value was estimated using QSAR models. According to the MCI method of the KOCWIN v2.00 module of EPI Suite v4.11, 1,8-diazabicyclo[5.4.0]undec-7-ene (CAS 6674 -22-2) has a Koc of 647 L/kg. The MCI module is more reliable than the log Kow method of KOCWIN v2.00, which estimates the KOC based on the n-octanol/water partition coefficient (measured log Kow: -2.20, @25°C, pH 7.0, BASF AG, Rep. No 11018710, 1989). The latter method resulted in a Koc of 223. These estimates are representative for uncharged molecules; the substance is within the applicability domain of the estimation models.

At environmentally relevant conditions, 1,8-diazabicyclo[5.4.0]undec-7-ene (CAS 6674-22-2) will be present in ionized form (pKa = 11.6 @20°C, BASF SE, Rep. No 11L00314, 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 model is not yet validated; in addition, the applicability domain is not clearly defined. Nevertheless, 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 (log Kow = -0.42, 25 °C, pH 12.4; BASF AG, 1989, report no. 110187/01).

The resulting Koc at pH 5-8 is 25 L/kg (log Koc: 1.40). 

Based on the corrections for the charged molecule according to Franco & Trapp (2008, 2009, 2010) as well as for the uncharged molecule, adsorption to the solid soil phase is not to be expected.

[LogKoc: 1.4]