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EC number: 203-417-8
CAS number: 106-63-8
See “Test material identity”
Date of QPRF
24 Oct. 2013
QPRF author and contact details
BASF SE, Dept. for Product Safety, Ludwigshafen, Germany
Endpoint(OECD Principle 1)
Aqueous hydrolysis rate
Algorithm(OECD Principle 2)
Model or submodel name
Reference to QMRF
Estimation of Aqueous Hydrolysis Rate Constants using HYDROWIN v2.00 (EPI Suite v4.11) (QMRF)
Predicted value (model result)
See “Results and discussion”
Input for prediction
Chemical structure via CAS number or SMILES
- SMILES: structure of the compound as SMILES notation
- Taft constant (sigma*)
- Steric factor (Es)
- Hammett constants (sigma-meta and sigma-para)
Applicability domain(OECD principle 3)
1) Chemical class
An equation for the estimation of the aqueous hydrolytic rate constant is available for the chemical class of the substance.
2) Fragments (On-Line HYDROWIN User’s Guide, Appendix E)
All fragments were identified.
The uncertainty of the prediction(OECD principle 4)
According to REACH Guidance Document R.7a, (Nov. 2012), hydrolysis kinetics are usually determined experimentally. The guidance document also lists HYDROWIN as a means to estimate the hydrolytic half-life. The estimation is limited to only a few chemical classes. The model marks uncertainties of the estimate due to substitute values for missing fragments. As yet, the QSAR equations in HYDROWIN have not been rigorously tested with an external validation dataset. Currently, the number of chemicals with evaluated hydrolysis rates is relatively small in number, and the available data have been used to train the QSAR regressions. The training data set for esters has an acceptable size (n = 124). Equations for the other chemical classes were developed on very small databases (n = 7 to 20); therefore the reliability of estimations for members of other chemical classes than esters is low.
The chemical mechanisms according to the model underpinning the predicted result(OECD principle 5)
Hydrolysis is a common degradation route in the environment, where reaction of a substance with water with a net exchange of the X group with an OH at the reaction centre such that RX + H2O →ROH + HX. Hydrolysis is often dependent upon pH as the reaction is commonly catalysed by hydrogen or hydroxide ions.
The model uses the principle of linear free energy relationships (LFER) to estimate the aqueous hydrolysis rate.
US EPA (2012). On-Line HYDROWIN User’s Guide, Appendix E: Fragment
Substituent Values Used by HYDROWIN.
ECHA (2012). REACH Guidance Document R.7a, (Nov. 2012). 381 pp.
Identified fragments for the current
If the substance is an ester:
R2 substituent is an alkyl carbon or an aromatic carbon.
R1 substituent is either an alkyl carbon, an aromatic carbon or a hydrogen.
Appendix E. Fragment Substituent Values Used
Fragment identified by HYDROWIN
Substitute fragment (warning by HYDROWIN)
Name of R group according to HYDROWIN
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