3,4-dihydro-2H-1,4-benzoxazin-6-ol

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

October 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE and MODEL
KOCWIN V2.00 (2010) from the Episuite platform V4.10

2. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
Oc1ccc2OCCNc2c1 and experimental LogKow=0.219

3. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: The soil adsorption coefficient (Koc) of non-ionised organic compounds, expressed as LogKoc.
- Unambiguous algorithm:
KOCWIN uses two models, one based on the Molecular Connectivity Index (MCI) and the second relates the logKow to the soil adsorption coefficient.
Molecular Connectivity Index (MCI):
Based on the publication of Meylan et al. (1992) with two separate regression performed, on developed specifically for non-polar compounds, and the second involves correction factors.
The equation derived by the non-polar (no correction factor) regression is:
log Koc = 0.5213 MCI + 0.60 (n = 69, r2 = 0.967, std dev = 0.247, avg dev = 0.199)

Adding in the correction factor regression yields the final MCI equation:
log Koc = 0.5213 MCI + 0.60 + ΣPfN
where ΣPfN is the summation of the products of all applicable correction factor coefficients multiplied by the number of times (N) that factor is counted for the structure.

Estimation Using Log Kow:
Based on the correlation between LogKoc and LogKow as published by Doucette (2000). Two equations have been developed one for non-polar compounds (no correction factor) and one integrating correction factors.
For nonpolar compounds:
log Koc = 0.8679 Log Kow - 0.0004 (n = 68, r2 = 0.877, std dev = 0.478, avg dev = 0.371)

For compounds having correction factors, the equation is:
log Koc = 0.55313 Log Kow + 0.9251 + ΣPfN
where ΣPfN is the summation of the products of all applicable correction factor coefficients by the number of times (N) that factor is counted for the structure.

- Defined domain of applicability:
KOCWIN applicability domain is defined according to two different parameters:
- the molecular weight of the target substance. It should be between 32.04 and 665.02 g/mol. These boundaries are the minimum and maximum values found in both the training set and the validation set,
- the lower and upper experimental LogKow included in both the training and the validation sets; which are respectively -5.98 and 9.1.

No formal QMRF is available for this model; all relevant information for drafting a QMRF is available in the User’s guide of KOCWIN sub-model.

5. APPLICABILITY DOMAIN
- Descriptor domain: The molecular weight and the LogKow of the substance are within the applicability domain: MW=151.17 g/mol and LogKow=0.219
- Structural and mechanistic domains:
Detection of several key chemical fragments influencing the soil adsorption coefficient reveals the proper description of the structure:
Nitrogen to non-fused aromatic ring
Ether, aromatic ring (-C-O-C-)
Nitrogen to Carbon (aliphatic) (-N-C)
Aromatic hydroxy (aromatic -OH)

6. ADEQUACY OF THE RESULT
As developed by Meylan et al. (1992), the atom/fragment theory is one of the most relevant method for estimating the soil adsorption coefficient. The substance (by the means of its molecular weight and its LogKow) is within the applicability domain of the model, and its structure is well recognised. The values predicted either from the MCI and from the LogKow are close to each other. Consequently, the prediction is considered robus and relevant and to fit the purpose for REACh and the environmental risk assessment.

Qualifier:

no guideline required

Principles of method if other than guideline:

- Software tool(s) used including version: KOCWIN V2.00 (2010) from the Episuite platform V4.10
- Model description and justification of QSAR prediction: see field 'Justification for non-standard information'

Type:

Koc

Value:

46.6 L/kg

Type:

log Koc

Value:

1.554 dimensionless

Adsorption and desorption constants:

Predicted LogKoc values from MCI: 1.8831
Predicted LogKoc values from LogKow: 1.2256
The mean value of the predicted LogKoc values from MCI and LogKow is calculated: LogKoc=1.554, which corresponds to a mean Koc value of 46.6 L/Kg.

Conclusions:

The mean value of the predicted LogKoc values from MCI and LogKow is calculated: LogKoc=1.554, which corresponds to a mean Koc value of 46.6 L/Kg.

Executive summary:

The LogKoc value of the substance was predicted by the mean of KOCWIN V2.00 (2010) model from the Episuite platform V4.10.

The predicted LogKoc values from MCI: 1.8831. The predicted LogKoc values from LogKow: 1.2256.

The mean value of the predicted LogKoc values from MCI and LogKow is calculated: LogKoc=1.554, which corresponds to a mean Koc value of 46.6 L/Kg.

As developed by Meylan et al. (1992), the atom/fragment theory is one of the most relevant method for estimating the soil adsorption coefficient. The substance (by the means of its molecular weight and its LogKow) is within the applicability domain of the model, and its structure is well recognised. The values predicted either from the MCI and from the LogKow are close to each other. Consequently, the prediction is considered robus and relevant and to fit the purpose for REACh and the environmental risk assessment.

Description of key information

The mean value of the predicted LogKoc values from MCI and LogKow is calculated: LogKoc=1.554, which corresponds to a mean Koc value of 46.6 L/Kg.

Key value for chemical safety assessment

Koc at 20 °C:

46.6