N-tert-butylbenzothiazole-2-sulphenamide

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Remarks:

adsorption

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

QSAR prediction

Guideline:

other: REACH guidance QSARs R6, May/July 2008

Principles of method if other than guideline:

Estimation Program Interface EPI-Suite version 4.11: KOCWIN (v2.00) for the estimation of the organic carbon-normalized sorption coefficient for soil and sediment (Koc).
The Estimation Program Interface was developed by the US Environmental Agency's Office of Pollution Prevention and Toxics, and Syracuse Research Corporation (SRC). © 2000 - 2012 U.S. Environmental Protection Agency for EPI SuiteTM (Published online in November 2012).

GLP compliance:

no

Type of method:

other: Estimation

Media:

soil

Radiolabelling:

no

Type:

log Koc

Value:

2.762

Remarks on result:

other: calculation (logKow method)

Type:

log Koc

Value:

4.059

Remarks on result:

other: calculation (MCI method)

Phase system:

other: Koc

Type:

other: Koc

Value:

578 L/kg

Remarks on result:

other: calculation (logKow method)

Phase system:

other: Koc

Type:

other: Koc

Value:

11 470 L/kg

Remarks on result:

other: calculation (MCI method)

Validity of the model:

1. Defined Endpoint: Organic carbon partition coefficient, given as logarithmic Koc and Koc

2. Unambigous algorithm: Based on structure of the molecule, the following fragment was applied: -N-C, Nitrogen to Carbon (aliphatic). The number of times of the fragments that occurs in the structure of the substance applied by the program is verified. For estimation of logKoc according to the logKow method the experimental logKow of 3.36 as calculated by the program was used.

3. Applicable domain: With a molecular weight of 238.4 g/mole the substance is within the range of the training set (32 - 665 g/mole) as well as in the validation set (27 - 991 g/mole). Regarding the structure of N-tert-butylbenzothiazole-2-sulphenamide, the fragment descriptors found by the program are complete.

4a. Statistical characteristics (MCI method): N training set without corrections = 69; N training set with correction = 447; N validation set = 158; Correction coefficient of the total training set without corrections r² = 0.967; Correlation coefficient of the total training set with corrections r² = 0.900; Correlation coefficient of the total validation set r² = 0.850.

4b. Statistical characteristics (Kow method): N training set without corrections = 68; N training set with correction = 447; N validation set = 150; Correction coefficient of the total training set without corrections r² = 0.877; Correlation coefficient of the total training set with corrections r² = 0.855; Correlation coefficient of the total validation set r² = 0.778.

5. Mechanistic interpretation: Log Koc is estimated based on the likeliness of a substance for sorption to surfaces of soil/sediment particles. The log Koc is a physical inherent property used extensively to describe a chemical's likeliness to adsob to organic carbon. Adequacy of prediction:

The result for N-tert-butylbenzothiazole-2-sulphenamide falls within the applicability domain described above and the estimation rules applied for the substance appears appropriate.

Validity criteria fulfilled:

not applicable

Conclusions:

The QSAR determination of the carbon partition coefficient for N-tert-butylbenzothiazole-2-sulphenamide was calculated at 578 L/kg (logKow method) and 11470 L/kg (MCI method) for the unaffected molecule of N-tert-butylbenzothiazole-2-sulphenamide as any decomposition (e.g. hydrolysis) of N-tert-butylbenzothiazole-2-sulphenamide is not taken into account by the program.

Executive summary:

The organic carbon partition coefficient (Koc) for N-tert-butylbenzothiazole-2-sulphenamide was predicted using the QSAR calculation of the Estimation Program Interface (EPI) Suite v 4.11. The Koc was estimated to be 578 L/kg (logKow method), and 11470 L/kg (MCI method). The results relate to the unaffected molecule of N-tert-butylbenzothiazole-2-sulphenamide as any decomposition (e.g. hydrolysis) of N-tert-butylbenzothiazole-2-sulphenamide is not taken into account by the program.

Description of key information

The QSAR determination of the carbon partition coefficient for N-tert-butylbenzothiazole-2-sulphenamide was calculated at 578 L/kg (logKow method) and 11470 L/kg (MCI method) for the unaffected molecule of N-tert-butylbenzothiazole-2-sulphenamide as any decomposition (e.g. hydrolysis) of N-tert-butylbenzothiazole-2-sulphenamide is not taken into account by the program. Due to the fast hydrolysis of TBBS also partition coefficients of the identified hydrolysis products MBT and ter-butylamine are taken for risk assessment.

Key value for chemical safety assessment

Koc at 20 °C:

578

Additional information

Due to the fast hydrolysis of TBBS, only adsorption coefficients of the degradation products are relevant for risk assessment of TBBS in the environment. The identified hydrolysis products are MBT and tert-butylamine. The measured logKoc-values of MBT for different tested soil types were in the range of 2.51 - 3.13, and for the tested sediment types between 3.33 - 3.55 (CMA, 1989). According to the classification scheme of Swann et al. (1983) experimentally estimated log Koc-values lower than 3.7 indicates a moderate to strong sorption potential to soil and sediment and suggests a slow migration potential to ground water. As a worst-case assumption, the lowest log Koc of 2.51 is used for further assessment such as distribution modeling and PNECs through EPM method. The hydrolysis product tert-butylamine however indicates a low affinity to adsorption with a logKoc of 1.43.

[LogKoc: 2.76]