2-chloro-2-methylpropane

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Data waiving:

study technically not feasible

Justification for data waiving:

the study does not need to be conducted because the substance decomposes

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1995

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)

Deviations:

not specified

GLP compliance:

no

Type of method:

flask method

Partition coefficient type:

octanol-water

Analytical method:

gas chromatography

Key result

Type:

log Pow

Partition coefficient:

0.35

Temp.:

20 °C

pH:

7

Conclusions:

The logPow of the hydrolysis product of the test item was reported to be 0.35 at 20 °C.

Reference 3

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2018-03-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient - HPLC Method)

GLP compliance:

no

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

gas chromatography

Type:

Pow

Temp.:

20 °C

Remarks on result:

not determinable

Details on results:

During the water solubility experiments the two phase system of test item/water had changed into one phase. In the subsequent GC analysis of aliquots of the water solubility experiments the test item specific signal at 3.2 min could not be detected anymore. Instead of this a delayed signal at 3.4 min was found. According to literature the test item hydrolyzes with a half-value time of (t05) = 109 s into t-butanol. Therefore as reference pure t-butanol was dissolved in methanol and analyzed with the identical GC method as the present test item. Because of corresponding retention times of t-butanol and the hydrolysis product of the water solubility experiments of around 3.4 min, it was assumed that the test item undergoes hydrolysis during the water solubility experiments. Another indication of a hydrolysis of the test item into t-butanol and hydrochloric acid was the low pH value of 0.7 measured after the water solubility experiments. Therefore the determination of the logPow of the test item is technically not feasible due to fast hydrolysis.

Conclusions:

The measurement of the logPow of the tests item is technically not feasible as the test item undergoes fast hydrolysis in contact with water.

Executive summary:

The water solubility of the test item was investigated according to OECD 105 using the shake flask method with GC analysis. During the water solubility experiments the two phase system of test item/water had changed into one phase. In the subsequent GC analysis of aliquots of the water solubility experiments the test item could not be detected anymore but another signal was detected. Therefore as reference pure t-butanol was dissolved in methanol and analyzed with the identical GC method as the present test item. Because of corresponding retention times of t-butanol and the hydrolysis product of the water solubility experiments, it was assumed that the test item undergoes hydrolysis during the water solubility experiments. Another indication of a hydrolysis of the test item into t-butanol and hydrochloric acid was the low pH value of 0.7 measured after the water solubility experiments. Therefore, in accordance with REACH Annex VII column 2, the determination of the logPow of the test item is technically not feasible due to fast hydrolysis.

Reference 4

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

Please refer to the QMRF and QPRF files provided under the section attached justification.

Qualifier:

according to guideline

Guideline:

other: REACH guidance on QSAR R.6

Principles of method if other than guideline:

Estimates the log octanol-water partition coefficient, log KOW, of chemicals using an atom/fragment contribution method.

GLP compliance:

no

Type of method:

calculation method (fragments)

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

SMILES: C(CL)(C)(C)C

Key result

Type:

log Pow

Partition coefficient:

2.45

Temp.:

25 °C

Remarks on result:

other: QSAR predicted value. The substance is within the applicability domain of the model.

KOWWIN Program (v1.68) Results:

===============================

 

Log Kow(version 1.68 estimate): 2.45

 

SMILES : C(CL)(C)(C)C

CHEM  : T-BUTYL CHLORIDE

MOL FOR: C4 H9 CL1

MOL WT : 92.57

 

TYPE	NUM	LOGKOW FRAGMENT DESCRIPTION	COEFF	VALUE
Frag	3	-CH3[aliphatic carbon]	0.5473	1.6419
Frag	1	-CL [chlorine, aliphatic attach]	0.3102	0.3102
Frag	1	-tert Carbon[3 or more carbon attach]	0.2676	0.2676
Const		Equation Constant		0.2290

Log Kow  =  2.4487

 

Conclusions:

Using KOWWIN v1.68 the logPow of the test item was calculated to be 2.45 at 25 °C. The substance is within the applicability domain of the model.

Executive summary:

The logPow was calculated using KOWWIN v1.68 as part of EPISuite v4.11 from US Environmental Protection Agency.

Using KOWWIN v1.68 the log Kow of the test item was calculated to be 2.45 at 25 °C (EPI Suite, 2014).

The adequacy of a prediction depends on the following conditions:

a) the (Q)SAR model is scientifically valid: the scientific validity is established according to the OECD principles for (Q)SAR validation;

b) the (Q)SAR model is applicable to the query chemical: a (Q)SAR is applicable if the query chemical falls within the defined applicability domain of the model;

c) the (Q)SAR result is reliable: a valid (Q)SAR that is applied to a chemical falling within its applicability domain provides a reliable result;

d) the (Q)SAR model is relevant for the regulatory purpose.

 

For assessment and justification of these 4 requirements the QMRF and QPRF files were developed and attached to this study record.

 

Description of the prediction Model

The prediction model was descripted using the harmonised template for summarising and reporting key information on (Q)SAR models. For more details please refer to the attached QSAR Model Reporting Format (QMRF) file. 

 

Assessment of estimation domain

The assessment of the estimation domain was documented in the QSAR Prediction Reporting Format file (QPRF). Please refer to the attached document for the details of the prediction and the assessment of the estimation domain.

Description of key information

The logPow was determied to be 2.45 at 20 °C.

Key value for chemical safety assessment

Log Kow (Log Pow):

2.45

at the temperature of:

20 °C

Additional information

Weight of evidence

In a weight of evidence approach the available date of the test item were evaluated. In the course of the investigation of the water solubility of the substance, the decomposition of the test item was observed. The test item decomposes rapidly in contact with water. Therefore, the determination of the log Pow was technically not possible. Tert-butanol was identified as hydrolysis product of the test item. Hansch et al, reported the logPow of tert-butanol to be 0.35 at 20 °C. In addition, QSAR estimation for the test item was conducted. The logPow was estimated to be 2.45. The logPow of the test item was regarded as worst case and thus, was used as key value.

Data waiving [reference 4.7-1]

In accordance with REACH Annex VII column 2, the study does not need to be conducted as the test item decompose (hydrolyse) fast in contact with water.

 

Study results [reference 4.7-2]

 The water solubility of the test item was investigated according to OECD 105 using the shake flask method with GC analysis. During the water solubility experiments the two phase system of test item/water had changed into one phase. In the subsequent GC analysis of aliquots of the water solubility experiments the test item could not be detected anymore but another signal was detected. Therefore as reference pure t-butanol was dissolved in methanol and analyzed with the identical GC method as the present test item. Because of corresponding retention times of t-butanol and the hydrolysis product of the water solubility experiments, it was assumed that the test item undergoes hydrolysis during the water solubility experiments. Another indication of a hydrolysis of the test item into t-butanol and hydrochloric acid was the low pH value of 0.7 measured after the water solubility experiments. Therefore, in accordance with REACH Annex VII column 2, the determination of the logPow of the test item is technically not feasible due to fast hydrolysis.

 

QSAR estimation [reference 4.7-3]

The logPow was calculated using KOWWIN v1.68 as part of EPISuite v4.11 from US Environmental Protection Agency.

Using KOWWIN v1.68 the log Kow of the test item was calculated to be 2.45 at 25 °C (EPI Suite, 2014).

 

The adequacy of a prediction depends on the following conditions:

a) the (Q)SAR model is scientifically valid: the scientific validity is established according to the OECD principles for (Q)SAR validation;

b) the (Q)SAR model is applicable to the query chemical: a (Q)SAR is applicable if the query chemical falls within the defined applicability domain of the model;

c) the (Q)SAR result is reliable: a valid (Q)SAR that is applied to a chemical falling within its applicability domain provides a reliable result;

d) the (Q)SAR model is relevant for the regulatory purpose.

 

For assessment and justification of these 4 requirements the QMRF and QPRF files were developed and attached to this study record.

 

Description of the prediction Model

The prediction model was descripted using the harmonised template for summarising and reporting key information on (Q)SAR models. For more details please refer to the attached QSAR Model Reporting Format (QMRF) file. 

 

Assessment of estimation domain

The assessment of the estimation domain was documented in the QSAR Prediction Reporting Format file (QPRF). Please refer to the attached document for the details of the prediction and the assessment of the estimation domain.

 

Publication Hansch et al [reference 4.7-4]

In the course of the development of QSAR models by Hansch et al, the test item 2-methyl-2-Propanol was investigated. The logPow was determined using the shake flask method and GC analysis. The logPow was determined to be 0.35 at 20 °C.