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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
calculation (if not (Q)SAR)
Remarks:
estimated by calculation
Adequacy of study:
key study
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 limited documentation / justification
Principles of method if other than guideline:
Method: estimated by calculation with MPBPWIN v1.43
GLP compliance:
no
Type of method:
other: Method: estimated by calculation with MPBPWIN v1.43
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
7.3
Temp.:
20 °C
pH:
> 5 - < 9
Details on results:
The log Pow of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was estimated by a model calculation based on the theoretical fragmentation of the molecule into suitable structures for which reliable log Pow values were used. The final result was obtained by summing the fragment values and the correction terms. Concerning pH and Temperature, no information is clearly given in EPISUITE outputs, consequently we consider that the estimation is done for relevant natural environmental conditions (pH = 5 – 9 and temperature = 20°C). Details are given in the table presented in "Remarks on results including tables and figures.

In conclusion, the log Pow of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was estimated to be log Pow = 7.3 using a model calculation, which is based on theoretical fragmentation.

Output of Episuite:

 TYPE NUM LOGKOW FRAGMENT DESCRIPTION COEFF VALUE 
 Frag 10 -CH3 [aliphatic carbon] 0.5473 5.473
 Frag 6 Aromatic Carbon 0.294 1.764
 Frag 4 -tert Carbon [3 or more carbon attach] 0.2676 1.0704
 Frag 4 -O- [oxygen attach] -0.3000** -1.2000
 Const   Equation Constant   0.229
** An estimated coefficient used
Log Kow  =  7.3364
Conclusions:
In conclusion, the log Pow of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was estimated to be log Pow = 7.3 using a model calculation, which is based on theoretical fragmentation.
Executive summary:

The log Pow of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was estimated by a model calculation based on the theoretical fragmentation of the molecule into suitable structures for which reliable log Pow values were used. The final result was obtained by summing the fragment values and the correction terms. In conclusion, the log Pow of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was estimated to be log Pow = 7.3 using a model calculation, which is based on theoretical fragmentation. Based upon these results, it can be concluded that [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is potentially bioaccumulable.

Description of key information

The partition coefficient, log Pow, of analogous 25155-25-3 [1,3(or 1,4)-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was calculated using the respective solubility in n-octanol and water and was determined to be > 5.5.  Therefore, the log Pow of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was also estimated by a model calculation based on the theoretical fragmentation of the molecule into suitable structures for which reliable log Pow values were used. The final result was estimated to be log Pow = 7.3 using a model calculation, which is based on theoretical fragmentation.

This is confirmed by a non-GLP study where the registered substance and its analogue (CAS 25155 -25 -3) where both tested and compared. Measured log Pow > 6.5 for both substances. The net retention time for both test substances is 36.73 min and 36.82 min. This shows that both substances have similar log Pow values.

Key value for chemical safety assessment

Log Kow (Log Pow):
7.3
at the temperature of:
20 °C

Additional information

The partition coefficient, log Pow, of analogous 25155 -25 -3 [1,3(or 1,4)-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was calculated using the respective solubility in n-octanol and water and was determined to be > 5.5. Therefore, the log Pow of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was also estimated by a model calculation based on the theoretical fragmentation of the molecule into suitable structures for which reliable log Pow values were used. The final result was obtained by summing the fragment values and the correction terms. In conclusion, the log Pow of [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide was estimated to be log Pow = 7.3 using a model calculation, which is based on theoretical fragmentation.

This is confirmed by a non-GLP study where the registered substance and its analogue (CAS 25155 -25 -3) where both tested and compared.

The purpose of this study was to determine the similarity of the partition coefficient (n-octanol/water) of two test substances. The difference between the two test substances is, one contains both meta and para substituents, the other only contains the meta substituent. The high performance liquid chromatography (HPLC) method, complying with the OECD Guideline No. 117, was used to determine the partition coefficient.

The log Pow value for both test substances, as determined from the test, were above the highest reference substance, i.e. 4,4’-DDT and therefore reported as log Pow > 6.5. The net retention time for both test substances is 36.73 min and 36.82 min. This shows that both substances have similar log Pow values.

Based upon these results, it can be concluded that [1,3-phenylenebis(1-methylethylidene)]bis[tert-butyl] peroxide is potentially bioaccumulable.