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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
other: Estimation based on a calculation has been carried out.
Adequacy of study:
key study
Study period:
Start date of the experimental work: 12 June 2009 and Completion date of the experimental work: 02 July 2009.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Conducted at a GLP accredited laboratory
Qualifier:
no guideline followed
Principles of method if other than guideline:
Experimental techniques are available for the determination of partition coefficient of a substance or preparation. These are described in EC Test A8 as Shake flask method and HPLC method. However, test A8 cannot to be carried out because the sample reacts with water. As a result, an estimation based on a calculation has been carried out.
One approach involves the use of empirically derived atomic or group fragment constants and structural factors which when summed for the whole molecule yields the partition coefficient directly. For an organic substance, the octanol/water partition coefficient (Log P) is calculated as follows:
Log P = sum of fragments (α) + sum of factors (β)
GLP compliance:
no
Type of method:
other: Estimation based on a calculation was performed.
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
8.56
Remarks on result:
other: estimated
Remarks:
calculation involves the use of empirically derived atomic or group fragment constants and structural factors which when summed for the whole molecule yields the partition coefficient directly.

Examining the structure of Suprasec 2020 (MDI homopolymer), the molecules contain fragments and factor groups and their corresponding values are listed below:

 Fragments Frequency  Value  Total value 
 -N=C=O  3  -  -
 -C6H5 benzene  6  1.90  11.40
 -CH2 -Aliphatic  3  0.20  0.60
 -NC(=O)N-  1 -1.28   -1.28
 >C=N  1  -1.52  -1.52
 Factors      
 Di-N  1  0.084  0.084
 Bond factor (chain)  9  -0.48  -0.48
 Bond factor (branch)  5  -0.24  -0.24
 Total (LOG P)      8.564

On the basis of this exercise, the estimated octanol/water partition coefficient of the material is 8.56.

Conclusions:
The estimated octanol/water partition coefficient of the material is 8.56.

Description of key information

A log Pow value of 8.56 was estimated by calculation. 

Key value for chemical safety assessment

Log Kow (Log Pow):
8.56
at the temperature of:
20 °C

Additional information

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