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Physical & Chemical properties

Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
For justification of read-across please refer to the read-across report attached to IUCLID section 13.
Reason / purpose for cross-reference:
read-across source
Type:
log Pow
Partition coefficient:
0.4
Temp.:
25 °C
Remarks on result:
other: neutral pH
Type:
Pow
Partition coefficient:
2.7
Temp.:
25 °C
Remarks on result:
other: neutral pH
Details on results:
Calculation method: Calculation of the Pow
The Pow of the test substance was calculated to be 2.3 (log Pow 0.36) using the Rekker calculation method.

Calculation of the pKa
Dilactide does not contain any acidic or basic groups.

HPLC Method
HPLC chromatograms of the test substance solution and corresponding blank are shown in Figure 1.
In the chromatogram of the test solution, one major peak and one small peak were observed.
The results of the HPLC method are given in Table 1. Figure 2 shows the calibration curve of the log k’ of the reference substances as function of log Pow. The equation of the regression line was: log k’= 0.624 = log Pow – 0.387 (r= 0.998, n= 12).

Table 1: log Pow of the test substance and reference substances

Substance

tr,1
[min]

tr,2
[min]

mean tr
(n=2)

log Pow

Pow

Area
%

 

 

 

 

 

 

 

Formamide (t0)

0.580

0.581

0.581

 

 

 

 

 

 

 

 

 

 

2-Butanone

0.947

0.946

0.947

0.3

 

 

Benzylalcohol

1.823

1.828

1.826

1.1

 

 

Nitrobenzene

3.785

3.787

3.787

1.9

 

 

Toluene

13.079

13.085

13.082

2.7

 

 

Bromobenzene

17.237

17.245

17.241

3.0

 

 

1,4-Dichlorobenzene

33.313

33.332

33.323

3.4

 

 

 

 

 

 

 

 

 

Test substance

1.016

1.021

1.019

0.4

2.7

99.9

Impurity I

1.589

1.586

1.588

1.0

10

0.1

 

 

 

 

 

 

 

Conclusions:
The log Pow of LL-lactide (determined by read-across from dilactide) is 0.4.
Executive summary:

The HPLC method (OECD guideline 117) was considered to be the most suitable method to determine the log Pow of dilactide. The Pow value of dilactide was determined to be 2.7, which corresponds to a log Pow of 0.4.

Since the partition coefficient is independent from stereochemistry, this can be directly extrapolated to LL-lactide by read-across.

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

Description of key information

The partition coefficient of LL-lactide (determined by read-across from dilactide) is log Pow = 0.4 based on the HPLC method (OECD 117).

Key value for chemical safety assessment

Log Kow (Log Pow):
0.4
at the temperature of:
25 °C

Additional information