Naphthenic acids, zinc salts

Melting point / freezing point

Link to relevant study record(s)

Reference

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Deviations:

no

GLP compliance:

yes

Type of method:

differential scanning calorimetry

Specific details on test material used for the study:

- Batch: A036/99 (Supplier batch number: SCC-1709-0300)
- Expiration date of the lot/batch: 31 August 2018
- Storage condition of test material: At room temperature, protected from light

Key result

Remarks on result:

not determinable

Remarks:

A glass transition was observed at -51.4°C (221.7K)

Preliminary test

Starting at 225°C, the weight of the sample decreased significantly. At 440°C, the sample weight had decreased by 25%. After the experiment, a brown/black residue was observed on the lid of the sample container and a brown/black molten residue remained in the sample container (original colour: brown). The change of the colour indicated reaction and/or decomposition of the test item.

         

Main test

During cooling, a glass transition was observed between -70°C and -40°C. During heating, aglass transition was observed between -75°C and -25°C. The inflection point of the glass transition was -50.922°C. An endothermic peak due to evaporation of volatile components was observed between 25°C and 125°C directly followed by a broad endothermic effect between 125°C and 300°C due to evaporation of components with a high boiling temperature. A next endothermic peak was observed starting at 350°C. The effect was due to reaction and/or decomposition of the test item. After the experiment, a brown molten residue remained in the sample container.

Experiment 2 was performed to obtain a duplicate value for the glass transition temperature. To investigate the endothermic peak between 25°C and 125°C, a repeated heating cycle was applied. Similar results as in Experiment 1 were obtained during the first cooling and first heating. With the first heating the inflection point of the glass transitionwas -51.839°C. During the second cooling, a glass transition between -75°C and -25°C was found. With the second heating, the inflection point of the glass transition was -50.537°C. This inflection point was not used for calculating the glass transition temperature, since as a result of first heating the composition of the test item might have been changed as was confirmed by the fact that no effect was observed between 25°C and 100°C, indicating that the volatile components had evaporated during first heating. After the experiment, a brown molten residue remained in the sample container.

Conclusion

The glass transition temperature was determined as the mean glass transition temperature of Experiment 1 (-50.922°C) and Experiment 2 (-51.839°C).

      

The melting and boiling temperature of Naphthenic acids, zinc saltswere tested by DSC. No melting point was determined. A glass transition ofthe test itemwas observed at -51.4°C (221.7K).

Conclusions:

The melting point of naphthenic acids, zinc salts could not be determined. A glass transition was determined at -51.4°C (221.7K).

Executive summary:

The melting point of naphthenic acids, zinc salts could not be determined in a GLP-compliant test, using differential scanning calorimetry, following OECD guideline 102 (CRL 2018). The study is considered relevant and reliable for use. The melting point of naphthenic acids, zinc salts could not be determined. A glass transition was determined at -51.4°C (221.7K).

Description of key information

The melting point of naphthenic acids, zinc salts could not be determined. A glass transition was determined at -51.4°C (221.7K).

Additional information

The melting point of naphthenic acids, zinc salts could not be determined in a GLP-compliant test, using differential scanning calorimetry, following OECD guideline 102 (CRL 2018). The study is considered relevant and reliable for use. The melting point of naphthenic acids, zinc salts could not be determined. A glass transition was determined at -51.4°C (221.7K).

Naphthenic acids, zinc salts is a UVCB consisting of a large number of different constituents. Melting point values have been predicted for representative structures within the UVCB. The melting points of the representative structures of zinc naphthenate were estimated using a QSAR model (MPBPVP v1.43 in EPISuite v4.11, US EPA 2010). The melting points of the representative structures for zinc naphthenate are estimated to be in the range of -20.85 - 149.83°C.