Disodium 3,3'-dithiobis[propanesulphonate]

Boiling point

Administrative data

Endpoint:

boiling point

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is a solid which decomposes before boiling

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
Decomposition: 288 - 313 °C (exp.), see IUCLID section 4.2.

Cross-reference

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 July - 16 August 2005 and 05 September - 17 October 2005

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

no guideline followed

Principles of method if other than guideline:

Investigations by differential scanning calorimetry (DSC) provide information on the thermal behavior of substances. Samples of the test substance and of a reference material are subjected to the same controlled temperature programme; they are heated in an oven at a constant heating rate, and the temperatur is measured in two containers. The difference in energy input necessary to maintain identical temperatures between the substance and the reference material is recorded. When the sample undergoes a phase transition, the corresponding change of enthalpy gives a departure form the base line of the heat flow record.
The DSC is mainly used as screening method for thermal stability analysis to determine the beginning of decomposition (onset temperature) and the heat of decomposition.

GLP compliance:

no

Type of method:

other: Differential scanning calorimetry (DSC)

Key result

Melting / freezing pt.:

>= 223 - <= 248 °C

Decomposition:

yes

Decomp. temp.:

>= 288 - <= 313 °C

Remarks on result:

other: No significant exothermic reaction up to 400°C; no information on pressure given.

No significant exothermic reaction up to 400°C. Temperature range of the endothermic event was 223 - 248 and 288 -313°C, as both melting and decomposition (i.e. phase transitions) result generally in an endothermic event at DSC, it can be reasonably concluded that the second event would be due to decomposition, not boiling.

The enthalpie measured for the events were 41/45 or 226 J/g, respectively.

Conclusions:

Melting range: 223 °C - 248 °C; decomposition: 288 - 313 °C

Executive summary:

The melting point of the test substance was determined by using differential scanning calorimetry (2005, non-GLP). No significant exothermic reaction up to 400°C was observed. The melting range of the test substance has been determined to be 223 - 313° C; there were two endothermic events at 223 - 248 °C and 288 -313°C. Both melting and decomposition (i.e. phase transitions) result generally in an endothermic event at DSC. Since there were two endothermic events measured, it can be reasonably concluded that the second event would be due to decomposition, not boiling (especially as boiling for salts is unlikely at these temperatures).