Sodium 4-vinylbenzenesulphonate

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

Study period:

2014/10/03 - 2014/10/16

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Reason / purpose for cross-reference:

reference to other study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

GLP compliance:

no

Type of method:

thermal analysis

Key result

Decomposition:

yes

Decomp. temp.:

> 431 - < 436.8 °C

Under Air

From R.T. to 100 °C

Sample weight was reduced by 6.4 wt% and endothermic peak was observed at 67 °C.   This observation seems to be due to loss of crystal water from the sample.

From 100 °C to 267 °C

Sample weight was increased by 2.7 wt% and exothermic peak was observed at 267 °C. This seems to be due to weight gain by oxidation of the substance.

From 267 °C to 654 °C

Sample weight was reduced by 67 wt% and exothermic peaks were observed at 441 °C, 571 °C and exothermic band was observed between 620 °C and 653 °C.

These weight losses seemed to be due to decomposition and/or combustion of the test substance.

The deformation of the TG and DTA curves were due to tentative temperature increase of test substance.

 

Under Nitrogen

From R.T to 100 °C 

The test sample weight was reduced by 5.3 wt% and endothermic peak was observed at 67 °C

This seemed to be due to elimination of crystal water in the test sample.

Exothermic peaks at 304 and 333 °C.

These peaks were due to phase transformation of the test substance because the change of the test substance weight was not observed.

From 400 °C to 800 °C

The test sample weight was reduced by 35.2 wt% and endothermic peak was observed at 437 °C.

This weight loss seemed to be due to decomposition of the test substance.

 

NaSS seemed to decompose above 270 °C under air and decompose above 400 °C under nitrogen atmosphere. 

Conclusions:

Sodium p-styrenesulfonate neither melt nor decomposed until 300 °C.

Executive summary:

The thermal behavior of sodium p-styrenesulfonate was investigated with TG-TDA measurement.

Measurement under nitrogen, endothermic absorption observed around 100 °C seemed to be due to water loss and exothermic peak observed around 330 ° C seemed to be due to polymerization of the test substance.

In the air, thermal behavior of the test sample was very complex, After loss of water around 100 °C, the weight of the test sample was decreased very slowly. At the 570 °C, clear exothermal peak, which might be assumed to be due to combusion, was observed.

Description of key information

The melting point of this substance was measured with TG-DTA method. This substance did not melt but only decomposed at from 431.0 degree Celsius to 436.8 degree Celsius under nitrogen atomosphere.

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

436 °C

Additional information

The decomposition temperature was measured by registrant under ISO 9001 with TG-DTA method under nitrogen atomosphere.

The melting point was reported in a literature, but measuring method was not known.

So, the data presented by registrant was adopted as decomposition temperature of Sodium p-vinylbenzenesulphonate.