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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Melting point / freezing point

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Administrative data

Link to relevant study record(s)

Description of key information

The HYDROTOPES Category comprises the following 6 substances:
STS - Sodium toluene 4-sulphonate (CAS 657-84-1, EC 211-522-5)
SXS - Sodium (xylenes and 4-ethylbenzene) sulphonate (EC 701-037-1)
NH4XS - Ammonium (xylenes and 4-ethylbenzene) sulphonate (EC 943-024-5)
SCS - Sodium p-cumenesulphonate (CAS 15763-76-5, EC 239-854-6)
KCS - Potassium p-cumenesulphonate (CAS 164524-02-1, EC 629-764-9)
NH4CS - Ammonium p-cumenesulphonate (CAS 680972-33-2, EC 811-484-5) 

The substances have the following melting point:

STS > 400 °C

SXS > 300 °C

NH4XS = 198 °C (Estimated)

SCS = 350 °C

KCS = 400 °C

NH4CS = 315 °C

For sake of completeness, the estimated melting point for the other Hydrotropes substances are:

STS = 228 °C

SXS = 233 °C

SCS = 236 °C

KCS = 236 °C

NH4CS = 200 °C

It needs to be considered that the hydrotropes experimental melting point values are higher than the estimated ones and it seems reasonable to consider the value of 300 °C as the key value for the chemical safety assessment.

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:
300 °C

Additional information

The minimun value resulting from an experimental test was taken for the risk assessment.