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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

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relative self-ignition temperature (solids)
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study scientifically not necessary / other information available
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Description of key information

Relative self-ignition temperature [HEDP-xK]: not relevant, no self-heating up to 400°C

Key value for chemical safety assessment

Additional information

In accordance with Column 2 of REACH Annex VII, the self-ignition properties study (required in Section 7.12) does not need to be conducted as the parent acid showed no evidence of self-heating up to 400°C.

HEDP-H has a measured melting point of >450°C (>723 K) at 1013 hPa using a differential scanning calorimetry (DSC) method. HEDP-xK is a member of the HEDP category, which is comprised of the acid form and any simple salts of the same acid.   The category hypothesis is that all the members are various ionised forms of the same parent acid. This category covers various sodium and potassium salts of 1-hydroxy-1,1-ethane-diphosphonic acid (HEDP). The different salts are prepared by neutralising the acid to a specific pH and accordingly the proportions of the constituents and their degree of ionisation are comparable between substances under similar conditions (in vivo and in the environment). All category members are based on the HEDP structure. Data are available for the acid form and some salts. HEDP-xK salt is marketed as neutralised aqueous solution.   The read-across is therefore based on the presence of common functional groups in both the acid and the salt. The main assumption is that sodium and potassium are not significant in respect of all the properties under consideration. The sodium and potassium salts are expected to decompose before boiling and have a high melting temperature.