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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Water solubility

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water solubility
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Principles of method if other than guideline:
No information is given
Type of method:
other: No data
Water solubility:
690 g/L
20 °C
Remarks on result:
other: Very soluble in water (69% at 20°C)

No other information is given.

The substance is very soluble in water as described from a handbook which has been subject to peer-review and in which the original data sources are traceable.

Description of key information

Water solubility: Commercially available HEDP-H in the form of aqueous solution products at typically 58 -62% w/w are miscible in water.

Key value for chemical safety assessment

Water solubility:
690 g/L
at the temperature of:
20 °C

Additional information

In support of the Key data, it is notable that in general, phosphonate salts are highly hydrophilic and extremely water soluble. Free acids are less soluble than the salts; however, aqueous solutions in excess of 1% active acid material can be prepared.

The parent acid (HEDP-H) substance was reported as very soluble in water with a concentration of 69% at 20°C but it is not clear from the source report whether this is expressed as %w/w, %v/v or %w/v. Since the solution density is much higher than 1, the equivalent water solubility in g/L using density and concentration is reported as ≥690 g/L. In addition, as the value is known to be extremely high, the exact value is considered not significant for the chemical safety assessment for human health or environment and this limit value is therefore sufficient and is considered to be reliable.


In available secondary sources to which reliability could not be assigned, water solubility values of 680 g/L at 25°C, 720 g/L at 20°C, ≥830 g/L and ≥820 g/L were obtained for HEDP-H.