Registration Dossier

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information

Appearance/physical state/colour:

The substance is an organic white powder at 20 ºC and 1013 hPa with no odour.

Melting point:

The melting temperature of the test material has been determined to be 266°C. NaDMH decomposed on melting according to EC Method A.1.

Boiling point:

As the test material has been determined to decompose on melting, no value for boiling temperature could be determined. The calculated value of boiling temperature is greater than 360°C (633 K).

Relative density:

The relative density of the test material has been determined to be 1.40 at 22.5 °C according to EC Method A.3.

Particle size distribution:

The substance will only be imported and used as a component of a liquid preparation. Therefore a particle size distribution study was not performed.

Vapour pressure:

The vapour pressure of NaDMH has been determined to be less than 1.4 x 10-4 Pa at 25°C according to EC Method A.4.

Partition coefficient:

A study according to EU Method A.8 was carried out. The partition coefficient of the test material has been determined to be 0.343 at 25°C, log Pow = -0.465.

Water solubility:

A standard EEC A6 Method was not applicable due to the extremely high water solubility of the substance (>10000 mg/L).

Surface tension:

Substances having a surface tension below 60 mN/m are regarded as being surface-acitve. The surface tension of a 1.13 g/L solution of NaDMH has been determined to be 60.9 mN/m at 24°C. The test material is considered not to be a surface-active material.

Flash point:

Flash point study is not applicable for solid substances therefore, a flammability study was performed.

Auto-ignition temperature:

The auto-ignition temperature of the test item was determined according to EU Method A.16. The test material has been determined not to have a relative self-ignition temperature below its melting temperature (>266°C).


NaDMH has been determined to be not highly flammable as it did not propagate combustion over the 200 mm of the preliminary screening test.

Explosiveness / Oxidising properties:

There are no chemical groups present that would imply explosive or oxidising properties therefore the result has been predicted negative.

Stability in organic solvents:

The stability in organic solvents is only required if stability of the substance is considered to be critical. The stability test in organic solvents is not considered to be critical for NaDMH as it is produced as aqueous solution and has been isolated only for testing/notification purposes.

Dissociation constant:

For the dissociation constant a result of 9.19 pKa was determined for the read-across substance 5,5-dimethylhydantoin (DMH) from e.m.f measurements on the cell H2/Acid-base solution/saturated KCl/HgCl/Hg.


NaDMH is a solid therefore the viscosity study is not applicable.