Registration Dossier

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information

The substance is manufactured and supplied as an aqueous solution. For the purposes of compliance, attempts were made to freeze dry a sample of the substance so that some of the applicable physico-chemical testing could be completed. NMR and IR were used to confirm that the freeze drying process had not degraded the substance immediately after drying. However, water solubility and partition coefficient, gave unexpected results. Further analytical work subsequently confirmed that the dry substance had degraded to some extent, forming the free amine. This reduced the reliability of studies performed using the freeze-dried substance, namely relative density, surface tension, water solubility, log Kow and flammability.

The substance is a highly hygroscopic white solid with a melting point expected to be in the range of 126 -136 °C, based on the melting points of the pure alkyl dimethylamine oxide (AO) constituents. Aliphatic amine oxides undergo thermal decomposition/Cope elimination between 110 -200 °C. The relative density of the substance is approximately 0.716. The vapour pressure is estimated to be between 1.6E-06 and 7.5E-05 Pa, based on the estimated vapour pressures of the individual AO constituents. The substance is surface active with a surface tension of 34.1 mN/m at 20ºC. The dissociation constant is 4.01. The substance is predicted to be non-explosive based on chemical structure and oxygen balance of the AO constituents and non-oxidising, based on chemical structure. The substance is non-flammable.

The log Kow is < 2.7. This value is considered to be conservative as it is based on the measured value for solubility in n-octanol and the CMC values for the C12 and C14 homologues. For comparison, a log Kow of -1.08 is derived from the measured n-octanol solubility of 33.9 g/L and the measured water solubility of 409.5 g/L.