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Physical & Chemical properties

Water solubility

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Reference
Endpoint:
water solubility
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the substance is hydrolytically unstable at pH 4, 7 and 9 (half-life less than 12 hours)

Description of key information

Water Solubility [ 1,1-dimethyl-N,N'-bis(1-methylpropyl)silanediamine]: not relevant

Water Solubility [dimethylsilanediol]: Above approximately 1000 mg/L condensation reactions can occur over time, limiting the concentration dissolved in water. The calculated solubility is 1.0E+06 mg/l (QSAR).

Water solubility [sec-butylamine]: 1.1E+05 mg/L at 20°C

Key value for chemical safety assessment

Additional information

The requirement to conduct a water solubility study for the substance is waived because in contact with water, the substance hydrolyses very rapidly to form dimethylsilanediol (CAS No. 1066-42-8) and sec-butylamine (CAS No. 13952-84-6).

The hydrolysis product, dimethylsilanediol, may undergo condensation reactions in water; these become important above approximately 1000 mg/l and can limit the concentration dissolved in water. For details, see the overall physicochemical properties discussion.

Dimethylsilanediol is very hydrophilic and hence the calculated solubility is 1E+06 mg/l at 20°C using a QSAR method. However, the saturation concentration of dimethylsilanediol in water is limited by condensation reactions rather than lack of true solubility as discussed above. A prediction of 1E+06 mg/l is indicative but has no practical meaning. The prediction is however considered valid for use in toxicokinetics modelling because it is considered to adequately describe the hydrophilicity of the substance and hence the partitioning behaviour.

Sec-butylamine has a reported water solubility of 1.1E+05 mg/L at 20°C (Yalkowsky 1992).

Reference:

Yalkowsky SH, Dannenfelser RM (1992). The AQUASOL dATAbASE of Aqueous Solubility. Fifth Ed, Tucson, AZ: Univ Az, College of Pharmacy