Registration Dossier
Registration Dossier
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EC number: 208-904-9 | CAS number: 546-56-5
Hydrolysis
Administrative data
Link to relevant study record(s)
- Endpoint:
- hydrolysis
- Data waiving:
- study technically not feasible
- Justification for data waiving:
- the study does not need to be conducted because the substance is highly insoluble in water
Reference
Description of key information
Hydrolysis: endpoint waived due to the substance being very highly insoluble in water.
Key value for chemical safety assessment
Additional information
The requirement to conduct a hydrolysis study was waived in accordance with Column 2 of REACH Annex VIII because the substance is highly insoluble in water. Octaphenylcyclotetrasiloxane has a predicted water solubility value of <1E-05 mg/l at 20°C.
Cyclic siloxanes such as octaphenylcyclotetrasiloxane can undergo hydrolysis reactions in water, resulting in breaking of the Si-O bonds. The first step is ring-opening to give a linear siloxanediol (octaphenyltetrasiloxanediol for the present substance). This intermediate then undergoes chain-shortening reactions to give the final silanediol product. For octaphenylcyclotetrasiloxane, the overall reaction is as follows:
[-Si(C6H5)2O-]4+ 4H2O → 4(C6H5)2Si(OH)2
The final product is diphenylsilanediol.
However, due to the extremely low water solubility of the substance, hydrolysis is not expected to be a significant removal process.
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