Registration Dossier
Registration Dossier
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EC number: 404-370-8 | CAS number: 126990-35-0 DCPMS; DYNASYLAN 9415; EURENOR 5023; SAN-30; WACKER SILAN CP2-DIMETHOXY; Z-6228
Endpoint summary
Administrative data
Description of key information
Dicyclopentyl(dimethoxy)silane, CAS 126990-35-0; EC No. 404-370-8 is a colourless liquid at ambient temperature and pressure, with a measured melting point of <-20°C at 1013 hPa and a measured boiling point of 260°C at 1013 hPa. The substance has a measured relative density of 0.984 at 20.5°C and a measured vapour pressure of 4 Pa at 20°C. The substance has a predicted log Kow of 5.5 at 20°C and a measured water solubility of 5.32 mg/L at 20°C. A 4.6 mg/L aqueous solution of dicyclopentyl(dimethoxy)silane had a measured surface tension of 72.4 mN/m at 20°C. Therefore, the substance is not surface active.
The substance is not classified for flammability on the basis of a measured flash point of 95-117°C at 1013 hPa (closed cup) and a measured boiling point of 260°C at 1013 hPa. The substance was not flammable in contact with water under the conditions of EU Test Method A.12 and also not pyrophoric under the conditions of EU Test Method A.13. It has a measured auto-ignition temperature of 228°C at 101.88-102.05 kPa. The substance was found not to be explosive under the conditions of EU Test Method A.14 and is not oxidising on the basis of chemical structure.
In contact with water, dicyclopentyl(dimethoxy)silane reacts moderately rapidly (half-life 19 hat pH 7 and 25°C) to produce dicyclopentylsilanediol, CAS 211495-85-1 and methanol (CAS 67-56-1; EC No. 200-659-6) according to the following equation:
(C5H9)2Si(OCH3)2 + 2H2O → (C5H9)2Si(OH)2 + 2CH3OH
In addition to the properties data for the parent, key physicochemical data for the hydrolysis products are presented.
Methanol is miscible with water, has low log Kow (-0.82 to -0.64) and high vapour pressure (12790 Pa at 20°C) (OECD 2004).
The saturation concentration in water of the silanol hydrolysis product, dicyclopentylsilanediol, is limited by condensation reactions to approximately 5 mg/L. However, it is soluble (calculated solubility is 2600 mg/L using a QSAR method) and has a predicted log Kow of 3.1. Dicyclopentylsilanediol is not surface active and is much less volatile than the parent substance with a predicted vapour pressure of 2.9E-4 Pa at 25°C. It is not expected to dissociate within relevant environmental pH range.
Reference:
OECD (2004). SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18 - 20 October 2004, Methanol, CAS 67-56-1
Additional information
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