Registration Dossier
Registration Dossier
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EC number: 252-161-3 | CAS number: 34708-08-2
Endpoint summary
Administrative data
Description of key information
Triethoxy(3-thiocyanatopropyl)silane, CAS 34708-08-2; EC No. 252-161-3, is a liquid at standard temperature and pressure, with a measured boiling point of 276°C at 1013 hPa. It has a measured relative density of 1.0317 at 20°C and a measured vapour pressure of < 100 Pa at 20°C.
The substance is not classified for flammability according to Regulation EC (No) 1272/2008 on the basis of a measured flash point of 105°C at 1013 hPa and a measured boiling point of 276°C at 1013 hPa. It has a measured auto-ignition temperature of 230°C at 998-1011 hPa and is not explosive and not oxidising on the basis of chemical structure.
In contact with water, triethoxy(3-thiocyanatopropyl)silane reacts moderately rapidly to form (3-thiocyanatopropyl)silanetriol and ethanol, CAS 64-17-5; EC No. 200-578-6 (half-lives: < 0.1 h at pH 4 and 20°C, 23 h at pH 7 and 25°C, 0.8 h at pH 9 and 25°C) according to the following equation:
N≡CSCH2CH2CH2Si(OCH2CH3)3 + 3H2O → N≡CSCH2CH2CH2Si(OH)3 + 3CH3CH2OH
Triethoxy(3-thiocyanatopropyl)silane has a predicted water solubility value of 140 mg/l at 20°C and a predicted log Kow of 3.1.
Due to the moderate hydrolysis of the registered substance in contact with water, the key physicochemical properties of the hydrolysis products are presented below.
Ethanol is miscible with water, has low log Kow (-0.3) and high vapour pressure (7910 Pa at 25°C).
The saturation concentration in water of the silanol hydrolysis product, (3-thiocyanatopropyl)silanetriol is limited by condensation reactions that can occur over time at loadings about 1000 mg/l. However, it is very hydrophilic (calculated solubility is 1.0E+06 mg/l at 20°C using a QSAR method) and has a low log Kow of -1.5 (predicted).
The silanol hydrolysis product is not expected to undergo significant dissociation within the environmentally-relevant range. The first dissociation constant of a structurally analogous silanetriol (phenylsilanetriol) has been reported to be around pKa of 10. (3-Thiocyanatopropyl)silanetriol is much less volatile than the parent substance with a predicted vapour pressure of 2.0E-06 Pa at 25°C and it is not surface active.
Additional information
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