Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Trimethoxyphenylsilane (CAS No. 2996 -92 -1) hydrolyses rapidly in contact with water (DT50 = 0.4 h, OECD 111) to phenylsilanetriol (CAS No. 3047 -74 -3) and methanol (CAS No. 67 -56 -1). The ECHA guidance R.16 states that “for substances where hydrolytic DT50 is less than 12 h, environmental effects are likely to be attributed to the hydrolysis product rather than to the parent itself” (ECHA, 2016). The ECHA guidance R.16 also suggests that in cases where the hydrolysis half-life is less than 12 h, the breakdown products, rather than the parent substance, should be evaluated for aquatic toxicity. Thus, the environmental fate assessment in this dossier is based on the hydrolysis products phenylsilanetriol and methanol.


Phenylsilanetriol is characterized by a high, estimated water solubility of 1.0E+06 mg/l at 20°C (QSAR) and a low potential for volatilization from water (Henry's Law Constant = 4.0 E-09 Pa m3mol-1at 12°C and estimated vapour pressure = 5.3E-05 Pa at 25°C). There is no evidence for any significant biodegradation. However, its potential for bioaccumulation and its affinity to soil and sediment is low based on its low log Kow (-0.021 at pH 7, OECD 107) and its estimated log Koc (1, QSAR), respectively.


The main target compartment of environmental methanol is air (73%) and water (16%) based on fugacity model calculations. Methanol is miscible with water at 20 °C, does not undergo hydrolysis and volatilization is not a significant removal process from the aquatic compartment (HLC = 0.461 Pa m3/mol, VP = 128 hPa). However, methanol is readily biodegradable and has a low potential for bioaccumulation (log Kow = -0.74). Its toxicity toward aquatic organisms is low, with acute toxicity values of well above 1000 mg/L. Overall, methanol is considered to have a low environmental hazard profile.

Source: OECD SIDS Initial Assessment Profile, SIAM, 2004