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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Trimethoxy(propyl)silane (CAS No. 1067-25-0) has a low predicted log Kow of 1.7. Furthermore, it hydrolyses rapidly in contact with water (DT50 = 2.6 h) to the silanol hydrolysis product propylsilanetriol and the alcohol hydrolysis product 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 TGD (EC2003) and ECHA guidance R.16 (ECHA 2010) also suggests that in case 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 propylsilanetriol and methanol rather than the parent substance.

Both hydrolysis products have low log Kow values indicating a low potential for bioaccumulation (propylsilanetriol: -1.4 (QSAR), methanol: --0.82 to -0.64, OECD SIDS, 2004). Therefore, in accordance with Annex IX, 9.3.2., Column 2 no study needs to be conducted since the log Kow is well below 3 and bioaccumulation is not expected.



OECD SIDS, 2004. Methanol - SIDS Initial Assessment Report For SIAM 19, Berlin, Germany: UNEP Publications.