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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Administrative data

Hazard for aquatic organisms

Hazard for air

Hazard for terrestrial organisms

Hazard for predators

Additional information

Conclusion on classification

The registered substance, 1-(tert-butyldimethylsilyl)piperazine (CAS No. 138938-64-4) hydrolyses very rapidly in contact with water to form tert-butyldimethylsilanol (CAS No. 18173-64-3) and piperazine.

REACH guidance (ECHA 2016, R.7b and R.16) states that "when the hydrolysis half-life is less than 12 hours, the breakdown products, rather than the parent substance, should be evaluated for aquatic toxicity". Therefore, the environmental hazard assessment is based on the properties of the silanol hydrolysis product, in accordance with REACH guidance.

The registrant holds data for the hydrolysis product, tert-butyldimethylsilanol (CAS No. 18173-64-3), which has reliable short-term E(L)C50 values of > 100 mg/l for fish, of 6.49 mg/l for Daphnia magna and of 84.0 mg/l for algae and is not expected to be significantly degradable.

Therefore these data are consistent with the following classification under Regulation (EC) No. 1272/2008 (as amended) (CLP):

Acute toxicity: Not classified.

Chronic toxicity: Category Chronic 2.

The non-silanol hydrolysis product, piperazine (CAS No. 110-85-0), has the following harmonised classification and labelling under Regulation (EC) No 1272/2008 (as amended) (CLP):

Acute toxicity: Not classified.

Chronic toxicity: Not classified.