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Environmental fate & pathways

Hydrolysis

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Description of key information

At 20°C the substance is hydrolytically unstable at pH 4, 7 and 9. It hydrolysed within minutes at pH 4 and 7, the calculated half-life time was 1.9 hours at pH 9.

Key value for chemical safety assessment

Half-life for hydrolysis:
1.9 h
at the temperature of:
20 °C

Additional information

Hydrolytic behavior of the substance was performed according to OECD Guidelines for Testing of Chemicals, Section 1 – Physical-Chemical Properties, OECD TG 111 (2004), Council Regulation (EC) No 440/2008, Guideline Part C – Methods for the Determination of Ecotoxicity, C.7. “Abiotic Degradation: Hydrolysis as a Function of pH” (adopted, May 2008).

Results of a preliminary water solubility and hydrolysis test showed that the substance is hydrolytically unstable at pH 4, pH 7 and pH 9 at room temperature.

At pH 4 and pH 7 rapid hydrolysis of the substance within a few minutes was observed. An exact determination of half-life time or hydrolysis rate was not possible and the half-life time is estimated to be < 10 min at pH 4 and < 1 hour at pH 7. Due to rapid hydrolysis, only tier 1 test were performed.

Degradation of the substance at pH 9 at 20°C was slowly enough to investigate the hydrolysis behaviour of the substance, including calculation of half-life time and hydrolysis rate.

Degradation was followed up to a decrease of test substance concentration of approx. 90% according to OECD TG 111. The stability of the substance was monitored by HPLC analysis using UV-detection. The HPLC chromatogram of the substance showed a partially resolved complex mixture corresponding to several main and minor components. The detectable peaks were integrated and evaluated as sum of main and minor components. Specificity of the method was checked by recording a HPLC-MS spectrum of the most intense HPLC peak was recorded at start of hydrolysis. The main signal can be assigned to one main component of the substance given by the idealized formula.

The degradation of the substance can be described by first order kinetics and a half-life time of 1.9 hours is obtained. Biotic degradation was not observed.

Determination of hydrolysis products was not possible, with the analytical method used to follow degradation of the parent substance. The substance is a reaction product with complex composition and is assessed as UVCB substance. It is assumed that hydrolysis of the substance results in a mixture of partially complex hydrolysis products, known as A) 2-ethyl-2-(hydroxymethyl)propane-1,3-diol, propoxylated, reaction product with methyl 3-oxobutanoate and B) 3-aminopropyldimethylamine.