Registration Dossier

Environmental fate & pathways

Hydrolysis

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

The results of key studies performed according to OECD Guideline 111 correspond to:
- Half-life (pH 4; 25°C) = 98 hours;
- Half-life (pH 7; 25°C)= 131.3 hours;
- Half-life (pH 8; 25°C) = 83 hours;
- Half-life (pH 9; 25°C) = 19.36 hours.

Key value for chemical safety assessment

Half-life for hydrolysis:
131.3 h
at the temperature of:
25 °C

Additional information

Four valid key studies are available to assess the hydrolysis potential of the substance as a function of pH. These studies were performed according to the OECD Guideline 111 with GLP statement.

The same preliminary test was performed for the four studies. In this preliminary test, the test substance was added into each buffer (pH 4, 7 and 9; de-oxygenated by bubbling nitrogen) as follow: 3.26 µL of test item were mixed with 1L of each buffer during 45 min under stirring. The solutions were then separated during 30 min. The upper parts were discarded and the solutions were transferred to 100 mL flasks. Two replicates were prepared for each buffer. All test vessels were incubated at 50 +/- 0.5 °C under stirring and kept protected from light during five days. The solutions were then analysed by Gas Chromatography (GC). GC results showed a decrease of the test substance with all buffers. Hydrolysis reached 90% within 5 days with formation of 2-ethylhexanol and probably t-butanol as degradation products. GC-MS allowed only the observation of 2-ethylhexanol, quantitatively for pH 9 and at lower levels for pH 7 and 4. t-Butanol, the other expected degradation product was not observed.

The definitive tests were performed at pH 4, 7, 8 and 9 (corresponding to the four key studies).

For this, a stock solution at 3 mg/L of the test substance was prepared into each buffer. All test vessels were incubated at 50, 37 and 15 °C. The solutions were then analysed along with time.

At pH 4 and 50°C, 93.7% hydrolysis was obtained after 25 hours. For the other temperatures, 98.7% of the test item was hydrolysed after 124 hours at 37°C and 62.5% after 32 days at 15°C.

At pH 7 and 50°C, 95% hydrolysis was obtained after 24 hours. For the other temperatures, 89.7% of the test item was hydrolyzed after 97.5 hours at 37°C and 60.8% after 33 days at 15°C.

At pH 8 and 50°C, 98% hydrolysis was obtained after 27 hours. For the other temperatures, 91.4% of the test item was hydrolyzed after 73 hours at 37°C and 72% after 30 days at 15°C.

At pH 9 and 50°C, 94% hydrolysis was obtained after 6 hours. For the other temperature, 97% of the test item was hydrolysed after 25 hours at 37°C and 73% after 124 hours at 15°C.

The results of these studies indicated pseudo-first order reaction kinetics. Therefore, the half-life time at 25°C was extrapolated from the results obtained at the 3 temperatures tested, for each pH, using Arrhenius equation.

The half-life times for the test substance as a function of pH are presented below:

- Half-life (pH 4; 25°C) = 98 hours;

- Half-life (pH 7; 25°C)= 131.3 hours;

- Half-life (pH 8; 25°C) = 83 hours;

- Half-life (pH 9; 25°C) = 19.36 hours.