Bisdecanoyl peroxide

Hydrolysis

Description of key information

Two key studies, OECD Guideline 111, GLP, validity 2:
- Half-life (pH 4; 37°C) = 559 hours = 23.3 days;
- Half-life (pH 7; 25°C)= 809 hours = 33.7 days;
- Half-life (pH 9; 25°C) = 772 hours = 32.2 days.

Key value for chemical safety assessment

Half-life for hydrolysis:

809 h

at the temperature of:

25 °C

Additional information

Two 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 two studies. In this preliminary test, the test substance was added into each buffer (pH 1.2, 4, 7 and 9) at 100 mg/L. In a first attempt, duplicate samples were filtered after 2 hours stirring for measuring initial concentrations. After 5 days at 50 °C, corresponding duplicate samples were also filtered and submitted to analysis. In a second simultaneous attempt, samples were not submitted to filtration. After 2 hours stirring duplicate samples were analysed in totality. After 5 days at 50 °C, corresponding duplicate samples were also submitted to analysis on the totality of the sample. Results of the first attempt using filtration did not allow to show if any hydrolysis occurred. Analytical results of the second attempt (samples without filtration) showed a decrease of test substance with all buffers.

The definitive tests were performed at pH 7 and 9 (corresponding to the first key study) and at pH 4 (corresponding to the second key study).

As water solubility of the test substance is very low (0.12 mg/L), it was decided to perform the definitive tests with an excess of test item and to follow apparition of decanoic acid in the different buffers at pH 4, 7 and 9. Decanoic acid showing a water solubility close to 150 mg/L, an estimation of half-lives of the test substance could be obtained from kinetics of its apparition. Initial amounts of 100 and 1000 mg/L of test item were used to observe comparatively the effect of the peroxide concentration. The solutions of test substance at 100 and 1000 mg/L were prepared in pH 4, 7 and 9 buffers. Respectively, 10 and 100 mg were added to 100 mL of the three buffers and placed at three temperatures: 50, 37 and 15 °C. Test vessels were entirely filled with test solutions and closed with butyl rubber caps. Samples were incubated and kept protected from light during the test.

For all the definitive tests, it was decided not to retain the results at 50°C where a thermic decomposition was probably interference with the hydrolysis reaction. For the experiments at pH 7 and 9, a mean of prepared solutions at 100 and 1000 mg/L was determined at 37 and 15°C to calculate the half-life times at 25°C using Arrhenius equation. However, for the experiment at pH 4, the results obtained at 15°C do not allow to calculate any half-life as the hydrolysis reaction was very slow. Therefore, for the experiment at pH 4, as no usable results were obtained both at 50 and 15°C, and as half-life result was only obtained at 37°C, it was not possible to calculate the value at 25°C using the Arrhenius-equation.

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

- Half-life (pH 4; 37°C) = 559 hours = 23.3 days;

- Half-life (pH 7; 25°C)= 809 hours = 33.7 days;

- Half-life (pH 9; 25°C) = 772 hours = 32.2 days.