2,2'-oxybis[5,5-dimethyl-1,3,2-dioxaphosphorinane] 2,2'-disulphide

Hydrolysis

Description of key information

In a test on hydrolysis as a function of pH significant hydrolysis was only observed at pH 9 and elevated temperature of 50°C. Half-lives and rate constants determined at pH 9 and more moderate temperatures of 20 and 30 °C were not significantly non-zero. 

Key value for chemical safety assessment

Half-life for hydrolysis:

2.99 d

at the temperature of:

50 °C

Additional information

Hydrolysis as a function of pH was determined for the submission substance according to OECD Guideline No. 111 and Council Regulation (EC) No. 440/2008, Method C.7 for the test item (compliant to GLP, RL1).

In the preliminary test no significant elimination was observed at pH 4, from which a half-life of > 1 year could be assumed at this pH for environmental typical temperatures. Therefore, the advanced test was conducted at pH 7 and 9 but not pH 4. The advanced test was conducted with a test item concentration of 0.7 mg/L in buffer solutions at pH 7 and 9 and temperatures of 20, 30 and 50 °C, respectively. At the pH 7 / 50 °C test condition no degradation was observed after approx. 200 h, therefore the test item was considered as hydrolytically stable under these condition and a half-life of > 1 year could be assumed for environmental typical temperatures. Only at the test condition pH 9 / 50 °C significant hydrolysis of the test item was observed. At the other two test conditions (20 and 30 °C of the same pH value) the reaction rate constants and half-lives could not be securely determined by employing the methods of the test guidelines and should only be seen as estimation with a high degree of uncertainty.

The following pseudo first order half-lives for the pH 9 test condition were calculated from the analysed concentrations:

20°C: 166 days (not significantly non-zero); 30°C: 195 days (not significantly non-zero); 50°C: 2.99 days (significantly non-zero).

Because no hydrolysis could be observed at environmentally relelvant temperatures, in line with OECD 111 no identification of transformation products was performed.