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Environmental fate & pathways

Hydrolysis

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Description of key information

Information from non-guideline experiments and from surrogate substances is available, which in a weight-of-evidence evaluation shows rapid hydrolysis of the submission to TTP and further to p-cresol. 

Key value for chemical safety assessment

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

Additional information

No OECD 111 Guideline study could be performed since it was technically not possible to establish a suitable analytical method.

But additional information from non-guideline experiments and from surrogate substances is available:

-       Investigations with NiL4 on its stability in water/THF:

Analytical results from laboratory tests applying semi-quantitative HPLC show that NiL4 is essentially insoluble in pure water and degrades slowly at room temperature. When dissolved in a THF/water solution, NiL4 decomposes within several hours to give free TTP ligand, TTP hydrolysis products, cresol and Ni metal. The decomposition of NiL4 is accelerated in the presence of an acid or a base

-       Evaluation of the EU TC NES Subgroup on PBT / vPvB substances:

1. Diisodecyl phenyl phosphite: This substance is closely related to the ligand of the NiL4 complex, tritolyl phosphite (TTP). An OECD 111 study is reported in the TC NES report, on which basis the TC NES Subgroup concluded that the substance is hydrolysed rapidly and should not be considered persistent.

2. Triphenyl phosphite (TPP): In the same report results from a hydrolysis study on TPP, which is also closely related to TTP, are evaluated. Based on these results the TC NES Subgroup concluded that TPP is hydrolytically unstable and should not be considered persistent.

-       Investigations on stability of NiL4 in acetonitril/water

In experiments undertaken to establish an analytical method for NiL4, the substance was detected with UPLC in acetonitril/water. The peak related to NiL4 decreased by 99% within 13 hours.

Taking into consideration this information in a weight-of-evidence evaluation it can be concluded that rapid hydrolysis of the submission substance occurs in aquatic environments at ambient temperature. Main hydrolysis products are assumedto be TTP, which (via phosphites containing one or two organic residues) is further degraded to p-cresol. Based on results available from studies at pH 2, 7, or 11 in water/THF half-lifes of less than 18 hours are expected.