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Environmental fate & pathways

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Hydrolysis


The half-life of the major constituent Structure A at 25°C was determined to be 24.2 days (pH 9), 102.4 days (pH 7) and 115.8 days (pH 4). It can be assumed that the transformation products of the test substance are further hydrolysed under separation of phenol. No data on the other constituents are available. But due to their butylation a lower water solubility is expected and therefore hydrolysis will be less probable.  


Stability during Use


During use as lubricant additive the constituent Structure A degrades to triphenyl phosphate which forms a multilayered solid film on the metal or metal oxide which will be further degraded. In a tribotesting study at 423K with poly-α olefin (PAO) it could be shown that the reaction products are pyrophosphate, organo-phosphate and sulfate species. This degradation is metal catalysed. Oxygenated compounds produced by the oxidation of the base oil adsorbed onto the iron surface and reacted with it to form carbonates and carboxylates (Mangolini et al. 2012; Mangolini et al. 2011; Johnson and Hils 2013). The same mechanism is assumed for the butylated constituents.


 


Mangolini F, Rossi A, Spencer ND. 2012. Tribochemistry of Triphenyl Phosphorothionate (TPPT) by in situ attenuated total reflection (ATR/FT-IR) tribometry. J Phys Chem 116: 5614-5627


Mangolini, F, Rossi A, Spencer ND. 2011. Influence of metallic and oxidized iron/steel on the reactivity of triphenyl phosphorothionate in oil solution. Tribol Int 44: 670–683


Johnson DW and Hils JE. 2013. Phosphate esters, thiophosphate esters and metal thiophosphates as lubricant additives. Lubricants 1(4): 132-148