Production of a Bicyclophosphate Neurotoxic Agent During Pyrolysis of Synthetic Lubricant Oil

Abstract

The formation of 4-ethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2.]octane-1-oxide ("trimethylolpropane phosphate"; "TMPP"; "EPTBO") from the thermal decomposition of a synthetic aircraft engine lubricant has been observed in yields ranging from 100 μg/g to over 9,000 μg/g oil. Although the exact composi tion of the oil studied is proprietary, two ingredients typically used in synthetic lubricants of this type, trimethylolpropane esters of carboxylic acids, and tricresylphosphate, are probable precursors. The production was a linear func tion of temperature over the range of 400 to 645 °C for one test system used, and showed a dramatic increase for a second set of pyrolysis conditions that in cluded higher pressure and longer heating time. Formation of decomposition products was rapid once decomposition temperatures were reached, with some TMPP production occurring within 2 minutes. The relative volatility of this syn thetic lubricant formulation compared with previously studied sources of TMPP (polyurethane foams) requires specific pyrolysis system modifications to carry out controlled decomposition studies. Worst-case conditions for decomposition and TMPP yield are discussed.