Degradation of Ester Lubricants

1. Degradation of Ester Lubricants John R. Lindsay Smith, Edward D. Pritchard, Moray S. Stark,* David J. Waddington Department of Chemistry, University of York York, YO10 5DD, UK Department of Chemistry

2. Degradation of Ester Lubricants Part 2: The Oxidation of Polyol Esters John R. Lindsay Smith, Edward D. Pritchard, Moray S. Stark,* David J. Waddington Department of Chemistry, University of York York, YO10 5DD, UK mss1@york.ac.uk www.york.ac.uk/res/gkg

3. Trimethylolpropane (TMP) Esters lubricant base fluid : TMP tridodecanoate Department of Chemistry

4. Trimethylolpropane (TMP) Esters lubricant base fluid : TMP tridodecanoate Model Compounds neopentyl hexanoate Department of Chemistry

5. Trimethylolpropane (TMP) Esters lubricant base fluid : TMP tridodecanoate Model Compounds neopentylglycol dibutanoate

6. Trimethylolpropane (TMP) Esters lubricant base fluid : TMP tridodecanoate Model Compounds TMP tributanoate neopentylglycol dibutanoate

7. Trimethylolpropane (TMP) Esters lubricant base fluid : TMP tridodecanoate Model Compounds TMP tributanoate neopentylglycol dibutanoate TMP trihexanoate

8. Oxidation of Ester Lubricants Reactor Steel : BS 316 PTFE Stirrer Conditions 160 ºC 0.5 cm3 lubricant 4.4 cm3, 5 barA Oxygen Department of Chemistry

9. Trimethylolpropane (TMP) Esters lubricant base fluid : TMP tridodecanoate Model Compounds TMP tributanoate neopentylglycol dibutanoate TMP trihexanoate

10. Oxidation of Neopentylglycol Dibutanoate : GC Trace GC: Supelcowax, 30 m, 0.25 mm ID, 0.25 m,FID time (min)

11. Oxidation of NPG Dibutanoate : Main Products time (min)

12. Oxidation of NPG Dibutanoate : Diol Formation time (min)

13. Oxidation of NPG Dibutanoate : Hydroxyesters time (min)

14. Oxidation of NPG Dibutanoate : Esters of Hydroxyesters time (min)

15. Oxidation of NPG Dibutanoate : α,β-Unsaturated Ester time (min)

16. Formation of α,β-Unsaturated Ester Department of Chemistry

17. Formation of α,β-Unsaturated Ester Department of Chemistry

18. Formation of α,β-Unsaturated Ester Department of Chemistry

19. Oxidation of NPG Dibutanoate : Cyclic Acetal time (min)

20. Formation of Cyclic Acetals Department of Chemistry

21. Formation of Cyclic Acetals Department of Chemistry

22. Formation of Cyclic Acetals Department of Chemistry

23. Trimethylolpropane (TMP) Esters lubricant base fluid : TMP tridodecanoate Model Compounds TMP tributanoate neopentylglycol dibutanoate TMP trihexanoate

24. Oxidation of TMP Tributanoate : GC Trace

25. Oxidation of TMP Tributanoate : Main Products Butanoic acid TMP Dibutanoate

26. Oxidation of TMP Tributanoate : Transesterification TMP Dibutanoate monoethanoate TMP Dibutanoate monomethanoate eg. methyl butanoate TMP Dibutanoate monopropanoate

27. Oxidation of TMP Tributanoate : Oxidation Products

28. Oxidation of TMP Tributanoate : Cyclic Acetal

29. Main Products of TMP Tributanoate Oxidation Department of Chemistry

30. Main Products of TMP Tributanoate Oxidation Department of Chemistry

31. Transesterification Products

32. Transesterification Products : II Department of Chemistry

33. Possible Hydrolysis of TMP Tributanoate? Department of Chemistry

34. Water Content During Autoxidation Department of Chemistry

35. Water Content During Autoxidation Department of Chemistry

36. TMP Tributanoate Oxidation : Viscosity Increase

37. Viscosity Increase : Correlation with TMP Dibutanoate

38. Viscosity Increase : Correlation with TMP Dibutanoate

39. Formation of High Molecular Weight Species mass 430 458 516 530 544 610 630 mass : 344 Department of Chemistry

40. Formation of High Molecular Weight Species : II oxidation oxidation (+ O2 - O) (+ RH) radical attack mass : 344 esterification + (-H2O) mass : 430

41. Formation of High Molecular Weight Species : III oxidation cleavage (+ O2 - O) mass : 344 radical attack + + mass : 458

42. Formation of High Molecular Weight Species : IV oxidation oxidation radical attack mass : 344 esterification + (-H2O) mass : 544

43. Trimethylolpropane (TMP) Esters lubricant base fluid : TMP tridodecanoate Model Compounds TMP tributanoate neopentylglycol dibutanoate TMP trihexanoate

44. TMP Trihexanoate vs. TMP Tributanoate Oxidation

45. TMP Trihexanoate vs. TMP Tributanoate Oxidation

46. Conclusions : Main Oxidation Mechanisms of Polyol Esters Department of Chemistry

47. Conclusions : Main Oxidation Mechanisms of Polyol Esters • Polyol Esters can decompose to the Diol and form Cyclic Acetals Department of Chemistry

48. Conclusions : Main Oxidation Mechanisms of Polyol Esters • Polyol Esters can decompose to the Diol and form Cyclic Acetals • Triol Ester decomposition dominated by Hydrolysis- Transesterification Department of Chemistry

49. Conclusions : Main Oxidation Mechanisms of Polyol Esters • Polyol Esters can decompose to the Diol and form Cyclic Acetals • Triol Ester decomposition dominated by Hydrolysis- Transesterification • High molecular weight species formed by esterification of alcohol oxidation products Department of Chemistry

50. Conclusions : Main Oxidation Mechanisms of Polyol Esters • Polyol Esters can decompose to the Diol and form Cyclic Acetals • Triol Ester decomposition dominated by Hydrolysis- Transesterification • High molecular weight species formed by esterification of alcohol oxidation products Acknowledgements Peter Smith andCastrol Department of Chemistry