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Moray S. Stark,* Max Smethurst and Alexandra Neal Department of Chemistry, University of York, York YO10 5DD, UK STLE 2006: Calgary 7 th - 11 th May 2006 Degradation of Methyl Ester Analogues of Vegetable Oils at Elevated Temperatures Department of Chemistry
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mss1@york.ac.uk www.york.ac.uk/res/gkg Moray S. Stark,* Max Smethurst and Alexandra Neal Department of Chemistry, University of York, York YO10 5DD, UK STLE 2006: Calgary 7 th - 11 th May 2006 Degradation of Methyl Ester Analogues of Vegetable Oils at Elevated Temperatures
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Degradation of Diesel Biofuels In the Sump In Fuel Lines During Storage Models of Degradation of Vegetable Oil Based Lubricants As Analogues for the Oxidation of Alkenes Formed by Aldol Condensation of Aldehydes Department of Chemistry Degradation of Methyl Ester Analogues of Vegetable Oils at Elevated Temperatures
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Oxidation of Methyl Esters Department of Chemistry Methyl Palmate (e.g. Palm Oil) (Methyl Hexadecanoate) Methyl Stearate (Methyl Octadecanoate) Methyl Oleate (e.g. Olive Oil) (methyl cis-9-octadecanoate) Methyl Linoleate (e.g. Soya Oil) (Methyl cis,cis-9,12-Octadecadienoate) Derived From Common Commercial Crop Oils
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Oxidation of Methyl Esters Department of Chemistry Derived From Common Commercial Crop Oils Methyl Palmate (e.g. Palm Oil) (Methyl Hexadecanoate) Methyl Stearate (Methyl Octadecanoate) Methyl Oleate (e.g. Olive Oil) (methyl cis-9-octadecanoate) Methyl Linoleate (e.g. Soya Oil) (Methyl cis,cis-9,12-Octadecadienoate)
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Bench-Top Reactors Department of Chemistry Oxidation Conditions Sealed Reactor Initial pressure: 1000 mbar O 2 Temperature: 130 ºC – 190 ºC Sampling: Throughout the reaction 10 sec – 10 hours
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Department of Chemistry Traditional Alkane Oxidation Mechanism
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Department of Chemistry Traditional Alkane Oxidation Mechanism
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Department of Chemistry Traditional Alkane Oxidation Mechanism
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Department of Chemistry Traditional Alkane Oxidation Mechanism
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Department of Chemistry Traditional Alkane Oxidation Mechanism
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Department of Chemistry Traditional Alkane Oxidation Mechanism H (C-H) 1 345 5 411 2 kJ mol -1 1: Handbook of Chemistry and Physics, pp9.64 – 9.72, Vol 86, CRC, 2005
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Department of Chemistry Traditional Alkane Oxidation Mechanism H (C-H) 1 345 5 411 2 kJ mol -1 1: Handbook of Chemistry and Physics, pp9.64 – 9.72, Vol 86, CRC, 2005
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Department of Chemistry Traditional Alkane Oxidation Mechanism 1: Handbook of Chemistry and Physics, pp9.64 – 9.72, Vol 86, CRC, 2005 H (C-H) 1 345 5 411 2 kJ mol -1
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Oxidation of Methyl Oleate : GC Analysis Department of Chemistry Oxidation Conditions: 170 ºC, 20 minutes GC conditions: ZB-5 column, 50-340 ºC, 6 ºC min -1 Product Identification: EI-MS and CI-MS Time (min)
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Oxidation of Methyl Oleate : GC Analysis Department of Chemistry Oxidation Conditions: 170 ºC, 20 minutes GC conditions: ZB-5 column, 50-340 ºC, 6 ºC min -1 Product Identification: EI-MS and CI-MS Time (min)
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Oxidation of Methyl Oleate : GC Analysis Department of Chemistry Oxidation Conditions: 170 ºC, 20 minutes GC conditions: ZB-5 column, 50-340 ºC, 6 ºC min -1 Product Identification: EI-MS and CI-MS Time (min) x 6
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Oxidation of Methyl Oleate : Epoxides Department of Chemistry Time (min)
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Oxidation of Methyl Oleate : Epoxides Department of Chemistry Oxidation Conditions: 170 ºC
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Department of Chemistry Epoxide Formation Mechanism C. B. Whitlock, J. Am. Oil Chem. Soc., 1976, 53, 586 M. S. Stark, J. Am. Chem. Soc. 2000, 122, 4162-4170 G. Lercker, et al., J. Chromatography A. 2003, 985, 333-342
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Department of Chemistry Epoxide Formation Mechanism C. B. Whitlock, J. Am. Oil Chem. Soc., 1976, 53, 586 M. S. Stark, J. Am. Chem. Soc. 2000, 122, 4162-4170 G. Lercker, et al., J. Chromatography A. 2003, 985, 333-342
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Department of Chemistry Epoxide Formation Mechanism C. B. Whitlock, J. Am. Oil Chem. Soc., 1976, 53, 586 M. S. Stark, J. Am. Chem. Soc. 2000, 122, 4162-4170 G. Lercker, et al., J. Chromatography A. 2003, 985, 333-342
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Department of Chemistry Epoxide Formation Mechanism C. B. Whitlock, J. Am. Oil Chem. Soc., 1976, 53, 586 M. S. Stark, J. Am. Chem. Soc. 2000, 122, 4162-4170 G. Lercker, et al., J. Chromatography A. 2003, 985, 333-342
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Department of Chemistry Epoxide Formation Mechanism C. B. Whitlock, J. Am. Oil Chem. Soc., 1976, 53, 586 M. S. Stark, J. Am. Chem. Soc. 2000, 122, 4162-4170 G. Lercker, et al., J. Chromatography A. 2003, 985, 333-342
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Department of Chemistry Epoxide Formation Mechanism C. B. Whitlock, J. Am. Oil Chem. Soc., 1976, 53, 586 M. S. Stark, J. Am. Chem. Soc. 2000, 122, 4162-4170 G. Lercker, et al., J. Chromatography A. 2003, 985, 333-342
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Department of Chemistry Reactions of Alkoxyl Radicals (e.g. 11-alkoxyl) C. B. Whitlock, J. Am. Oil Chem. Soc., 1976, 53, 586
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Department of Chemistry Reactions of Alkoxyl Radicals (e.g. 11-alkoxyl) C. B. Whitlock, J. Am. Oil Chem. Soc., 1976, 53, 586
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Oxidation of Methyl Oleate : Ketones and Alcohols Department of Chemistry Time (min) e.g.
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Oxidation of Methyl Oleate : Alcohols and Ketones Department of Chemistry Oxidation Conditions: 170 ºC e.g.
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Department of Chemistry Reactions of Alkoxyl Radicals (e.g. 11-alkoxyl) C. B. Whitlock, J. Am. Oil Chem. Soc., 1976, 53, 586 Methyl-11-oxoundec-9-enoateHeptyl radical
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Department of Chemistry Reactions of Alkoxyl Radicals (e.g. 11-alkoxyl) C. B. Whitlock, J. Am. Oil Chem. Soc., 1976, 53, 586 Heptanal Methyl-11-oxoundec-9-enoate Heptane
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Oxidation of Methyl Oleate : Alkoxyl Fragmentation Department of Chemistry Time (min) Heptanal Methyl-11-oxoundec-9-enoate Heptane
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Oxidation of Methyl Oleate : Volatile Products Department of Chemistry Oxidation Conditions: 170 ºC
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Department of Chemistry Formation of Alkoxyl Radicals E. N. Frankel, W. E. Neff, W. K. Rohwedder, Lipids, 1977, 12, 901-907 E. N. Frankel, et al., J. C. S. Perkin Trans. I, 1984, 2233
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Department of Chemistry Formation of Alkoxyl Radicals E. N. Frankel, W. E. Neff, W. K. Rohwedder, Lipids, 1977, 12, 901-907 E. N. Frankel, et al., J. C. S. Perkin Trans. I, 1984, 2233
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Department of Chemistry Formation of Alkoxyl Radicals E. N. Frankel, W. E. Neff, W. K. Rohwedder, Lipids, 1977, 12, 901-907 E. N. Frankel, et al., J. C. S. Perkin Trans. I, 1984, 2233
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Department of Chemistry Formation of Alkoxyl Radicals E. N. Frankel, W. E. Neff, W. K. Rohwedder, Lipids, 1977, 12, 901-907 E. N. Frankel, et al., J. C. S. Perkin Trans. I, 1984, 2233
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Department of Chemistry Formation of Alkoxyl Radicals E. N. Frankel, W. E. Neff, W. K. Rohwedder, Lipids, 1977, 12, 901-907 E. N. Frankel, et al., J. C. S. Perkin Trans. I, 1984, 2233
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Department of Chemistry Formation of Alkoxyl Radicals E. N. Frankel, W. E. Neff, W. K. Rohwedder, Lipids, 1977, 12, 901-907 E. N. Frankel, et al., J. C. S. Perkin Trans. I, 1984, 2233
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Oxidation of Methyl Oleate : Alkoxyl Fragmentation Department of Chemistry Time (min)
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Oxidation of Methyl Oleate : Dehydrodimers Department of Chemistry Time (min) e.g.
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Oxidation of Methyl Oleate : Dehydrodimers Department of Chemistry Time (min)
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Oxidation of Methyl Oleate : Polymeric Products Department of Chemistry Oxidation Conditions: 170 ºC e.g.
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Simulation of Methyl Oleate Oxidation Department of Chemistry Chemical Mechanism Based on 2-Butene Oxidation
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Simulation of Methyl Oleate Oxidation Department of Chemistry MeO + O2 => allyl + HO2 allyl + O2 => allylO2 allylO2 + MeO => allylO2H + allyl allylO2H => allylO + OH allylO2 + MeO => tepox + allylO allylO2 + MeO => cepox + allylO allylO + O2 => allylket + HO2 allylO + MeO => allylOH + allyl allyl + allyl => dimer allylO2 + allylO2 => allylO + allylO + O2 allylO2 + allylO2 => allylket + allylOH + O2 HO2 + MeO => tepox + OH HO2 + MeO => cepox + OH HO2 + MeO => allyl + H2O2 OH + MeO => H2O + allyl allylO => ald1 + alkyl alkyl + MeO => alkane + allyl alkyl + O2 => alkylO2 alkylO2 + MeO => tepox + alkylO alkylO2 + MeO => cepox + alkylO alkylO + O2 => ald2 + HO2 Chemical Mechanism Based on 2-Butene Oxidation 24 reactions 22 species (7 products)
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Simulation of Methyl Oleate Oxidation : Epoxides Department of Chemistry Oxidation Conditions: 170 ºC
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Simulation of Methyl Oleate Oxidation : Epoxides Department of Chemistry Oxidation Conditions: 170 ºC
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Simulation of Oxidation : Alcohols and Ketones Department of Chemistry Oxidation Conditions: 170 ºC e.g.
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Simulation of Oxidation : Alcohols and Ketones Department of Chemistry Oxidation Conditions: 170 ºC e.g.
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Conclusions Time Development of Oxidation Products Measured Epoxides of Dominant Products Epoxidation Dominant Fate of Peroxyl Radicals Fragmentation of Alkoxyl Radicals Also Significant Many Alkane Products Formed, Even in Presence of O 2 Chemical Kinetics Model of Oxidation Developed Department of Chemistry
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Future Work Link Viscosity Change to Product Formation Study Polymeric Products by HPLC-GPC Complete Computer Simulation of Oxidation Acknowledgements Trevor Dransfield (University of York) for GC-MS Moray Stark mss1@york.ac.uk www.york.ac.uk/res/gkg
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Degradation of Methyl Ester Analogues of Vegetable Oils at Elevated Temperatures (Abstract for STLE 2006: Calgary 7th- 11th May 2006) Degradation of Methyl Ester Analogues of Vegetable Oils at Elevated Temperatures (Abstract for Talk for STLE Annual Conference, Calgary, May 2006) Moray S. Stark* and Alexandra Neal Department of Chemistry, University of York, York YO10 5DD, UK There is great interest in the development of lubricants derived from vegetable oils, as these have the potential to have many benefits in terms of biodegradability, sustainability and performance. However, the functional groups of vegetable oil derived lubricants that give them their biodegradability can also allow them to degrade during actual use, via radical oxidation mechanisms. To try to aid our understanding of the limits of vegetable oil derived lubricants, the oxidation of methyl ester analogues of vegetable oils (methyl stearate, oleate and linoleate) at elevated temperatures (110 -150ºC) has been examined experimentally using GC-MS, and their relative rates of oxidation established. The oxidation products formed have also been identified, with chemical mechanisms suggested to account for the observed products, analogous to mechanisms previously proposed for low temperature oxidation of vegetable oils or high (combustion) temperature mechanisms of alkene oxidation. * Biography for Presenting Author The presenting author has a BSc and PhD in Physics, but has been working as a Chemist for longer than he can remember. The past few years have been spent specialising in the study of the oxidation mechanisms of hydrocarbon and ester lubricant base fluids and the effects that oxidation has on the rheology of lubricants.
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