The Oxidation of Polyol Esters
50
Degradation of Ester Lubricants Department of Chemistry John R. Lindsay Smith, Edward D. Pritchard, Moray S. Stark,* David J. Waddington Department of Chemistry, University of York York, YO10 5DD, UK
Transcript of The Oxidation of Polyol Esters
Degradation of Ester Lubricants
Department of Chemistry
John R. Lindsay Smith, Edward D. Pritchard, Moray S. Stark,* David J. Waddington
Department of Chemistry, University of York York, YO10 5DD, UK
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
[email protected] www.york.ac.uk/res/gkg
Trimethylolpropane (TMP) Esters
O
OO
O
O
O
lubricant base fluid : TMP tridodecanoate
Department of Chemistry
Trimethylolpropane (TMP) Esters
O
OO
O
O
O
lubricant base fluid : TMP tridodecanoate
Model Compounds
O
O
neopentyl hexanoate
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Trimethylolpropane (TMP) Esters
O
OO
O
O
O
lubricant base fluid : TMP tridodecanoate
neopentylglycol dibutanoate
O
O
O
O
Model Compounds
Trimethylolpropane (TMP) Esters
O
OO
O
O
O
lubricant base fluid : TMP tridodecanoate
O
OO
O
O
O
neopentylglycol dibutanoate
O
O
O
O
TMP tributanoate
Model Compounds
Trimethylolpropane (TMP) Esters
O
OO
O
O
O
lubricant base fluid : TMP tridodecanoate
O
OO
O
O
OO
OO
O
O
O
neopentylglycol dibutanoate TMP trihexanoate
O
O
O
O
TMP tributanoate
Model Compounds
Oxidation of Ester Lubricants
ReactorSteel : BS 316PTFE Stirrer
Conditions160 ºC0.5 cm3 lubricant4.4 cm3, 5 barA Oxygen
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Trimethylolpropane (TMP) Esters
O
OO
O
O
O
lubricant base fluid : TMP tridodecanoate
O
OO
O
O
OO
OO
O
O
O
neopentylglycol dibutanoate TMP trihexanoate
O
O
O
O
TMP tributanoate
Model Compounds
Oxidation of Neopentylglycol Dibutanoate : GC Trace
O
O
O
O
time (min)
GC: Supelcowax, 30 m, 0.25 mm ID, 0.25 m,FID
time (min)
O
OH
O
OH
O
Oxidation of NPG Dibutanoate : Main Products
time (min)
O
OH
O
OH
O
OH
OH
Oxidation of NPG Dibutanoate : Diol Formation
Oxidation of NPG Dibutanoate : Hydroxyesters
time (min)
O
O
O
O
OH
O
O
O
O
O
O
O
O OH
Oxidation of NPG Dibutanoate : Esters of Hydroxyesters
time (min)
O
O
O
O
O
OO
O
O
O
O
O
Oxidation of NPG Dibutanoate : α,β-Unsaturated Ester
time (min)
O
O
O
O
O
O
O
O
O
O
O
O
O
O
Formation of α,β-Unsaturated Ester
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Formation of α,β-Unsaturated Ester
O
O H
O
O
O O
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Formation of α,β-Unsaturated Ester
O
O H
O
O
O O
O
O
O
O
O
O
H+
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Oxidation of NPG Dibutanoate : Cyclic Acetal
time (min)
O
O
H
H
Formation of Cyclic Acetals
OH
OH
H H
O
..
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Formation of Cyclic Acetals
OH
OH
H H
O
..H
OH2+
OH
OH..
+ H+
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Formation of Cyclic Acetals
OH
OH
H H
O
..H
OH2+
OH
OH..
+ H+
O
O H
H
- H2O - H+
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Trimethylolpropane (TMP) Esters
O
OO
O
O
O
lubricant base fluid : TMP tridodecanoate
O
OO
O
O
OO
OO
O
O
O
neopentylglycol dibutanoate TMP trihexanoate
O
O
O
O
TMP tributanoate
Model Compounds
Oxidation of TMP Tributanoate : GC Trace
O
OO
O
O
O
Oxidation of TMP Tributanoate : Main Products
OH
O
O
OO
OH
O
O
OO
O
O
O
Butanoic acid
TMP Dibutanoate
Oxidation of TMP Tributanoate : Transesterification
O
O
R' O
OO
O
O
O
O
OO
O
O
O
O
OO
O
O
O
H
TMP Dibutanoate monomethanoate
TMP Dibutanoate monoethanoate
TMP Dibutanoate monopropanoate
eg. methyl butanoate
Oxidation of TMP Tributanoate : Oxidation Products
OO
OO
O
O
O
O
O
O
O
O
O
O
O
Oxidation of TMP Tributanoate : Cyclic Acetal
O
O
O
H
H
O
0
0.5
1
1.5
0 5 10 15
time (hours)
conc
entra
tion
(mol
/l)
TMP dibutanoatebutanoic acid
Main Products of TMP Tributanoate Oxidation
O
OO
OH
O
OH
O
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0
0.5
1
1.5
2
0 5 10 15
time (hours)
conc
entra
tion
(mol
/l)
TMP dibutanoatebutanoic acidoxygen
Main Products of TMP Tributanoate Oxidation
O
OO
OH
O
OH
O
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0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 5 10 15
time (hours)
conc
entra
tion
(mol
/l)
TMP dibutanoateTMP monopropanoateTMP monoethanoateTMP monomethanoate
Transesterification Products
O
OO
OH
O
O
OO
O
O
O
H
O
OO
O
O
O
O
OO
O
O
O
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10 15
time (hours)
conc
entra
tion
(mol
/l)
butanoic acidpropyl butanoateethyl butanoatemethyl butanoate
Transesterification Products : II
OH
O
O
O
O
O
O
O
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Possible Hydrolysis of TMP Tributanoate?
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 0.2 0.4 0.6 0.8 1 1.2 1.4
butanoic acid + derivatives (mol/l)
TMP
dib
utan
oate
+ d
eriv
ativ
es (m
ol/l)
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Water Content During Autoxidation
OH
O
O
OO
OH
O
0
0.5
1
1.5
2
0 5 10 15
time (hours)
conc
entra
tion
(mol
/l)
TMP dibutanoatebutanoic acidoxygen
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0
0.5
1
1.5
2
0 5 10 15
time (hours)
conc
entra
tion
(mol
/l)
TMP dibutanoatebutanoic acidoxygenwater
Water Content During Autoxidation
OH
O
O
OO
OH
O
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TMP Tributanoate Oxidation : Viscosity Increase
8.8
9
9.2
9.4
9.6
0 1 2 3 4 5
time (hours)
visc
osity
(@40
C, c
P)
Viscosity Increase : Correlation with TMP Dibutanoate
O
OO
OH
O
O
OO
O
O
O
8.8
9
9.2
9.4
9.6
0 5 10 15 20
TMP dibutanoate % (mol/mol )
visc
osity
(@40
C, c
P)
Viscosity Increase : Correlation with TMP Dibutanoate
O
OO
OH
O
O
OO
O
O
O
8.8
9
9.2
9.4
9.6
0 5 10 15 20
TMP dibutanoate % (mol/mol )
visc
osity
(@40
C, c
P)
experimentalmodel mixture
Formation of High Molecular Weight Species
O
OO
O
O
O
mass : 344 mass430458516530544610630
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Formation of High Molecular Weight Species : II
O
OO
O
O
O
oxidation oxidation
+esterification
(-H2O)
mass : 344
mass : 430
radical attack
O
O
O
O
O
O
O
O
O
OO
O
O
O
O
(+ O2 - O)O
OO
O
O
O
OH
(+ RH)
O
OO
O
O
O
OH
OH
O
Formation of High Molecular Weight Species : III
O
OO
O
O
O
O
OO
O
O
H
oxidation
mass : 344
mass : 458
radical attack
O
OO
O HO
O
O
O
OH
O
OH
O
O
OO
O
O
H
+
cleavageO
OO
O
O
O
O
O
O
+
(+ O2 - O)
Formation of High Molecular Weight Species : IV
O
OO
O
O
O
O
OO
O
O
H
O
OOH
O
O
O
O
O
O
O
OO
O
O O
oxidation oxidation
+(-H2O)
mass : 344
mass : 544
O
OO
O
O
OH
O
OO
O
O
OHradical attack
esterification
Trimethylolpropane (TMP) Esters
O
OO
O
O
O
lubricant base fluid : TMP tridodecanoate
O
OO
O
O
OO
OO
O
O
O
neopentylglycol dibutanoate TMP trihexanoate
O
O
O
O
TMP tributanoate
Model Compounds
0
0.2
0.4
0.6
0.8
0 5 10 15
time (hours)
TMP
Die
ster
(mol
/l)
TMP Trihexanoate vs. TMP Tributanoate Oxidation
O
OO
O
O
O
O
OO
OH
O
0
0.2
0.4
0.6
0.8
0 5 10 15
time (hours)
TMP
Die
ster
(mol
/l)
TMP Trihexanoate vs. TMP Tributanoate Oxidation
O
OO
O
O
O
O
OO
O
O
O
O
OO
OH
O
O
OO
OH
O
Conclusions : Main Oxidation Mechanisms of Polyol Esters
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Conclusions : Main Oxidation Mechanisms of Polyol Esters
• Polyol Esters can decompose to the Diol and form Cyclic Acetals
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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
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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
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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 and Castrol
Department of Chemistry
