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*E-mail: [email protected] Alder Ene Functionalization of Polyisobutene Oligomer with Polar Enophiles. Andrea Pucci ,* Riccardo Rausa, Francesco Ciardelli Department of Chemistry and Industrial Chemistry, University of Pisa, Via Risorgimento 35, 56126 Pisa, Italy

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*E-mail: [email protected]

Alder Ene Functionalization of Polyisobutene Oligomer with Polar Enophiles

Andrea Pucci,* Riccardo Rausa, Francesco Ciardelli

Department of Chemistry and Industrial Chemistry, University of Pisa, Via Risorgimento 35, 56126 Pisa, Italy

ENI S.p.A. Div. Refining & Marketing; Centro Ricerche di S. Donato M.se.

S. Donato Milanese (Mi) Italy

PolyLab-CNR, c/o DCCI, University of Pisa, via Risorgimento 35, I-56126 Pisa, Italy


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Polyisobutene requirements

Introduction

Almost 60% is used for lubricant additives but significant amounts are also used in gasoline additives. The increasingly requirements placed on PIB can no longer be satisfied with one type of PIB: synthesis of highly reactive (HR) PIB

~ 85% by mol a-olefin

~ 10% % by mol b-olefin

~ 3% by mol tetrasub. olef.

Pure isobutene

BF3 catalyst

  • New and innovative synthesis like copolymerisation or functionalisation

  • Ashless, Chlorine free Additives

  • Narrow molecular weight distribution: improved low T properties

  • Engine performance of additives strongly improved

http://www.performancechemicals.basf.com


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Thermal induced Alder-ene mechanism

Polyisobutene reactivity

Introduction

PIB reactivity with enophiles, the case of maleic anhydride:

polyisobutene succinic anhydrides (PIBSA) and their succinimides (PIBSI) derivatives are widely employed as detergent-dispersant additives in lubricants or fuels formulations:

A. Pucci, C. Barsocchi, R. Rausa, L. D’Elia, F. Ciardelli, Polymer2005, 46, 1497


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ene species

electron-deficient enophile

Polyisobutene reactivity

Introduction

Thermal induced Alder-ene mechanism

The reaction between the ene and enophile requires more dramatic conditions, such as highly electron-deficient enophile and elevated temperature. Temperature higher than 150°C, long residence times and MAH as enophile must generally be used for Alder Ene polymer modifications

G. Moad, Prog. Polym. Sci.1999, 24, 81.


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Aim of the work

experimental conditions

The Alder ene functionalization of double bonds containing polyisobutene oligomer with different enophiles: maleic anhydride (MAH) or diethyl maleate (DEM). The role of the reaction conditions and the use of some Lewis acids (XnM) as catalysts are discussed.

M.R. Thompson et al. Polymer1998, 39, 327; J. Polym. Sci. Part A: Polym. Chem.1998, 36, 2371; J. Appl. Polym. Sci.1999, 71, 503

aIn all cases, 100 g of PIB (Glissopal 1300, BASF) was employed and the reaction maintained for 21 hours; bDEM as enophile


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The reactions were followed by FTIR spectroscopy, monitoring the disappearance of the vinylidene peak of PIB centred at 890 cm-1

Synthetic details

characterization

  • T  180 °C

  • t ~ 21 h

  • N2 atmosphere

  • unreacted MAH was stripped off under vacuum at high T


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-

Conversion

characterization

The reaction conversion degrees were evaluated after elution over silica gel of weighted amounts of the dried polymer dissolved in n-heptane. The eluted phases, containing just the unreacted PIB, were vacuum evaporated, dried at under pressure (0.2 mmHg) and weighted.

aRuCl3 as cat

bSnCl3 as cat

cDEM as enophile


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Functionalisation degree

characterization

  • FTIR spectroscopy (MAH and DEM)

  • NMR spectroscopy (MAH and DEM)

  • Potentiometric titration (MAH)

  • Luminescence spectroscopy (examples)


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DES

SA

Functionalisation degree

characterization

FTIR spectroscopy (MAH and DEM)

SA: C=O sym 1855 cm-1

C=O asym 1780 cm-1

DES: C=O 1735 cm-1


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A1: 1738 cm-1nC=O

A2: 1472 cm-1dCH2

Functionalisation degree

characterization

FTIR spectroscopy (MAH and DEM)

Correlation curve

Z. S. Fodor et al. J. Polym. Sci. Polym. Chem. Ed.1984, 22, 2539


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Functionalisation degree

characterization

NMR spectroscopy (MAH and DEM)

M. Tessier and E. Marechal J. Polym. Sci.:Part A: Polymer Chemistry, 26, 2785-2810 1988


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Functionalisation degree

characterization

NMR spectroscopy (MAH and DEM)


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Sample dissolved in toluene/2-propanol/water (25/24.5/0.5 v/v)

total acid number (TAN):

TANcorr = TAN/conversion degree

US 4,952,328 (Lubrizol corporation)

in 2-propanol

Functionalisation degree

characterization

Potentiometric titration (MAH):

ASTM D-664


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Functionalisation degree

results

aRuCl3 as cat

bSnCl3 as cat

cDEM as enophile


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1H NMR investigation

results

Quantification of bis-maleation


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acid-promoted isomerization

Catalyst effect

results

endo: 10% by mol

endo: 16% by mol

endo: 30% by mol


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O

O

O

O

O

O

O

O

O

O

Catalyst effect

results

Secondary effect: promotion of polyMAH products


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A. Pucci et al., Macromol. Chem. Phys. 2008, 209, 900–906;

ACS Noteworthy Chemistry - June 16, 2008

lexc = 366 nm

Emission spectra of heptane solutions of PIBSA 7 as a function of polymer molar concentration

Emission (lexc. = 350 nm) and absorption (inset) spectra of 1.45·10-3 M heptane solutions of PIBSA derivatives at different reaction time (hours)

Luminescence spectroscopy (examples)

results


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Luminescence spectroscopy (examples)

results

The fluorescence quantum yield (Φf) in solutions and polymer films was determined relative to quinine sulphate (Φsf = 0.54 in 0.1 M H2SO4) using the following relation:

  • Φsf :quantum yield of standard

  • the integrals are the area under fluorescence peaks (= 0.54).

  • A and AS (= 0.02) are the absorbances of the molecule and standard, respectively, at the excitation wavelength (350 nm).

  • n is the refractive index of the medium. The refractive index of heptane is 1.39

 = 70800

= 1.09

Comparison between Фf and FD of PIBSA derivatives as a function of reaction time and non-linear regression fits of the experimental data


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Remarks on Alder-Ene reaction

Conclusions

  • The functionalization reactions performed on HR PIB oligomers by using maleic anhydride (MAH) as enophile gave conversion degree ~ 70% and provided materials with high functionalization degree, i.e. 1.5 mol of SA per mol of reacted polymer: a) no important differences at two PIB/MAH ratio (P1 vs P2); b) no detectable changes of molecular weight and molecular weight distribution were found;

  • The use of ruthenium chloride and stannous chloride as Lewis acid catalysts to increase the reaction rate and the grafting extent did not positively affect the functionalization process, likely due to the promotion of exo → endo isomerization process of the PIB reactive vinylidene units and MAH oligomerization.

  • On the other hand, the diethyl maleate (DEM) gave low conversion degree due to its minor reactivity as enophile compared to MAH. Nevertheless FD of 1.5-1.6 as for MAH were obtained thanks also to the improved mixing efficiency of the liquid enophile.


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Remarks on characterization techniques

Conclusions

  • High degree of agreement among characterization methods (FTIR, 1H NMR and potentiometric titration) for the assessment of the FD;

  • Interesting results (in agreement as well) coming from luminescence investigations


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Acknowledgements

  • Dr. Chiara Barsocchi (on leave from DCCI, Pisa)

  • Dr. Vincenzo Liuzzo

  • Dr. Massimiliano Boccia (now Acta nanotech)


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Polyisobutene applications

Introduction

http://www.agip.eni.it/


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Polyisobutene applications

Introduction

Applications of PIB oligomers (molar mass: 500-5000 range)

  • Lube oil additives

  • Fuel additives

  • 2-stroke engine oils

  • Isolating oils

  • Sealants Adhesives

March 2008


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Functionalisation degree

characterization

FTIR spectroscopy (MAH and DEM)

Deconvolution


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