The Effect of Diazabutadiene Ligands on Living Radical Polymerization

1
The Effect of Diazabutadiene Ligands on Living
Radical Polymerization Department of Chemistry,
University of Warwick, Coventry CV4 7AL U.K.
Lindsay Ellis, Simon Harrisson David Haddleton
Project Outline
ATP Mechanism
Ligands for ATP

• Synthesize ligands of various chain lengths
• Polymerize MMA using ligands and either CuBr or
  CuCl at various temperatures in toluene
• Investigate the usefulness of these ligands for
  ATP with MMA

• Purpose of ligand to solubilize the
  transition-metal salt in the organic media and to
  adjust the redox potential of the metal centre
• Position of equilibrium controls polymerization

• Effect of changing pyridine structure?
• Effect of changing the R group?
• (1) and (2) are effective ligands for ATP, will
  that effectiveness transpose to (3)?

Synthesis and Polymerization
Kinetic Results
(1) Propyl (2) Pentyl (3) Octyl Add amine
dropwise to stirred solution of 2,3-butadione in
ether in ice bath. Dry with excess MgSO4, rotary
evaporate off ether Distill to purify (1) and
(2) Recrystallize (3) in methanol All were pure
by 1H and 13C NMR and CHN analysis
Propyl Good conversions 65 - 85 PDI 1.30
1.76 Pentyl OK conversions 54 - 74 PDI 1.70
2.12 Octyl Mixed Conversion 19 - 88 PDI
1.71 2.55
Comparison of the Three Ligands with CuCl at 90oC
Comparison of the Three Ligands with CuBr at 90oC
Propyl Ligand conversion 72 Mn 9000, PDI
1.76 kPol 0.286 Pentyl Ligand conversion 53
Mn 8000, PDI 1.78 kPol 0.130 Octyl
Ligand conversion 19 Mn 1600, PDI
2.39 kPol 0.079
Propyl Ligand conversion 63 Mn 9970, PDI
1.83 kPol 0.302 Pentyl Ligand conversion 61
Mn 9000, PDI 1.70 kPol 0.234 Octyl
Ligand conversion 52 Mn 7900, PDI
1.62 kPol 0.164
Conclusions
Acknowledgements

• Diimines poor ligands for ATP
• Are not electron rich enough to facilitate
  transition from CuI to CuII species
• Leads to high termination rates and loss of
  control over reaction
• Therefore high PDI and low conversions

• Simon Harrisson
• Professor David Haddleton
• Entire Polymer Group