Sustainable Routes to Biodegradable Plastics and Synthetic Biodiesel Fuel – Polymers from CO 2 Objective: UofC: Richard Jordan (PI), Dept. of Chemistry Ben Petro (PD) Tim Lau (GS) ANL:Jeffrey Miller (PI), Chemical Sciences and Engineering Division

Carbon Dioxide  Fully oxidized carbon  Anthropogenic carbon ca. 7 Gt per year  Cheap, readily available, sustainable  Potential C1 building block  Thermodynamically stable, chemically unreactive

CO 2 as a Chemical Feedstock Bosch-Meiser urea process Salicyclic acid Urea: Fertilizer Chemical intermediate 10 8 tons/y Salicyclic acid: pharma Specialty polycarbonates CH/CO 2 polycarbonate: not commercial

Objective: Copolymerize CO 2 with Ethylene Potential payoff: new strategies for catalysis new sustainable routes to useful polymers and fuels new insights to CO 2 activation Target Chemistry: High MW: aliphatic polyesters biodegradable plastics Low MW: synthetic diesel fuel Key Issues: polyolefins aliphatic polyesters polyolefin catalysis design polyolefin catalysts that can incorporate CO 2

Polyolefin Plastics Olefin Polymerization Characteristics:tune properties by microstructure control cheap, many applications; 200 x 10 6 tons/y not biodegradable Catalysts: heterogeneous Ziegler-Natta or Cr homogeneous single-site

Aliphatic Polyesters PBS Characteristics:properties similar to polyolefins tune properties by microstructure control reactive ester group --> readily biodegradable expensive (5 – 10x PO) PCL

Objective: Copolymerize CO 2 with Ethylene Potential payoff: new strategies for catalysis new sustainable routes to useful polymers and fuels new insights to CO 2 activation Target Chemistry: High MW: aliphatic polyesters biodegradable plastics Low MW: synthetic diesel fuel Key Issues: polyolefins aliphatic polyesters polyolefin catalysis design polyolefin catalysts that can incorporate CO 2

Olefin Polymerization Catalysis Representative single-site catalysts Chain growth by insertion Design requirements: metal alkyl vacant coord sites activate olefin for Nu - attack

Simple Olefin Polymerization Mechanism

CO 2 Poisons Olefin Polymerization Catalysts CO 2 insertion Metal carboxylate structures Metallocene deactivation

Wacker synthesis of VOAc Nucleophilic Reactivity of Carboxylates Key step Implication for polymerization

Wacker synthesis of VOAc Nucleophilic Reactivity of Carboxylates Key step Implication for polymerization

New Strategy for Ethylene/CO 2 Copolymerization Key L n M requirements multiple ethylene insertions CO 2 insertion activate ethylene for external Nu - attack no β-O 2 CR elimination tolerant of ester groups incorporate into appropriate binuclear structure Binuclear catalyst

New Strategy for Ethylene/CO 2 Copolymerization Key L n M requirements multiple ethylene insertions CO 2 insertion activate ethylene for external Nu - attack no β-O 2 CR elimination tolerant of ester groups incorporate into appropriate binuclear structure Binuclear catalyst

New Strategy for Ethylene/CO 2 Copolymerization Key L n M requirements √ multiple ethylene insertions CO 2 insertion activate ethylene for external Nu - attack √ no β-O 2 CR elimination √ tolerant of ester groups √ incorporate into appropriate binuclear structure Binuclear catalyst

Discrete Phosphine-sulfonate Pd Catalysts Catalyst Framework Synthesis Structures

Polymerizations by (PO)PdMe(py) Catalysts HDPE Tolerance of esters Key Properties: Pd(II), electronic asymmetry, neutral

Self-Assembly of Tetranuclear OPO Catalyst

Pd1 Pd1A N1 C1 C1A N1A P1A P1 S1A S1 O2 O1 S2 O1A O3 Li1 Li1A O4 O5 O6 O2A O3A C2

Towards CO 2 Reactivity CO 2 does not insert Working hypothesis: Pd-Me insufficiently electron rich

Design Modifications in Progress Make more electron rich Exploit secondary interactions

(PO)PdR catalysts polymerize ethylene to HDPE (PO)PdR catalysts tolerate esters and are resistant to  -O 2 CR elim (OPO)PdR catalysts self-assemble into tetramers with desired Pd--Pd orientation (PO)PdR and (OPO)PdR catalysts do not react with CO 2 Polymers from Ethylene and CO 2 Results to date Current goals Modify (PO)PdR and (OPO)PdR catalysts to enable CO 2 incorp Demonstrate Wacker type reactivity with (PO)PdR and (OPO)PdR More robust self-assembled multinuclear catalysts Ethylene/CO 2 copolymerization

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