Borane catalyzed polymerization and depolymerization reactions controlled by Lewis acidic strength

Andrea, Kori A.; Wheeler, Mikhailey D.; Kerton, Francesca M.

doi:10.1039/d1cc02218k

Cited by 19 publications

(19 citation statements)

References 31 publications

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“…One limitation is the energy cost of CHO production — either by sourcing it from benzene or using recently reported routes from fatty acids [8b] . To date, there are only investigations of poly(cyclohexene carbonate) decomposition to cyclic carbonate (cyclohexene carbonate, CHC) [5b, 9, 15] . PCHC recycling to cyclohexene oxide (CHO) might be feasible if the barrier to epoxide formation were reduced.…”

Section: Figurementioning

confidence: 99%

Chemical Recycling of Poly(Cyclohexene Carbonate) Using a Di‐Mg^II Catalyst

et al. 2022

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Chemical recycling of polymers to true monomers is pivotal for a circular plastics economy. Here, the first catalyzed chemical recycling of the widely investigated carbon dioxide derived polymer, poly(cyclohexene carbonate), to cyclohexene oxide and carbon dioxide is reported. The reaction requires dinuclear catalysis, with the di‐MgII catalyst showing both high monomer selectivity (>98 %) and activity (TOF=150 h−1, 0.33 mol %, 120 °C). The depolymerization occurs via a chain‐end catalyzed depolymerization mechanism and DFT calculations indicate the high selectivity arises from Mg‐alkoxide catalyzed epoxide extrusion being kinetically favorable compared to cyclic carbonate formation.

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Section: Figurementioning

confidence: 99%

Chemical Recycling of Poly(Cyclohexene Carbonate) Using a Di‐Mg^II Catalyst

et al. 2022

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“…In comparison, organocatalyst systems show lower activities, with typical TOF values being below 300 h À 1 but may have advantages in terms of ease of use/commercial availability. For example, catalysts based on bases like t BuP 1 (TOF = 48 h À 1 , 100 °C), [57] BEt 3 /DBU (TOF = 27 h À 1 , 60 °C), [58] BPh 3 /PPNCl (TOF = 200 h À 1 , 0.2 mol %, 130 °C) [59] or (9-BBN)B-(C 4 H 10 )-NMe 2n Bu (TOF = 258 h À 1 , 0.25 mol%, 120 °C). [60] Since 5 shows the best performances of the series, its rate law was investigated for the ring opening copolymerization of anhydride/epoxide.…”

Section: Chemistry-a European Journalmentioning

confidence: 99%

Heterodinuclear Mg(II)M(II) (M=Cr, Mn, Fe, Co, Ni, Cu and Zn) Complexes for the Ring Opening Copolymerization of Carbon Dioxide/Epoxide and Anhydride/Epoxide

Williams

Reis

Deacy

et al. 2022

Chemistry A European J

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The catalysed ring opening copolymerizations (ROCOP) of carbon dioxide/epoxide or anhydride/epoxide are controlled polymerizations that access useful polycarbonates and polyesters. Here, a systematic investigation of a series of heterodinuclear Mg(II)M(II) complexes reveals which metal combinations are most effective. The complexes combine different first row transition metals (M(II)) from Cr(II) to Zn(II), with Mg(II); all complexes are coordinated by the same macrocyclic ancillary ligand and by two acetate co‐ligands. The complex syntheses and characterization data, as well as the polymerization data, for both carbon dioxide/cyclohexene oxide (CHO) and endo‐norbornene anhydride (NA)/cyclohexene oxide, are reported. The fastest catalyst for both polymerizations is Mg(II)Co(II) which shows propagation rate constants (kp) of 34.7 mM−1 s−1 (CO2) and 75.3 mM−1 s−1 (NA) (100 °C). The Mg(II)Fe(II) catalyst also shows excellent performances with equivalent rates for CO2/CHO ROCOP (kp=34.7 mM−1 s−1) and may be preferable in terms of metallic abundance, low cost and low toxicity. Polymerization kinetics analyses reveal that the two lead catalysts show overall second order rate laws, with zeroth order dependencies in CO2 or anhydride concentrations and first order dependencies in both catalyst and epoxide concentrations. Compared to the homodinuclear Mg(II)Mg(II) complex, nearly all the transition metal heterodinuclear complexes show synergic rate enhancements whilst maintaining high selectivity and polymerization control. These findings are relevant to the future design and optimization of copolymerization catalysts and should stimulate broader investigations of synergic heterodinuclear main group/transition metal catalysts.

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“…Very recently, Kerton reported an aryl borane (BPh 3 )-based catalytic system which showed the power to polymerize epoxides, anhydrides and CO 2 , resulting in perfectly alternating block copolymers such as poly(CHO/PAH-alt-CHO/CO 2 ) (Scheme 7). 86 Most interest- ingly, when poly(CHO/PAH-alt-CHO/CO 2 ) was exposed to more Lewis acidic BCF [tris( pentafluorophenyl)borane], the polycarbonate block was selectively degraded to cis-CHC, while the polyester block remains completely intact.…”

Section: Six-three Bicyclic Oxidesmentioning

confidence: 99%

Chemically recyclable polymer materials: polymerization and depolymerization cycles

Wang

2022

Green Chem.

126

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Borane catalyzed polymerization and depolymerization reactions controlled by Lewis acidic strength

Abstract: Triphenylborane catalyzes the polymerization of anhydrides and epoxides along with the block copolymerization of anhydride/ epoxides with epoxides/CO2. Switching to the more Lewis acidic borane, tris(pentafluorophenyl)borane, the carbonate block of...

Cited by 19 publications

References 31 publications

Chemical Recycling of Poly(Cyclohexene Carbonate) Using a Di‐Mg^II Catalyst

Chemical Recycling of Poly(Cyclohexene Carbonate) Using a Di‐Mg^II Catalyst

Heterodinuclear Mg(II)M(II) (M=Cr, Mn, Fe, Co, Ni, Cu and Zn) Complexes for the Ring Opening Copolymerization of Carbon Dioxide/Epoxide and Anhydride/Epoxide

Chemically recyclable polymer materials: polymerization and depolymerization cycles

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Borane catalyzed polymerization and depolymerization reactions controlled by Lewis acidic strength

Abstract: Triphenylborane catalyzes the polymerization of anhydrides and epoxides along with the block copolymerization of anhydride/ epoxides with epoxides/CO2. Switching to the more Lewis acidic borane, tris(pentafluorophenyl)borane, the carbonate block of...

Cited by 19 publications

References 31 publications

Chemical Recycling of Poly(Cyclohexene Carbonate) Using a Di‐MgII Catalyst

Chemical Recycling of Poly(Cyclohexene Carbonate) Using a Di‐MgII Catalyst

Heterodinuclear Mg(II)M(II) (M=Cr, Mn, Fe, Co, Ni, Cu and Zn) Complexes for the Ring Opening Copolymerization of Carbon Dioxide/Epoxide and Anhydride/Epoxide

Chemically recyclable polymer materials: polymerization and depolymerization cycles

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Chemical Recycling of Poly(Cyclohexene Carbonate) Using a Di‐Mg^II Catalyst

Chemical Recycling of Poly(Cyclohexene Carbonate) Using a Di‐Mg^II Catalyst