Mechanistic Insights into the Alternating Copolymerization of Epoxides and Cyclic Anhydrides Using a (Salph)AlCl and Iminium Salt Catalytic System

Megan E Fieser, Maria J. Sanford, Lauren A. Mitchell, Christine R. Dunbar, Mukunda Mandal, Nathan J. Van Zee, Devon M. Urness, Chris Cramer, Geoffrey W. Coates, William B Tolman

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Mechanistic studies involving synergistic experiment and theory were performed on the perfectly alternating copolymerization of 1-butene oxide and carbic anhydride using a (salph)AlCl/[PPN]Cl catalytic pair. These studies showed a first-order dependence of the polymerization rate on the epoxide, a zero-order dependence on the cyclic anhydride, and a first-order dependence on the catalyst only if the two members of the catalytic pair are treated as a single unit. Studies of model complexes showed that a mixed alkoxide/carboxylate aluminum intermediate preferentially opens cyclic anhydride over epoxide. In addition, ring-opening of epoxide by an intermediate comprising multiple carboxylates was found to be rate-determining. On the basis of the experimental results and analysis by DFT calculations, a mechanism involving two catalytic cycles is proposed wherein the alternating copolymerization proceeds via intermediates that have carboxylate ligation in common, and a secondary cycle involving a bis-alkoxide species is avoided, thus explaining the lack of side reactions until the polymerization is complete.

Original languageEnglish (US)
Pages (from-to)15222-15231
Number of pages10
JournalJournal of the American Chemical Society
Volume139
Issue number42
DOIs
StatePublished - Oct 25 2017

Fingerprint

Anhydrides
Epoxy Compounds
Copolymerization
1,2-epoxybutane
Salts
Polymerization
Butenes
Discrete Fourier transforms
Aluminum
Catalysts
Oxides
Ligation
Experiments

Cite this

Mechanistic Insights into the Alternating Copolymerization of Epoxides and Cyclic Anhydrides Using a (Salph)AlCl and Iminium Salt Catalytic System. / Fieser, Megan E; Sanford, Maria J.; Mitchell, Lauren A.; Dunbar, Christine R.; Mandal, Mukunda; Van Zee, Nathan J.; Urness, Devon M.; Cramer, Chris; Coates, Geoffrey W.; Tolman, William B.

In: Journal of the American Chemical Society, Vol. 139, No. 42, 25.10.2017, p. 15222-15231.

Research output: Contribution to journalArticle

Fieser, ME, Sanford, MJ, Mitchell, LA, Dunbar, CR, Mandal, M, Van Zee, NJ, Urness, DM, Cramer, C, Coates, GW & Tolman, WB 2017, 'Mechanistic Insights into the Alternating Copolymerization of Epoxides and Cyclic Anhydrides Using a (Salph)AlCl and Iminium Salt Catalytic System', Journal of the American Chemical Society, vol. 139, no. 42, pp. 15222-15231. https://doi.org/10.1021/jacs.7b09079
Fieser, Megan E ; Sanford, Maria J. ; Mitchell, Lauren A. ; Dunbar, Christine R. ; Mandal, Mukunda ; Van Zee, Nathan J. ; Urness, Devon M. ; Cramer, Chris ; Coates, Geoffrey W. ; Tolman, William B. / Mechanistic Insights into the Alternating Copolymerization of Epoxides and Cyclic Anhydrides Using a (Salph)AlCl and Iminium Salt Catalytic System. In: Journal of the American Chemical Society. 2017 ; Vol. 139, No. 42. pp. 15222-15231.
@article{a981457bb1ed483fae3e715081ea17d1,
title = "Mechanistic Insights into the Alternating Copolymerization of Epoxides and Cyclic Anhydrides Using a (Salph)AlCl and Iminium Salt Catalytic System",
abstract = "Mechanistic studies involving synergistic experiment and theory were performed on the perfectly alternating copolymerization of 1-butene oxide and carbic anhydride using a (salph)AlCl/[PPN]Cl catalytic pair. These studies showed a first-order dependence of the polymerization rate on the epoxide, a zero-order dependence on the cyclic anhydride, and a first-order dependence on the catalyst only if the two members of the catalytic pair are treated as a single unit. Studies of model complexes showed that a mixed alkoxide/carboxylate aluminum intermediate preferentially opens cyclic anhydride over epoxide. In addition, ring-opening of epoxide by an intermediate comprising multiple carboxylates was found to be rate-determining. On the basis of the experimental results and analysis by DFT calculations, a mechanism involving two catalytic cycles is proposed wherein the alternating copolymerization proceeds via intermediates that have carboxylate ligation in common, and a secondary cycle involving a bis-alkoxide species is avoided, thus explaining the lack of side reactions until the polymerization is complete.",
author = "Fieser, {Megan E} and Sanford, {Maria J.} and Mitchell, {Lauren A.} and Dunbar, {Christine R.} and Mukunda Mandal and {Van Zee}, {Nathan J.} and Urness, {Devon M.} and Chris Cramer and Coates, {Geoffrey W.} and Tolman, {William B}",
year = "2017",
month = "10",
day = "25",
doi = "10.1021/jacs.7b09079",
language = "English (US)",
volume = "139",
pages = "15222--15231",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "42",

}

TY - JOUR

T1 - Mechanistic Insights into the Alternating Copolymerization of Epoxides and Cyclic Anhydrides Using a (Salph)AlCl and Iminium Salt Catalytic System

AU - Fieser, Megan E

AU - Sanford, Maria J.

AU - Mitchell, Lauren A.

AU - Dunbar, Christine R.

AU - Mandal, Mukunda

AU - Van Zee, Nathan J.

AU - Urness, Devon M.

AU - Cramer, Chris

AU - Coates, Geoffrey W.

AU - Tolman, William B

PY - 2017/10/25

Y1 - 2017/10/25

N2 - Mechanistic studies involving synergistic experiment and theory were performed on the perfectly alternating copolymerization of 1-butene oxide and carbic anhydride using a (salph)AlCl/[PPN]Cl catalytic pair. These studies showed a first-order dependence of the polymerization rate on the epoxide, a zero-order dependence on the cyclic anhydride, and a first-order dependence on the catalyst only if the two members of the catalytic pair are treated as a single unit. Studies of model complexes showed that a mixed alkoxide/carboxylate aluminum intermediate preferentially opens cyclic anhydride over epoxide. In addition, ring-opening of epoxide by an intermediate comprising multiple carboxylates was found to be rate-determining. On the basis of the experimental results and analysis by DFT calculations, a mechanism involving two catalytic cycles is proposed wherein the alternating copolymerization proceeds via intermediates that have carboxylate ligation in common, and a secondary cycle involving a bis-alkoxide species is avoided, thus explaining the lack of side reactions until the polymerization is complete.

AB - Mechanistic studies involving synergistic experiment and theory were performed on the perfectly alternating copolymerization of 1-butene oxide and carbic anhydride using a (salph)AlCl/[PPN]Cl catalytic pair. These studies showed a first-order dependence of the polymerization rate on the epoxide, a zero-order dependence on the cyclic anhydride, and a first-order dependence on the catalyst only if the two members of the catalytic pair are treated as a single unit. Studies of model complexes showed that a mixed alkoxide/carboxylate aluminum intermediate preferentially opens cyclic anhydride over epoxide. In addition, ring-opening of epoxide by an intermediate comprising multiple carboxylates was found to be rate-determining. On the basis of the experimental results and analysis by DFT calculations, a mechanism involving two catalytic cycles is proposed wherein the alternating copolymerization proceeds via intermediates that have carboxylate ligation in common, and a secondary cycle involving a bis-alkoxide species is avoided, thus explaining the lack of side reactions until the polymerization is complete.

UR - http://www.scopus.com/inward/record.url?scp=85032272623&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85032272623&partnerID=8YFLogxK

U2 - 10.1021/jacs.7b09079

DO - 10.1021/jacs.7b09079

M3 - Article

VL - 139

SP - 15222

EP - 15231

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 42

ER -