Mechanism of Propylene Oxide Polymerization Promoted by N-Heterocyclic Olefins

Handle URI:
http://hdl.handle.net/10754/623866
Title:
Mechanism of Propylene Oxide Polymerization Promoted by N-Heterocyclic Olefins
Authors:
Al-Ghamdi, Miasser ( 0000-0002-7192-4660 ) ; Cavallo, Luigi ( 0000-0002-1398-338X ) ; Falivene, Laura ( 0000-0003-1509-6191 )
Abstract:
We report a mechanistic DFT investigation of the organopolymerization of propylene oxide (PO) promoted by N-heterocyclic olefins (NHOs) in combination with benzylic alcohol (BnOH). Calculations support the experimentally based hypothesis of two competing pathways, namely, the anionic and zwitterionic pathways. The former is based on an acid–base cooperativity between BnOH and the NHO, promoting ring opening of PO by BnO–. The latter occurs through the formation of a zwitterionic adduct by nucleophilic attack of the exocyclic carbon atom of the NHO on the PO, with the concerted ring opening of PO. The two initiating species cannot interconvert, and chain elongation can proceed from both initiation adducts. Potential energy surfaces were computed for a set of NHOs to clarify the effects of the steric and electronic properties of the NHO on the system reactivity. The results achieved represent useful insight toward the synthesis of PPO with better properties with respect to the polymer obtained with the experimental tested systems because the computationally proposed NHO system is the only one that favors the mechanism leading to higher molecular weight.
KAUST Department:
KAUST Catalysis Center (KCC)
Citation:
Al Ghamdi M, Cavallo L, Falivene L (2017) Mechanism of Propylene Oxide Polymerization Promoted by N-Heterocyclic Olefins. The Journal of Physical Chemistry C 121: 2730–2737. Available: http://dx.doi.org/10.1021/acs.jpcc.6b10977.
Publisher:
American Chemical Society (ACS)
Journal:
The Journal of Physical Chemistry C
Issue Date:
11-Jan-2017
DOI:
10.1021/acs.jpcc.6b10977
Type:
Article
ISSN:
1932-7447; 1932-7455
Sponsors:
This work was supported by funding from King Abdullah University of Science and Technology (KAUST).
Additional Links:
http://pubs.acs.org/doi/full/10.1021/acs.jpcc.6b10977
Appears in Collections:
Articles; KAUST Catalysis Center (KCC)

Full metadata record

DC FieldValue Language
dc.contributor.authorAl-Ghamdi, Miasseren
dc.contributor.authorCavallo, Luigien
dc.contributor.authorFalivene, Lauraen
dc.date.accessioned2017-05-31T11:23:10Z-
dc.date.available2017-05-31T11:23:10Z-
dc.date.issued2017-01-11en
dc.identifier.citationAl Ghamdi M, Cavallo L, Falivene L (2017) Mechanism of Propylene Oxide Polymerization Promoted by N-Heterocyclic Olefins. The Journal of Physical Chemistry C 121: 2730–2737. Available: http://dx.doi.org/10.1021/acs.jpcc.6b10977.en
dc.identifier.issn1932-7447en
dc.identifier.issn1932-7455en
dc.identifier.doi10.1021/acs.jpcc.6b10977en
dc.identifier.urihttp://hdl.handle.net/10754/623866-
dc.description.abstractWe report a mechanistic DFT investigation of the organopolymerization of propylene oxide (PO) promoted by N-heterocyclic olefins (NHOs) in combination with benzylic alcohol (BnOH). Calculations support the experimentally based hypothesis of two competing pathways, namely, the anionic and zwitterionic pathways. The former is based on an acid–base cooperativity between BnOH and the NHO, promoting ring opening of PO by BnO–. The latter occurs through the formation of a zwitterionic adduct by nucleophilic attack of the exocyclic carbon atom of the NHO on the PO, with the concerted ring opening of PO. The two initiating species cannot interconvert, and chain elongation can proceed from both initiation adducts. Potential energy surfaces were computed for a set of NHOs to clarify the effects of the steric and electronic properties of the NHO on the system reactivity. The results achieved represent useful insight toward the synthesis of PPO with better properties with respect to the polymer obtained with the experimental tested systems because the computationally proposed NHO system is the only one that favors the mechanism leading to higher molecular weight.en
dc.description.sponsorshipThis work was supported by funding from King Abdullah University of Science and Technology (KAUST).en
dc.publisherAmerican Chemical Society (ACS)en
dc.relation.urlhttp://pubs.acs.org/doi/full/10.1021/acs.jpcc.6b10977en
dc.titleMechanism of Propylene Oxide Polymerization Promoted by N-Heterocyclic Olefinsen
dc.typeArticleen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.identifier.journalThe Journal of Physical Chemistry Cen
kaust.authorAl-Ghamdi, Miasseren
kaust.authorCavallo, Luigien
kaust.authorFalivene, Lauraen
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