Ethylene Oxide Polymerization Catalyzed by Aluminum Complexes of Sulfur-Bridged Polyphenols

Wasserman, Eric; Annis, Ioana; Chopin, Lamy; Price, Philip C.; Petersen, Jeffrey L.; Abboud, Khalil A.

doi:10.1021/ma049209d

Cited by 25 publications

(23 citation statements)

References 31 publications

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“…Wasserman informed on aluminium compounds derived of tridentate thiobisphenolate ligands and showed they are efficient catalysts for ethylene oxide polymerization [39]. Okuda [40] and Janas [41] have reported new aluminium and aluminium/titanium derivatives of similar ligands with structures related to those of our own unpublished work and some of the presented herein.…”

Section: Introductionmentioning

confidence: 63%

Organogallium complexes incorporating tridentate thioetherbiphenolate ligands 2,2′-thiobis(4,6-di-tert-butylphenolate), Stdiol and 2,2′-thiobis(4,6-dimethylphenolate), Smdiol

Cruz-Burelo

Montiel‐Palma

Muñoz‐Hernández

2006

Main Group Chemistry

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Organogallium(III) thioetherbisphenolate complexes of general formulae SmdiolGaMe-THF (1), StdiolGaMe-THF (2), SmdiolGaMe (3) and StdiolGaMe (4) (Smdiol ¼ 2,2 0 -thiobis(4,6-dimethylphenolate); Stdiol ¼ 2,2 0 -thiobis(4,6-diterbuthylphenolate)), were synthesised by methane elimination reactions from GaMe 3 and the diol proligands SmdiolH 2 and StdiolH 2 . The molecular structure of 1 is monomeric and shows the Ga centre adopting a trigonal bipyramidal structure with one of the apical positions occupied by the oxygen atom of a coordinated THF molecule. While the solution spectroscopic data of 4 is in support of a monomeric, probably tetrahedral, species its solid state structure shows a polymeric array built upon intermolecular sulphur-to-gallium interactions resulting in a distorted trigonal bipyramid. The Smdiol derivatives 1 and 3 show modest catalytic activities in Diels-Alder cycloaddition reactions of methacrolein and cyclopentadiene. In addition, StdiolGaH (7) is conveniently synthesized from reaction of StdiolGaCl and t BuLi at room temperature. Compound 7 readily hydrolyses in the presence of trace amounts of water leading to StdiolGa(OH) (8) whose solid state structure was determined.

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Section: Introductionmentioning

confidence: 63%

Organogallium complexes incorporating tridentate thioetherbiphenolate ligands 2,2′-thiobis(4,6-di-tert-butylphenolate), Stdiol and 2,2′-thiobis(4,6-dimethylphenolate), Smdiol

Cruz-Burelo

Montiel‐Palma

Muñoz‐Hernández

2006

Main Group Chemistry

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“…The high-resolution mass spectra were recorded with an Agilent Technologies 1200 Series mass spectrometer with a time-of-flight analyzer. S LH 2 , [17] SO LH 2 , [8] SO2 LH 2 [8] and PPh 4 A C H T U N G T R E N N U N G [VO 2 Cl 2 ] [18] were obtained by following literature procedures.…”

Section: Methodsmentioning

confidence: 99%

Haloperoxidase Activity of Oxovanadium(V) Thiobisphenolates

Werncke

Limberg

Knispel

et al. 2011

Chemistry A European J

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By employing the 2,2'-thiobis(2,4-di-tert-butylphenolate) ligand ((S)L(2-)) a novel oxovanadium(V) complex, (PPh(4))(2)[(S)LV(O)(μ(2)-O)(2)V(O)(S)L] (1), was synthesised that exhibits haloperoxidase activity: on addition of H(2)O(2) a sequence of successive peroxide formation and intramolecular thioether oxidation events (sulfoxide and sulfone) led to a mixture of five products, which were all identified unambiguously, partly through an independent synthesis and characterisation. It was shown that internal thioether oxidation proceeds through peroxide formation, but the sulfoxidation of external thioether functions requires further activation of the peroxide function by protons or alkyl cations. Consistently, the employment of tBuOOH instead of H(2)O(2) led to a very active system for the catalytic sulfoxidation of thioethers.

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“…The structure of the catalyst and the specific mechanism of its operation have unfortunately never been directly investigated. 21 Subsequent developments in aluminum-catalyzed epoxide polymerization resulted in a variety of new catalytic concepts, 29,30 and many approaches provide novel and highperformance characteristics. 31−42 Significantly, a general-use, facile, consensus technique for epoxide polymerization has not emerged.…”

Section: ■ Introductionmentioning

confidence: 99%

Demystifying the Mechanism of Regio- and Isoselective Epoxide Polymerization Using the Vandenberg Catalyst

et al. 2018

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A combined theoretical and experimental investigation into the structure and mechanism of the classical Vandenberg catalyst for the isoselective polymerization of epoxides has led to a consistent mechanistic proposal. The most likely reaction pathway was based on a bis(μ-oxo)di(aluminum) (BOD) resting state that proceeded through a mono(μoxo)di(aluminum) (MOD) transition state. The isoselectivity of the Vandenberg catalyst was derived from the rigidity of the BOD structure and its bonding to the ultimate and penultimate oxygen heteroatoms along the polyether backbone. The energetic driving force for isoselectivity was the loss of an energetically favorable secondary Al−O interaction during enchainment of oppositely configured epoxides, providing a ca. 2 kcal/mol driving force for the emergent isoselectivity. Experimental spectroscopic and kinetic evidence based on model BOD and MOD complexes support the new mechanistic framework developed using density functional theory calculations. A purposefully synthesized BOD analogue of the proposed Vandenberg structure produced a characteristically isotactically enriched poly(allyl glycidyl ether) as produced by the classical Vandenberg catalyst. In situ 1 H NMR spectroscopy of a Vandenberg-catalyzed polymerization of allyl glycidyl ether revealed the activation enthalpy (ΔH ‡ = 21 kcal/mol) and energetics of epoxide−aluminum coordination (ΔH = −4.0 ± 1.0 kcal/mol, ΔS = −0.018 ± 0.004 kcal/(K mol)) by observation of the shifting acetylacetonate signal located on the active site of the Vandenberg catalyst in the 1 H NMR spectra of polymerization.

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Ethylene Oxide Polymerization Catalyzed by Aluminum Complexes of Sulfur-Bridged Polyphenols

Cited by 25 publications

References 31 publications

Organogallium complexes incorporating tridentate thioetherbiphenolate ligands 2,2′-thiobis(4,6-di-tert-butylphenolate), Stdiol and 2,2′-thiobis(4,6-dimethylphenolate), Smdiol

Organogallium complexes incorporating tridentate thioetherbiphenolate ligands 2,2′-thiobis(4,6-di-tert-butylphenolate), Stdiol and 2,2′-thiobis(4,6-dimethylphenolate), Smdiol

Haloperoxidase Activity of Oxovanadium(V) Thiobisphenolates

Demystifying the Mechanism of Regio- and Isoselective Epoxide Polymerization Using the Vandenberg Catalyst

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