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Issue 18, 2017
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A new route for the preparation of enriched iso-polylactide from rac-lactide via a Lewis acid catalyzed ring-opening of an epoxide

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Abstract

Tetraphenylporphyrin aluminum(III) salts, TPPAlX, where X = Me, OEt, OiPr, OCHMeCH2Cl, and Cl, and bis(triphenylphosphine)imminium chloride, PPN+Cl (1 : 1) react with rac-lactide, rac-LA, in neat propylene oxide, PO, to yield chains of enriched isotactic polylactide, PLA, with end groups of PO–Cl and with time these yield cyclic polymers (PO)n(PLA) where n = 2 or 3 and even higher. There is no reaction between TPPAlOR (R = Et or iPr), PPN+Cl, and rac-LA in neat THF at 25 °C even though TPPAlOR (R = Et or iPr) and PPN+Cl in neat PO yields polypropylene oxide with a terminal OR group, H(PO)nOR. Taken together, Al(III) acts as a Lewis acid in the ring-opening of PO, in which PPN+Cl is present and the incipient ClCH2CHMeO initiates the ROP of LA to yield anion chains of [(PLA)-OCHMeCH2Cl], and then the ring-opening of PO yields cycles, (PO)n(PLA), with the liberation of Cl. The polymer was isolated by the addition of MeOH/HCl and end group analysis by mass spectrometry.

Graphical abstract: A new route for the preparation of enriched iso-polylactide from rac-lactide via a Lewis acid catalyzed ring-opening of an epoxide

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Publication details

The article was received on 11 Aug 2016, accepted on 03 Apr 2017 and first published on 18 Apr 2017


Article type: Paper
DOI: 10.1039/C6DT03198F
Citation: Dalton Trans., 2017,46, 5938-5945
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    A new route for the preparation of enriched iso-polylactide from rac-lactide via a Lewis acid catalyzed ring-opening of an epoxide

    M. Anker, C. Balasanthiran, V. Balasanthiran, M. H. Chisholm, S. Jayaraj, K. Mathieu, P. Piromjitpong, S. Praban, B. Raya and W. J. Simonsick, Dalton Trans., 2017, 46, 5938
    DOI: 10.1039/C6DT03198F

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