Carbon 13 NMR study of oligo(propylene oxide)s

Abstract

Samples of dimer and trimer derived from chiral propylene oxide, having head-to-tail linkages were prepared using an aluminium complex of a Schiff's base and were studied by means of I3C NMR spectroscopy. Based on these spectroscopic data and on J-Modulated Spin Echo Technique (JMSET), analysis of a racemic oligomer (m, = 11) was carried out. Resonances of carbon atoms of central and terminal units were identified. End-group carbon atoms (with the exception of cH2C1) present large configurational effects as compared to internal carbon atoms.

Cooperative catalysis with binary Lewis acid–Lewis base system for the coupling of carbon disulfide and epoxides

“…The salenM(III)X complexes were prepared according to the literature methods . These complexes are all sensitive to moisture and should be stored in a nitrogen atmosphere.…”

“…The salenM(III)X complexes were prepared according to the literature methods. [14,20,21] These complexes are all sensitive to moisture and should be stored in a nitrogen atmosphere. The representative procedure for these aluminum complexes are available online as supporting information.…”

Salen‐Complex‐Mediated Formation of Cyclic Carbonates by Cycloaddition of CO2 to Epoxides

“…The first aluminum salen complexes were prepared as early as 1989 by Le Borgne and co-workers, who showed their effectiveness for the living polymerization of epoxides. [29] However, it was not until 2002 that He et al investigated new applications in catalysis and synthesis with a green approach, thus preferring the use of relatively nontoxic metals such as aluminum and avoiding the use of chlorinated solvents. They initially studied the formation of propylene oxide in a supercritical (sc) carbon dioxide/ethylene oxide mixture by utilizing a set of binary catalysts comprising an aluminum salen complex (34 a; Scheme 13) with a quaternary ammonium or phosphonium salt.…”

Metall‐Salen‐vermittelte Bildung cyclischer Carbonate durch Cycloaddition von CO2 an Epoxide

“…Die ersten Aluminium-Salen-Komplexe wurden bereits 1989 von Le Borgne und Mitarbeitern hergestellt, die ihre Wirksamkeit in der lebenden Polymerisation von Epoxiden zeigten. [29] [b] T [8C] TOF [9] [h À1 ] [32] Basierend auf ihren früheren Arbeiten mit heterogenen Cr III -Salen-Komplexen auf Kieselgel verwendeten García und Mitarbeiter polymere Al III -Salen-Komplexe, deren Grundgerüst aus einem teilvernetzten Polystyrol (Al III -Salen/PS; Schema 14 b) oder Poly(ethylenglycolbismethacrylat) (Al III -Salen/PEA; Schema 14 a) besteht. [33] Das vernetzte Poly(styrol-co-p-divinylbenzol)-Gerüst besitzt Aminomethylgruppen, die zur kovalenten Verankerung eines Salenliganden geeignet sind.…”