%0 Journal Article
%T 1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ¦Å-caprolactone and rac-lactide under solvent-free conditions
%A Astrid Hoppe
%A Faten Sadaka
%A Claire-H¨¦l¨¨ne Brachais
%A Gilles Boni
%J Beilstein Journal of Organic Chemistry
%D 2013
%I 
%R 10.3762/bjoc.9.73
%X The ring-opening polymerization of ¦Å-caprolactone (¦Å-CL) and rac-lactide (rac-LA) under solvent-free conditions and using 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO2) as precatalyst is described. Linear and star-branched polyesters were synthesized by successive use of benzyl alcohol, ethylene glycol, glycerol and pentaerythritol as initiator alcohols, and the products were fully characterized by 1H and 13C{1H} NMR spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). BMIM-2-CO2 acts as an N-heterocyclic carbene precursor, resulting from in situ decarboxylation, either by heating under vacuo (method A) or by addition of NaBPh4 (method B). Possible catalytic and deactivation mechanisms are proposed.
%K aliphatic polyesters
%K green polymerization reaction
%K imidazolium-2-carboxylates
%K N-heterocarbene precursor
%K organocatalysis
%U http://dx.doi.org/10.3762/bjoc.9.73