1592654-09-5Relevant articles and documents
Lactide polymerization catalyzed by Mg and Zn diketiminate complexes with flexible ligand frameworks
Whitehorne, Todd J. J.,Vabre, Boris,Schaper, Frank
, p. 6339 - 6352 (2014)
Diketimine ligands bearing N-benzyl, N-9-anthrylmethyl and N-mesitylmethyl substituents (nacnacBnH, nacnacAnH, and nacnac MesH) were prepared from condensation of the amine with either acetyl acetone or its ethylene glycol monoketal. Chlorination with N-chlorosuccinimide in the 3-position yielded ClnacnacBnH and ClnacnacAnH. The ligands were reacted with Zn(TMSA)2 (TMSA = N(SiMe 3)2) to yield nacnacAnZn(TMSA) and ClnacnacBnZn(TMSA). Protonation with isopropanol afforded nacnac AnZnOiPr and ClnacnacBnZnOiPr. Reaction of the diketimines with Mg(TMSA)2 afforded nacnacAnMg(TMSA), nacnac MesMg(TMSA), ClnacnacBnMg(TMSA) and Clnacnac AnMg(TMSA). Subsequent protonation with tert-butanol produced nacnacMesMgOtBu and ClnacnacBnMgOtBu, but only decomposition was observed with N-anthrylmethyl substituents. Most complexes were characterized by X-ray diffraction studies. TMSA complexes were monomeric and alkoxide complexes dimeric in the solid state. All alkoxide complexes, as well as nacnacAnMg(TMSA)/BnOH and ClnacnacAnMg(TMSA)/BnOH were moderately to highly active in rac-lactide polymerization (90% conversion in 30 s to 3 h). nacnacAnZnOiPr produced highly heterotactic polymers (Pr = 0.90), ClnacnacBnMgOtBu/BnOH produced slightly isotactic polymers at -30°C (Pr = 0.43), and all other catalysts produced atactic polymers with a slight heterotactic bias. This journal is the Partner Organisations 2014.