Catalytic behavior of silyl-amide complexes for lactide polymerization

Simple magnesium alkoxides: synthesis, molecular structure, and catalytic behaviour in the ring-opening polymerization of lactide and macrolactones and in the copolymerization of maleic anhydride and propylene oxide

“…28,29 Generally, the most investigated catalysts for the ROP of cyclic esters and for the ROCOP of epoxides and anhydrides are heteroleptic complexes of non-toxic metals such as magnesium [30][31][32] and zinc, [33][34][35] in which the metal center is coordinated to electronically and sterically tailored ancillary ligands and labile ligand/s that often behave as initiating groups; while this strategy offers the benefits of a very efficient control over polymerization behavior (such as tacticity), [36][37][38] its disadvantages include somewhat less sustainable nature of the catalyst because of the required multistep synthesis of ancillary ligands. In contrast, recent studies have demonstrated that simple metal-alkoxides or metal-amides, which are commonly used as metal precursors in coordination chemistry, may represent a more sustainable route for polyester synthesis [39][40][41][42][43][44] and/or their degradation by alcoholysis. 45,46 In 2012, Chen and Cui reported a very simple binary catalyst Mg n Bu 2 /Ph 2 CHOH that showed very high activity in the ROP of lactide (LA), in the presence of a large excess amount of alcohol.…”