Ring-Opening Polymerization of Trimethylene Carbonate Using Aluminum(III) and Tin(IV) Salen Chloride Catalysts

Abstract

Aluminum and tin salen complexes have been shown to effectively catalyze the ring-opening polymerization (ROP) of trimethylene carbonate (TMC) to polycarbonate. The most active salen derivative in each instance contained a phenylene backbone with chloro substituents in the 3,5-positions of the phenolate rings, with the aluminum derivatives being significantly more active than their tin(IV) counterparts. Importantly, the resultant polycarbonate was shown by 1 H NMR to be void of ether linkages. The reaction was demonstrated to proceed via a mechanism first order in both [catalyst] and [monomer] and to involve TMC ring-opening by way of acyl oxygen bond cleavage. Consistent with a reaction pathway involving an insertion of the monomer into the metal-nucleophile bond (e.g., Al-Cl or Sn-Cl), the activation parameters were determined to be ∆H q ) 51 kJ/mol and ∆S q ) -141 J/(mol deg).

Aluminum Methyl and Chloro Complexes Bearing Monoanionic Aminephenolate Ligands: Synthesis, Characterization, and Use in Polymerizations

“…This has previously been suggested as a plausible mechanism for ROP of trimethylene carbonate using a chloro-aluminum salen complex. 73 Due to the broad polydispersity of the polymer produced using 4 and 5 without BnOH, the polymerization mechanism for these systems was not studied in detail. The resulting polymers were characterized using 1 H NMR spectroscopy and MALDI-TOF MS, as discussed below.…”

Zwitterionic ring opening polymerization of lactide by metal free catalysts: Production of cyclic polymers

“…Such conditions induce side reactions such as transesterification and racemization, which hamper the control over the polymerization process. The scientific interest in well-defined architectures including telechelic-, block-, graft-, and star-shaped polymers has initiated major research efforts toward initiators to yield welldefined poly(lactide)s. The ROP of lactides have been investigated using various metal catalysts, including complexes of Sn, [5][6][7] Y, 8 Ln, [9][10][11][12][13] Fe, 14 Ca, 15 Ti, 16 Mg, 17 Al, [18][19][20] and Zn, [21][22][23][24][25] which generally proceeds by insertion of monomer into the metal-alkoxide bond. Some of these initiators have proved to be very attractive since they give rise to a controlled polymerization of lactide.…”

Synthesis, characterization, and in vitro antimicrobial activities of organotin(IV) complexes of Schiff bases with ONO‐type donor atoms

“…Although the true mechanism of biological action is not understood completely, there appears to be enough evidence that the activities of organotin(IV) compounds are dependent on both the covalently bonded organic groups and the ligands. The organotin(IV) complexes have also found applications in the fields of catalysis [25,26], fluorescence probing of DNA traces [27], and nonlinear optics [9,28].…”