Presentation Title

Polymerization of lactide by aluminum ion pairs studied with 27Al NMR

Presentation Type

Poster

Department

Chemistry

Major

Chemistry

Abstract

Polymerization of lactide by aluminum ion pairs studied with 27Al NMR

Logan A. Schmitz, Arnold L. Rheingold, David B. Green, Joseph M. Fritsch

Aluminum ion pair complexes containing an octahedral bis-ligated aluminum cation and a tetrahedral tetraphenoxide aluminate anion have been shown to polymerize lactide into poly-lactic acid (PLA). The structure of the active catalyst was investigated through the synthesis of aluminum complexes in different coordination environments were distinguishable by 27Al NMR (octahedral d 23 ppm and tetrahedral d 42 ppm). The bis-ligated octahedral cation with tetrachloro aluminate (27Al NMR signals at 23 and 103 ppm) and lithium tetraphenoxide aluminate (27Al NMR signal at 46 ppm) were prepared, studied with 27Al NMR, and their lactide polymerization activity assessed. Since neither fragment exhibited polymerization characteristics similar to the original system, the ion pair complex was further studied with variable temperature 27Al NMR.

Faculty Mentor

Dr. Joseph Fritsch

Funding Source or Research Program

Summer Undergraduate Research Program, Undergraduate Research Fellowship

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Polymerization of lactide by aluminum ion pairs studied with 27Al NMR

Polymerization of lactide by aluminum ion pairs studied with 27Al NMR

Logan A. Schmitz, Arnold L. Rheingold, David B. Green, Joseph M. Fritsch

Aluminum ion pair complexes containing an octahedral bis-ligated aluminum cation and a tetrahedral tetraphenoxide aluminate anion have been shown to polymerize lactide into poly-lactic acid (PLA). The structure of the active catalyst was investigated through the synthesis of aluminum complexes in different coordination environments were distinguishable by 27Al NMR (octahedral d 23 ppm and tetrahedral d 42 ppm). The bis-ligated octahedral cation with tetrachloro aluminate (27Al NMR signals at 23 and 103 ppm) and lithium tetraphenoxide aluminate (27Al NMR signal at 46 ppm) were prepared, studied with 27Al NMR, and their lactide polymerization activity assessed. Since neither fragment exhibited polymerization characteristics similar to the original system, the ion pair complex was further studied with variable temperature 27Al NMR.