6533b854fe1ef96bd12af26a

RESEARCH PRODUCT

NMR and Quantum-Chemical Study on the Structure of Ester Enolate−Aluminum Alkyl Complexes as Models of the Active Center in the Anionic Polymerization of Methacrylates in Toluene

Axel H. E. MüllerBernd MathiaschHelmut SchlaadHorst WeissSusanne SteigerBardo Schmitt

subject

chemistry.chemical_classificationReaction mechanismPolymers and PlasticsOrganic ChemistrySolution polymerizationPolymerCarbon-13 NMRTolueneInorganic ChemistryActive centerchemistry.chemical_compoundMonomerAnionic addition polymerizationchemistryPolymer chemistryMaterials Chemistry

description

6Li and 13C NMR on ethyl α-lithioisobutyrate (EiBLi) and quantum-chemical (DFT) calculations on methyl α-lithioisobutyrate (MiBLi) were used to elucidate the structure of the active center in the anionic polymerization of methacrylates in the presence of triethylaluminum (AlEt3) in toluene. This study reveals ester enolate/aluminum alkyl complexes with different degrees of association, (MiBLi·AlEt3)n (n = 1, 2, 4), and different stoichiometries, MiBLi·xAlEt3 (x = 1, 2). In the presence of methyl pivalate (MPiv), which is taken as a model compound for the monomer and polymer, complexes such as (MiBLi·MPiv·AlEt3)n (n = 1, 2) are formed. These complexes can dissociate into MiBLi·2AlEt3 and MPiv·AlEt3 when AlEt3 is used in excess.

yearjournalcountryeditionlanguage
1999-11-24Macromolecules
https://doi.org/10.1021/ma990453s