Potassium enolates of N,N-dialkylamides as initiators of anionic polymerization

Authors

  • Takashi Ishizone,

    Corresponding author
    1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-H-119, Ohokayama, Meguro-Ku, Tokyo 152-8552, Japan
    • Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-H-119, Ohokayama, Meguro-Ku, Tokyo 152-8552, Japan
    Search for more papers by this author
  • Daizaburo Yashiki,

    1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-H-119, Ohokayama, Meguro-Ku, Tokyo 152-8552, Japan
    Search for more papers by this author
  • Motoyasu Kobayashi,

    1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-H-119, Ohokayama, Meguro-Ku, Tokyo 152-8552, Japan
    Search for more papers by this author
  • Takashi Suzuki,

    1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-H-119, Ohokayama, Meguro-Ku, Tokyo 152-8552, Japan
    Search for more papers by this author
  • Mana Ito,

    1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-H-119, Ohokayama, Meguro-Ku, Tokyo 152-8552, Japan
    Search for more papers by this author
  • Seiichi Nakahama

    1. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-H-119, Ohokayama, Meguro-Ku, Tokyo 152-8552, Japan
    Search for more papers by this author

Abstract

Stable potassium enolates of N,N-diethylacetamide [α-potassio-N,N-diethylacetamide (1)], N,N-diethylpropionamide [α-potassio-N,N-diethylpropionamide (2)], and N,N-diethylisobutyramide [α-potassio-N,N-diethylisobutyramide (3)] were prepared by the proton abstraction of the corresponding N,N-diethylamides with diphenylmethylpotassium (Ph2CHK) or potassium naphthalenide in THF. The relative nucleophilicity of 13 was estimated to be in the order of 1 < 3 < 2 from the results of the alkylation reaction with methyl iodide. N,N-diethylacetamide transferred its α-proton to 2 quantitatively in THF at 0 °C, whereas no reaction occurred between N,N-diethylisobutyramide and 2; this indicated the relative basicity to be 1 < 23. Anionic polymerizations of N,N-diethylacrylamide (DEA) and methyl methacrylate were quantitatively initiated with 2 in THF at −78 °C, whereas the initiation efficiencies of 2 for styrene and 2-vinylpyridine were about 2 and 67%, respectively. The initiation of DEA with 13 at −78 or 0 °C in THF gave poly (DEA)s having broad molecular weight distributions (MWDs; Mw/Mn = 2) and ill-controlled molecular weights. In contrast, poly(DEA)s of narrow MWDs (Mw/Mn < 1.2) and predicted Mn's were obtained with 2 in the presence of diethylzinc (Et2Zn) at −78 °C, whereas the initiations with 1/Et2Zn and 3/Et2Zn at −78 °C resulted in poor control of the molecular weights. At the higher temperature of 0 °C, all the binary initiator systems (13/Et2Zn) induced controlled polymerizations of DEA in terms of the conversion, molecular weight, and MWD. The poly(DEA)s produced with 13/Et2Zn at 0 °C showed mr-rich configurations (mr = 76–89%), as observed for the poly(DEA) generated with Ph2CHK/Et2Zn. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1260–1271, 2007

Ancillary