Ammonium tagged Hoveyda-Grubbs catalysts immobilized on magnetically separable core-shell silica supports for ring-closing metathesis reactions


ÖZTÜRK B. Ö.

MICROPOROUS AND MESOPOROUS MATERIALS, vol.267, pp.249-256, 2018 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 267
  • Publication Date: 2018
  • Doi Number: 10.1016/j.micromeso.2018.04.002
  • Title of Journal : MICROPOROUS AND MESOPOROUS MATERIALS
  • Page Numbers: pp.249-256
  • Keywords: Hoveyda-Grubbs type catalysts, Non-covalent immobilization, Magnetic nano-particles, Olefin metathesis, OLEFIN METATHESIS, RUTHENIUM CATALYSTS, NHC LIGAND, COMPLEXES, BEARING

Abstract

Ammonium tagged Hoveyda-Grubbs (Ru-1) catalyst was immobilized on core-shell structured silica gel bearing a magnetic nano-sized alpha-Fe2O3 core via non-covalent interactions. Core-shell silica gel materials were synthesized using a two-step coating procedure of alpha-Fe2O3 in the presence of cationic (dodecyl trimethyl ammonium chloride, DTMAC) and non-ionic (Synperonic F108) surfactants and tetraethoxysilane (TEOS) as the silica source. Double SiO2 coated SiO2(2)@alpha-Fe203 supports with a high surface area of 646 m(2)/g and pore size/volumes of 2.88 nm/0.393 cm(3) were obtained after removal of template surfactants from silica gel by extraction. Supported catalyst, Ru-1@SiO2(2)@alpha-Fe2O3, was found to be very active in ring-closing metathesis (RCM) reactions of diethyl diallyl malonate (DEDAM) and various dienes. The catalyst can be easily separated from the reaction mixture with the aid of a magnet and was reusable up to eight times with low Ru leaching levels.