Silica-Supported zirconium complexes and their polyoligosilsesquioxane analogues in the transesterification of acrylates: Part 2. activity, recycling and regeneration

Valérie Salinier, Geraldp Niccolai, Véronique Dufaud*, Jean-Marie Maurice Basset

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

The catalytic activity of both supported and soluble molecular zirconium complexes was studied in the transesterification reaction of ethyl acrylate by butanol. Two series of catalysts were employed: three well defined silica-supported acetylacetonate and n-butoxy zirconium(IV) complexes linked to the surface by one or three siloxane bonds, (=SiO)Zr(acac)3 (1) (=3iO)3Zr(acac) (2) and (=SiO)3Zr(0-n-Bu) (3), and their soluble polyoligosilsesquioxy analogues (c-C5H9) 7Si8O12(CH3)2Zr(acac) 3 (I'), (c-C5Hc,)7Si7O 12Zr(acac) (Z'), and (cC5Hg)7Si 7O12Zr(O-W-Bu) (3'). The reactivity of these complexes were compared to relevant molecular catalysts [zirconium tetraacetylacetonate, Zr(acac)4 and zirconium tetra-n-butoxide, Zr(O-n-Bu)4]. Strong activity relationships between the silica-supported complexes and their polyoligosilsesquioxane analogues were established. Acetylacetonate complexes were found to be far superior to alkoxide complexes. The monopodal complexes 1 and V were found to be the most active in their respective series. Studies on the recycling of the heterogeneous catalysts showed sig-nificant degradation of activity for the acetylacetonate complexes (1 and 2) but not for the less active tripodal alkoxide catalyst, 3. Two factors are thought to contribute to the deactivation of catalyst: the lixivation of zirconium by cleavage of surface siloxide bonds and exchange reactions between acetylacetonate ligands and alcohols in the substrate/product solution. It was shown that the addition of acetylacetone to the low activity catalyst Zr(O-M-Bu)4produced a system that was as active as Zr(acac)4. The applicability of ligand addition to heterogeneous systems was then studied. The addition of acetylacetone to the low activity solid catalyst 3 produced a highly active catalyst and the addition of a stoichiometric quantity of acetylacetone at each successive batch catalytic run greatly reduced catalyst deactivation for the highly active catalyst 1.

Original languageEnglish (US)
Pages (from-to)2168-2177
Number of pages10
JournalAdvanced Synthesis and Catalysis
Volume351
Issue number13
DOIs
StatePublished - Sep 1 2009

Keywords

  • Acetylacetonate and alkoxy ligands exchange
  • Catalyst regeneration
  • Recycling
  • Silica-supported zirconium complexes
  • Transesterification of (meth)acrylates

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

Fingerprint Dive into the research topics of 'Silica-Supported zirconium complexes and their polyoligosilsesquioxane analogues in the transesterification of acrylates: Part 2. activity, recycling and regeneration'. Together they form a unique fingerprint.

Cite this