title: Alkylchlorotins grafted to cross-linked polystyrene beads by a -(CH2)n- spacer (n=4, 6, 11): selective, clean and recyclable catalysts for transesterification reactions.
abstract: Insoluble polystyrene grafted compounds of the type (P-H)(1-t){P-(CH2)n SnBu(p)Cl(3-p)}(t), (P-H)(1-t){P-(CH2)n SnBuO}(t) and (P-H)(1-t)[{P-(CH2)n SnBuCl}2O](t/2), in which (P-H) is a cross-linked polystyrene; n=4, 6, and 11; p=0 and 1; and t the degree of functionalisation, were synthesised from Amberlite XE-305, a polystyrene cross-linked with divinylbenzene. The compounds were characterised by using elemental analysis, and IR, Raman, solid-state 117Sn NMR, and 1H and 119Sn high-resolution MAS NMR spectroscopy. The influence of the spacer length and the tin functionality on the catalytic activity of these compounds, as well as their recycling ability, was assessed in the transesterification reaction of ethyl acetate with various alcohols. These studies showed significant differences in the activity of the catalysts interpreted in terms of changes in the mobility of the catalytic centres. Some of the supported catalysts could be recycled at least seven times without noticeable loss of activity. The residual tin content in the reaction products was found to be as low as 3 ppm.
authors.affiliation: High Resolution NMR Centre, Department of Polymer Science and Structural Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Carlos
authors.initials: C
authors.lastname: Camacho-Camacho
authors.forename: Monique
authors.initials: M
authors.lastname: Biesemans
authors.forename: Manu
authors.initials: M
authors.lastname: Van Poeck
authors.forename: Frédéric A G
authors.initials: FA
authors.lastname: Mercier
authors.forename: Rudolph
authors.initials: R
authors.lastname: Willem
authors.forename: Karine
authors.initials: K
authors.lastname: Darriet-Jambert
authors.forename: Bernard
authors.initials: B
authors.lastname: Jousseaume
authors.forename: Thierry
authors.initials: T
authors.lastname: Toupance
authors.forename: Uwe
authors.initials: U
authors.lastname: Schneider
authors.forename: Ursula
authors.initials: U
authors.lastname: Gerigk