Immobilization of ruthenium catalysts for allylations with allyl alcohol

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 2010-09, Vol.330 (1), p.26-34
• Main Authors: van Rijn, Jimmy A., Bouwman, Elisabeth, Drent, Eite
• Format: Article
• Language: English
• Subjects: Allyl alcohol; Allylation; Catalysis; Chemistry; Exact sciences and technology; General and physical chemistry; Immobilization; Phenol; Ruthenium; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2010.06.027

Immobilization of [RuCp(PP)] + complexes was achieved via electrostatic or coordination interactions. In the catalytic allylation of phenol the selectivity is dependent on the method used for immobilization of the catalyst. [RuCp(PP)] + complexes active for allylation of alcohols with allyl alcohol as the allylating agent were immobilized on solid supports. Two different immobilization methods have been applied: (1) via electrostatic interactions of the cationic complex on ion-exchange resins, where the anion is present on the support and (2) via a coordination bond with a ligand covalently-bound on the support. Both methods give high yields of immobilized complex through relatively simple procedures. The catalysts immobilized via ionic interactions prove to be able to allylate both 1-octanol and 4- tert-butylphenol with very low leaching of the catalyst, thus forming allyl octyl ether and C-allylated phenol, respectively. The accumulation of water in the highly hydrophilic resin precludes the O-allylation of phenol and also retards the C-allylation reaction. The catalysts immobilized via a coordination bond are not hydrophilic; with these catalysts selective O-allylation of phenols is achieved, with recycling of the catalysts over multiple runs. Leaching of the catalyst from the support is somewhat higher than for the electrostatically-bound catalyst and quarternisation (allylation) of the excess of phosphine groups present on the support plays an important role in the activity of the immobilized catalysts for the allylation reaction.