title: One-pot sequences of reactions with sol-gel entrapped opposing reagents: an enzyme and metal-complex catalysts.
abstract: We extend our sol-gel methodology of one-pot sequences of reactions with opposing reagents to an enzyme/metal-complex pair. Sol-gel entrapped lipase and sol-gel entrapped RhCl[P(C(6)H(5))(3)](3) or Rh(2)Co(2)(CO)(12) were used for one-pot esterification and C-C double bond hydrogenation reactions, leading to saturated esters in good yields. When only the enzyme is entrapped, the homogeneous catalysts quench its activity and poison it. Thus, when 10-undecenoic acid and 1-pentanol were subjected in one pot to the entrapped lipase and to homogeneously dissolved RhCl[P(C(6)H(5))(3)](3) under hydrogen pressure, only 7% of the saturated 1-pentyl undecanoate was obtained. The yield jumped 6.5-fold when both the enzyme and the catalyst were immobilized separately in silica sol-gel matrixes. Similar one-pot esterifications and hydrogenations by sol-gel entrapped lipase and heterogenized rhodium complexes were carried out successfully with the saturated nonoic, undecanoic, and lauric acids together with several saturated and unsaturated alcohols. The use of (S)-(-)-2-methylbutanol afforded an optically pure ester. The heterogenized lipase is capable of inducing asymmetry during esterification with a prochiral alcohol. Both the entrapped lipase and the immobilized rhodium catalysts can be recovered simply by filtration and recycled in further runs without loss of catalytic activity.
authors.affiliation: Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Faina
authors.initials: F
authors.lastname: Gelman
authors.forename: Jochanan
authors.initials: J
authors.lastname: Blum
authors.forename: David
authors.initials: D
authors.lastname: Avnir
mesh_terms: D000438:Alcohols / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry; D002384:Catalysis; D004800:Enzymes, Immobilized / Q000737:chemistry*; D004952:Esters / Q000138:chemical synthesis*; D005782:Gels / Q000737:chemistry; D008049:Lipase / Q000737:chemistry* / Q000378:metabolism; D009942:Organometallic Compounds / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*
chemical_list: D000438:Alcohols; D002264:Carboxylic Acids; D004800:Enzymes, Immobilized; D004952:Esters; D005782:Gels; D009942:Organometallic Compounds; D012238:Rhodium; D008049:Lipase