Göran Verspui

Reaction intermediates in the Pd/tppts-catalyzed aqueous phase hydrocarboxylation of olefins monitored by NMR spectroscopy (tppts=P(C6H4-m-SO3Na)3) ☆

Abstract The involvement of water-soluble Pd–hydride, Pd–alkyl and Pd–acyl complexes as intermediates in the catalytic cycle of the Pd-catalyzed aqueous phase hydrocarboxylation of olefins was demonstrated. Kinetic investigations have shown that the conversion of a Pd–acyl to a Pd–hydride complex is a rate-determining, pseudo first-order reaction.

Catalytic conversions in water: Part 11: Highly active water-soluble palladium-catalysts in the hydrocarboxylation of olefins and the alternating copolymerization of CO and olefins in water

Abstract Water-soluble palladium complexes of the sodium salt of trisulfonated triphenylphosphine (tppts, P(C 6 H 4 - m -SO 3 Na) 3 ) catalyze the aqueous biphasic hydrocarboxylation of olefins. High catalytic activities were observed with small, sparingly water-soluble olefins such as propene (TOF>2800 h −1 in the conversion to n - and isobutyric acid). Although selectivities ( n / iso ratio) were rather moderate in the hydrocarboxylation of propene and 1-octene, high selectivities (>99%) were observed in the conversion of isobutene or cyclopentene to 3-methylbutyric acid and cyclopentanecarboxylic acid, respectively. The water-soluble Pd catalyst based on the bidentate phosphine dpppr-s (1,3-C 3 H 6 (P(C 6 H 4 - m -SO 3 Na) 2 ) 2 ) catalyzes the alternating copolymerization of CO and olefins to polyketones. Activities >4.0 kg of copolymer per gram Pd per hour were found in the alternating copolymerization of CO and ethene.

Catalytic conversions in water, part 8 : carbonylation and hydrocarboxylation reactions catalyzed by palladium trisulfonated triphenylphosphine complexes

Abstract The water-soluble Pd(tppts)3 complex (tppts=P(C6H4-m-SO3Na)3) is an active catalyst for the carbonylation of benzylic type alcohols in aqueous/organic two-phase systems in the presence of a Bronsted acid cocatalyst. For example, 1-(4-isobutylphenyl)ethanol afforded 2-(4-isobutylphenyl)propionic acid in 82% selectivity at 83% conversion and 5-hydroxymethylfurfural (HMF) gave 5-formylfuran-2-acetic acid in 72% selectivity at 90% conversion. In the latter case, use of an acid with a strongly coordinating anion led to the preferential formation of the reduction product 5-methylfurfural (MF), e.g. HI afforded MF in >99% selectivity. Pd(tppts)3 is also an usual active catalyst (T.O.F.>2500) for the biphasic hydrocarboxylation of propene to n- and isobutyric acid, being substantially more active than the analogous Pd/PPh3 in organic media.

Catalytic conversions in water: Part 19. Smooth hydroformylation of N-allylacetamide in mono- and biphasic aqueous media

Abstract The Rh/tppts (tppts=P(C 6 H 4 - m -SO 3 Na) 3 ) catalysed hydroformylation of N -allylacetamide in water proceeds at a much faster rate and in a much higher selectivity (>99%) towards the aldehydes, 4-acetamidobutanal and 2-methyl-3-acetamidopropanal, than the Rh/PPh 3 catalysed reaction in organic solvents, such as THF, toluene and methanol. In water, at 90°C and 50 bar H 2 /CO, turnover frequencies (TOF)>10.700 h −1 were observed. Unfortunately, both catalysts exhibited a rather low regioselectivity (linear/branched (l/b) ratio=1.1–1.5) which for Rh/tppts was found not to depend on the temperature, pressure, or ligand concentration. By using phosphate buffers the optimum pH of the aqueous reaction mixture was found to be pH 7.0. Under basic conditions (pH 11.0), the l/b ratio increased to l/b=6.5, while the overall selectivity towards the aldehydes decreased to 41%. In a toluene/water biphasic system, due to the presence of water, the selectivity towards the aldehydes remained >99%. Although Rh/PPh 3 (operating in the organic phase) was less active compared to Rh/tppts (operating in the aqueous phase), Rh/PPh 3 could easily be separated from the aqueous product layer. The hydrophobic Rh/Xantphos catalyst (Xantphos=4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) afforded a product mixture with l/b ratios up to 20 and could be recycled in five consecutive runs without loss in activity.

Catalytic conversions in water. Part 9. High activity of the Pd/dpppr-s/Brønsted acid system in the alternating copolymerization of ethene and carbon monoxide {dpppr-s = C3H6-1,3-[P(C6H4-m-SO3Na)2]2}

The formation of alternating copolymers of ethene and carbon monoxide proceeds rapidly in the aqueous phase in the presence of a water-soluble palladium catalyst and a Bronsted acid; activities of >4 kg of polymer per g palladium per hour were observed.

Selective hydroformylation of N-allylacetamidein an inverted aqueous two-phase catalytic system, enabling a shortsynthesis of melatonin

Water increases the selectivity in the Rh–phosphine catalysed hydroformylation of N-allylacetamide; an aqueous–organic biphasic system, containing a hydrophobic Rh-catalyst, provided facile catalyst/product separation, after which the aqueous product phase could be used in a one-pot synthesis of N-acetyl-5-methoxytryptamine (melatonin).