Georgios Papadogianakis

Catalytic conversions in water. Part 5 : Carbonylation of 1-(4-isobutylphenyl)ethanol to ibuprofen catalysed by water-soluble palladium-phosphine complexes in a two-phase system

1-(4-Isobutylphenyl)ethanol (IBPE) was carbonylated to 2-(4-isobutylphenyl)propionic acid (ibuprofen) in an aqueous/organic two phase system using the water-soluble Pd(tppts) 3 catalyst [tppts = P(C 6 H 4 -m-SO 3 Na) 3 ] in the presence of p-CH 3 C 6 H 4 SO 3 H at 363 K, 15 MPa CO pressure and a palladium concentration of 150 ppm without addition of organic solvents. Under these conditions the conversion of IBPE was 83% and the selectivity to ibuprofen 82% with no decomposition of the Pd(tppts) 3 catalyst. Both the activity and selectivity were strongly influenced by the tppts/Pd molar ratio and the nature of the added Bronsted acid. Maximum efficiency was observed for P/Pd = 10. Acids of weakly or non-coordinating anions, such as p-CH 3 C 6 H 4 SO 3 H, CF 3 COOH or HPF 6 afforded carbonylation. No catalytic activity was observed in the presence of acids of strongly coordinating anions, such as HI. The water-soluble Pd/dppps catalyst [dppps = Ar 2-n Ph n P-(CH 2 ) 3 -PP h Ar 2-h ; Ar = C 6 H 4 -m-SO 3 Na; n = n = 0: 86% and n = 0, n = 1: 14%] exhibited low catalytic activity and the major product obtained was the linear isomer of ibuprofen, 3-(4-isobutylphenyl) propionic acid (3-IPPA) with selectivities up to 78%. Replacement of tppts by a ligand containing less -SO 3 Na groups such as monosulphonated triphenylphosphine (tppms) gives rise to a dramatic drop in the catalytic activity and selectivity to ibuprofen. No catalytic activity was observed using palladium catalysts modified with 2-pyridyldiphenylphosphine (PyPPh 2 )and tris(2-pyridyl) phosphine (PPy 3 ) which are both water soluble in their protonated form. A catalytic cycle is proposed to explain the observed results.

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 4: Carbonylation of 5-hydroxymethylfurfural (HMF) and benzyl alcohol catalysed by palladium trisulfonated triphenylphosphine complexes

Abstract Carbonylation of renewable 5-hydroxymethylfurfural (HMF) under aqueous phase catalytic conditions using the water soluble catalyst Pd(TPPTS)3 (TPPTS = sodium salt of trisulfonated triphenylphosphine, P(C6H4-m-SO3Na)3) was investigated. Pd(TPPTS)3 was easily prepared in situ via complexation of PdCl2 in an aqueous TPPTS solution and reduction with carbon monoxide. Using the Pd(TPPTS)3 catalyst at 70°C, 5 bar CO pressure and [Pd] = 150 ppm chemoselective carbonylation of HMF was observed to yield 5-formylfuran-2-acetic acid (FFA) as the sole carbonylation product; the only by-product was 5-methylfurfural (MF). The formation of MF under these conditions amounts to a new type of catalytic and very selective reduction with CO, formally equivalent to hydrogenolysis of an alcohol group without using H2. This is surprising since one would expect the water gas shift reaction. Both the activity and selectivity of HMF carbonylation were strongly influenced by the TPPTS Pd molar ratio; maximum efficiency being observed for PPTS Pd = 6 . The nature of the anion of the added acid markedly influenced the selectivity. Acids of weakly or non-coordinating anions, such as H3PO4, CF3COOH, p-CH3C6H4SO3H, H2SO4, and HPF6 afforded mainly carbonylation. The selectivity decreased dramatically with acids of strongly coordinating anions such as HBr and HI. With the latter the only product observed was MF. Replacement of TPPTS by ligands containing less −SO3Na groups such as disulfonated triphenylphosphine (TPPDS) or disulfonated tris(p-fluorophenyl)phosphine (TFPPDS) gives rise to a dramatic drop in the catalytic activity. Using palladium catalysts modified with monosulfonated triphenylphosphine (TPPMS) only traces of FFA and MF were obtained. Pd(TPPTS)3 in aqueous media similarly catalyses the selective carbonylation of benzyl alcohol to phenylacetic acid. In sharp contrast, classical hydrophobic Pd PPh 3 catalysts are inactive in this carbonylation reaction in organic solvents. A catalytic cycle is proposed to explain the observed results.

Catalytic conversions in water: Part 13. Aerobic oxidation of olefins to methyl ketones catalysed by a water-soluble palladium complex – mechanistic investigations

Abstract Water-soluble palladium(II) bathophenanthroline is a stable, recyclable catalyst for the selective aerobic oxidation of terminal olefins to the corresponding 2-alkanones in a biphasic liquid–liquid system. Kinetic measurements indicate that the active catalyst is a homogeneous mononuclear species.

Factors effecting the hydrogenation of fructose with a water soluble Ru-TPPTS complex. A comparison between homogeneous and heterogeneous catalysis

Abstract Inulin, a polysaccharide containing one d -glucose and 10 to 50 d -fructose units, when hydrolysed and hydrogenated in a one pot approach, would be an attractive d -mannitol feedstock. For this purpose, the hydrogenation was studied with fructose as a model compound, using a water soluble, homogeneous catalyst. This catalyst contains ruthenium as the active metal, and trisulfonated triphenylphosphine (TPPTS, P(m-C6H4SO3Na)3), as the ligand. The effects of temperature, pressure, catalyst/substrate and ligand/metal ratios on the activity and selectivity were investigated. The reaction was shown to be homogeneously catalysed, despite the formation of some ruthenium particles at higher temperatures (>90°C), and the active complex was studied with 1 H and 31 P NMR. Addition of HCl or salts (NaCl, Nal and CaCl2) increased the selectivity to d -glucitol and the catalytic activity. Upon deuterogenation of fructose with H2 in D2O, D was built in only at the 2-position.

Catalytic conversions in water. Part 10.† Aerobic oxidation of terminal olefins to methyl ketones catalysed by water soluble palladium complexes

Water soluble palladium(II) complexes of bidentate diamine ligands, such as bathophenanthroline disulfonate, are stable, recyclable catalysts for the selective aerobic oxidation of terminal olefins to the corresponding alkan-2-ones in a biphasic liquid–liquid system.

Catalytic conversions in water: a novel carbonylation reaction catalysed by palladium trisulfonated triphenylphosphine complexes

The renewable basic chemical 5-hydroxymethylfurfural (HMF) is selectively carbonylated to the new compound 5-formylfuran-2-acetic acid using a water-soluble palladium complex of trisulfonated triphenylphosphine as the catalyst in an acidic aqueous medium at 70 °C and 5 bar CO pressure; when hydrogen iodide is the acid component, the reaction follows a different course and HMF is selectively reduced to 5-methylfurfural.

Catalytic conversions in water: 17O, {1H}31P and 35Cl NMR study of a novel stoichiometric redox reaction between PdCl2, tppts and H2O [tppts = P(C6H4-m-SO3Na)3]

17 n O, {1H}31P and 35Cl NMR are used to investigate the mechanism of the reaction of PdCl2 with tppts [tppts = P(C6H4-m-SO3Na)3] in 17O enriched water to give the novel complex [PdCl(tppts)3]+1, which is reduced quantitatively to Pd(tppts)32 with tppts (8 d, 25 °C); with CO (2 bar) reduction to 2 is quantitative in 5 min at 25 °C.