Ph. Kalck

Carbon nanotubes produced by fluidized bed catalytic CVD: first approach of the process

Abstract Multi-walled carbon nanotubes have been produced with high yield on an iron supported catalyst by catalytic chemical vapor deposition in a fluidized bed reactor. The choice of such a technique allows to reach high selectivity towards the desired material. A remarkable feature of this process is the huge bed expansion observed during the nanotubes growth that affects the fluidization regime due to the evolution of the apparent density of the composite powder. The catalytic powder, the composite material and the purified nanotubes have been analyzed by SEM, TEM and BET nitrogen adsorption.

Multifactorial analysis in the study of hydroformylation of oct-1-ene using supported aqueous phase catalysis

Abstract The influence of the hydration and the surface characteristics of five supports in the hydroformylation of oct-1-ene by supported aqueous phase catalysis (SAPC) using [Rh2(μ-StBu)2(CO)2(TPPTS)2] as catalyst was studied. The results confirm that the size of the pores and the amounts of water were found to be the determining factors contributing to the SAPC. According to the size of pores there is a critical value for which the SAPC takes place either in the classical model or in conditions where the pores are filled. When the pores are fully filled the SAPC can operate efficiently onto the external surface, stabilising the conversion in a relatively wide range of support hydration.

Selective catalysis of the hydration of nitriles into amides. Part II[1]. Kinetic investigation of the reaction catalyzed by [PdCl(OH)(bipy)(H2O)]. Generalization of the reaction

Abstract We have investigated the influence on the yields of (i) the water to nitrile ratio, (ii) the addition at equal periods of the consumed reagents in the hydration of acetonitrile into acetamide catalyzed by the complex [PdCl(OH)(bipy)(H2O)]. A kinetic investigation of the reaction has been carried out and we present a rate law which shows the inhibiting effect of acetamide and (to some extent) of the nitrile. Our results are in agreement with an intramolecular attack of the OH group on the coordinated nitrile. The complexes of general formula [Pd(X)(OH)(L2)(H2O)], X = CH3COO−, Br−, OH−, L2 = bipy, o-phen…, were shown to achieve the selective hydration of various organic nitriles into the corresponding amides.

DIRECT SYNTHESIS OF ACETALS BY RHODIUM CATALYSED HYDROFORMYLATION OF ALKENES IN THE PRESENCE OF ORTHOFORMATE

Abstract The two catalyst precursors [Rh 2 (μ-penicillamine) 2 (CO) 4 ][OTf] 2 and [Rh 2 (μ-cysteine) 2 (CO) 4 ][OTf] 2 in the presence of 4 equivalents of P(OPh) 3 in triethyl orthoformate as solvent and reactant, permit the low pressure hydroformylation of various alkenes into the corresponding acetals. Apart from a few low-yield by-products resulting from isomerization of the substrates, the carbonylated products obtained directly and exclusively are acetals.

Regioselective hydration of acrylonitrile to give acrylamide catalyzed by (Pd(OH)2(bipyridine)(H2O))

Abstract Satisfactory yields were observed for the selective hydration of acrylonitrile to give acrylamide when using the complex (Pd(OH)2(bipy)(H2O))

Selective catalysis of the hydration of nitriles to amides: evidence for an efficient homogeneous precursor containing a PdOH bond

Abstract The preparation of the complex [PdCl(OH) (bipy)](where bipy is 2,2′-bipyridine and can be replaced by a chelating nitrogen-containing ligand) was realized by addition of an equivalent of NaOH to the complex [PdCl 2 (bipy)]. Studies of the hydration of acetonitrile, performed at pH 5.5, show that acetamide was selectively obtained; the yields of amide were improved when the complex [PdCl 2 (bipy)] was treated with an equivalent of OH − from an anion exchange resin to give the complex [PdCl(OH)-(bipy)] n in the absence of Cl − ions in solution. The reactivity studies revealed lower yields and in some cases loss of selectivity when using the systems {PdCl 2− 4 + NaOH}, {Pd(bipy) 2+ 2 + NaOH} {PdCl 2 (bipy) + NaOH} or {Na 2− PdCl 4 + bipy + NaOH}. The synthesis in the presence of an anion exchange resin allowed us to isolate the complex [PdCl(OH)(bipy)(H 2 O)] n in a pure form and in the solid state.

Influence of various parameters on the selectivity of the production of aldehydes starting from alkenes issued from the biomass and using the catalyst precursors Rh2(μ-sr)2(CO)2(PA3)2

Abstract The effects of solvent, ligand L and R group for the catalyst precursor [Rh2(μ-SR)2(CO)2L2] and of the allyl benzene (estragole, eugenol, eugenol methyl ether and safrole) on the yields, rates and regioselectivities of the substrate conversion into aldehydes have been examined. The reactions can be performed in 90 min at 80 °C and 5 bars of a CO/H2 mixture to give up to 95% of the expected aldehydes with complete selectivity. Polar but non-coordinating solvents are preferable

Use of Dinuclear Templates to Perform the Hydroformylation Reaction

The hydroformylation of alkene into the corresponding linear and branched aldehyde is a very important reaction (Cornils 1980, Marko 1974 and Tkatchenko 1982)