Progress reaction profiles are affected by both catalyst activation and deactivation processes occurring alongside the main reaction. These processes complicate the kinetic analysis of reactions, ...often directing researchers toward incorrect conclusions. We report the application of two kinetic treatments, based on variable time normalization analysis, to reactions involving catalyst activation and deactivation processes. The first kinetic treatment allows the removal of induction periods or the effect of rate perturbations associated with catalyst deactivation from kinetic profiles when the quantity of active catalyst can be measured. The second treatment allows the estimation of the activation or deactivation profile of the catalyst when the order of the reactants for the main reaction is known. Both treatments facilitate kinetic analysis of reactions suffering catalyst activation or deactivation processes.
Keep calm and carry on (doing kinetics): Two different kinetic analysis methods, based on variable time normalization analysis (VTNA), are described for studying reactions with catalyst deactivation and activation processes. The cases studied are a hydroformylation reaction catalyzed by a supramolecular rhodium complex and an aminocatalytic Michael reaction.
An enantiopure helical ferrocene (R p)-5 with five ortho-condensed aromatic rings was synthesized using a PtCl2-catalyzed cycloisomerization of planar-chiral 2-ethynyl-1-(4-phenanthrenyl)ferrocene ...(R p)-6f, prepared in 3 steps from known enantiopure sulfinyl ferrocenyl boronic acid (S S,S p)-7, as the source of planar chirality. This pentacyclic helical ferrocene showed a very high optical rotation value and strong circular dichroism (CD) signals.
An efficient approach to (Rp) planar-chiral tri- and tetracyclic ortho-condensed aromatic ferrocenes was developed through the enantioselective cationic Au(i)-catalyzed cycloisomerization, in the ...presence of bidentate phosphine ligand (R)-DTBM-Segphos, from readily available ortho-alkynylaryl ferrocenes under very mild conditions (11 examples, up to 92% yield and 93% ee).
Progress reaction profiles are affected by both catalyst activation and deactivation processes occurring alongside the main reaction. These processes complicate the kinetic analysis of reactions, ...often directing researchers toward incorrect conclusions. We report the application of two kinetic treatments, based on variable time normalization analysis, to reactions involving catalyst activation and deactivation processes. The first kinetic treatment allows the removal of induction periods or the effect of rate perturbations associated with catalyst deactivation from kinetic profiles when the quantity of active catalyst can be measured. The second treatment allows the estimation of the activation or deactivation profile of the catalyst when the order of the reactants for the main reaction is known. Both treatments facilitate kinetic analysis of reactions suffering catalyst activation or deactivation processes.
Mit der Zeit gehen: Zwei verschiedene kinetische Analysemethoden auf Basis der zeitvarianten Normierungsanalyse (VTNA) werden für die Untersuchung von Reaktionen mit Katalysator‐Desaktivierungsprozessen und ‐Aktivierungsprozessen beschrieben. Die studierten Fälle sind eine von einem supramolekularen Rh‐Komplex katalysierte Hydroformylierung und eine aminokatalytische Michael‐Reaktion.
Ring-opening polymerization and teroligomerization processes that involve two different epoxides and carbon dioxide are significantly more efficiently executed in a supercritical CO2 medium. Here, we ...demonstrate that this generally considered green medium is advantageous for the catalytic formation of both conventional and biobased co- and teroligomers avoiding the occurrence of diffusion-limited catalysis while maximizing the polymer quality, yield, and carbonate content.
An efficient approach to (
R
p
) planar-chiral tri- and tetracyclic
ortho
-condensed aromatic ferrocenes was developed through the enantioselective cationic Au(
i
)-catalyzed cycloisomerization, in ...the presence of bidentate phosphine ligand (
R
)-DTBM-Segphos, from readily available
ortho
-alkynylaryl ferrocenes under very mild conditions (11 examples, up to 92% yield and 93% ee).
An asymmetric gold(
i
)-catalyzed intramolecular hydroarylation of aquiral 2-alkynylaryl ferrocenes provides (
R
p
) planar-chiral
ortho
-condensed aromatic ferrocenes in high yield and enantioselectivity.
Active catalysts derived from cobalt and the Xantphos ligand were synthesised, characterised and tested in the hydroformylation of pure linear alkenes or their mixtures. The preformed complex Co
2
...(CO)
6
(Xantphos) showed similar reactivity and selectivity towards aldehydes to the active catalyst formed
in situ
from equimolar amounts of Co
2
(CO)
8
and Xantphos. In the case of oct-1-ene, the linear aldehyde was obtained with good chemo- and regio-selectivity (linear to branched ratio was up to 75 : 25). For all octene isomers, tandem isomerisation-hydroformylation processes took place. Regioselectivities for all the studied octene isomers remained practically constant, independent of the position or geometry of the C&z.dbd;C double bond in the starting material. Moreover, by-products were formed in similarly small amounts for all the octene isomers. We also demonstrated that this chemistry is an interesting strategy for valorising mixtures of linear hexenes, heptenes or octenes by transforming the initial mixture into one major aldehyde (addition of a CHO group to the C
1
carbon of the alkene skeleton, up to 73% selectivity). Moreover, these mixtures of alkenes were hydroformylated with low final amounts of non-hydroformylated alkenes, hydrogenated alkenes and alcohols.
Active catalysts derived from cobalt and the Xantphos ligand were synthesised, characterised and tested in the hydroformylation of pure linear alkenes or their mixtures.
Over several years, our research team has contributed to ligand design for metal-catalyzed stereoselective transformations. This has been achieved with the synthesis and application to organic ...transformations of interest of an array of structurally diverse P-containing ligands. These range from highly modular enantiopure phosphine–phosphite ligands to supramolecularly regulated enantioselective phosphorus-based catalysts. Our research in supramolecular interactions has also led to the discovery of an unprecedented halogen-bonded rhodium-catalyst.
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