Novel Palladium‐Catalysed Hydroamination of Myrcene and Catalyst Separation by Thermomorphic Solvent Systems

Abstract

Hydroamination is an elegant and atom economical reaction to convert alkenes into amines. One of the few technical realisations of this reaction is the hydroamination of myrcene to diethylgeranyl-A C H T U N G T R E N N U N G amine, an important precursor of (À)-menthol. However, this so-called "Takasago process" is catalysed by high amounts of alkali metals, especially lithium, which makes it a relatively expensive approach. In the present work, the hydroamination of myrcene with morpholine is catalysed by palladium complexes with bidentate ligands such as bis(diphenylphosphino)butane (DPPB) or bis(2-diphenylphosphinophenyl) ether (DPEphos). The systematic optimisation of the reaction parameters under single-phase conditions led to yields of the 1,4-adducts of higher than 90%. The only side products proved to be the telomers of myrcene, whose formation could be decreased by using appropriate reaction conditions. The method of temperature-dependent solvent systems was successfully applied to separate the palladium catalyst from the amines with a palladium leaching lower than 1.0%.

Hydroformylation of piperylene and efficient catalyst recycling in propylene carbonate

“…During the solvent screening, it turned out that polar solvents like DMF or acetonitrile, which form convenient TMS systems with long chain alkanes and have shown potential in several other catalytic reactions, 42,43 only give low yields in piperylene hydroformylation. Next to come is the implementation of a convenient recycling strategy.…”

Phase Equilibria in Systems of Morpholine, Acetonitrile, and n-Alkanes

“…(The latter did not improve by fitting a non-zero binary interaction parameter to the n-alkane/morpholine system.) Commonly applied reactant concentrations for the hydroamination, however, are less than 5 mol % of morpholine, 4 and in this region the binodals as well as the slope of the tie lines are captured quite well.…”

“…Article systems composed of acetonitrile and n-alkanes, k ij is described as a function of temperature following eq 4: 8 (4) where a and b are functions of the number of carbon atoms of the n-alkane, 8 as given in eqs 5 and 6. (6) Using this correlation, the upper critical solution temperatures of the solvent systems composed of acetonitrile and nalkanes could be described in remarkably good agreement with experimental data.…”

“…4 It is expected that the length of the alkane determines the width of the miscibility gap and therewith the catalyst leaching. Lee et al 10 correlated experimental data of ternary systems composed of the acetonitrile, morpholine, and n-alkanes from n-octane to ndodecane using NRTL.…”

A Continuous Process for the Purification of Terpenyl Amines Using a Reversible Acid‐Base Reaction

“…Hydroamination of myrcene with morpholine yields the desired TPAs (Scheme ). This reaction can be catalyzed by homogeneous transition metal catalysis and has already been demonstrated in batch , as well as continuous experiments .…”