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Behr A.,Laboratory of Technical Chemistry Chemical Process Development | Wintzer A.,Laboratory of Technical Chemistry Chemical Process Development
Chemical Engineering and Technology | Year: 2015

With the hydroaminomethylation of the natural compound limonene with ammonia an atom-economic method for the synthesis of primary amines is described. This tandem reaction allows the direct conversion of the unfunctionalized monoterpene to a valuable amine product. For the first time, ammonia served as substrate to result in a maximum primary amine yield of 25%. To overcome unwanted side reactions, a biphasic solvent system was used, consisting of an aqueous catalyst phase and an organic product phase. As catalyst the water-soluble transition metal complex [Rh(cod)Cl]2/triphenylphosphine trisulfonate was chosen. In combination with the surfactant hexadecyltrimethylammonium chloride it provided a good phase interaction and the possibility for easy phase separation after the reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Behr A.,Laboratory of Technical Chemistry Chemical Process Development | Wintzer A.,Laboratory of Technical Chemistry Chemical Process Development | Lubke C.,Laboratory of Technical Chemistry Chemical Process Development | Muller M.,Laboratory of Technical Chemistry Chemical Process Development
Journal of Molecular Catalysis A: Chemical | Year: 2015

The reductive amination of the natural product citronellal with ammonia is presented as a new and atom economic way to its primary amine derivatives. The aqueous ammonia phase contains the homogeneous catalytic system [Rh(cod)Cl]2/TPPTS in a biphasic solvent system, whereas the starting material and the products remain in the apolar solvent phase. This concept supresses side reactions effectively, achieving a high yield of primary amines of up to 87%. Systematic investigations demonstrate that the cleavage of the secondary imine as an undesired by-product is necessary in achieving high selectivites, which can be controlled by the reaction conditions. Surfactants, ionic liquids or native cyclodextrins and their derivates prove to be useful phase transfer agents for optimising the interaction between the organic and the aqueous phase. The use of the ionic liquid [DecMIM]Br and the cyclodextrin derivative methyl-β-cyclodextrin provided especially fast and accurate phase separation. © 2015 Elsevier B.V. All rights reserved. Source

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