Hydroaminomethylation of the Renewable Limonene with Ammonia in an Aqueous Biphasic Solvent System

Abstract

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.