The term hydroaminomethylation refers to a one-pot cascade reaction of an alkene hydroformylation followed by reductive amination. Because water is the only byproduct, this reaction sequence represents an atom-efficient, elegant way to produce amines. Scheme 1 shows the hydroaminomethylation sequence for ethylene, hydroformylation followed by reaction with diethylamine to form N,N-diethylpropan-1-amine (DEPA) through an enamine intermediate.Despite the fact that the hydroaminomethylation sequence was first described by Reppe and Vetter already in 1949, [1,2] extensive research in this field has only taken place in recent years. [3][4][5] From this work it is evident that a major challenge in hydroaminomethylation is to realize high chemoselectivity, in particular to suppress aldol condensation of the aldehyde intermediate (Scheme 2).Hydroaminomethylation has been shown to work even with unmodified rhodium catalysts, although with moderate selectivities. [6] In 1999, Beller and co-workers [7] reported on TPPTS-and BINAS-modified rhodium complexes in the hydroaminomethylation using ammonia as the amine substrate. A dual-metal catalyst (Rh, Ir) and a liquid-liquid biphasic reaction system (water, MTBE) were applied in this work. Besides the desired primary amine product, secondary amines, tertiary amines, imines, enamines, and aldol condensation products were formed. Later, the same group obtained much better selectivities using Rh-IPHOS [8] and Rh-Xantphos-systems. [9,10] For the hydroaminomethylation of terminal, aliphatic olefins, very high n/iso ratios of the product amines could be realized (n/iso > 98:2). Beller and co-workers also investigated the hydroaminomethylation of 1-octene in supercritical ammonia and found yields for primary nonylamine of up to 60 % under optimized reaction conditions. [11] Ionic liquids (ILs) were first applied in the hydroaminomethylation by Eilbracht and co-workers, [12] who patented the use of ionic liquids to recycle unmodified rhodium and iridium catalysts. More recently, Vogt and co-workers [13] reported on the hydroaminomethylation of long-chain (C 6 -C 12 ) olefins with piperidine as the amine substrate using a liquid-liquid biphasic reaction system with Rh/Sulfoxantphos in 1-methyl-3-pentylimidazolium tetrafluoroborate [C 5 mim][BF 4 ] as the IL phase. [14] The results were compared with toluene/MeOH and a significant decrease in sideproduct formation was found in the IL system.Herein, we describe catalytic hydroaminomethylation in a continuous gas-phase reaction using supported ionic liquid phase (SILP) materials as microscopically homogeneous but macroscopically heterogeneous catalysts. Within SILP catalysts, a thin IL film creates a uniform solvent environment for the dissolved transition-metal complex, [15] while the highly porous solid on which this ionic catalyst solution is supported creates a high gas-liquid interfacial area for fast mass transport ( Figure 1). [16,17] Product/catalyst separation takes place in the system by evaporation of the products from the Sche...
