Synthesis of secondary amines by reductive amination of aldehydes with nitroarenes over supported copper catalysts in a flow reactor

Process Intensification of Continuous-Flow Imine Hydrogenation in Catalyst-Coated Tube Reactors

“…[29][30][31] Imines subsequently can be hydrogenated to amines via transfer hydrogenation or by molecular hydrogen over homogeneous or heterogeneous catalysts. [32][33][34][35] The possibility of using flow chemistry for imine reduction has been already noted in a previous research. 36 However, the vast majority of the modern research on secondary amine synthesis is carried out in batch reactors and the advantages of continuous-flow might be overlooked.…”

Cu‐Al mixed oxide derived from layered double hydroxide as an efficient catalyst for continuous‐flow reductive amination of aromatic aldehydes

“…Catalytic experiments were performed using H-Cube Pro™ setup (Thalesnano, Budapest, Hungary) equipped with stainless-steel CatCart®30 reactor (catalyst bed length of 24 mm, inner diameter of 4 mm). 22,23,42,43 Before the catalytic run, the catalyst (0.165 g of 250-500 μm particles) was reduced by a mixture of hydrogen with methanol at 120°C for 1 h (pressure of 20 bar, flow rates of methanol and H 2 were 0.5 and 15 mL min −1 , respectively). 22,23 Afterwards, the inlet was switched to the flask containing the reaction mixture and this point in time was chosen as the starting point of the experiment.…”

“…Several methodologies have been developed to obtain secondary amines via N-alkylation of primary amines with alkyl halides 6 or alcohols, [6][7][8][9] Buchwald-Hartwig reaction, 10,11 and reductive amination of carbonyl compounds. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Among all these transformations, reductive amination over heterogeneous metal catalysts is a promising method due to the use of inexpensive and environmentally benign molecular hydrogen as a reducing agent. [15][16][17][18][19][20][21][22][23][24][25][26] This process involves reversible condensation of primary amine with aldehyde or ketone to form imine and the hydrogenation of imine into the secondary amine.…”

Catalytic Reductive Amination of Aldehydes and Ketones With Nitro Compounds: New Light on an Old Reaction

“…Considerable efforts have been made toward finding nonnoble metal catalysts to replace noble metals in the reductive amination of carbonyl compounds with nitro compounds. Supported catalysts based on nickel (Fiore et al, 2019;Li et al, 2019), cobalt (Stemmler et al, 2014;Jagadeesh et al, 2017;Senthamarai et al, 2018), copper (Nuzhdin et al, 2017), and iron (Natte et al, 2017) nanoparticles were developed. An important advantage of non-noble metal catalyzed reactions is their tolerance to C-I and C-S bonds, which undergo hydrogenolysis with palladium/platinum catalysts (Stemmler et al, 2014;Natte et al, 2017;Pedrajas et al, 2017;Fiore et al, 2019).…”