Nickel Catalyzed Conversion of Cyclohexanol into Cyclohexylamine in Water and Low Boiling Point Solvents

Abstract

Abstract:Nickel is found to demonstrate high performance in the amination of cyclohexanol into cyclohexylamine in water and two solvents with low boiling points: tetrahydrofuran and cyclohexane. Three catalysts, Raney Ni, Ni/Al 2 O 3 and Ni/C, were investigated and it is found that the base, hydrogen, the solvents and the support will affect the activity of the catalyst. In water, all the three catalysts achieved over 85% conversion and 90% cyclohexylamine selectivity in the presence of base and hydrogen at a high temperature. In tetrahydrofuran and cyclohexane, Ni/Al 2 O 3 exhibits better activity than Ni/C under optimal conditions. Ni/C was stable during recycling in aqueous ammonia, while Ni/Al 2 O 3 was not due to the formation of AlO(OH).

Amination of Cyclohexanol over a Ni‐Based Catalyst – Part II: Catalyst Stability and Reaction Pathway

“…Furthermore, the formation of by‐products has also been verified in this work, which results from reactions with the formed primary amines as aminating agents, in this case the reaction between CHOL intermediaries and CHA and/or aniline 2, 7, 8, 14–16, 24. In order to fully understand how side reactions occur and which species are involved, CHOL conversion was varied by changing its WHSV at a constant temperature of 200 °C and NH 3 :H 2 :CHOL molar ratio of 2.2:2.2:1.…”

“…Amines are a highly important class of chemicals owing to their wide applicability on most distinctive fields 1, 2. They can be synthesized by several methods, namely, by hydroamination, hydroaminomethylation, reduction of nitriles and nitro compounds or reductive amination 3–7.…”

Plasma‐Made (Ni0.5Cu0.5)Fe2O4 Nanoparticles for Alcohol Amination under Microwave Heating

“…Heterogeneous Ni has been widely explored since its first report in 1932 by Winans et al ., requiring though 100 bar H 2 at 200 °C for the alkylation of cyclohexylamine with EtOH . Ni has also been shown by Shimizu and others to be highly competent for BH when supported on θ‐Al 2 O 3 , and can even perform ammonia alkylation in flow synthesis . However, Ni is a carcinogenic and allergenic metal, driving the search towards partial substitution with other metals, for instance Cu .…”

“…[33] Ni has also been shown by Shimizu and others to be highly competent for BH when supported on θ-Al 2 O 3 , [34] and can even perform ammonia alkylation in flow synthesis. [35,36] However, Ni is a carcinogenic and allergenic metal, driving the search towards partial substitution with other metals, for instance Cu. [37] The Ni/Cu pair is indeed active for alcohol amination: Cu acts as a dehydrogenation catalyst for the starting alcohol, while Ni performs the hydrogenation of the imine.…”

Synthesis of Industrial Primary Diamines via Intermediate Diols – Combining Hydroformylation, Hydrogenation and Amination

“…Although primary amines are of great industrial importance, only a few catalytic systems for the selective amination of alcohols to primary amines have been described in the literature thus far . Apart from recent progress made in the field of heterogeneous catalysis, mainly using nickel‐based catalysts, only three successful attempts have been made by Milstein, Beller, and Vogt in the field of in homogenous catalysis ,,. Unfortunately, the pathways examined in these investigations also led to the formation of undesired secondary amines.…”