Magnetically Recyclable Heterogeneous Cobalt Ferrite Catalyst for the Direct N‐Alkylation of (Hetero)aryl Amines with Alcohols

Abstract

Herein we report the use of spinel cobalt ferrite nanoparticles as an efficient and selective catalyst for the mono N-alkylation of aryl and hetero aryl amines with various aromatic and aliphatic alcohols. Based on our experiments, the optimum condition for good to excellent yield were observed with alcohol (1.0 mmol), aniline (1.2 mmol), KOH (0.5 equiv), and CoFe 2 O 4 nanocatalyst (10 mol%) in toluene at 130°C in 24 hours. Further control experiment studies revealed that the reaction does not proceed in the absence of the catalyst or a strong base. This magnetically recyclable nanocatalyst does not require any ligands and is easily synthesized at low temperature. The reutilization of the recovered catalyst in a fresh reaction gave good to excellent yield. The experiment results strongly suggest a borrowing hydrogen pathway for Nalkylation under our standard conditions. The utility of these nanocatalysts was also demonstrated for the dehydrogenative synthesis of heterocycles like indole and quinolines.

Studies on PVDF/ferrite composite films on flexible substrates for pyroelectric energy conversion

“…The resulting precipitate was collected and washed several times with DI water before being decanted using an external magnet and dried at 100 °C for 24 hours. 17–19…”

“…The resulting precipitate was collected and washed several times with DI water before being decanted using an external magnet and dried at 100 1C for 24 hours. [17][18][19] Nickel ferrite (NF) was synthesized by a hydrothermal method. Nickel(II) nitrate hexahydrate (Ni(NO 3 ) 2 Á6H 2 O 99% purity, SRL), oxalic acid (SRL 99.5%) and iron(III) nitrate nonahydrate (Fe(NO 3 ) 2 Á9H 2 O 98% purity, SRL) in a 1 : 2 : 4 ratio were separately dissolved in DI water.…”

Sonochemically induced cube-shaped NiFe2O4 nanoparticle-catalyzed selective oxidation of benzyl alcohol to benzaldehyde

“…[3][4][5][6] The major benefits of spinel ferrite NPs are easy manufacturing and functionalization, as well as isolation of the catalyst from the reaction mixture by a simple magnetic decantation. 5,7 In several chemical processes such as photocatalytic degradation of dyes, 8 alkylation, 9 dehydrogenation, 10 oxidation, 11 C-C coupling, 12 and so forth, spinel ferrite plays a significant role as a catalyst. In the nanometer dimension, spinel ferrites offer superior catalytic activity because of their smaller size, enhanced surface area, and selectivity.…”

Accessing 2‐Aryl Quinolines via Acceptorless Dehydrogenation and Transfer Hydrogenation Under Base and Solvent‐Free Reaction Conditions

“…In the last decade, acceptorless dehydrogenation, borrowing hydrogen, and transfer hydrogenation strategies have gained popularity to overcome these challenges [15,16] . Owing to this, there are numerous reports on acceptorless dehydrogenative synthesis of quinolines utilizing homogenous catalytic system involving metals such as Co, [17] Cu, [18] Ir, [19] Fe, [20] Mn, [21] Ni, [22] Re, [23] Ru, [24] Zn, [25] and heterogeneous catalyst such as Co on C 3 N 4 , [26] CuO, [27] CuNiFeO, [28] Fe 2 O 3 , [29] CoFe 2 O 4 , [30] Ir on mesoporous silica, [31a] porous organic polymer supported Ir catalyst, [31b] covalent triazine framework supported Ir complex, [31c] Pd on polymer support [32] . However, the synthesis of quinoline via transfer hydrogenation strategy remains less explored [33–36] .…”