Direct Amide Synthesis over Composite Magnetic Catalysts in a Continuous Flow Reactor

Abstract

Composite magnetic catalysts containing different amounts of sulfated titania (33–50 wt %) have been prepared by means of high energy ball-milling between TiO2 and NiFe2O4. The catalysts have been characterized with N2 adsorption/desorption isotherms, XRD, temperature programmed oxidation (TPO) and vibrating sample magnetometer (VSM). The catalytic activity was measured in the reaction of aniline and 4-phenylbutyric acid in the continuous mode under conventional and inductive heating. The effect of catalyst loading in the reactor on reaction and deactivation has been studied, indicating the catalyst containing 50 wt % titania gave the highest reaction rate and least deactivation. The operation in a flow reactor under inductive heating increased the amide yield by 25% as compared to conventional heating. The initial reaction rate decreased by 30% after a period of 15 h on stream. The catalyst activity was fully restored after a treatment with an air flow at 400 °C.

Amide Bonds Meet Flow Chemistry: A Journey into Methodologies and Sustainable Evolution

“…Also very recently, in 2021, Liu and Rebrov developed another atom‐efficient way to amide bonds through the use of titania‐based catalyst in form of a magnetic composite (Table 1, entry 10) [75] . A mixture of NiFe 2 O 4 and sulfated titania was mechanochemically reacted in order to prepare the composite magnetic catalyst.…”

“…Also very recently, in 2021, Liu and Rebrov developed another atom‐efficient way to amide bonds through the use of titania‐based catalyst in form of a magnetic composite (Table 1 , entry 10). [75] A mixture of NiFe 2 O 4 and sulfated titania was mechanochemically reacted in order to prepare the composite magnetic catalyst. The catalyst was used in the reaction between aniline and 4‐phenylbutyric acid (PBA) in batch as well as in a continuous‐flow reactor under both conventional and inductive heating.…”

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

“…Here, too, the reactor material can either be heated directly by induction or there are additives in the fixed-bed material that interact with the oscillating electromagnetic field. Recently, Rebrov and co-workers disclosed the direct amide formation of a carboxylic acid and anilline using high energy ball milling to prepare the sulfated TiO 2 (50 wt %)/NiFe 2 O 4 (50 wt %) catalyst that serves as fixed-bed material ( Scheme 11 , case A) [ 72 – 73 ]. The reaction was carried out at 150 °C and an internal pressure of 7 bar.…”

Commercial Cu2Cr2O5Decorated with Iron Carbide Nanoparticles as a Multifunctional Catalyst for Magnetically Induced Continuous‐Flow Hydrogenation of Aromatic Ketones

“…[1] Attempts were also made to exploit the benefits associated with magnetic induction in heterogeneous catalysis. [2] More recently,small magnetic nanoparticles heated by magnetic induction were used either as heating agents or directly as catalysts to effectively activate chemical transformations in the gas phase (e.g., Fischer-Tropsch, [3] CO 2 methanation, [4] propane dehydrogenation, [4e] methane steam reforming [5] )a sw ell as in solution (e.g., hydrogenation, [6] amidation, [7] water splitting, [8] hydrogenolysis [9] ). Under magnetic induction, the heat required to unlock catalytic activity is generated directly by the magnetic nanocatalysts (Figure 1).…”