MgBr₂ supported on Fe₃O₄@SiO₂ ~ urea nanoparticle: An efficient catalyst for ortho‐formylation of phenols and oxidation of benzylic alcohols

Abstract

Urea was successfully immobilized on the surface of chloropropyl‐modified Fe3O4@SiO2 core–shell magnetic nanoparticles, then supported by MgBr2 and acts as a unique catalyst for oxidation of benzylic alcohols to aldehydes and ketones, and ortho‐formylation of phenols to salicylaldehydes. The prepared catalyst was characterized by FT‐IR, transmission electron microscopy, scanning electron microscopy, X‐ray powder diffraction, dispersive X‐ray spectroscopy, CHN and TGA. It was found that Fe3O4@SiO2 ~ urea/MgBr2 showed higher catalytic activity than homogenous MgBr2, and could be reused several times without significant loss of activity.

Pyrethroid insecticides. Chapter III: Synthesis of 3-phenoxy mandelonitrile

“…In some cases the oxidant has been inserted in a nickel-alumina matrix 82a to produce the reagent 82b (Scheme 73, entry a; Scheme 74, entry a), 224 or complexed through an organic linker to a magnetic end of a silicon coated © AUTHOR magnetite as in the case of 83c (Fe3O4; Scheme 73, entry b, Scheme 74, entry b). 230 In other cases, the metal (Pt, Pd) supported on pulverulent carbon is directly used. Scheme 73.…”

“…Aerobic oxidation of 3-phenoxybenzyl alcohol (4c) to 3-phenoxybenzaldehyde (4a) using Ni, Pt and Pd containing catalysts. 200,224,230 3.4.2.1.1. Nickel-promoted oxidation of 3-phenoxybenzyl alcohol.…”

“…224 Scheme 74. Heterogeneous Ni/Al catalyst, 224 and magnesium bromide complex to a silicon coated magnetite 230 for activation of molecular oxygen.…”

“…The branched urea complexed magnesium bromide (83c), that usually allows the efficient formylation of phenols in ortho position, proved even more efficient to oxidize benzyl alcohols to the corresponding aldehydes without overreduction. 230 The transformation of 3-phenoxybenzyl alcohol (4c) to the aldehyde (4a) takes place in less than 2 h at 60 °C with 30% hydrogen peroxide and 0.02 mg of catalyst 83c per mmole of alcohol (Scheme 73, entry b). 230 Furthermore the catalyst 83c is easily extracted from the medium using a magnet and has been recycled for at least five time without affecting its catalytic activity.…”

Synthesis of a highly active amino‐functionalized Fe3O4@SiO2/APTS/Ru magnetic nanocomposite catalyst for hydrogenation reactions

“…(3‐Aminopropyl)triethoxysilane (APTS) has been grafted on the surface of silica shells, where the amino groups of APTS can act as robust stabilizers for supporting metal nanoparticles, thus increasing reusability . Amino‐functionalized Fe 3 O 4 @SiO 2 shows excellent catalytic activity in the selective oxidation of alcohols and the Suzuki reaction . Ruthenium‐based catalysts have attracted much attention owing to their versatile roles in many catalytic reactions, including the hydrogenation of levulinic acid, CO 2 hydrogenation to formic acid, oxidation of methanol and CO 2 methanation …”