Continuous Flow Photo-oxidations Using Supported Photocatalysts on Silica

Abstract

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Continuous flow technology-a tool for safer oxidation chemistry

“…In addition, Amara and co-workers reported the straightforward preparation of heterogeneous photocatalysts by non-covalently immobilizing Ru(bpy) 3 Cl 2 or the sulfonate salt of 5,10,15,20-tetrakis( N -methylpyridinium-4-yl)porphyrin (TMPyP 4+ ) on commercial SiO 2 using electrostatic interactions. 247 The photooxidation of 1,5-dihydroxynaphthalene (1,5-DHN) to juglone proceeded with quantitative yield and up to a 24-fold improvement in productivity relative to the batch reaction; the system employs TMPyP@SiO 2 as the photocatalyst in a fixed-bed flow photoreactor (Fig. 81).…”

Visible Light-Induced Aerobic Oxidative Dehydrogenation of C–N/C–O to C=N/C=O Bonds Using Metal-Free Photocatalysts: Recent Developments

“…Furthermore, non-complexed 102 in a continuous flow photoreactor [231] and a gigantic porphyrin-based organic cage with 12 units of tetra(4-aminophenyl)porphyrin and 24 moieties of 2-hydroxy-5-octyloxy-1,3-benzenedicarboxaldehyde [232] were used as photocatalysts in the preparation of Juglone (85, R 1 = R 2 = R 5 = H, R 4 = OH) from 1,5-dihydroxynaphthalene in good to excellent yields. However, those catalysts were not recycled.…”

Performances of Homogeneous and Heterogenized Methylene Blue on Silica Under Red Light in Batch and Continuous Flow Photochemical Reactors

“…In particular, we investigated the straightforward non-covalent immobilization of PCs on silica particles which resulted in an improved reactivity and stability (Tambosco et al, 2018), and provided additional physical properties such as magnetism (Terra et al, 2020) or plasmonic resonance (Gellé et al, 2021). We also developed a continuous flow photochemical process with a fixed photocatalytic bed reactor to leverage productivity issues (Blanchard et al, 2020). Important efforts have been made to intensify photochemical processes by means of flow chemistry and this technology is the most promising for larger-scale photochemical manufacturing.…”

“…Important efforts have been made to intensify photochemical processes by means of flow chemistry and this technology is the most promising for larger-scale photochemical manufacturing. However, this approach remains limited to homogeneous or gas/liquid conditions and yet, processing heterogeneous solid/liquid and solid/liquid/gas reactions is still underdeveloped (Carofiglio et al, 2008;Woźnica et al, 2014;Amara et al, 2015;Mendoza et al, 2018;Pieber et al, 2018;Blanchard et al, 2020;Mendoza et al, 2020;Radjagobalou et al, 2020).…”