The first report of deep eutectic solvent (DES) nano‐photocatalyst (n‐TiO₂‐P25@TDI@DES (urea: ZnCl₂)) and its application on selective oxidation of benzyl alcohols to benzaldehydes

Abstract

BACKGROUNDDeep eutectic solvents (DESs) are prepared by mixing solid organic precursors to form a liquid driven from strong hydrogen‐bond interactions. The physical and chemical properties of these compounds have been widely investigated, and it has been shown that they are benign media for biotransformations, organicsynthesis, biodieselpreparation, and a sustainable media for nanoscale and functional materials.RESULTSThis study is the first report on the synthesis of n‐TiO2‐P25@TDI@DES (urea: ZnCl2) with photo catalytic activity. This nano photocatalyst was obtained through covalent grafting of TiO2‐P25 nanoparticles to an inexpensive and highly reactive linker (2,4‐toluene diisocyanate). The presented nano photocatalyst has been employed as a covalently grafted Lewis acidic deep eutectic solvent to oxidize various primary benzyl alcohols to their corresponding carbonyl compounds by sodium nitrate as oxidant, under visible light exposure.CONCLUSIONThis highly efficient nanocatalyst was investigated by various characterization techniques including fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy equipped with energy‐dispersive X‐ray spectroscopy (SEM with EDX), and elemental analysis. Owing to its enhanced catalytic activity, thermal stability, and environmentally friendly nature, the present method can be regarded as an attractive green chemistry approach. © 2020 Society of Chemical Industry (SCI)

Glucose‐assisted preparation of n‐TiO2‐P25/Ag: An efficient and robust photocatalyst for enhancing visible‐light photo‐oxidation of benzyl alcohol

“…Nitrate reduces to nitrite, and nitrite individually cannot completely promote the reaction. [ 46,49 ]…”

“…Nitrate reduces to nitrite, and nitrite individually cannot completely promote the reaction. [46,49] On the other hand, the scavenging experiment was employed to prove that holes were major species for the oxidation of benzyl alcohol. Triethanolamine (TEOA) as a hole-scavenger was added to the reaction system to F I G U R E 1 2 Recycling of n-TiO 2 -P25/Ag F I G U R E 1 3 Possible S-scheme mechanism of n-TiO 2 -P25/Ag under blue LED light irradiation; *RP, reduction products remove holes.…”

“…Therefore, an optimum percentage of metals on TiO 2 facilitates the photocatalytic activity. [40] Considering the above points in mind, and within the framework of our continuing efforts for design and employ novel heterogeneous nanocatalysts [41][42][43][44][45] and their extension in photocatalytic reactions, [46][47][48][49] in this study, a new way is introduced for Ag deposition on the surface of nano TiO 2 -P25. Several processes have been explored to synthesize composite with Ag nanoparticles successfully.…”

Deep eutectic solvent‐assisted synthesis of highly efficient nanocatalyst (n‐TiO2@TDI@DES (ZnCl2:urea)) for chemoselective oxidation of sulfides to sulfoxides

“…The weight losses (14 wt.%) at 170-250 C can be assigned to the TDI-modified titania, whereas the next step at T > 250 C can be related to the thermal degradation of TDI groups. [81] Upon DES immobilization on n-TiO 2 @TDI surface, the weight loss in the n-TiO 2 @TDI@DES showed an enhancement. Similarly, the TGA findings of TiO 2 @TDI@DES (Figure 4c) manifested three prominent weight losses.…”

“…[78][79][80] The successful immobilization of DESs on n-TiO 2 NPs can be confirmed due to the emergence of the other peaks, which are properly in line with the anatase phase of n-TiO 2 . [81] The presence of ZnCl 2 was further assessed by the EDX results.…”