Handy and highly efficient oxidation of benzylic alcohols to the benzaldehyde derivatives using heterogeneous Pd/AlO(OH) nanoparticles in solvent-free conditions

Ultrasonic irradiation-assisted MnFe2O4 nanoparticles catalyzed solvent-free selective oxidation of benzyl alcohol to benzaldehyde at room temperature

Magnetic nanoparticles (NPs) play a vital role in heterogeneous catalysis because of their easy separation, and effective recyclability. Herein, we report the synthesis of MnFe2O4 NPs for use as catalysts in the selective oxidation of benzyl alcohol to benzaldehyde under mild conditions. The MnFe2O4 NPs have been synthesized by precipitation method followed by hydrothermal ageing at 180 °C for 4.0 h. We have investigated the effect of chitosan and carboxymethyl cellulose on the size or morphology of the formed MnFe2O4 NPs. The X-ray diffraction study confirms the formation of pure and crystalline MnFe2O4 with varying average crystallite sizes ranging from 18 to 28 nm based on the type of additive used. The electron microscopy study reveals that the additive plays a significant role in controlling the morphology of the formed MnFe2O4 NPs. These MnFe2O4 NPs exhibit superparamagnetic behaviour at room temperature and can effectively catalyze the solvent-free selective oxidation of benzyl alcohol to benzaldehyde in the presence of tert-butyl hydroperoxide at room temperature under ultrasonic irradiation. The developed protocol can be extended to various substituted benzyl alcohols having both the electron withdrawing and electron donating groups to afford moderate to excellent yield of the products. The catalyst is magnetically retrievable, highly stable, and can be reused up to the sixth run without significant loss of catalytic activity.

On-Surface Alcohol Oxidation Monitored by Paper Spray Mass Spectrometry: The Role of Ruthenium as Catalyst

Paper spray ionization mass spectrometry (PS-MS) is employed herein as a convenient platform to investigate an on-surface catalytic process, that is, the oxidation of alcohols induced by ruthenium salts. The tag-charged benzyl alcohol 1 (m/z 166), used as a suitable prototype starting substrate, is quickly oxidized by tert-butyl hydroperoxide (TBHP) in an on-surface process catalyzed by ruthenium trichloride (RuCl₃). The PS(+)-MS revealed the formation of products from the oxidation of alcohol 1. RuCl₃ and TBHP played a crucial role in this process since when salts of other metals (platinum, palladium, and iron) and another oxidizing agent (hydrogen peroxide) are employed, no reaction is observed. Moreover, UV radiation and heating accelerate the on-surface alcohol 1 oxidation. Finally, an exciting possibility is to employ PS-MS to investigate similar organic catalytic reactions to accelerate them and detect unstable intermediates, indiscernible in the condensed phase.

In situ supported Pd NPs on biodegradable chitosan/agarose modified magnetic nanoparticles as an effective catalyst for the ultrasound assisted oxidation of alcohols and activities against human breast cancer

In this content, a green approach for the ultrasound promoted in situ immobilization of Pd NPs over biodegradable chitosan/agarose modified ferrite NP (Fe₃O₄@CS-Agarose/Pd) is developed. The structural and physicochemical features of the material were estimated using advanced analytical techniques like FT-IR, ICP-OES, FESEM, EDS, XRD, TEM and VSM. The magnetic material was catalytically explored in the oxidation of alcohols under ultrasonic waves. Sonication had a significant role in enhancing the catalytic performance in the alcohol's oxidation as compared to conventional heating. The heterogeneous nanocatalyst was efficiently recycled up to 10 times with nominal loss in catalytic activity. Towards the biological applications, the Fe₃O₄@CS-Agarose/Pd nanocomposite showed high antioxidant activities against DPPH free radicals, comparable to standard butylated hydroxytoluene (BHT). In addition, it exhibited excellent cytotoxicity in terms of % cell viability against breast adenocarcinoma (MCF7), breast carcinoma (Hs 578Bst), infiltrating ductal cell carcinoma (Hs 319.T), and metastatic carcinoma (MDA-MB-453) cell lines. The best anti-breast cancer potential of the nanocomposite was observed in Hs 319.T cell line.