Search

We investigated the selective oxidation of styrenes to benzaldehydes by using a non-irradiated TiO 2 -H 2 O 2 catalytic system. The oxidation promotes multi-step reactions from styrenes, including the cleavage of a C=C double bond and the addition of an oxygen atom selectively and stepwise to provide the corresponding benzaldehydes in good yields (up to 72%). These reaction processes were spectroscopically shown by fluorescent measurements under the presence of competitive scavengers. The absence of the signal from OH radicals indicates the participation of other oxidants such as hydroperoxy radicals (•OOH) and superoxide radicals (•O 2 - ) into the selective oxidation from styrene to benzaldehyde.

Abstract. Continuous‐flow epoxidation of aliphatic and aromatic alkenes with hydrogen peroxide (H2O2) was carried out to give epoxides using a fixed‐bed liquid flow reactor equipped with a solid titanium silicalite‐1 (TS‐1) catalyst column. The developed flow reaction enables continuous synthesis of 4‐phenyl‐1,2‐epoxybutane from 4‐phenyl‐1‐butene in 90%–98% yields (22.4 g) for 150 h from a catalyst column of 5 mm inner diameter with 100 mm length. Employment of a mixed solution of MeCN and MeOH with preservation of the Ti active site in TS‐1 crystal structures with few defects permits continuous epoxidation of less‐reactive long‐chain terminal alkene and multifunctional alkene to give epoxides in 12%–98% yields with 78%–99% selectivity. [ABSTRACT FROM AUTHOR]

Switchable synthesis of aldehydes and carboxylic acids from alcohols by Pt‐catalysed H2O2 oxidation is performed for the first time using flow reactors. The use of an optimised amount of zero‐valent Pt black diluted with SiO2 catalyst demonstrates controlled H2O2 oxidation of allylic alcohols, benzyl alcohols, and aliphatic alcohols. From a probe reaction, Pt catalytic activity to produce a carboxylic acid from the corresponding alcohol improves depending on the temperature increasing from 40 to 90 °C. The set of reaction conditions about the combination of temperature and flow rate as a simple trigger works sensitively to divide the formation of aldehydes and carboxylic acids without tuning by additives. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide epoxidation, Alkene, Epoxide, Titanium silicate zeolite, Flow reactor Cover Picture: Continuous Synthesis of Epoxides from Alkenes by Hydrogen Peroxide with Titanium Silicalite-1 Catalyst Using Flow Reactors (Adv. Keywords: Hydrogen peroxide epoxidation; Alkene; Epoxide; Titanium silicate zeolite; Flow reactor EN Hydrogen peroxide epoxidation Alkene Epoxide Titanium silicate zeolite Flow reactor 3180 3180 1 10/18/23 20231013 NES 231013 The inside cover picture of a waterfall stream illustrates the continuous synthesis of various epoxides from olefins, with hydrogen peroxide as an oxidant, catalyzed by titanium silicalite-1 (TS-1). [Extracted from the article]

A practical and environmental-friendly method was developed to convert vinyl ether into acetate by using a palladium complex with phosphine ligand and hydrogen peroxide. The only by-product is water. [ABSTRACT FROM AUTHOR]

High-yield syntheses of epoxides using an iron complex having two types of picolinates in the presence of hydrogen peroxide under halide-free reaction conditions were achieved. The reaction is very simple. The complex, prepared with iron(II) acetate, 2-picolinic acid (picH) and 6-methyl-2-picolinic acid (Me-picH) in acetonitrile, quickly catalyzed an epoxidation of styrene (15 min.) at 25 °C with 1.40 equivalents of 35% aqueous hydrogen peroxide solution to afford styrene oxide in 95% yield with 96% selectivity. We also carried out a 100-g scale epoxidation of styrene using 1.25 equivalents of 35% aqueous hydrogen peroxide solution with the iron catalyst to give styrene oxide in 80% isolated yield. The developed iron catalyst was efficiently applicable to the epoxidation of various aromatic olefins to give the corresponding epoxides in high yields. To obtain more information about this catalytic system, the pre-catalyst of this reaction was isolated and the structure was determined to be [Fe(pic)(Me-pic)2] by single-crystal X-ray analysis. The [Fe(pic)(Me-pic)2] catalyst effectively epoxidized styrene to styrene oxide in 93% yields. The system should be suitable for large-scale preparations of aromatic olefins due to the employment of simple ligands with halide- and amine-free reaction conditions. [ABSTRACT FROM AUTHOR]

We investigated the selective oxidation of styrenes to benzaldehydes by using a non-irradiated TiO2–H2O2 catalytic system. The oxidation promotes multi-step reactions from styrenes, including the cleavage of a C=C double bond and the addition of an oxygen atom selectively and stepwise to provide the corresponding benzaldehydes in good yields (up to 72%). These reaction processes were spectroscopically shown by fluorescent measurements under the presence of competitive scavengers. The absence of the signal from OH radicals indicates the participation of other oxidants such as hydroperoxy radicals (•OOH) and superoxide radicals (•O2−) into the selective oxidation from styrene to benzaldehyde. [ABSTRACT FROM AUTHOR]

Palladium(II)-catalyzed chemoselective oxidation of α,β-unsaturated aldehydes with hydrogen peroxide to give α,β-unsaturated carboxylic acids was performed. Cinnamaldehyde was effectively catalyzed by palladium(II) trifluoroacetate to generate cinnamic acid in 92% yield under organic solvent-free conditions. The reaction appears to be applicable to various α,β-unsaturated aldehydes. [ABSTRACT FROM AUTHOR]

An abstract of the article "Chemoselective Palladium-Catalyzed Oxidation of Vinyl Ether to Acetate Using Hydrogen Peroxide" is presented.

Abstract: The selective hydrogen peroxide oxidation of vinyl ethers to give acetates was developed using triphenylphosphine palladium and triethyl amine catalysts under mild reaction conditions. [Copyright &y& Elsevier]