Direct Synthesis β-Acyloxy Aldehydes from Linear Allylic Esters Using O2 as Sole Oxidant

A simple and practical preparation of β-O substituted aldehydes directly from linear allylic esters is developed. Using bis(benzonitrile)palladium chloride as the catalyst and O2 as sole oxidant, the tandem isomerization-...

Green Procedure for Aerobic Oxidation of Benzylic Alcohols with Palladium Supported on Iota-Carrageenan in Ethanol

The search for selective heterogeneous catalysts for the aerobic oxidation of alcohols to ketones and aldehydes has drawn much attention in the last decade. To that end, different palladium-based catalysts have been proposed that use various organic and inorganic supports. In addition, supports that originate from a biological and renewable source that is also nontoxic and biodegradable were found to be superior. We heterogenized palladium chloride or acetate complexes with triphenylphosphine trisulfonate on iota-carrageenan xerogel by simple mixing of the complex and the polysaccharide in water. The resulting polysaccharide-catalyst mixture then underwent deep freeze and lyophilization, after which the catalyst was characterized by TEM, XPS and SEM-EDS and tested in aerobic oxidation. The new heterogeneous catalysts were successfully used for the first time in the aerobic oxidation of benzylic alcohols. Moreover, they were easily removed from the reaction mixture and recycled, yielding an increase in activity with each subsequent reuse. As determined by TEM and XPS, the reduction in palladium and the formation of nanoparticles during the reaction in ethanol yielded more active species and, therefore, higher conversion rates. A SEM-EDS analysis indicated that the palladium was thoroughly dispersed in the xerogel catalysts. Moreover, the xerogel catalyst was observed to undergo a structural change during the reaction. To conclude, the new heterogeneous catalyst was prepared by a simple and straightforward method that used a non-toxic, renewable and biodegradable support to yield an active, selective and recyclable heterogeneous system.

Facile and practical hydrodehalogenations of organic halides enabled by calcium hydride and palladium chloride

Herein, a convenient hydrodehalogenation method was described by employing less-explored calcium hydride as the reductant. A wide range of organic halides such as aromatic bromides, aromatic chlorides, aromatic triflates, aliphatic...

Catalytic Oxidation of Quinine Using Hydrogen Peroxide with Palladium as Catalyst

The oxidation of quinine using hydrogen peroxide yielded quinine N-oxide as a major product. The reaction can be accelerated in the presence of palladium chloride (PdCl2) as catalyst. The trace products, however, were identified as the further oxidation products at quinoline moiety producing N-Oxide as a major product and the secondary alcohol at C-9 producing the ketone, furthermore the alkene translocation product. The trace products were successfully isolated and characterized by NMR protons and carbons. Purification of the product was performed by column chromatography.

Efficient technology for the extraction of non-ferrous metals from liquid production waste

The results of the study of Cu(II) to Cu(I) reduction process in chloride-sulfate solutions under the action of carbon monoxide at atmospheric pressure in the presence of palladium chloride(II) acting as catalyst are reported. This process is described by general equation: 2Cu2+ +2SO2-4 +2Cl +CO+H O- 2 →Pd(II) 2CuCl+CO +2H +2SO2 + 2-4 . It has been shown product mix in the sediment obtained hydrocarbonyl process. Thus, the recovery process Cu(II) → Cu(I) with the action of CO is catalyzed by Pd(II) in the initial stage, and then develops in an autocatalytic mode with the subsequent redox decomposition intermediate. As a reducing agent serve ligand molecules of CO which are in activated state: CO+HO=CO +2H +2e2 2 + .

Peculiarities of palladium-containing MFI-type zeolites as catalysts of isomerization of linear alkanes

Platinum group metals are widely used as a hydrogenating-dehydrogenating component of a number of petroleum refining and petrochemical catalysts, in particular for isomerization of linear alkanes. The main direction in improving the preparation of these catalysts is to reduce their cost by optimizing the metal component amount. However, insufficient attention was paid to the method of introduction of an active metal into the carrier; at the same time, this issue is especially important in case of zeolite catalysts, for which ion exchange can be used in addition to traditional impregnation. Therefore, the purpose of this work was to compare the catalytic efficiencies of Pd-containing MFI zeolites in which metal was introduced by two methods: impregnation from a solution of palladium chloride and ion exchange from tetraamminepalladium(II) chloride in the amount of 0.5 wt.% in terms of pure metal. Study of texture characteristics by nitrogen low-temperature adsorption/desorption technique showed that the specific surface area of samples and the total sorption volume remained practically unchanged, regardless of the procedure of metal component introduction. A significant decrease in average pore size was observed only in case of ion-exchange metal introduction; this indicated the localization of palladium mainly in zeolite pores, which was confirmed by transmission electron microscopy. The stage of transformation from ammonium form to hydrogen one strongly affects the activity of samples, this stage should precede the final stage of metal recovery. The highest yield of hexane isomers of about 46.5 wt.% with the selectivity of 88.7% was observed over a catalyst with Pd introduced by ion-exchange method with the smallest palladium particles (3–7 nm).

Green Synthesized Palladium Coated Titanium Nanotube Arrays for Simultaneous Azo-Dye Degradation and Hydrogen Production

In this study, electrodes of titanium dioxide nanotube arrays (TNAs) were successfully synthesized by applying the anodic oxidation etching method, as well as the use of green synthetic technology to add reducing agents of tea or coffee to reduce metal palladium from palladium chloride. Synthesis of palladium modified TNAs (Pd/TNAs) was conducted by the microwave hydrothermal method after the metal palladium was reduced. In order to identify the surface structure, light absorption and elemental composition, TNAs and Pd/TNAs were characterized by X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Furthermore, to test the photocurrent density, electron resistance, and hydroxyl radicals by I-t plot, electrochemistry impedance spectroscopy (EIS), and electron paramagnetic resonance (EPR) were investigated. The photocurrent (4.0 mA/cm2) of Pd/TNAs-C (using coffee as the reducing agent) at +1.0 V (vs. Ag/AgCl) was higher than that of the pure TNAs (1.5 mA/cm2), illustrating that Pd/TNAs-C can effectively separate photogenerated electrons and holes. Pd/TNAs is a favorable material as a photoanode for the photoelectrochemical (PEC) removal of organic pollutants in wastewater.