Palladium-catalyzed amination of quinaldine-5-triflate

Palladium-catalyzed amination reactions of quinoline triflate and the effect of a Pd catalyst, its ligands, solvents, bases, and temperature were studied. This method facilitated an easier pathway for the preparation of aminoquinoline derivatives as potential precursors of new serotoninerg agents.      

Influence of the addition of Pd and Cu to cobalt catalysts prepared by SMAI for F-T synthesis

The Co-Pd/SiO₂ and Co-Cu/SiO₂ catalysts were prepared via solvated metal atom impregnation (SMAI) method and investigated for the Fischer-Tropsch (F-T) synthesis. The catalysts contained 5wt.% Co and a weight ratio of Pd (or Cu) to Co of 1/30. XPS indicated that Co, Pd and Cu were in metallic state. The results of XPS and magnetic measurements showed that Co and Pd (Cu) were alloyed. The Co particles on the catalysts were very highly dispersed and they displayed superparamagnetic behavior. FT-IR indicated that the electrons shifted from Cu and Pd to Co. Catalytic tests showed that CO hydrogenation rates followed the order Pd-Co > Cu-Co > Co.      

Fluorescent chemosensors for metal ions based on 3-(2-benzoxazol-5-yl)alanine skeleton

The ability of new chelate ligands, benzoxazol-5-yl-alanine derivatives substituted in position 2 by heteroaromatic substituent, to form complexes with selected metal ions in acetonitrile are studied by means of absorption and steady-state and time-resolved fluorescence spectroscopy. Among the ligands studied, only azaaromatic derivatives form stable complexes with transition metal ions in the ground state. Their absorption bands are bathochromically shifted enabling to use those ligands as ratiometric sensors. The fluorescence of each ligand is quenched by metal ions, however, in the presence of Cd(II) and Zn(II) ions a new red shifted emission band is observed.      

Complex formation reactions of palladium(II)-1,3-diaminopropane with various biologically relevant ligands. Kinetics of hydrolysis of glycine methyl ester through complex formation

The interaction of [Pd(DAP)(H₂O)₂]²⁺ (DAP = 1,3-diaminopropane) with some selected bio-relevant ligands, containing different functional groups, were investigated. The ligands used are dicarboxylic acids, amino acids, peptides and DNA constituents. Stoichiometry and stability constants of the complexes formed are reported at 25°C and 0.1 M ionic strength. The results show the formation of 1:1 complexes with amino acids and dicarboxylic acids. The effect of chelate ring size of the dicarboxylic acid complexes on their stability constants is examined. Peptides form both 1:1 complexes and the corresponding deprotonated amide species. DNA constituents form 1:1 and 1:2 complexes. The effect of dioxane on the acid dissociation constants of CBDCA and the formation constant of its complex with Pd(DAP)²⁺ was reported. The kinetics of hydrolysis of glycine methyl ester bound to [Pd(DAP)(H₂O)₂]²⁺ was studied at 25°C and 0.1M ionic strength.      

Alkylation of ambident indole anion in ionic liquids

Alkylation of indole salts in different ionic liquids is reported. Ionic liquids increase the alkylation reaction rate of ambident indole anion and reduce the effects of counter ions and/or additives, the alkylation reaction rates being independent of the presence of small amounts of protic solvents or water.      

Sub-millivolt amplitude potential oscillations observed in the noise of hydrogen evolution on Ag and Cu microelectrodes

A strange effect was observed while using the method of quasi-simultaneous determination of electrochemical voltage noise and impedance to obtain information on the kinetics of the hydrogen evolution reaction on Ag and Cu microelectrodes. Beyond a certain polarizing current density we found microvolt-amplitude potential oscillations on both electrodes with a frequency in the 5 Hz–5 kHz range. The oscillations were observed in every single experiment with Ag and Cu, while no oscillatory behavior was observed during the control experiments with the Pt microelectrode. The presence of the oscillations indicates that the mechanism of hydrogen evolution is more complex compared to the original assumption.      

Separation of Ga(III) from Cu(II), Ni(II) and Zn(II) in aqueous solution using synthetic polymeric resins

Poly (acrylamide-acrylic acid-dimethylaminoethylmethacrylate), p(AM-AA-DMAEM) and Poly(acrylamide-acrylic acid)-ethylenediaminetetracetic acid disodium, p(AM-AA)-EDTANa₂ were prepared by gamma radiation-induced template polymerization technique and used for the separation of Ga (III) from Cu (II), Ni (II), and Zn (II) in aqueous media. The effect of pH and contact time on the separation process was studied. The optimum pH value for the separation process is 3–3.5. The result shows that Ga (III) is first extracted while Cu (II), Ni (II) and Zn(II) are slightly extracted at this pH value. The recovery of metals using HCl, HNO₃ and H₂SO₄ has been studied. The resins may be regenerated using 2M HCl solutions.      

Crystallographic and structural characterisation of heterometallic platinum compounds: Part I. Heterobinuclear Pt compounds

This review covers almost 290 heterobinuclear Pt derivatives. When the heterometals (M) are non transition and the binuclear are found both with and without a metal to metal bond. Where M is a transition metal or actinide, only those with a metal-metal bond have been included here. There are thirteen non-transition metals (Sn, Hg, Ge, Sb, Tl, Zn, Pb, Cd, Na, K, Ga, Ca and In). The shortest Pt-M bond distance is 235.2(1) (Pt-Ge). There are eighteen transition metals (Fe, W, Rh, Re, Pd, Ag, Ir, Mo, Mn, Re, Co, Cu, Cr, Au, Ni, Ti, Ta and V). The shortest Pt-M bond distance is 249.5(2) pm (Pt-Cr). There is one example of an actinide, Pt-Th at 298.4(1) pm. The Pt atom has oxidation numbers 0, +2 and +4. The Pt coordination geometries include square planar (most common), trigonal bipyramidal, pseudo octahedral (Pt(IV)) and a few prevalently capped trigonal prismatic seven coordinate species. There are at least two types of isomerism distortion and polymerisation. Factors affecting bond lengths and angles are discussed and some ambiguities in coordination polyhedra are outlined.      

Chemometric analysis of heavy metal content for various environmental matrices in terms of their use in biomass thermal processing

Chemometric analysis was performed to determine the heavy metal content, such as Zn, Cd, Ni, Mn, Cu, Pb, and Fe, in 36 samples of Scots Pine taken from 9 locations within the Upper Silesian Industrial Basin. The samples, after being pre-processed, were examined for the above elements through the use of atomic absorption spectroscopy (AAS). The highest concentration of heavy metals was discovered in samples from Jaworzno. Based on the concentration assessment, the relationship between element quantity, sampling location, and matrix type has been determined, and definite element group co-existence has been confirmed and described.      

One step synthesis of Diflunisal using a Pd-diamine complex

Diflunisal and Felbinac, two FDA-approved NSAIDs and other biphenyl carboxylic acids were prepared in one step by a simple and clean Suzuki cross-coupling reaction using an easily synthesized, air and moisture stable, palladium-diamine complex. The yield (93%) for the one-step preparation of Diflunisal is the best reported without using a glovebox and a phoshine-based catalyst.      

Kinetics and mechanism of the C-S coupling reactions of aryl Grignard reagents with aryl arenesulfonates

The kinetics of the C-S coupling of arylmagnesium bromides with phenyl tosylate has been studied in THF: toluene at 90°C. The reaction is first order in Grignard reagent and first order in phenyl tosylate. Kinetic data, Hammett relationship and activation parameters are consistent with a nucleophilic addition mechanism involving rate determining attack of carbanion to sulfonyl group followed by a fast phenoxide group leaving.      

Aminophosphine complex as a catalyst precursor in Suzuki coupling reactions

A palladium complex with an aminophosphine ligand has been prepared and investigated as a catalyst precursor in Suzuki coupling reactions in toluene. Nanoparticles composed of elemental palladium have been isolated from the reaction media and analyzed using transmission electroscopic microscope (TEM), which shows the essential catalysts palladium nanoparticles to have a size of ca. 3.0 nm. dedicate to the 60th birthday of Prof. Dr. Yuan Kou     

Ion-pair chromatographic monitoring of photographic effluents

Ion-pair chromatographic technique was developed for the rapid and simple determination of the main contaminants (bromide, iodide, sulphite, thiosulphate, thiocyanate, iron(III)-EDTA chelate, free EDTA, hydroquinone and phenidone) in spent photographic solutions. Free EDTA was converted into stable Ni(II)-EDTA chelate prior to analysis. The optimal mobile phase conditions were established by varying the concentrations of tetrabutylammonium (TBA) phosphate and acetonitrile, pH and ionic strength. Separation of five inorganic anions, two metal chelates and two neutral compounds was accomplished in about 30 min using a mobile phase containing 7.5 mmol/L TBA-phosphate, 10 mmol/L NaCl (pH 6.5) and 20% (v/v) acetonitrile. The detection limits (UV detection at 210 nm) ranged from 0.4 μmol/L for phenidone to 8 μmol/L for sulphite with a linearity of 2–2.5 orders of magnitude. The method was applied to the rapid monitoring of spent photographic solutions before and after decomposition. The recovery tests established for two samples were within the range 95–103%.      

Review of analytical methods for the determination of chlorine dioxide

The present study reviews more than twenty years (1985-present) of published research on the development and application of analytical procedures for the determination of chlorine dioxide, a widely used disinfectant and bleaching agent. The review covers a variety of techniques including batch and automated spectrophotometry and fluorimetry, electroanalysis and chromatography. The analytical figures of merit to the methods are presented, while critical discussion regarding their advantages and disadvantages is addressed.      

Ionic liquid-functionalized SBA-15 mesoporous material: efficient heterogeneous catalyst in versatile organic reactions

Ionic liquid-functionalized mesoporous materials exhibited high catalytic activity in versatile organic reactions, such as cycloaddition of carbon dioxide (CO₂) with epoxide, aza-Michael addition of amines to α, β-unsaturated carbonyl compounds, and the Biginelli reaction of aldehyde, ethyl acetoacetate and urea. Recycling of the catalyst in these reactions could be carried out and the catalyst used at least five times without significant loss in activity.      

Aromatic properties of 8-hydroxyquinoline and its metal complexes

Chelatoaromaticity (aromaticity of chelate complexes) has been recently recognized as an important property influencing the stability of chelate compounds. In this paper, aromaticity of various forms of 8-hydroxyquinoline (anion, neutral molecule, zwitterion and cation) as well as its chelate complexes with magnesium and aluminium ions are investigated. Aromatic properties of these compounds are analyzed using several aromaticity indices based on energetic, geometric, magnetic and electronic physical manifestations of this phenomenon. Results of performed calculations have shown different aromatic properties for the two rings (pyridine and benzene) occurring in the studied ligand. Aromaticity of these rings in metal complexes of 8-hydroxyquinoline is significantly higher than that in corresponding ligand anion. This means that during complexation the aromaticity of the ligand increases and the chelatoaromatic effect stabilizes the studied metal complexes. In contrast, metallocyclic rings of studied metal complexes have non-aromatic properties, and, consequently, the metallocyclic ring is not stabilized by chelatoaromaticity. We conclude that, in the complex, every 8-hydroxyquinoline unit and the metal ion are separated p-electronic systems.      

Synthesis of Xenbucin using Suzuki reaction catalyzed by Pd/C in water

Xenbucin 1, an analgesic drug, was synthesized in 4 steps using two different routes. The biaryl fragment could successfully be produced via a Pd/C catalysed Suzuki coupling in water using sodium tetraphenylborate as a phenylation reagent. Overall yields of the routes were 36% and 59%, respectively.      

Indirect determination of lutetium by differential pulse anodic stripping voltammetry at a hanging mercury drop electrode

Lutetium has been determined by differential pulse anodic stripping voltammetry in an acidic solution containing Zn-EDTA. Lutetium (III) ions liberated zinc (II), which was preconcentrated on a hanging mercury drop electrode and stripped anodically, resulting in peak current linearly dependent on lutetium (III) concentration. Less than 0.4 ng mL⁻¹ lutetium could be detected after a 2 min deposition.      

N- Hydroxyphthalimide and transition metal salts as catalysts of the liquid-phase oxidation of 1-methoxy-4-(1-methylethyl)benzene with oxygen

The oxidation process of 1-methoxy-4-(1-methylethyl)benzene catalysed by N-hydroxyphthalimide (NHPI) or NHPI in combination with Cu(II), Co(II), Mn(II) and Fe(II) salts was studied. The effects of the amount of catalyst and the temperature were determined. 1-Methyl-1-(4-methoxyphenyl)ethyl hydroperoxide was obtained in a yield of 73 mol% when 1-methoxy-4-(1-methylethyl)benzene was oxidised for 3 h at 60°C in acetonitrile as a solvent in the presence of NHPI. 1-(4-Methoxyphenyl)ethanone with high selectivity up to 68–75 mol%, but low yield amounting to 11 mol% was obtained when 1-methoxy-4-(1-methylethyl)benzene was oxidised in the presence of the NHPI/Cu(II) system at 120°C.