Interfacial activity of 4-alkylphenylamines and the rate of palladium(II) extraction

Interfacial tension isotherms were determined in hydrocarbon-water systems for 4-alkylphenylamines containing from 6 to 16 carbon atoms in their alkyl chains, and the surface excess isotherms were computed and interpreted using various adsorption isotherms. Palladium(II) was extracted with 4-alkylphenylamines from 3 M HCI solutions. The maximum extraction rate of palladium(II) is observed for 4-decyl- and 4-dodecylphenylamines which exhibit good interfacial activity. Compounds soluble in the aqueous phase (4-hexylphenylamine) or in toluene (4-hexadecylphenylamine) extract palladium(II) slower than 4-decyl- and 4-dodecyl- phenylamines.     

Reduction of nitroaromatics with poly(vinylpyridine) complexes of palladium(II) and platinum(II)

Palladium(II) and platinum(II) anchored to 2- and 4-vinylpyridine polymers of different molecular weights were used for the dihydrogen reduction of various nitroaromatics and benzaldehyde in ethanol at 50°C. Palladium(II) complexes were far more effective than their platinum(II) analogues and the activity decreased with increasing molecular weights of the polymers. The nitroaromatics were selectively and almost completely reduced to the corresponding anilines. During reduction, the orange palladium(II) complexes changed to voluminous green precipitates, which could be used repeatedly and preserved for a long time without any loss of activity. A rate equation of the type: rate = K[Cat] [H₂] has been derived and a reduction mechanism has been proposed on the basis of experimental results and kinetic data.     

Polymerization and characterization of various di(pyridine)bis(trihalophenolato)cobalt(II) complexes in solid and melt states

The syntheses of distorted tetrahedral bis(pyridine)bis(trihalophenolato)cobalt(II) complexes from an aqueus solution were achieved and their characterization by FT‐IR, X‐ray, DSC, UV‐visible and elemental analysis in solid state or in melt form is reported. Polymerizations of these complexes were accomplished either at constant temperature, employing different time intervals or constant decomposition times while varying the temperature range. The slow decomposition at constant temperature leads to long chain products, whereas long chains formed at higher temperatures were during a constant time. The resulting poly(dihalophenylene oxide)s were characterized by FT‐IR, ¹H NMR, ¹³C NMR spectral analysis, differential scanning calorimetry and molecular weight determinations by viscometric method. © 2001 Society of Chemical Industry     

2-(4-氨基苯基)吡啶合成方法的改进

以对硝基苯胺的重氮盐和吡啶为原料,经过Gomberg-Bachmann反应和Pd-C还原反应,合成了一种电致磷光材料关键中间体2-(4-氨基苯基)吡啶。     

Determination of cobalt(II), nickel(II) and palladium(II) Ions via fabric phase sorptive extraction in combination with high-performance liquid chromatography-UV detection

A method for the determination of Co(II), Ni(II) and Pd(II) in aqueous samples by fabric phase sorptive extraction-high-performance liquid chromatography-UV detection (FPSE-HPLC-UV) is developed. A preconcentration step was necessary due to the trace level concentrations of these elements in aqueous samples. Sol-gel polytetrahydrofuran nanocomposite was selected as the sorbent. All major FPSE parameters were optimized. The limit of detection for Co(II), Ni(II) and Pd(II) morpholino dithiocarbamate complexes were found at much lower concentration level compared with earlier reported data with excellent reproducibility. The new FPSE-HPLC-UV method can be used for routine determination of these metal species in various aqueous environmental samples and in different alloys.     

Equilibrium and kinetic studies of the extraction of chelated copper(II) anions with Aliquat 336

The equilibrium and kinetics of solvent extraction of Cu²⁺ from aqueous solutions containing equimolar EDTA with Aliquat 336 in n‐decanol and kerosene at 298 K were investigated. The concentrations of Cu²⁺ (8–50 mol m^?3), Cl^? (5–60 mol m^?3), and Aliquat 336 (20–100 mol m^?3) were varied. A semi‐empirical model with three parameters was proposed to describe the equilibrium behavior, in which the non‐idealities in both aqueous and organic phases were considered. Over the ranges studied, the model agreed reasonably well with the experimental data (standard deviation, 15%). The forward and backward reaction rate constants were determined as (5.31 ± 0.16)×10^?6 m^9/4 mol^?3/4 s^?1 and (2.62 ± 0.09)×10^?7 s^?1, respectively, at 298 K. An interfacial reaction mechanism was proposed, which revealed that the reaction between the chelated anions and trimeric amine molecules at the interface was rate limiting. The derived rate laws were consistent with the experimental results. © 2002 Society of Chemical Industry     

Highly selective solvent extraction of Zn(II) and Cr(III) with trioctylmethylammonium chloride ionic liquid

This study investigates the recovery of Zn(II) and Cr(III) from aqueous solutions based on solvent extraction with trioctylmethylammonium chloride [TOMA⁺][Cl-], commercialy named Aliquat 336. Single metal solutions and binary mixtures of both metals were considered. The effect of relevant operating conditions such as pH, contact time, initial concentration, O/A phase volumetric ratio, and temperature were evaluated. Additionally, loading capacity and stripping studies were performed. Results showed that [TOMA⁺][Cl^?] is an effective extracting agent for Zn(II), reaching maximum removal capacity at pH 1.8 and demonstrating fast extraction kinetics. Extraction efficiencies above 99% were achieved at 0.5, 0.75, and 1.00 O/A volumetric phase ratios for 0.1 g/L initial Zn(II) concentration. At 1 g/L and 10 g/L concentration, for the same O/A ratios, approximately 88% of the initial Zn(II) was extracted. In contrast, it was found that negligible amounts of Cr(III) were transferred to the [TOMA⁺][Cl^?] phase at the 1-5 pH range. Selectivity studies showed that Zn(II) removal is boosted in the presence of Cr(III), although no Cr(III) is extracted. [TOMA⁺][Cl^?] exhibited a high Zn(II) storage capacity, since after 25 loading cycles with 1 g/L, the loading capacity reached approximately 13.5 g/L, and after five loading cycles with 5 g/L, the capacity reached 19.4 g/L. Stripping tests revealed that NaOH is an efficient agent for the removal of Zn(II) from the ionic liquids, reaching 98.5% removal after two cycles, whereas HNO₃ is not a suitable agent, reaching less than 40% removal after three cycles. [TOMA⁺][Cl^?] revealed high potential for separating Zn(II) from Cr(III).     

Palladium(II) extraction from concentrated chloride media: Reactions involving thioamide derivatives

This work focuses on the detailed study of the palladium(II) extraction reactions by N-methyl-N-phenyl-octanthioamide (MPHTA) and N-methyl-N-cyclohexyl-octanthioamide (MCHTA) in toluene, since their ability to efficiently and selectively recover Pd(II) from a wide range of HCl concentrations is already known. Equilibrium data are presented and discussed, and further complemented by information depicted from UV–visible and NMR spectra. The determined apparent molar volumes show that MPHTA is monomeric, and MCHTA exhibits a slight tendency to aggregate. The Pd(II) extraction reactions by MPHTA and MCHTA are equivalent until 4.5 M HCl, passing through the formation of inner-sphere complexes with the metal ion.     

Synthesis, characterization and olefin polymerization studies of iron(II) and cobalt(II) catalysts bearing 2,6-bis(pyrazol-1-yl)pyridines and 2,6-bis(pyrazol-1-ylmethyl)pyridines ligands

The complexes Py(PzR₃)₂MCl₂ (R = H, Me; M = Fe, Co) and Py(CH₂PzR₃)₂MCl₂ (R = H, Me; M = Fe, Co) have been synthesized, characterized and used in the ethylene polymerization. Treatment of these iron and cobalt complexes with methylaluminoxane (MAO) as cocatalyst leads to active ethylene polymerization catalysts that produced linear polyethylene. In general, iron catalysts were more active than cobalt analogs. The steric and electronic effects of the ligands were study over the catalytic activity toward ethylene polymerization. Complexes with small substituents groups (R = H) on the pyrazolyl ring, increase the catalytic activity in comparison to complexes with bigger substituents groups (R = CH₃). Additionally, complexes with methylene groups placed between pyridine and pyrazole rings of ligands have less catalytic activity than complexes without the methylene group (CH₂). The presence of methyl groups (R = CH₃) in iron and cobalt complexes allow to obtain polyethylene with molecular weights higher than the one obtained with complexes without these methyl groups. Additionally, complexes with methylene groups present between pyridine and pyrazole rings generate polyethylenes with molecular weight higher than the ones produced with complexes without these methylene groups.     

Synthesis,characterization and antibacterial activity of Pd(II), Pt(II) and Ag(I) complexes of 4-ethyl and 4-(p-tolyl)-1-(pyridin-2-yl)thiosemicarbazides

Pd(II), Pt(II) and Ag(I) ions were found to form stable complexes with 4-(p-tolyl)- or 4-ethyl-1-(pyridin-2-yl)thiosemicarbazides (Hp-TPTS or HEPTS). The complex structure was elucidated by analysis (elemental and thermal), spectroscopy (electronic, IR and ¹H NMR spectra) and physical measurements (magnetic susceptibility and molar conductance). The ligands coordinate to the metal ions as monobasic bidentate through nitrogen and sulfur atoms. The electronic spectra of the Pt(II) complexes in DMF showed a metal to ligand charge transfer transition at 11,935–13,260 cm^?1. The structural, electronic and vibrational features of HEPTS and Hp?TPTS were discussed on the basis of semi-empirical quantum mechanic calculations [ZINDO/S and semi-empirical parameterization (PM3)]. The simulated IR and electronic spectra are found reasonable in accordance with the experimental data. Finally, the antibacterial activities of the ligands and their complexes were investigated and some were found promising.     

Highly selective separation and recovery of Pd(II) from the automotive catalyst residue with the thiocarbamoyl substituted azothiacalix[4]arene derivative

New ligand, namely, 5, 11, 17, 23-tetrakis-((p-chlorophenyl) azo)-25,26,27,28-tetrakis ((dimethylthio carbamoyl)oxy) thiacalix[4]arene (CADTTCA), has been investigated for separation and recovery of Pd(II) through solvent extraction technique. Experimental parameters such as contact time, diluents, effect of H⁺ and Cl^? concentration, and acid durability have been thoroughly investigated. The loading capacity toward Pd(II) was determined to be 113 mg/L using 0.25 mM CADTTCA. The extractant showed high selectivity and extractability for Pd(II) than the other metal ions present in automotive catalyst residue (ACR) solution containing platinum group (PGMs) metal ions (i.e., Pd(II), Pt(IV), Rh(II), La(III), Al(III) and Ce(III)). The recovery percentage of Pd(II) was 98% after five extraction-scrubbing-stripping cycles. The probable extraction mechanisms were established through the FT-IR spectral analysis.     

Separation and concentration processes of solutions of Co(II), Ni(II), Cr(III), Fe(III) and Mn(II) by extraction with toluene-dissolved rosin

The extraction and stripping of Co(II), Ni(II), Cr(III) and Fe(III) from aqueous solutions by rosin dissolved in toluene has been investigated. Results obtained show that rosin is better extractant than abietic or n-lauric acids under comparable conditions. From these results, and the data of Mn(II) solvent extraction studied previously under the same conditions, a separation and concentration process for these five cations in aqueous solutions has been designed. Saturated solutions of Fe(III), Cr(III), Mn(II) and finally Co(II) and Ni(II) have been obtained successively by extraction and stripping, by addition of ammonium hydroxide to obtain the appropriate pH value, and by modifying adequately the organic phase/aqueous phase volume ratio.     

叔胺萃取分离钴(II)、铁(II)

研究了不必预先氧化二价铁,直接用叔胺从氯化物溶液中萃取分离钴(II)、铁(II)的新方法. 考察了不同改性剂对叔胺萃取钴(II)、铁(II)的影响以及各种因素对钴(II)、铁(II)萃取、洗涤及反萃的影响. 提出了用叔胺萃取分离钴(II)、铁(II)的最佳工艺参数.     

Lewis Acid Behavior of Cationic Complexes of Palladium(II) and Platinum(II): Some Examples of Catalytic Applications

The behavior of a variety of cationic diphosphine complexes of Pd(II) and Pt(II) as Lewis acid catalysts is reviewed. The reactions considered are the Baeyer–Villiger oxidation of ketones, the acetalization of aldehydes and ketones and the Diels–Alder reaction in both their regular and enantioselective version.     

硫氰酸锰及其相关衍生物的合成及化学表征

合成了金属有机配合物非线性光学晶体硫氰酸汞锰，及其相关衍生物，二二甲亚砜合硫氰酸汞锰，乙二醇一甲醚合硫氰酸汞锰，二水合二N，N－二甲基乙酰胺合硫氰酸汞锰，二水合二N－甲基－α－吡咯烷酮合硫氰酸汞锰。采用元素分析，红外光谱以及紫外－可见－近红外透央求我谱分析对其进行了化学表征。     

Ligand-Tuning of the Stability of Pd(II) Conjugates with Cyanocobalamin

Besides the well-known functions performed by vitamin B₁₂ (CblCN) in biochemical processes of the human body, an increasing interest has been raised by the possibility of its use as a transmembrane drug carrier, capable, among others, of enhancing the accumulation of inorganic cytostatics in cancer cells. The present study was aimed at determining the possibility of the formation of CblCN conjugates with Pd(II) complexes. A key aspect was their stability, which we attempted to tune by appropriate choice of ligands. Syntheses, spectroscopic analysis of postreaction systems and kinetic investigations of conjugate formation reactions, have been complemented by DFT modelling. The obtained results showed that ligand charge, geometry and electron affinity may have a significant impact on carrier binding and release leading to the activation of the Pd(II) complex. This provides a rationale to expect that with appropriate composition of the coordination sphere, it will be possible to extend the spectrum of less toxic inorganic chemotherapeutics.     

吡啶类缓蚀剂及其在Al(111)表面吸附行为的密度泛函理论分析

利用密度泛函理论方法研究了3种吡啶类缓蚀剂分子(吡啶、3-甲基吡啶和4-甲基吡啶)的反应活性及溶剂条件下在Al(111)表面的吸附行为。分子反应活性的量化计算结果表明,3种缓蚀剂分子的前线轨道均分布在吡啶环上,亲核和亲电活性中心均位于吡啶环的N原子上。分子与Al表面吸附的量化计算结果表明,3种分子均能与Al(111)面发生化学吸附,吸附强度顺序与实验测得的缓蚀效率顺序相一致,且缓蚀剂分子与Al(111)面的相互作用是由成键原子的轨道杂化所致。此外,3-甲基吡啶和4-甲基吡啶两个分子还能平行于Al(111)面发生物理吸附。     

Interfacial Activity of Hydroxyoximes and mechanism and kinetics of palladium(II) extraction

Surface excess isothermers were determined and interpreted for systems containing 2-hydroxy-5-t-nonylbenzaldehyde oxime ( 1 ), 2-hydroxy-5-t-octylacetophenone oxime ( 2 ) and 2-hydroxy-5-t-octylbenzophenone oxime ( 3 ). These surface excess isotherms were used to predict reaction orders with respect to hydroxyoximes for various versions of interfacial process. Agreement with the experimental data was observed both for the interfacial and bulk aqueous mechanism. The surface activity of extractants cannot be recognized as the sole evidence for the interfacial mechanism of extraction. More experimental kinetic data are needed in order to determine the effect of hydroxyoxime concentration upon the reaction order. According to the interfacial mechanism, with the formation of the stable 2:1 complex as the limiting step the reaction order in hydroxyoxime equal to 1 is observed over a large range of hydroxyoxime concentration, but increases to 1.5-2.0 for very low concentrations.     

Monomers and polymers of 4‐(N,N‐diallylamino)pyridine functions

4‐(N,N‐Diallylamino)pyridine (DAAP), N,N‐diallylaminobenzene (DAAB), N,N,N′,N′‐tetrallyl‐4,4′‐diaminobenzidine (AAB), N,N,N′,N′‐tetrallyl‐4,4′‐diaminodiphenyl sulfone (AABS), and N,N,N′,N′‐tetrallyl‐4,4′‐diaminodiphenyl ether (AABE) were prepared by sodium substitution and N‐allylation. Moreover, linear polyDAAP, poly(DAAP‐co‐DAAB), and network poly(DAAP‐co‐AAB), poly(DAAP‐co‐AABS), and poly(DAAP‐co‐AABE), all being polymers containing supernucleophilic groups, were synthesized in the cyclopolymerization. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 363–367, 2000     

Oxidation of 4‐nitrophenol in water over Fe(III), Co(II), and Ni(II) impregnated MCM41 catalysts

BACKGROUND: Nitrophenols are toxic constituents of the effluents of petroleum, textile, dye, iron and steel, foundries, pharmaceutical and electrical manufacturing industries. Aromatic nitro compounds are particularly resistant to normal chemical or biological oxidation making them environmentally persistent. Advanced oxidation using appropriate catalysts mineralize these organics to harmless final products. In this work, MCM41‐based catalysts incorporating Fe(III)‐, Co(II)‐ and Ni(II)‐ cations were used for oxidizing 4‐nitrophenol in water under variable conditions of reaction time, pH, mole ratio of the reactant and the oxidant, catalyst load, feed concentration, and temperature. RESULTS: The catalysts prepared were characterized with X‐ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), cation exchange capacity (CEC) and atomic absorption spectrometry (AAS) measurements. In typical reaction conditions of temperature 353 K, time 300 min, catalyst load 2 g L^?1 and 10^?3 mol L^?1 4‐nitrophenol, the oxidation was 48.7, 52.2 and 55.2% with H₂O₂ and 42.5, 56.6 and 60.2% without H₂O₂ for Fe(III)‐, Co(II)‐ and Ni(II)‐MCM41, respectively. Pseudo‐first‐order kinetics with kinetic constant of 2.0 × 10^?3 to 5.5 × 10^?3 Lg^?1 min^?1 was proposed along with a possible mechanism. 4‐nitrocatechol, 4‐nitropyrogallol, 1,2,4‐trihydroxybenzene, hydroquinone, acrylic acid, malonic acid, and oxalic acid were identified in the oxidation products. CONCLUSION: Introduction of Fe(III)‐, Co(II)‐ and Ni(II)‐ into MCM‐41 by impregnation produced effective catalysts for wet oxidation of 4‐nitrophenol. The catalysts were able to oxidize 4‐NP even without the presence of an oxidizing agent. The results suggest that the transition metal loaded MCM41 brings about a more effective interaction between 4‐NP molecules and OH radicals. Copyright © 2008 Society of Chemical Industry