Versatile cobalt complexes for initiating immortal ring‐opening polymerization (ROP) of lactide (LA), mediating living radical polymerization of t‐butyl acrylate (tBA) and catalyzing copolymerization of LA and tBA by combination of ROP and organometallic‐mediated radical polymerization

Low‐cost, highly active and versatile amino‐bis(phenolate) cobalt complexes are developed. The cobalt complexes can control living polymerization of different categories of monomers including lactide (LA) by immortal ring‐opening polymerization in argon and even in air and acrylate via living radical polymerization (LRP). The cobalt‐based catalysts were used for copolymerization of LA and acrylate. The immortal polymerization of LA using the cobalt complexes as initiators proceeds in argon and even in air and without the requirement for extensive drying techniques or inert atmosphere whilst retaining end‐group fidelity. The cobalt complexes are used to mediate LRP of t‐butyl acrylate (tBA) in methanol. The block copolymerization of LA and tBA catalyzed by single‐site cobalt organometallic catalyst is also reported for the first time. This cobalt system offers a versatile and green way to produce homopolymers and block copolymers.     

Determination of microgram amounts of cobalt in sodium metal: 2-Nitroso-r-naphthol spectrophotometric method

A colorimetric method, with 2-nitroso-1-naphthol, is outlined for determining cobalt in sodium metal, which is used as a coolant in nuclear reactors. The sodium metal is reacted with water, neutralized with hydrochloric acid, and the cobalt content determined ; the cobalt nitrosonaphtholate is extracted with carbon tetrachloride and the absorbance is measured at 535 mμ. Chloride ion is requisite for the extraction of the cobalt complex in dilute solutions. Lithium and potassium as well as sodium have no effect. Ammonium ions have an adverse effect. As little as 0,1 p.p.m. cobalt can be determined in sodium metal. In order to determine cobalt in the fractional p.p.m. range, 10 g of sample are used. The molar extinction coefficient is 11,780.     

Cobalt(II) Tetraaminotetranitrophthalocyanine and Its N-Acyl Derivatives

The reaction of 4-acylamino-5-nitrophthalocyanines with cobalt(II) chloride was used to prepare for the first time the corresponding cobalt phthalocyanines. Hydrolysis of cobalt(II) tetra-4-acetylamino-tetra-5-nitrophthalocyanine gave cobalt(II) tetra-4-aminotetra-5-nitrophthalocyanine. The effect of amino(acylamino) and nitro groups on the properties of the metal complexes, particularly on their electronic absorption spectra, was demonstrated.     

Effect of the composition of pyrophosphate electrolyte on the kinetics of cobalt electrodeposition

Potentiometric titration was used to study the equilibrium in a solution of the pyrophosphate cobalt complex in a wide range of pH values. The effect of the solution pH and the concentrations of the cobalt complex and the free ligand on the kinetics of cobalt electrodeposition was examined.     

Cobalt thin films on gold: A new reference material for the quantification of cobalt phthalocyanine and cobalt porphyrin modified gold electrodes with synchrotron radiation micro X-ray fluorescence spectroscopy

New reference materials consisting of cobalt thin films on gold were prepared by sputter deposition. The thickness and homogeneity of the films were characterized using synchrotron radiation micro-XRF. The samples can be used as reference materials to quantify cobalt phthalocyanine and cobalt porphyrin modified gold electrodes which have been analyzed with synchrotron radiation micro-XRF.     

Coordination compounds of hydrazine derivatives with transition metals,part XVIII. Cobalt(II) and cobalt(III) chelates with schiff bases derived from hydrazine-S-methyldithiocarboxylate and thiosemicarbazide

Summary The reactions of aldehydic and ketonic Schiff bases derived from hydrazine-S-methyl dithiocarboxylate and thiosemicar-bazide with cobalt(II) acetate were investigated. Octahedral tris ligand cobalt(III) chelates were formed with aldehydic Schiff bases whereas tetrahedral bis ligand cobalt (II) chelates were isolated with ketonic Schiff bases.N-isopropylidene hydrazine-S-methyldithiocarboxylate, however, gave both octahedral tris cobalt(III) and tetrahedral bis cobalt(II) chelates. These results are interpreted in terms of the steric requirements of the Schiff base used.     

超临界二氧化碳体系中正八面体氧化钴颗粒的生长及其表征

研究了正八面体氧化钴颗粒在超临界二氧化碳体系中的合成过程。在密闭的不锈钢高压反应釜中,1.0 g乙酸钴和12.0 g干冰在450 ℃下,反应12 h后合成粒径大约10 μm的正八面体氧化钴颗粒。通过XRD、 XPS、TEM、 SEM以及拉曼光谱的分析,氧化钴颗粒是由八个{111}面包裹着的正八面体单晶组成。条件实验显示,超临界二氧化碳体系是正八面体氧化钴颗粒合成的充分条件。其生长机理可能是：乙酸钴在超临界二氧化碳体系中的热分解;氧化钴的结晶和定向缓慢生长。在性能方面,初步研究了正八面体氧化钴颗粒在作为锂离子电池电极材料的应用。     

Determination of ultra-trace levels of cobalt by ion chromatographic separation and chemiluminescence detection

A luminol chemiluminescence detection/flow injection analysis technique coupled with ion chromatography (IC) has been examined for the selective determination of cobalt (II) at pg ml^?1 levels. A barium chloride solution was used as an eluent in the IC to separate cobalt(II) from interferents. When a 100-μ1 sample injection volume was used, the detection limit was 1.0 pg ml^?1 cobalt; the minimum detectable amount of cobalt was 100 fg. The calibration graph was linear above 10 pg ml^?1 and the linear dynamic range extended over six orders of magnitude. The relative standard deviation for ten replicate measurements of 30 pg ml^?1 cobalt was 3.8%. The results of the analysis of a synthetic sample corresponding to a boiling-water reactor coolant and some commercially available copper(II) standard solutions are given.     

Determination of cobalt by substoichiometric extraction with β-hydroxy-naphthaldoxime

A substoichiometric radiochemical solventextraction method is described for the determination of cobalt, employing β-hydroxy-naphthaldoxime and chloroform as reagent and extractant, respectively. The extraction behaviour of the complex of cobalt with the reagent in the pH-range 8–9.5 and the effects of various metal ions on the extraction are critically studied. The method is used to determine the cobalt content in some pharmaceutical drugs.     

Determination of cobalt in solid matrices by neutron activation analysis

The concentration of cobalt in 2 solid matrices was determined by neutron activation analysis (NAA) using standard solutions which were prepared by dissolving pure cobalt in nitric acid. The matrices assayed were a cobalt-aluminium wire and an iron foil and the respective Co concentrations found were 0.488% and 0.138%. Both solid materials can equally be used as standard references of cobalt in NAA. Subcadmium and epicadmium neutron fluxes in the reactor core were determined using Co?Al and Au?Al alloy wires. Very good agreement was obtained for all irradiation configurations of the target monitors cobalt and gold.     

Analytical properties of 2-nitro-5,6-dimethyl-1,3-indanedione dithiosemicarbazone

The synthesis, characterization and analytical properties of 2-nitro-5,6-dimethyl-1,3-indanedione dithiosemicarbazone (NDIDT) are described. NDIDT is used as a chromogenic reagent for the rapid spectrophotometric determination of cobalt(II), palladium(II) and osmium(VIII). The spectrophotometric method developed for cobalt has been used in the analysis of alloys.     

Anion-exchange separation of iron,cobalt and nickel

From 90% acetone-10% 6 M hydrochloric acid medium, cobalt and nickel are strongly adsorbed on the anion-exchange resin Dowex I-X8; iron is not adsorbed and can thus be separated from cobalt and nickel. Cobalt and nickel are then separated by elution with 70% acetone-30% 2 M hydrochloric acid; nickel is eluted before cobalt. The method can be applied to the determination of nickel and cobalt in materials with high iron content such as steels ; compleximetric titrations are used for the final step.     

Second and first-derivative spectrophotometry for efficient simultaneous and individual determination of palladium and cobalt using 1-(2-pyridylazo)-2-naphthol in sodium dodecylsulfate micellar media.

1-(2-Pyridylazo)-2-naphthol (PAN) has been used for the simultaneous and individual determination of palladium and cobalt at trace levels. PAN complexes of palladium and cobalt at neutral pH form green-color neutral complexes, which are soluble in aqueous SDS micellar media. Under optimum conditions, calibration graphs for individual determinations by zero and first-derivative spectrophotometry, and also for simultaneous determinations by second-derivative spectrophotometry were obtained. A zero-crossing method using second-derivative spectrophotometry at 628 or 578 and 614 nm, respectively, for cobalt and palladium was used for simultaneous determinations. The method is able to determine the cobalt-to-palladium ratio, 5:1 to 1:10 (Wt/Wt), accurately. The accuracy and reproducibility of the determination method for various known amounts of cobalt and palladium in their binary mixtures were tested. The effects of diverse ions on the determination of cobalt and palladium to investigate the selectivity of the method were also studied. The recommended procedures were applied to a synthetic binary alloy, cobalt in vitamin B12 and B-complex ampoules, a Co2O3-Co3O4 laboratorial chemical mixture, some synthetic cobalt-alloy samples, a Pd-charcoal catalyst, and some synthetic palladium alloys.     

原子吸收法测定矿石中钴的不确定度评定

利用原子吸收光谱法评定了矿石中钴测定的不确定度,为质量控制提供有效、可靠的测量数据。结果表明,测量结果的不确定度由钴的质量浓度C0、称样质量m0、试液定容体积V等引入的不确定度分量组成,而主要分量是钴的质量浓度。     

A facile spectrophotometric method for cobalt determination using alpha-benzilmonoxime in sodium dodecylsulfate micellar solutions.

Alpha-benzilmonoxime in sodium dodecylsulfate micellar media has been used for the spectrophotometric determination of cobalt at pH 9.0. The linear range of calibration is 0.05-1.50 microg cm(-3) of cobalt at 380 nm with molar absorptivity of 3.72 x 10(4) dm3 mol(-1) cm(-1), which is about 1.5-times greater than that of the alpha-benzilmonoxime extraction based method. The relative standard deviations, recoveries, detection limit and effects of diverse ions on the determination of cobalt were studied. These analytical results were satisfactory. The method was successfully applied to the determination of cobalt in the various samples.     

Spectrophotometric simultaneous determination of cobalt, copper and nickel using nitroso-R-salt in alloys by partial least squares

Partial least squares modeling as a powerful multivariate statistical tool applied to spectrophotometric simultaneous determination of cobalt, copper, and nickel in aqueous solutions. The concentration range for cobalt, copper and nickel were 0.4-2.6, 0.6-3.4, 0.5-5.5 ppm, respectively. The experimental calibration set was composed with 36 sample solutions using a mixture design for three component mixtures. The absorption spectra were recorded from 470 to 600 nm. The effect of pH on the sensitivity and selectivity was studied according to net analyte signal (NAS). The values of root mean square difference (RMSD) for cobalt, copper and nickel using partial least squares (PLS) were 0.0192, 0.0263 and 0.0446 ppm, respectively. The effects of various cations and anions were investigated. The method was used to determination of cobalt, copper and nickel in two sample alloys based on copper, nickel and cobalt (known as cunico) and based on cobalt, nickel and iron (known as conife).     

Controlled synthesis of cobalt nanocrystals on the carbon spheres for enhancing Fischer–Tropsch synthesis performance

Non-porous carbon sphere was used as support to synthesize supported cobalt Fischer-Tropsch catalysts with high activity and durability. Strong metal-support interaction was avoided and intrinsic activity of pristine cobalt nano-particles was studied. Thermal decomposition synthesis method was applied to obtain cobalt catalysts with high dispersion and narrow particle size distribution. Furthermore the cobalt size can be controlled by the molar ratio of o-dichlorobenzene/benzylamine. Compared with supported cobalt catalysts prepared by incipient wetness impregnation method and ultrasonic impregnation method,the catalyst prepared by thermal decomposition method showed higher catalytic activity, higher long chain hydrocarbons selectivity and lower methane selectivity.     

A sensitive and simple extractive-spectrophotometric method for the determination of microgram amount of cobalt by using alpha-benzilmonoxime.

Alpha-benzilmonoxime has been used for the extraction and determination of cobalt at microgram amount. The reagent reacts with cobalt(II) in the pH range of 8.8 - 9.3 to form a yellow-color chelate, which is extracted in chloroform, toluene, and some other non-polar solvents. The chelate is stable in chloroform for about one day. Under the optimum conditions of the a-benzilmonoxime concentration and pH of 9.0, Beer's law was obeyed in the concentration range of 0.08 - 2.2 microg/ml cobalt. The molar absorptivity of the extracted species was 2.55 x 10(4) dm3/mol cm at 380 nm, with a detection limit of 0.01 microg/ml cobalt. Relative standard deviations of 0.4, 0.8 and 2.3% were found for the determination of cobalt concentrations of 2.2, 1.1 and 0.08 microg/ml, respectively. The effect of diverse ions on the determination of 1.00 microg/ml of cobalt has been studied. The method was applied to the determination of cobalt in vitamin B12 and B-complex ampoules, a Co2O3-Co3O4 laboratory chemical mixture and some synthetic alloy samples. The method is sensitive, simple, rapid and accurate.     

层状嵌接式卟啉钴的合成,表征及其对H2O2催化降解研究

采用有机溶剂在层状锑磷酸中在位分步分成了层状嵌接卟啉然材料；用红外光谱、紫外可见光 、Ｘ射线衍射和顺磁共振技术对其进行了表征。该合成材料对Ｈ２Ｏ２降解反应体系的进一步研究表明，卟啉钴嵌接于锑磷层状环境中对Ｈ２Ｏ２具有良好的催化降解活性和抗失活稳定性。     

Gravimetric determination of cobalt and nickel,and their separations from copper with n-benzoylphenylhydroxylamine

N-Benzoylphenylhydroxylamine can be used for the gravimetric determination of cobalt and nickel. The precipitates can be weighed as such, or ignited and weighed as cobalt sulphate or nickclous oxide. Cobalt or nickel can be separated from copper with the reagent.