Shape of the proton potential in an intramolecular hydrogen-bonded system. Part II

The crystals of 5,5′-dibromo-3-diethylaminomethyl-2,2′-biphenol N-oxide were studied by X-ray and FT-IR spectroscopy. Within this molecule two short OHO intramolecular hydrogen bonds are formed. The NO?H⁺?O⁻ bond between the OH and the N-oxide groups is very strong, of 2.419(7) Å between the oxygen atoms. The proton potential of this hydrogen bond is flat, broad and has probably no barrier—consequently it could not be located from X-ray diffraction data. The other hydrogen bond formed between two hydroxyl groups appears asymmetrical from FT-IR spectra, and shows also relatively limited proton polarizability. The molecular conformation is non-planar, due to strong overcrowding effect between the oxygen atoms involved in the hydrogen bonds.     

Selective spectrophotometric determination of TNT in soil and water with dicyclohexylamine extraction

Contaminated land and groundwater remediation in military waste dumping sites often necessitates the use of simple, cost-effective, and rapid tests for detecting trinitrotoluene (TNT) residues in the field along with their dinitro-analogues. A simple, rapid, low-cost, and field-adaptable (on-site) colorimetric method was developed for quantifying TNT in the presence of RDX, PETN, picric acid, 2,4-DNT (dinitrotoluene), dinitrophenol, and dinitroaniline. Most commercialized methods for TNT assay-with the exception of Cold Regions Research and Engineering Laboratory of the U.S. Army (CRREL) method-use proprietary chemicals, and the color stability and intensity are highly dependent on the composition of the organic solution comprised of acetone or methanol. The developed colorimetric method is based on the extraction of TNT from water-acetone solution into an organic solvent mixture of dicyclohexylamine (DCHA)-isobutyl methyl ketone (IBMK) (10:1, v/v), filtration through a filter paper into a stoppered optical cell containing anhydrous sodium sulfate, and measurement of the absorbance of the organic extract at 531 nm after 5 min. The red-violet color of the extract was due to intermolecular charge-transfer (CT) between the electron attracting TNT and electron-donating DCHA, and the molar absorptivity for TNT in final organic solution was (1.16 ± 0.02) × 10⁴ L mol⁻¹ cm⁻¹.The R.S.D. of the slope of calibration line was 0.7%. The LOD of the method in the final organic phase was 0.38 μM TNT, and LOD values expressed on the basis of original soil TNT content were 0.5, 1.3, and 1.5 ppm (μg g⁻¹) for clay, loamy clay, and sandy soils, respectively. Unlike other spectrophotometric methods, the developed assay was basically tolerant to common cations and anions found in soil and water at 100-fold weight ratios, and to soil humic acids. Among a number of compounds that may be encountered in polynitro-explosive storage and waste reclaimation sites such as picric acid, dinitrophenol, 2,4-dinitrotoluene, dinitroaniline, RDX, PETN, and tetryl, only tetryl interfered with the developed TNT assay. Water tolerance and exploitability over a wide pH range were other superiorities over the CRREL method. The CT-complex was relatively stable, as the absorbance of the organic extract was not significantly influenced from the dilution of the water-acetone phase. Aside from the extractive-photometric procedure established for aqueous solutions, a simulated field colorimetric assay for TNT directly applicable to soil was also devised, based on direct color development in a 4:1 (v/v) acetone-dicyclohexylamine organic extract of soil at a liquid-to-solid ratio of 5 mL g⁻¹.     

Catalytic air oxidation of manganese in synthetic waters

An attempt was made to study the oxidation of manganese by air in synthetic waters. A series of batch experments were performed at differnet values of concentration, temperature and pH. Unoxidized manganese in the solution was determined by formaldoxime spectrometric method. Results of these studies indicated that the air oxidation of manganese soluble in water can be effectively performed in basic media and that oxidation yield increasedwith an increase in pH and concentration. The yield was very high in the presence of manganese dioxide, sepiolite or clinoptilolite in solution and, the oxidation was almost completed especially at high values of pH and concentration. The reaction was found to be first order with respect to Mn²⁺ with a very low activation energy. A yield of 62% was obtained for the air oxidation of wastewater taken from the treatment plant of Corum Municipality.     

含铈多元氧化物的活性结构及在丙烯氨氧化中的作用

本文利用流化床反应器研究了多元复合氧化物PMo_(12)Bi_3Fe_(8-x)Ce_xK_(0.1)O_y(x=0-8)中稀土元素铈对丙烯氨氧化的催化作用,并用x-射线衍射、红外光谱、扫描电镜和热重技术表征了催化剂的结构,发现x=2-3时,丙烯腈的收率最高。催化剂中存在Fe_2(MoO_4)_3,Ce_2(MoO_4)_3、α-Bi_2O_3、3MoO_3。这三种物相的互相溶解和凝结形成固溶体和准均相,使活源。份在各物相表面或界面上均匀分布,由此产生的各活性组份的协调作用是催化活性的主要来性组铈能抑制MoO_3升华,稳定活性相结构。     

Precipitation and recrystallization of uniform CuCl particles formed by aggregation of nanosize precursors

Uniform, spherical CuCl particles were obtained by mixing aqueous solutions of CuCl ₂ and ascorbic acid in the presence of polyvinylpyrrolidone (PVP) as dispersing agent. The size and the uniformity of the resulting particles depended on the volume ratio of the reactant solutions, their concentrations, the distribution of the stabilizers, and the mixing method. The single jet precipitation yielded large spheres of broad size distributions, while the particles obtained by the double jet technique were rather uniform in size. The final colloidal CuCl particles were formed by the aggregation of nanocrystals, initially generated in the system. Depending on the pH of the reaction mixture, these particles slowly change to large CuCl crystals on aging in the mother liquor.     

Ba-K-Bi-O和Ba-K-Pb-O氧化物的碘量滴定

本文提出了碘量法滴定Ba－K－Bi-O和Ba－K－Pb－O氧化物中Ba和Pb的名义价态，然后据此计算这些氧化物中K和Ba含量的方法。该法适用于正常条件下合成的具有ABO3型钙钛矿结构的Ba－K－Bi-O和Ba－K－Pb－O晶体。用本法的滴定结果表明，Tc为31K的Ba－K－Bi-O超导体的K含量为0．4，当K含量减少时，Tc随之下降。     

Glow discharge mass spectrometry

Over the past twenty years or so, glow discharge mass spectrometry (GDMS) has become the industry standard for the analysis of trace elements in metals and semiconductors. A review of its history is followed by a picture of the present situation and a look to where the future may lie. Applications are summarised, including the ability of GDMS to offer depth-resolved data and non-conductor analysis, and the well-documented quantitative nature of the results is reviewed. The effects resulting from the physical properties of the analyte material are discussed at length. Finally, recent work such as fast flow sources and pulsed glow discharges is reviewed.     

Activated alpha-alkyl-alpha-arylacetic acid enantiomers for stereoselective thin-layer chromatographic and high-performance liquid chromatographic determination of chiral amines

The separation of racemic benoxaprofen into the two benoxaprofen enantiomers by preparative high-performance liquid chromatography and the application of the activated enantiomers as derivatization reagents for the simultaneous stereoselective determination of chiral amines in biological material is described. Activated (+)- and (-)-benoxaprofen are both shown to be very sensitive and stable chiral fluorescence markers, applicable to thin-layer chromatography as well as to high-performance liquid chromatography.     

酞菁钴液相催化氧化羰基硫(COS)的研究

本文首次报道在液相中，用金属酞菁催化氧化脱除羰基硫（COS）。发现COS先被水解成HS~－，HS~-再被氧化成S，酞菁钴（CoPC）的活性高于其它金属酞菁（MPC），酞菁苯环上推电子基因使酞菁的催化活性提高，双核酞菁钴的活性高子单核酞菁钴。D296树脂负载的酞菁钴的催化活性高于均相酞菁钴的活性。