Effect of adsorption of vapours on the electrical conductivity of some polyene semiconductors: adsorption and desorption kinetics

The change in semiconductive properties of β-apo-8′-carotenal, astacene and methyl bixin on adsorption of various vapours on the crystallite surfaces has been studied at a constant sample temperature. The adsorption of vapours enhances the semiconductivity of the polyenes appreciably. This enhancement depends on the chemical nature and also on the pressure of the adsorbed vapour. The adsorption and desorption kinetics follow the modified Roginsky-Zeldovich relation. A two stage desorption process, the first stage of which gives a Lennard-Jones potential energy curve and is followed by a rate-determining transition over a potential energy barrier to the second stage of adsorption forming weakly bound complexes between the vapour molecules and the polyene crystallites, can explain satisfactorily the experimentally observed kinetic data.     

氟阴离子在有机合成中的应用：Ⅱ.无水氟化钾催化乙酐与苯甲醛的Perkin反应

用无水醋酸盐催化苯甲醛与乙酐的Perkin反应,一般反应时间较长,产率最高为55—60％.用三乙胺、吡啶和无水碳酸钾等作催化剂,产率也无明显提高.近年来氟阴离子在有机合成中的应用迅速发展,我们曾用无水氟化钾催化成功地实施了丙二酸二乙酯与苯甲醛的Knoevenagel缩合,并研讨了该反应的微环境效应.本工作首次用无水氟     

An overview of laboratory performance studies conducted by the IAEA for marine pollution studies of metals and organic contaminants

Aspects of the International Atomic Energy Agency (IAEA) Analytical Quality Control Services (AQCS) for marine environmental studies are discussed, focusing on recent laboratory performance studies (LPS) and the production of reference materials for trace metals and organic compounds in various marine matrices. The IAEA has organized seventeen global interlaboratory studies for a range of organic contaminants. Of note has been the inclusion of numerous polychlorinated biphenyl congeners (PCBs) and some sterols of anthropogenic origin. Concurrently, there have been eleven worldwide intercomparison exercises for trace metals in the marine environment, most of which included methylmercury. Although such interlaboratory studies can help improve performance in individual laboratories and regional laboratory networks, the results reveal that problems remain in the determination of some metals and many organic contaminants.     

有机试剂结构与性质的研究XII有机试剂的pKa与改进的Swain－Lupton参数

有机试剂的ｐＫ０ａ是其重要的物化参数，它是有机试剂酸碱性的度量，决定其配合物的稳定性．根据Ｓｗａｉｎ－Ｌｕｐｔｏｎ的工作，每个取代基的效应可用两个参数：场／诱导效应参数与共振效应参数来描述．本文应用Ｈａｎｓｃｈ改进的参数值研究了ｐＫａ与取代基常数的相关性，建立了下式．ｐＫａ＝ｐＫ０ａ＋ｒ１Ｆ＋ｒ２Ｒ     

Ga3(HPO3)4F4(H3DETA) (DETA=diethylenetriamine): A new open-framework fluorinated gallium phosphite with pentameric building unit

Ga₃(HPO₃)₄F₄(H₃DETA) is a new open-framework fluorinated gallium phosphite obtained by mild hydrothermal synthesis using diethylenetriamine as templated agent and characterized by single crystal X-ray diffraction, the powder X-ray diffraction, IR spectroscopy, TGA, ICP and elemental analyses. It crystallizes in the monoclinic space group C2/c, a=12.741(6) Å, b=12.068(6) Å, c=11.988(5) Å, β=94.902(8)^o, V=1836.6(15) Å³, Z=4. The construction of 3D open-framework structure in the title compound may be viewed as the assembly of pentameric building units and HPO₃ groups. The pentameric building unit is the first to be found, which lead to form the three types of channels along a-, b- and c-axes, respectively, in gallium phosphite. The triprotonated DETA cations are inserted within the 10-membered ring channels and interact with anions of the framework via hydrogen bonds.     

Quantification of several atmospheric gases from high resolution infrared solar spectra obtained at the south pole in 1980 and 1986

Simultaneous total column amounts of a number of minor and trace atmospheric gases above the South Pole in December 1980 and December 1986 have been deduced from analysis of high resolution solar absorption spectra recorded (by F. J. M. and F. H. M.) from Amundsen-Scott South Pole Station. These spectra also contain some limited information on the vertical profiles of the observed atmospheric gases.The data sets were recorded with a Bomem Michelson-type interferometer and analyzed with a spectral least-squares fitting procedure, utilizing the best available spectroscopic line parameters and absorption cross sections. Because the same instrument, line parameters, and analysis method have been used in analyzing the December 1980 and December 1986 data sets, the precision in comparing the column amounts from these two dates is rather high, about 10–20% for the stronger absorbing gases. For this reason, it has been possible to quantify or determine upper limits for differences between the December 1980 and December 1986 total column amounts, of a number of atmospheric gases including O₃, N₂O, HNO₃, CO₂, CH₄, and CF₂C_{1 2} (CFC 12). In addition, vertical column amounts for a number of atmospheric gases covered only in the December 1986 observations have been derived, including HC1, NO, NO₂, and C₂H₆. Some of these results will be discussed here. The HC1 measurements are especially interesting since the observed amounts are higher than expected from observations made at lower latitudes in the northern and southern hemispheres.     

Investigation on spontaneous ignition of two kinds of organic material with water

A systematic investigation was performed to elucidate the cause of spontaneous ignition of Refuse Derived Fuel (RDF) and Meat Bone Meal (MBM). Heat generation in both RDF and MBM with addition of water liquid and vapor at room temperature was determined by isothermal calorimetry. Compared with water liquid, the heat of wetting by sorption of water vapor at 80% relative humidity and 25 °C was larger, which can raise the temperature of RDF and MBM more than 30 and 56 °C, respectively. Heat generation due to fermentation occurred and the temperature of RDF and MBM reached or exceeded 80 °C after 5 days for RDF and 4 days for MBM at 100% RH. The spontaneous ignition for RDF and MBM results from heat of wetting and fermentation at room temperature and a further exothermic reaction at higher temperature.     

Ozone as an oxygen source for alkene ene-reactions

Summary A strategy was developed which uses the adduct of ozone and triphenyl phosphite as a substitute for photochemically generated singlet oxygen in ene reactions of olefins. The resulting allylic hydroperoxide can be conveniently reduced by a second mole of phosphite to yield the corresponding allylic alcohol. The aryl phosphate produced as the by-product can either be recycled by reduction or used itself as a commodity. As an example, the two key steps of the rose oxide synthesis involving singlet oxygen can thus be reduced to a one pot procedure. With respect to the reaction mechanism, additional arguments for the direct reaction of the olefin with the phosphite ozonide were gathered. A simple decomposition of the ozonide to produce singlet oxygen was made rather unlikely.

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Ozon als Sauerstoffquelle für En-Reaktionen von Olefinen

Zusammenfassung Es wurde eine Strategie zum Ersatz von photochemisch erzeugtem Singlett-Sauerstoff durch das Addukt aus Ozon und Triphenylphosphit zum Einsatz in En-Reaktionen von Olefinen entwickelt. Das entstehende allylische Hydroperoxid kann durch ein zweites Molekül Phosphit einfach zum entsprechenden allylischen Alkolhol reduziert werden. Das als Nebenprodukt entstehende Arylphosphat kann entweder durch Reduktion recycliert oder direkt als Handelsware weiterverwendet werden. Auf diese Weise können zum Beispiel die beiden Stufen der Rosenoxidsynthese, an denen Singlett-Sauerstoff beteiligt ist, zu einer Eintopfreaktion vereinfacht werden. Bezüglich des Reaktionsmechanismus wurden zusätzliche Hinweise auf die direkte Reaktion des Phosphitozonids mit dem Olefin gefunden. Eine Zersetzung des Ozonids unter Bildung von Singlettsauerstoff ist nicht wahrscheinlich.

     

Synthesis and electrochemical properties of Zn3V3O8 as novel anode material

Zn₃V₃O₈ two-dimensional micro sheets are successfully synthesized by combination of solvothermal method and heat treatment. The Zn₃V₃O₈ has better electrochemical performances after calcinations.     

Organic fuelled flames in selective ionization detectors for chromatography

Summary The selectivities of two flame-based ionization detectors identified as a Remote FID (RFID) and a Flame Thermionic Ionization Detector (FTID) have been improved by introducing methane as a fuel for the flame. Both the RFID and FTID feature a detector struture in which the ionization polarizer and collector are located several centimeters downstream of an oxygen-rich flame, rather than immediately adjacent to the flame as in a flame ionization detector. The RFID detects long-lived negative ions produced in the flame by the combustion of lead, tin, phosphorus, or silicon compounds. The FTID re-ionizes and detects neutral electronegative products generated by combustion of nitrogen, halogen, or phosphorus compounds. An organic-fuelled RFID can detect 1 pg Pb (Sn, P)/sec with a selectivity of the order of 10⁶ versus hydrocarbons. An organic fuelled FTID is applicable to detection of compounds at nanogram and higher levels. FTID selectivity for PCB compounds in a transformer oil matrix is of the order of 10⁵1. The improved selectivity achieved by using an organic-fuelled flame is also applicable to the detection of phospholipid and other non-volatile N, P, or Cl compounds using an FID/FTID detector accessory for a TLC/FID analyser.