The photolysis of W(CO)6in CH2Cl2 produces (CO)5WCH2Cl2. The high reactivity of (CO)5WCH2Cl2 (1) was exploited to synthesize a vinylidene complexes via the acetylene-vinylidene rearrangement. The addition of a terminal
acetylene (H-C≡C-COOCH3) to a solution of (1) produced the η2-acetylene-pentacarbonyltungsten complex (CO)5W(η2-HC≡C-COOCH3) in good yield. The production of the vinylidene complex (CO)5W=C=CH-COOCH3in equilibrium with the acetylene complex in the reaction medium was verified experimentally by reaction with excess imine.
The heterocyclic organometallic compound of tungsten obtained was separated and purified and its structure was studied by
IR, 1H NMR, 13C NMR and mass spectrometry in comparison with the thermal analysis and elemental analysis data. The final aim of this investigation
is the development of a new alternative route to a β-lactame with antibacterial activity.
The use of the antibiotic agent tetracycline for analytical purposes in solvent extraction procedures is presented. Individual
extraction curves for the lanthanides, zinc, scandium, uranium, thorium, neptunium and protactinium were obtained. Separation
of those elements one from another, and of uranium from selenium, bromine, antimony, barium, tantalum and tungsten was carried
out. In all cases benzyl alcohol was the diluent used to dissolve tetracycline hydrochloride. Sodium chloride was used as
supporting electrolyte for the lanthanide separations and sodium perchlorate for the other elements mentioned. Stability or
formation constants for the lanthanide complexes as well as for thorium complex with tetracycline were determined by using
the methods of average number of ligands, the limiting value (for thorium), the two parameters and the weighted least squares.
For the lanthanides, the stability constants of the complexes Ln(TC)3 go from 9.35±0.22 for lanthanum up to 10.84±0.11 for lutetium. For the Th(TC)4 complex the formation constant is equal to 24.6±0.3. Radioisotopes of the respective elements were used for the determinations.
When more than one radioelement was present in an experiment, a multichannel analyser coupled to Ge(Li) or NaI(Tl) detectors
was used for counting the activities. When only one radioisotope was used, counting of the radioisotopes was made with a single-channel
analyser (integral mode counting) coupled to a NaI(Tl) detector. Uranium was determined by activation analysis (epithermal
neutrons). Radioisotopes of the elements were obtained by irradiation in the IPEN swimming-pool reactor. The natural radioisotope2 3 4Th was used as label in the thorium experiments. In some separation procedures such as in the case of the pair uranium-neptunium,
and of the pair scandium-zinc, the separation was obtained by properly adjusting the pH value of the aqueous phases, before
the extraction operation. In other cases, addition of masking agents to the extraction system was required in order to perform
the separation between the elements under study. In this way ethylenediaminetetraacetic acid (EDTA) was used as masking agent
for scandium and the lanthanides in order to allow separation of uranium from those elements. Diethylenetriaminepentaacetic
acid (DTPA) was used as masking agent for thorium in order to extract uranium into the organic phase. Separations of protactinium
from thorium, and of uranium from protactinium and thorium, were accomplished by using sodium fluoride as masking agent for
protactinium and DPTA as masking agent for thorium and protactinium at the same time. In the case of the separation of the
lanthanides one from another it is necessary to resort to a multi-stage extraction procedure since the stability constants
for those elements are too close.
Silicon has been found to be an essential element for the growth and development of many ecomomically important plants such
as sugarcane, rice, oats, and wheat. A method is described for the quantitative determination of silicon in plant samples.
Measurements were made with two Ge(Li) detectors matched with a multiplexing unit to provide a single amplified signal to
a computerized analyzer system. For those materials containing greater than 0.5 weight percent silicon, the reaction29Si(n, p)29Al (1273 keV) provides a direct measurement of the quantity of silicon provided the irradiation is done in a special boron
nitride capsule to reduce interferences from thermal neutron reactions and a correction is made for the single escape line
from28Al (1268 keV). For lesser quantities of silicon, a technique which utilizes the fast neutron reaction28Si(n, p)28Al is preferred. Corrections for the interference produced by the presence of phosphorus31P(n, α)28Al are made by determining the phosphorus content following the instrumental analysis using a unique application of neutron
activation analysis, i. e., measurement of tungsten in tungstomolybdophosphoric acid produced when molybdate and tungstate
ions are added to dissolved samples of the plant material containing phosphorus. Aluminum, which may also produce an interference
by thermal neutron reaction27Al(n, γ)28Al, is determined directly from the original activation data after subtracting out the effect of the phosphorus. Thus, three
irradiations in the pneumatic sample irradiator are necessary; one short irradiation (1 min) without thermal neutron shielding,
a longer irradiation (6 min) in the boron capsule, and a final irradiation of the tungstomolybdophosphoric acid provide all
data required to accurately determine silicon in plant materials. A computer program has been developed that provides rapid
reduction of the data in final report format. Elements such as sodium, chlorine, calcium, manganese, potassium, and magnesium
extrinsic to the analysis for silicon are also determined by this method. The method has been tested on a large number of
samples and reliable results are obtained with less than 0.2 g of sample.
fabrication, thermal processing and characterization of novel electroceramic materials with tetragonal tungsten bronze structure. In general, a special interest was directed on modelling relaxation processes in polar dielectric ceramics and investigating the
Authors:Imre Miklós Szilágyi, Eero Santala, Mikko Heikkilä, Marianna Kemell, Timur Nikitin, Leonid Khriachtchev, Markku Räsänen, Mikko Ritala, and Markku Leskelä
paratungstate (APT), (NH 4 ) 10 [H 2 W 12 O 42 ]·4H 2 O at 200–250 °C [ 46 , 47 ], though other studies could not confirm this [ 48 ]. The thermal behavior of APT is very well known as it is an important starting material for making tungsten oxides, tungsten
samples depends on the type of tungsten precursor (WCl 6 > (NH 4 ) 6 H 2 W 12 O 40 > H 2 WO 4 ) [ 18 ]. Here we present the photocatalytic degradation of Malachite Green (MG) with composite thin films TiO 2 /WO 3 . Since 1933 [ 19 ], the MG dye
“Continuous flow synthesis of tungsten oxide (WO3) nanoplates from tungsten(VI) ethoxide” M. Gimeno-Fabra , P. Dunne , D. Grant , P. Gooden , E. Lester * Chemical Engineering Journal 2013 , 226 , 22 – 29 .