Distribution of137Cs,40K,238U and232Th in soils from Northern Venezuela

More than one hundred undisturbed soil samples from Northern Venezuela and the islands of Margarita and Los Roques have been analyzed for¹³⁷Cs,⁴⁰K,²³⁸U and²³²Th by -ray spectroscopy. The specimens were taken from between 5–10 cm below the earth's surface. Thus, they are valid not only for the¹³⁷Cs deposition studies but also for the estimation of the natural -ray dose from primordial radionuclides that form the terrestrial component. The concentration of⁴⁰K was directly determined from its 1461 keV -ray, while those of¹³⁷Cs,²³⁸U and²³²Th were performed using a -ray from one of their daughter radionuclides: the 661 keV -ray of^137mBa for¹³⁷Cs, the 1760 keV -ray of²¹⁴Bi for²³⁸U and the 2620 keV -ray of²⁰⁸Tl for²³²Th. Finally, the concentration values were compared with those of global estimates.     

Hydrolysis of 4-acetyl-3α, 4α-epoxycarane

Conclusions The acid hydrolysis of 4-acetyl-3,4-epoxycarane proceeds with opening of the oxide ring at the carbon atom not attached to an electronegative substituent to give the diol 4-acetyl-3, 4-caranediol.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1052–1054, May, 1980.     

Chemical substance,material, product,goods, waste: a changing ontology

A chemical substance (CS) is instantiated in the material world by a number of quantities of such substance (QCSs), placed in different locations. A change of location implies a change in the net of relationships entertained by the QCS with the region wherein it is found. This fact entails changes of the ontological status of the CS, as this is not fully determined by the inherent features of the CS and includes a relevant relational contribution. In order to demonstrate this thesis, we have chosen to analyse the status of quantities of a same CS that are synchronically located in different spacetime regions: a synthetic lab, a lab where the QCS is turned into a material, an industrial plant, the market where the QCS gets a price and a dump waste where the QCS is discarded, respectively:

Chemical substance Open image in new window material Open image in new window (industrial) product Open image in new window goods Open image in new window waste

The use of first-order predicate logic, mereology and locative logic allows carrying out a regimentation process that highlights the ontological commitments implied by the formal expressions through which each element of the aforementioned series can be described. The presence of relational properties discloses the systemic nature of the CS instantiated within a spacetime region. The implications of such an aspect are discussed.

     

Synthesis, Structure, and Fluorescence of Isomeric Indolizinediones. Carbonyl-Bridged Isodipyrrinones

Summary. In one-pot reactions, pyrrole-- and -aldehydes condense readily with 4-ethyl-3-methyl-3-pyrrolin-2-one to give isodipyrrinone analogs, which undergo intramolecular cyclization when the pyrrolealdehyde possesses an or -CO₂R group. The resulting regioisomeric pyrroloindolizinediones, with structures confirmed by NMR analysis, exhibit strong fluorescence, with quantum yields (_F) as high as 0.91 at _em450–550nm.     

Rhenium complexes with π-acetylenic ligands that contain silicon,germanium, and tin

Conclusions A study was made of the reaction of CpRe(CO)₂·THF with acetylenes of type Ph₃MCCPh, where M=Si, Ge, Sn. The previously unknown acetylenic complexes of rhenium CpRe(CO)₂(-Ph₃MCCPh), where M=Si and Ge, were isolated and studied, and it was shown that these complexes can undergo partial rearrangement to compounds with phenylvinylidene ligands.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1124–1126, May, 1979.     

Carbonylation of lower olefins in the presence of complexes of BF3 with propionic,acetic, or monochloroacetic acids

Conclusions The 3BF₃·2CH₂C1COOH+BF₃-2CH₃COOH system effectively catalyzes the selective carbonylation of propylene and n-butylenes. At 95–105°C and a CO pressure of 200 atm, with an equimolar ratio catalystolefin water, propylene or mixed n-butylenes give isobutyric or-methylbutyric acid in near-quantitative yield.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 110–112, January, 1978.     

Kinetics of CH radical reactions with N2O,SO2, OCS,CS2, and SF6

Pulsed laser photolysis/laser-induced fluorescence (LIF) is utilized to measure absolute rate constants of CH radical reactions as a function of temperature and pressure. Multiphoton dissociation of CHBr₃ at 266 nm is employed for the generation of CH (X²Π) radicals. The CH radical relative concentration is monitored by exciting fluorescence on the R₁(2) line of the (A²Δ – X²Π) transition at 429.8 nm. A resistively heated cell allows temperature studies to be performed from room temperature to ≈?670 K. The following Arrhenius equations are derived: With the exception of SF₆, the reactions of sulfur containing species proceed at rates that are near the theoretical gas kinetic collision frequency. Additionally, these reactions all have activation energies that are near zero or slightly negative. These observations are consistent with an insertion-decomposition mechanism being dominant under these conditions.     

Bi2O3 Hierarchical Nanostructures: Controllable Synthesis,Growth Mechanism,and their Application in Photocatalysis

Flower power : Unique 3D flower‐like Bi₂O₃ hierarchical nanostructures were synthesized using a mild aqueous template‐free method (see figure). By introducing VO₃^? into the reaction system, which mediated the nucleation and growth of Bi₂O₃, the in situ self‐assembly of 3D hierarchitectures from 2D nanosheets has been realized.

     

Composition,structure, and anisotropy of magnetic properties of d- and dℝ-tartrates of Dy3+ from proton magnetic relaxation and magnetic birefringence data

We have determined the composition and stability of d- and d-tartrates of Dy³⁺. In the pH region 4.0–7.0, we have shown that binuclear particles are formed. The relative stability of isomeric d- and d-tartrates of Dy³⁺ is determined only by the statistical factor. From data on the paramagnetic birefringence effect, binuclear d- and d-tartrates of dysprosium(III) have a polycyclic structure including six five-membered metallocycles, two of which are condensed with the central twelve-membered ring. The paramagnetic anisotropy of Dy³⁺ in the studied dimers has twice the absolute value of the anisotropy of the aqua ion of Dy³⁺ (k=–2860·10^–29 cm³). Using the magnetic susceptibility measurements, we have demonstrated the virtually complete absence of Dy³⁺–Dy³⁺ magnetic interactions in binuclear d- and d-tartrates.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 47–52, January, 1990.We thank A. E. Nepryakhin for taking the NMR spectra, and O. Yu. Tarasov for calculating the values of the molar magnetic susceptibility.     

The Gas-Phase Ion/Molecule Reactions of C3H5X (X = C1, Br,I)

The ion/molecule reactions of the molecular ion, the C₃H ion, and the C₃H ion obtained from 3-chloropropene. 1-bromopropene, 2-bromopropene, 3-bromopropene, bromocyclopropane. and 3-iodopropene have been studied with their neutral precursor in a Fourier-transform mass spectrometer (FT/ICR). The molecular ions react to yield primarily C₆H except for the ion derived from 1-bromopropene that is unreactive. The kinetics of the 3-bromopropene molecular ion reveals that 18% of these ions must possess a different structure which is unreactive. The fact that C₃H ions obtained from 2-bromopropene are the only ones to undergo proton transfer is taken as evidence that only this parent compound gives rise to 2-propenyl cations by low-energy electron impact. The C₃H ions generated in these systems are shown to be roughly an equal mixture of propargylium ions that react to yield C₆H and unreactive cyclopropenium ions.     

Subgroup 4 (Ti,Zr, Hf) derivatives of Cobalt Carbonyls

Bimetallic and trimetallic compounds containing unsupported bonds of subgroup 4 metals (M = Ti, Zr, Hf) and Co were prepared by hydride elimination (A) from RM derivatives (R¹ = PhCH₂; RN; R² = Me, Et)) and by salt elimination (B) from RMX (X = Cl, Br; R.¹ = PhCH₂, RN and R³O; R³= i-Pr, n-Bu)) by reaction with HCo(CO)₄ and Na[Co(CO)₄], respectively. Compounds RMCo(CO)₄ with R¹ = PhCH₂, RM[Co(CO)₄]₂ R.¹ = PhCH₂, were prepared both by methods A and B, while (R³O)₄-n Ti[Co(Co)₄]n (n = 1, 2) compounds were obtained by reaction B. Several tertiary phosphine and phosphite derivatives of the former two types were obtained by substitution of a carbonyl group by PR ligand or by A type reaction of HCo(CO)³(PR with RM compounds.     

Determination of vitamins A,B1, B2, D3 and C by densitometry of thin-layer chromatograms

Summary A method for densitometric determination of vitamins A, B₁, B₂, D₃, and C separated by t. l. c. is described. A silica gel layer is used with a solvent system of acetone-methanol-benzene (128). The spots are evaluated by direct densitometric light emission measurements. Preliminary separation of the vitamins one from another or from other pharmaceuticals is not necessary. The accuracy of the method is about 6%. The accuracy for vitamin A is up to 12%.

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Zusammenfassung Ein Verfahren zur Bestimmung der dünnschichtchromatographisch getrennten Vitamine A, B₁, B₂, D₃ und C wurde beschrieben. Dazu dient eine Kieselgelschichte mit Aceton Methanol Benzol (128) als Lösungsmittel. Die Flecken werden densitometrisch gemessen. Eine vorhergehende Trennung der einzelnen Vitamine voneinander bzw. von anderen pharmazeutischen Begleitstoffen ist nicht nötig. Die Methode ist auf etwa 6% genau, für Vitamin A auf 12%.

     

Synthesis,structure, and spectral properties of some bioxazoles

Syntheses of systems containing two oxazole rings [2-phenyl-, 2-(2-furyl)-, and 2-(2-thienyl)-2,5-bioxazoles, and 2,2-(2,5-furylene)bisoxazole] from aldehydes obtained by formylating 2-phenyl-, 2-(2-furyl)-, and 2-(2-thienyl)oxazole have been developed. Terephthalate and thiophen-2,5-dicarboxylate esters have been used to obtain 2,2-(1,4-phenylene)- and 2,2-(2,5-thienylene)bisoxazoles. The PMR, UV, and luminescence spectra of these systems have been examined, and quantum chemical calculations carried out in the PPP approximation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 826–836, June, 1986.     

Synthesis of δ-alkoxy-α, α-dicarbonyl-substituted dienes and study of their valence isomerization

Methods of synthesis of dienic -alkoxy-, -dicarbonyl-substituted compounds were experimentally examined. The structure of the synthesized compounds was studied by¹H and¹³C-NMR methods. It was shown that the -alkoxy diesters are present in equilibrium with 2H-pyrans, while -alkoxy--methyl diesters and 2-(3-alkoxypropen-2-ylindene)indanediones exist in an open form and do not undergo cyclization into 2H-pyrans.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2561–2565, November, 1990.     

Determination of Cd,Mo, Cr and Co in biological materials by RNAA

A method for the determination of trace amounts of Mo, Cd, Co and Cr in biological materials by neutron activation analysis with radiochemical separation is presented. The method is based on the ion-exchange scheme developed by SAMSAHL, where Co and Cr are trapped on BioRad Chelex-100 and Cd and Mo on BioRad AG2X8. The elements Mo, Cd and Co can be determined without systematic errors. For the element chromium the situation is less clear, partially due to lack of sufficient certified reference materials for Cr. The method has been used in the characterization of candidate reference materials. Detection limits in these materials range from 1.5 g/kg for Co to 10 g/kg for Cr. Actual levels as low as 8 g/kg for Cd and 7 g/kg for Co were measured.     

Darstellung,Kristallstruktur und spektroskopische Eigenschaften der Clusteranionen [(Mo6Br)X]2− mit Xa = F,Cl, Br,I

Synthesis, Crystal Structure and Spectroscopic Properties of the Cluster Anions [(Mo₆Br )X ]^2? with X^a = F, Cl, Br, I The tetrabutylammonium (TBA), tetraphenylphosphonium (TPP) and tetraphenylarsonium (TPAs) salts of the octa-μ₃-bromo-hexahalogeno-octahedro-hexamolybdate(2?) anions [(Mo₆Br)X]^2? (X^a = F, Cl, Br, I) are synthesized from solutions of the free acids H₂[(Mo₆Br)X] · 8 H₂O with X^a = Cl, Br, I. The crystal structures show systematic stretchings in the Mo? Mo bond length and a slight compression of the Brⁱ₈ cube in the F^a to I^a series. The cations do not change much. The i.r. and Raman spectra show at 10 K almost constant frequencies of the (Mo₆Brⁱ₈) cluster vibrations, whereas all modes with X^a ligand contribution are characteristically shifted. The most important bands are assigned by polarization measurements and the force constants are derived from normal coordinate analysis. The ⁹⁵Mo nmr signals are shifted to lower field with increasing electronegativity of the X^a ligands. The fluorine compound shows a sharp ¹⁹F nmr singlet at ?184.5 ppm.     

Reaction of 2,3-dioxo-4-(N,N-dimethylaminomethylene)hexahydroazepine with hydroxylamine

Depending on the conditions selected, the reaction of 2,3-dioxo-4-(N,N-dimethylaminomethylene)hexahydroazepine with hydroxylamine gives 2,3-dioxo-4-formylhexahydroazepine 4-oxime, 8-oxo-8H-4,5,6,7-tetrahydroisoxazolo[5,4-c]azepine, or 2-oxo-3-hydroxy-4-cyano-2H-1,5,6,7-tetrahydroazepine. The reaction of the latter with aromatic amines and hydrazine hydrate was used to synthesize 3-arylamino-2-oxo-4-cyano-2H-1,5,6,7-tetrahydroazepines and 3-amino-8-oxo-8H-4,5,6,7-tetra-hydropyrazolo[5,4-c]azepine, respectively. The structures of the compounds obtained were confirmed by the IR, UV, and PMR spectra.Communication XXXI from the series Research on Lactams. See [1] for communication XXX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1252–1255, September, 1978.     

Sequential separation by HDEHP of carrier-free101,105,106Rh,103,104,105,106,110,112Ag and104,105,107,109,111Cd produced in alpha-particle activated palladium

Carrier free^101,105,106Rh,^{103,104,105,106,110,112}Ag and^{104,105,107,109,111}Cd radioisotopes were produced simultaneously by -particle irradiation of palladium target material in a variable energy cyclotron. The radioisotopes produced were extracted and separated from the activated target by LLX using HDEHP as liquid cation exchanger. With the help of -ray spectrometry the presence of several radioisotopes in the activated target matrix and their purity at each step of the separation was confirmed.     

Synthesis of some O,O-diethyl S-(β-acylaminoethyl) dithiophosphates

The ethyleneimides of N-phthalyl-D,L-valine, N-phthalyl-D,L-glycine, N-phthalyl-D,L-alanine, N-carbobenzoxy-D,L-valine, N-benzoyl-D,L-leucine, and of the -methyl ester of N-carbobenzoxy-L-glutamic acid and monomethyl succinate were synthesized. A number of O,O-diethyl S-(-acrylaminoethyl) dithiophosphates were obtained by opening the ethyleneimine ring in the ethyleneimides of N-acylated amino acids with diethyl dithiophosphoric acid. The -chloroethylamides of phthalyl-D,L-valine, N-acetyl-D,L-valine, and monomethyl succinate were obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 479–482, April, 1972.     

Kinetics,mechanism, and endo selectivity of Diels–Alder reactions of alkylmonosubstituted ethenes with cyclohexa-1,3-diene in the gas phase

The reactions where Y = CH₃ (M), C₂H₅ (E), i? C₃H₇ (I), and t? C₄H₉ (T) have been studied between 488 and 606 K. The pressures of CHD ranged from 16 to 124 torr and those of YE from 57 to 625 torr. These reactions are homogeneous and first order with respect to each reagent. The rate constants (in L/mol·s) are given by The Arrhenius parameters are used as a test for a biradical mechanism and to discuss the endo selectivity of the reactions.