Double dimethylammonium sulphates of Tb,Dy, Ho,Er, Tm,Yb, Lu and Y

Double sulphates of rare earths with dimethylammonium, with empirical formula (CH₃)₂NH₂Ln(SO₄)₂·4H₂O (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu and Y), were studied by means of thermogravimetry, derivative thermogravimetry and differential thermal analysis from 20 to 700°. Quantitative gravimetric analysis was used for the determination of rare earths and sulphate. The mechanism of thermal decomposition is also suggested.

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Zusammenfassung Doppelsulfate der seltenen Erden mit Dimethylammoniumionen der empirischen Formel (CH₃)₂NH₂Ln(SO₄)₂·4H₂O (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu und Y) wurden mittels TG, DTG und DTA im Temperaturbereich von 20–700° untersucht. Die Seltenen Erden und Sulfat wurden gravimetrisch bestimmt. Ein Mechanismus der thermischen Zersetzung wird vorgeschlagen.

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, 20–700° (₃)₂N₂Ln(S₄)₂·4₂, Ln=Tb, Dy, , Er, Tm, Yb, Lu Y. . .

     

A new selective reagent for the spectrofluorometric determination of beryllium

The fluorescence properties of the beryllium and aluminum complexes with 2, 4-dioxo-4-(4-hydroxy-6-methyl-2-pyrone-3-yl) butyric acid ethyl ester (Ligand) were studied and optimal conditions for their fluorometric determination were established. Beryllium can be determined in the linearity range of 0.5–2.0 μg/ml and aluminum 0.5–1.5 μg/ml. The effect of diverse ions on the determination of beryllium is discussed.A simple procedure for the fluorometric determination of beryllium in human blood plasma in the concentration range of 5–50 μg Be/ml is described.     

Determination of Phenolic Acids in Herba Epilobi by ITP–CE in the Column-Coupling Configuration

The combination of capillary isotachophoresis (ITP) and capillary zone electrophoresis (CZE) in the column-coupling configuration has been optimized in a mode in which the background electrolyte employed in the CZE step was different from the leading and terminating electrolytes of the ITP step. The optimum composition of the electrolyte system was 0.01 M HCl, 0.02 M IMI, 0.2% HEC, pH 7.2 (leading electrolyte), 0.01 M HEPES, pH 8.2 (terminating electrolyte), and 25 mM MES, 50 mM TRIS, 30 mM boric acid, 0.2% HEC, pH 8.3 (background electrolyte). All solutions contained 20% methanol. The timing of the transfer of isotachophoretically stacked analyte zones into the CZE column was also optimized. An ITP–CZE method with UV detection at 270 nm was developed for separation of nine phenolic acids (protocatechuic, syringic, vanillic, cinnamic, ferulic, caffeic, ρ-coumaric, chlorogenic, and gentisic acids) in a model mixture and used for assay of some of these acids in a methanolic extract of herba epilobi. Application of ITP–CZE resulted in 100-fold better sensitivity than conventional CZE; limits of detection ranged between 10 and 60 ng mL⁻¹. When MES–TRIS–borate-based buffer, pH 8.3, was used in the CZE separation step the linearity of the ITP–CZE response was satisfactory (correlation coefficients were from 0.9937 to 0.9777). Repeatability was also satisfactory (RSD values ranged between 0.77% and 1.28% for migration times and between 1.65% and 13.69% for peak area). Revised: 23 March and 27 April 2006     

The Study of Americium, Yttrium and Lead Complexation by Humic Acids of Different Origin

Complexation equilibrium of metals by three humic acids of different origin with ultrafiltration method was investigated at pH 4 a 5 and ionic strength I = 0.1M NaClO₄. Commercial (Aldrich) and two original humic acids (peat and soil, obtained by six step isolation process from the material from Trnava county, close to the NPP Jaslovské Bohunice) were used in this study. For the evaluation of the results, the model of metal ion charge neutralization upon humic acid functional group proposed by the Kim and Czerwinski was used. Complexation constants were calculated using the terms of this model (operational concentration, loading capacity). The values of log = 5.39±0.16 for yttrium, 6.15±0.16 for americium and 5.20±0.08 for lead were found. Correlation of free metal concentration and ratio of molar fraction of complexing functional groups confirms the validity of charge neutralisation model for metal and polyelectrolyte complexation study.     

Reaktion der α, γ, δ, ζ-Tetraketone mit Selentetrachlorid und Schwefeldichlorid

Zusammenfassung , , , -Tetraketone (1) reagieren in der Dienolform (2) mit Bleitetraacetat², Selendioxid³, Selentetrachlorid und Schwefeldichlorid. Hauptprodukt der Reaktion mit SeCl₄, ist 2,5-Diacyl-3,4-dihydroxyselenophen (10), mit SCl₂, 2,5-Diacyl-3,4-dihydroxythiophen (11). Es wird die Synthese einer Reihe von Verbindungen der Struktur1, 10 und11 beschrieben.

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, , , -Tetraketones (1) react in dienolic form (2) with lead tetraacetate², selenium dioxide³, selenium tetrachloride and sulphur dichloride. The main product of the reaction with SeCl₄ is 2,5-diacyl-3,4-dihydroxyselenophene (10), and with SCl₂ 2,5-diacyl-3,4-dihydroxy-thiophene (11). A series of compounds with the structures1, 10, and11 is described.

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Herrn Prof. Dr.F. Wessely zum 70. Geburtstag freundlichst zugeeignet.     

Necrosaminreihe, 5. Mitt.: Über eine einfache Synthese von aliphatischen α-Diaminen

Zusammenfassung Es wird eine Reaktionsfolge beschrieben, die eine einfache Darstellung der langkettigen -Diamine erlaubt. Die Synthese wird an Beispielen des 2,3-Diamino-tridecans (7 a), 2,3-Diamino-nonadecans (7b) und 4,5-Diamino-eicosans (14) geprüft. -Aminosäuren und Carbonsäureanhydride werden mittels derDakin-West-Reaktion in die -Acylamidoketone übergeführt.7a und7b werden über die Stufen -Acetamidoketon (4), -Aminoketon (5), Oxim (6) und dessen Reduktion mit Lithiumaluminiumhydrid gewonnen.14 wird über die Stufen 2-Benzoylaminomargarinsäure (10), 5-Benzoylamino-eicosanon-(40 (11), 5-Benzoylaminoeicosanon-(4)-oxim (12) und 4-Amino-5-benzylamino-eicosan (13) dargestellt.

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A simple synthesis of long-chain -diamines is described. The method is illustrated by the preparation of 2,3-diaminotridecane (7a), 2,3-diaminononadecane (7b) and 4,5-diaminoeicosane (14). In the first reaction step -amino acids and carboxylic acid anhydrides are converted into -acylamido ketones by means of theDakin-West reaction. Both7 a and7 b are prepared through the intermediates -acetamido ketone (4), -amino ketone (5) and oxime (6) followed by the reduction of the latter with lithium aluminum hydride.14 is prepared via 2-benzoylaminomargaric acid (10), 5-benzoylamino-4-eicosanone (11), 5-benzoylamino-4-eicosanone oxime (12) and 4-amino-5-benzylaminoeicosane (13).

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4. Mitt.:P. Alaupovi undM. Protenik, Croat. Chem. Acta28, 225 (195).     

Direct spectrographic determination of impurities in uranium tetrafluoride

A direct spectrographic method for tlic determination of some impurities in UF₄ is described. The sample in the graphite electrode was covered with a layer of alumina before the arc was struck; alumina prevents the volatilization of UF₄ and thus avoids high spectral and background interferences. To stabilize the discharge, a controlled atmosphere of argon and oxygen was used. The impurity elements were divided into 3 categories according to their volatility: high (B, Si), medium (Co, Mn, V, Mo, Ti, etc.), and low (Ni, Pb, alkaline earths, etc.). Impurities of high and medium volatility could be determined with germanium or aluminum as internal standard. The sensitivities found for this method generally agreed with those of the carrier distillation method. The coefficients of variation varied from 8 to 25% at the 25 p.p.m. level.     

Die Oxydation von Blei in Wasser bei Gegenwart von atmosphärischem Sauerstoff, 2. Mitt.

Zusammenfassung Der zeitliche Verlauf der Oxydation von granuliertem Blei ist unregelmäßig, weil sich dessen Oberfläche während der Reaktion nicht konstant vermindert. Die Reaktion verläuft an der Luft mit und ohne CO₂ mit gleicher Geschwindigkeit, weil auch an der Luft nur eine Mischung von Bleioxyd und Hydroxydcarbonat entsteht. Auf die geometrische Oberfläche bezogen, hat die Oxydationsgeschwindigkeit unter den beschriebenen Bedingungen eine Größenordnung von 0,6 g/dm²h. Auch die Abhängigkeit der oxydierten Bleimenge vom Partialdruck des Sauerstoffes (0,00–0,21) wurde bestimmt. Die Bleikonzentration hat in breitem Intervall praktisch keinen Einfluß. Der Lichteinfluß ist positiv, auf die Reaktion in der Dunkelheit bezogen, ist die oxydierte Bleimenge 1,2mal höher. Die Bedingungen für die Herstellung von tetragonalem Bleioxyd, dessen Bildung über das rhombische Bleioxyd verläuft, werden wiedergegeben.Mit 3 Abbildungen     

Thermal isomerizations of cis,anti,cis-tricyclo[6.4.0.0]dodec-3-ene to trans- and cis,endo-tricyclo[6.2.2.0]dodec-9-ene: diradical conformations and stereochemical outcomes in [1,3] carbon shifts

The gas-phase thermal isomerizations at 315 °C of cis,anti,cis-tricyclo[6.4.0.0^2,7]dodec-3-ene to trans-tricyclo[6.2.2.0^2,7]dodec-9-ene and to cis,endo-tricyclo[6.2.2.0^2,7]dodec-9-ene favor the former, the more geometrically strained product, by a ratio of 2.4:1. These products correspond to suprafacial inversion (si) and suprafacial retention (sr) stereochemical outcomes. The reaction stereochemistry shown by the 11-carbon homolog, cis,anti,cis-tricyclo[6.3.0.0^2,7]undec-3-ene, is strikingly different: the [1,3] carbon shift takes place to give only the ‘forbidden’ sr product. Two related bicyclic vinylcyclobutanes, 8-deuterio- and 8-exo-methylbicyclo[4.2.0]oct-2-enes, evidence contrasting reaction stereochemical predilections in [1,3] shifts, but the 12-carbon tricyclic system and the 8-exo-methyl bicyclic analog isomerize with the same si:sr ratio! These observations prompt fresh considerations of structural influences on conformational preferences available to the alkyl, allyl diradical reactive intermediates involved.