Thermal behaviourof complexes of antipyrine derivatives Part III.

The thermal behaviour of the mixed-ligand complexes of cobalt(II) and copper(I) ions with antipyrine derivatives of 1,2-ethanediamine or piperazine (BAMP and TAMEN), with water and with 2-mercapto-benzothiazole (Hmbt) was investigated. The complexes contain 2-mercaptobenzothiazole (Hmbt, in the case of cobalt(II) ion) or dimercaptobenzothiazine (mbt–mbt, in the case of copper(I) ion) molecules as ligands and perchlorate (ClO₄^–) or thiocyanate (SCN – ) ion as counterion. By heating, water and ligands release the solid phase at lower temperature. At higher temperatures process of different organic reactions of ligands (e.g. polymerization, polycondensation) could be suggested to interpret the relative high final mass values.     

Elaboration of a programmed,semi-automated radiochemical processing system for neutron activation analysis of some volatile elements

Based on the method of SAMSAHL a programmed, semi-automated processing system has been developed and tested for the neutron activation analysis of the following elements: As, Se, Sb, Br, Sn and Te. The main characteristics of the procedure are the following: wet ashing of the sample (by means of digestion in a mixture of concentrated sulphuric acid and hydrogen peroxide), bromination, and chlorination. The procedure is controlled via the appropriate dosage of the reagents and a carefully managed thermal balance. The chemical yield and its reproducibility were determined by tracer techniques using exactly the same parameters as for the active runs. According to the results the method can be used for the routine determination of the given elements except antimony. Presented at the 4th Symposium on the Recent Developments in Neutron Activation Analysis, 1975, Cambridge.     

Generalized Hückel treatment of a simple model of transannular interaction and excimer formation

The model of two interacting ethylene molecules having D _2h symmetry was studied using generalized Hückel method. The validity of - separation was tested on this model. The general character of the ground state and lower lying excited states of the model was discussed and the implications drawn concerning transannular interaction and excimer formation. The values obtained for the dissociation energy of the first excited state of our model and corresponding equilibrium intermolecular distance are of right order of magnitude.

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Zusammenfassung Mittels der verallgemeinerten Hückel-Methode wurde das Modell von zwei Äthylenmolekülen mit der Symmetrie D _2h studiert. An diesem Modell wurde die Gültigkeit der - -Separation geprüft. Der allgemeine Charakter des Grundzustandes und der niedriger liegenden angeregten Zustände des Modells wird erörtert und die Folgerungen in Bezug auf transannulare Wechselwirkung und Excimer-Entstehung diskutiert. Die erhaltenen Werte für die Dissoziationsenergie des ersten angeregten Zustandes von unserem Modell und den entsprechenden intermolekularen Gleichgewichtsabstand haben die richtige Größenordnung.

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Résumé Le modèle à symétrie D _2h de deux molécules d'éthylène en interaction a été étudié en utilisant la méthode généralisée de Hückel. On a examiné la validité de la séparation - sur ce modèle. Le caractère général de l'état fondamental et celui des états excités inférieurs du modèle furent discutés et on a fait des déductions sur l'interaction transannulaire et sur la formation d'«excimères». Les valeurs obtenues pour l'énergie de dissociation du premier état excité de notre modèle et la distance intermoléculaire d'équilibre corréspondante ont l'ordre de magnitude correct.

     

Behavior and characteristics of biogenic amines, ornithine and lysine derivatized with the o-phthalaldehyde-ethanethiol-fluorenylmethyl chloroformate reagent

The stability and characteristics of the ornithine (Orn), lysine (Lys), putrescine (Put), cadaverine (Cad), 1,7-diaminoheptane (Diah), spermidine (Spd) and spermine (Spm) derivatives obtained with the o-phthalaldehyde (OPA)-ethanethiol (ET)-fluorenylmethyl chloroformate (FMOC) reagent has been investigated. The stoichiometry of the introduced, two-step derivatization process has been followed by photodiode array (DAD) and fluorescence (FL) detections, simultaneously, while the composition of derivatives was confirmed by on-line HPLC-electrospray ionization (ESI) MS measurements. Depending on the composition of the OPA reagents, in addition to the secondary amino group-containing Spd and Spm, under common aqueous conditions also Orn and Lys do react with FMOC resulting in derivatives of various compositions. Applying the OPA-ET reagent of increasing methanol (Met) content (38-80%, v/v) the formation of the FMOC group containing Orn and Lys derivatives could be considerably decreased. Optimum elution condition (18 min, including equilibration) was developed for the simultaneous quantitation of Orn, Lys, Put, Cad, Diah, Spd and Spm, in the presence of the rest of protein amino acids. The practical utility of the method was demonstrated by the analysis of mouse tissues. Average reproducibility of quantitations, characterized with the relative standard deviation percentages of fluorescence intensities and UV responses, in order of listing, proved to be 2.1% and 2.1%, respectively.     

Interaction of diquat and paraquat with humic acid and the influence of salt concentration and pH on the strength of interaction

Summary The interaction of the herbicides diquat and paraquat with humic acid and the influence of various salts and pH on the strength of interaction was studied by charge-transfer chromatography. Interactions between humic acids and both herbicides, probably by complex formation, were confirmed; they were stronger with paraquat than with diquat. The complex formation makes the herbicides more hydrophilic, facilitating their movement on cellulose surface. Salts in the environment significantly decreased the strength of interaction, indicating the hydrophilic character of the interactive forces. The charge of the cation also influenced the strength of interaction whereas the effect of ion radii was negligible. The effect of pH was lower than that of salt concentration.     

A spectrometric,separation and voltammetric study of the complexation reactions of bromazepam with iron(ii),copper(ii) and cobalt(ii)

Bromazepam, in the form of a cationic iron(II) chelate, can be determined spectrophotometrically at 588 nm with a limit of detection of ca. 10^-6 M. When this chelate is ion-paired with perchlorate, it can be extracted into organic solvents such as 1,2-dichloroethane and 4-methyl-2-pentanone, and determined by atomic absorption spectrometry with a limit of detection of 1.5 × 10^-5 M bromazepam at the iron resonance 248.3-nm line. Ion-pairs involving the Fe(II), Cu(II) and Co(II) chelates and perchlorate can be separated by h.p.l.c. using a C₁₈ reverse-phase column and a mobile phase of 4:1 water—methanol, with a u.v. detector at 242 nm. This approach allowed for the determination of iron(II) ions in aqueous solution with a limit of detection of 10^-8 M. The h.p.l.c. method could also be used to quantify bromazepam spiked in plasma in the concentration range 1–10 μg ml^-1, following extraction of bromazepam from plasma and subsequent formation of the iron(II) ion-pair. Copper(II) forms a labile chelate with bromazepam in pH 4.8 acetate buffer which, when subjected to differential pulse voltammetry at the hanging mercury drop electrode, gives rise to a catalytic phenomenon which can be utilised for the determination of bromazepam in the concentration range 10^-5–10^-9 M.     

Analytische Aspekte der Oxydation organischer Stickstoffverbindungen mit Chromsäure. XXIII

Zusammenfassung Die früher beschriebene Halbmikromethode zur Bestimmung von Isonitrosogruppen in organischen Verbindungen wurde in den Mikromaßstab übergeführt. Sie beruht auf der Reaktion der Substanz mit Eisen(III)-sulfat in verd. Schwefelsäure. Dabei wird der Oximstickstoff als Distickstoffoxid frei, das mit Kupfer zu elementarem Stickstoff reduziert und im Mikroazotometer gemessen wird. Für die Berechnung des Oximstickstoffgehaltes aus den abgelesenen Gasvolumina wurden Werte für die konstante und proportionale Volumenkorrektur mit Hilfe der Methode der Regressionsgeraden experimentell festgestellt. Beide Werte sind den bei der N-N-Gruppenbestimmung benützten Volumenkorrekturen fast gleich. Die Bestimmung von Oximgruppen ist durch die Anwesenheit von Nitro- oder Aminogruppen nicht gestört. Diese Gruppen können aus derselben Einwaage durch nachfolgende Oxydation mit Chromsäure bestimmt werden.

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Analytical aspects of the oxidation of organic nitrogen compounds with chromic acid. XXIII

Summary The semimicro method previously described for the determination of isonitroso groups in organic compounds has been converted to the microscale. It is based on the reaction of the material with iron(III)-sulfate in dilute sulfuric acid. The oxime nitrogen is thus liberated as dinitrogen oxide, which is reduced to elementary nitrogen by copper and measured in the mieroazotometer. To calculate the oxime nitrogen content from the read-off gas volume, values for the constant and proportional volume correction with the aid of the regression lines were established experimentally. Both values are almost equal in the case of the determination of the volume corrections employed in the determination of the N-N-groups. The presence of nitro-or amino groups does not interfere with the determination of oxime groups. These groups may be determined from the same sample by subsequent oxidation with chromic acid.

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XXII. Mitteilung s.¹.     

Alkylation of β-diketones through their co(II), co(III) and zn(II) complexes. 1-Bromoadamantane as alkylating agent.

α-(1-adamantyl)-β-diketones are now accessible by the alkylation of Co(II) complexes of β-diketones with 1-bromoadamantane. The intermediacy of adamantyl cation is proposed. Co(II), Co(III) and Zn(II) complexes of pentane-2,4-dione react with alkyl halides precursors of stabilized carbenium ions, to give 3-alkylpentane-2,4-diones.     

Some basic electrochemistry and the cold nuclear fusion of deuterium

The role of electrochemistry in the discovery and interpretation of the alleged cold nuclear fusion is discussed.     

Neues verfahren zur bestimmung der acetylgruppe

A simple and accurate method is described for the determination of acctyl groups in various organic compounds. The compound is dissolved or suspended in absolute methanol and saponified with a known quantity of potassium methylate solution. The excess potassium methylate is then hydrolysed and determined as potassium hydroxide by titration, an appropriate indicator being used.