Koordinationschemische Untersuchungen an Zinkdialkylen. X. Über die Reaktion von Zinkdimethyl mit sekundären Aminen

Dimethyl zinc reacts with diethyl amine, piperidine and morpholine forming definite 1:2- or 1:1-complexes. The weaker basic secondary amines pyrroline, pyrazolidine and imidazoline cause the evolution of methane and the formation of the corresponding zinc amides. In this way zinc pyrrolide, zinc pyrazolide and zinc imidazolide were obtained in form of pure substances.     

The ETACS European project for testing the comparability of sensors and analysers

ETACS is the official acronym for the European project "European Testing and Assessment of Comparability of On-line Sensors/Analysers". This project has three main objectives to achieve the comparability of performance data for sensors and analysers in the environmental field. First, to develop a test protocol for validation and comparison of the performance of on-line sensors/analysers. The test protocol is intended to be generic, that is independent of the specific sensors/analysers and the specific parameters to be monitored. Second, the practical testing of this test protocol to assess its applicability and to develop the techniques used. Finally, to achieve widespread acceptance of the test protocol by producer/suppliers, users and relevant authorities to assist its early adoption as an agreed European standard. Laboratory tests for producing the test protocol have been carried out and completed to check the applicability of such a protocol.     

Salting-in of alcohols in aqueous solutions by tetraalkylammonium bromides at the freezing temperature

The freezing-point depression of the ternary systems tetraalkylammonium bromides-t-butanol-water for the first five homologs of R₄NBr was measured. In the case of Bu₄NBr, the effect of size of the alcohol (methahol ton-butanol) was also investigated. From the corresponding freezing-point data for the binary systems the apparent salting constants were calculated. The true salting constantsk _s were obtained by extrapolation to infinite dilution. These are all very close to zero at the freezing temperature. From the corresponding thermochemical data the temperature dependence ofk _s was calculated, and above 5°C all the R₄NBr salts int-butanol; the salting-in increases with temperature and with the size of the hydrophobic cations. The scaled-particle theory is at present the only one which can account semiquantitatively for the temperature dependence of the salting-in effect. On leave of absence from Chemistry Department, The University, Sheffield S3 7HF, England To whom correspondence should be addressed.     

Neopentylallylsodium

Neopentylallylsodium (NpANa) has been prepared by the reaction of neopentylallyllithium with an equivalent amount of sodium 2,2-dimethyl-1-butoxide in hydrocarbon solvent. NpANa is stable in diethyl ether and THF solvents for extended periods of time, and proton NMR and UV data are reported for NpANa in THF at various temperatures. A more substantial degree of ionic delocalization is indicated for NpANa as compared to NpALi and apparently is greater for the trans isomer of NpANa. UV absorption maxima for NpANa and NpALi are explained in terms of cis/trans ratios rather than in terms of ion pairing.     

High-performance liquid chromatography – atmospheric pressure negative chemical ionisation – mass spectrometry of 2,4-dinitrophenyl derivatives of amines

High-performance liquid chromatography (HPLC) coupled to mass spectrometry (MS) is used to detect 2,4-dinitrophenyl (DNP) derivatives of amines by means of negative chemical ionisation at atmospheric pressure. The high sensitivity and good comparability of UV- and MS-detection of DNP-derivatives of amines is shown by several examples. The high selectivity of the derivatisation and the detection method (UV and MS) is used for the analysis of unknown amines in aqueous phases after hydrolytic degradation of polyamide-amine- or polyamine-epoxide-adducts as well as for the characterisation of commercial products.     

Esters and amides from aziridine 2-carboxylic acid salts

Potassium salts of aziridine-2-carboxylic acid derivatives are efficiently converted into esters of amides by reactions with alkyl halides, alkyl dihalides or by acylation with trimethylacetyl chloride followed by aminolyses.     

Metall-Pseudohalogenide. 28. Notiz zur IR-Absorption der koordinationspolymeren Metalltricyanmethanide M(C(CN)3)2 im Bereich von 200–400 cm−1

Metal Pseudohalides. 28. Remark on the I.R. Absorption of the Coordination Polymeric Compounds M(C(CN)₃)₂ in the Region of 200–400 cm^?1 The infrared spectra of the tricyanmethanides of 3d metals M(C(CN)₃)₂ (M = Mn, Fe, Co, Ni, Cu, Zn) in the region of 200–400 cm^?1 are reported. Significant absorption bands between about 220 and 290 cm^?1 are assigned to M—N-stretching frequencies.     

Determination of227Ac in geological materials through neutron activation and alpha-spectrometric assay of induced228Th

A new route has been developed for the micro-determination of²²⁷Ac in geological materials by neutron activation. The method is based on intense neutron irradiation of the analysed samples followed by separation and α-spectrometric determination of²²⁸Th, the β-decay product of the 6.1 hrs²²⁸Ac isotope formed. Two alternatives are considered for analysis related to the origin of the analysed matrix. The high sensitivity of the method is documented by the determination of 10^?17 g²²⁷Ac/g sample. The method is successfully applied for age determination of five uranium containing materials and old uranium glass from Bohemia, CSSR.     

Eine neue Verbindung der Zusammensetzung 9 BaNiO2·2 BaCO3

Zusammenfassung Bei der Reaktion von BaCO₃ mit NiO bildet sich unter bestimmten Bedingungen ein kristallines Pulver der Zusammensetzung 9 BaNiO₂ · 2 BaCO₃. Die Verbindung zeigt scharfe Röntgeninterferenzen, die sich kubisch indizieren lassen. Es wurden elektronenmikroskopische Aufnahmen gemacht sowie Elektronenstrahlfeinbereichsbeugungen durchgeführt. Das IR-Spektrum wurde aufgenommen und die magnetische Suszeptibilität bestimmt.

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A new compound 9 BaNiO₂·2 BaCO₃

During the reaction of BaCO₃ with NiO under special conditions a crystalline powder with the composition 9 BaNiO₂ · 2 BaCO₃ is formed. This compound shows clear X-ray patterns which can be indexed using a cubic cell. Electron microscopic investigations have been carried out and selected area diffraction patterns have been taken. The IR-spectrum and the magnetic susceptibility have been proved.

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Mit 3 Abbildungen     

Datenverarbeitung in der analytischen Chemie

Zusammenfassung Die beiden Hauptaufgaben der analytischen Chemie sind nach wie vor die quantitative und die qualitative Analyse, die immer weiter in Richtung Ultraspurenbestimmung voranschreitet und so mit der quantitativen Analyse eng verknüpft ist.Ein Sonderfall der qualitativen Analyse ist die Strukturanalyse, die in der organischen Chemie größte Bedeutung hat. Die heute geübte Arbeitsweise umfaßt dabei die Gewinnung von Meßdaten in reiner Handarbeit, die teilmechanisierte Gewinnung von Meßdaten mit Hilfe der instrumentellen Analytik, wobei individuelle Hand- und Kopfarbeit nach wie vor überwiegt und schließlich die vollmechanisierte Gewinnung von Meß-daten, welche nur dann wirtschaftlich eingesetzt werden kann, wenn auch die Verarbeitung der Zwischendaten maschinell erfolgt. Am Beispiel der klassischen und der modernen Titration, der Gas-Chromatographie, der Massenspektrometrie und der Kopplungstechnik von stofftrennenden und strukturerkennenden Methoden werden die Arten der Datenerzeugung, die Vielfalt des Datenanfalles und die Anforderung an eine Datenverarbeitung unter dem Gesichtspunkt der industriellen Analytik diskutiert.Bei der instrumentellen Analyse entstehen meistens Daten mit viel höherer Geschwindigkeit und erheblich höherer Dichte als bei der klassischen Analyse. Es muß nun entschieden werden, ob eine Zwischenspeicherung (Schreiber, Magnetbandschreiber mit allen ihren Vorteilen) noch ausreicht, oder ob eine on-line-Verbindung mit einer Datenverarbeitungsanlage notwendig ist. Dies ist dann der Fall, wenn eine zeitraubende Zwischenspeicherung nicht mehr akzeptiert werden kann oder der Datenanfall pro Zeiteinheit durch Handarbeit nicht mehr ökonomisch bewältigt werden kann.Entscheidend ist es, die wirklich vertretbare Forderung nach der Geschwindigkeit, mit der die Enddaten ermittelt werden müssen, mit dem Zeitbedarf der Probengewinnung, Probennahme, Probenaufbereitung abzustimmen. Ferner ist es wichtig, den Umfang der wirklich nötigen Daten auf das Mindestmaß zu reduzieren. Die anschließende Berechnung über Aufwand und Ergebnis der Datenverarbeitung in der analytischen Chemie kann dann die richtige Antwort auf das zu wählende System — Rechenschieber, Tischrechner, programmierter Tischrechner, Kleinstcomputer, Computer — geben. Beispiele dazu werden diskutiert.

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Summary Quantitative und qualitative analysis continue to be the two main fields of analytical chemistry, and analytical chemistry keeps moving forward in the direction of minimum-concentration analysis, thus being closely related to quantitative analysis.Structural analysis, which is of outstanding importance in organic chemistry, is a special form of qualitative analysis. Modern procedures include methods in which the data are gathered exclusively by hand, semi-mechanized methods using instrumental techniques (in which the hand and the head still play a predominant role) and, last but not least, fully mechanised techniques which are uneconomical unless the intermediate data are also processed by machine. The types of data processing, the complexity of the data obtained and the requirements to be met by the processing system are discussed from the point of view of industrial analysis with reference to classical and modern titration, gas chromatography, mass spectrometry and systems combining separation and structure-finding methods.Instrumental methods usually yield the information at much higher speed and in rather more concentrated form than classical procedures. It is now necessary to decide wether intermediate storage ([magnetic tape] recording equipment with all its advantages) is still adequate or wether some on-line connection to a computer is required. The latter is a must when time-consuming intermediate storage is not acceptable or the amount of data obtained per unit time cannot be economically dealt with by hand.The important thing is to correlate the (really justifiable) demand for the speed of determining the final data to the time required for preparing, taking and processing the samples. Calculation of the expenditure incurred and the results of data processing can provide the right answer as to the equipment to be used, i. e. slide rule, calculating machine, programmed calculating machine, mini-computer or computer. Examples are discussed.

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Herrn Professor Dr. Steinhofer zum 60. Geburtstag gewidmet.