Die Firma Leopold Cassella & Co.

Leopold Cassella & Co. originated in the Frankfurt ghetto as a trading company for natural dyestuffs, and developped into a worldwide acting enterprise by the joint activities of the Cassella‐Gans‐Weinberg families. After the invention of the first synthetic dyes the owner families 1870 founded a chemical and dyestuff factory. Clever exploration and exploitation of the chemistry of naphthaline and its derivatives made the works into the largest and most profitable azo‐dyestuff‐company of the world about 1900. Leopold Cassella & Co. offered their products worldwide thru a network of fully and partly owned, cooperating companies. In 1925 the company joined IG‐Farbenindustrie AG, but remained an own entity, until the Nazi‐government – which brought distress and death to many members of the ownerfamilies – 1938 ordered the full integration (arization) into IG‐Farbenindustrie AG. After the demolition of IG‐Farbenindustrie AG following the end of World War II, Cassella 1952 evolved as an independent dyestuff AG, the majority of which 1970 was bought by Hoechst AG. 1995 Cassella was fully integrated into Hoechst AG, which dissolved itself shortly thereafter. Following a short term with Clariant of Switzerland, the Fechenheim works were sold to private investors, who founded AllessaChemie GmbH, which will celebrate their 10th anniversary on July 1, 2011.     

Otto Liebknecht – eine ungewöhnliche Karriere

With his name Dr. Otto Liebknecht got a big burden. He was born as son of Wilhelm Liebknecht, one of the leaders of the German Social Democratic movement. His brother was Karl Liebknecht, founder of the Communist Spartakusbund. After finishing his studies in Chemistry in 1899 at the University of Berlin Liebknecht had to look for a long time until he got an employment at Degussa in Frankfurt. it turned out to be a big fortune for the company to get the new staff member. Liebknecht developed a production process for sodium perborate, a big and successfull beaching agent in detergents until today, After a dispute about royalities Liebknecht quit his job at Degussa after 25 years and worked with other German companies. In his last years he was appointed Professor of Organic and Inorganic Chemistry at the University of Berlin.     

The possible discovery of neutron activation in 1910

One-hundred-two years ago, on 21 April 1910, the Austrian chemist Carl Auer von Welsbach published a short comment on a fundamental discovery he had made in the field of nuclear sciences. He reported that “jonium” (²³⁰Th) was able to induce radioactivity in other materials if stored in contact with the ionium sample. He was well aware that this observation was “not quite in agreement with current theories”, because, as a basic principle, a radioactive substance cannot activate an inactive substance. Since he could not remove any superficial contamination, he concluded that the previously inactive materials had become radioactive themselves. Auer von Welsbach predicted that this observation “might be of importance for the mysterious field of radioactivity research”. In fact, we believe that in this experiment he incidentally discovered neutron activation and the production of artificial radionuclides (24 years before I. Curie and F. Joliot) or even induced nuclear fission. The neutron source in his experiments is yet unknown and shall be identified in this project. The neutrons could have been produced from nuclear reactions with impurities of beryllium in the sample. Auer von Welsbach may even have observed nuclear fission 29 years before O. Hahn, F. Straßmann, L. Meitner and O. R. Frisch. In any case, he may have noticed the effects of neutron radiation—22 years before its discovery by J. Chadwick. The main aim of this interdisciplinary project (of which preliminary results are presented herein) is to repeat the 1910-experiment and to identify the source of the neutrons. It will be equally important to investigate the historical reasons and circumstances why Auer’s report remained mostly uncommented in the scientific community. The hypothetical consequences are worth discussion: Auer’s publication could have started the “nuclear age” much earlier than it finally began, with all the consequences for mankind.     

ESCA-studies on activated silicagel surfaces preconcentrating heavy metal ions

Summary The theoretical ion-exchange capacity of an aminosilylated silicagel surface loaded with dithiocarbamate (DTC) groups was calculated by correlation of the results of a BET measurement, a quantitative determination of the concentration of reactive single hydroxyl groups on the surface, and ESCA intensities. ESCA spectra suggest many functional groups to be thiuram disulfide ones and not DTC ones as believed before. Quantitative ESCA measurements show that aminosilylated silicagel surfaces are only partially transformed to the DTC form. In spite of their chemical instability, the concentration of heavy metal ions (Pb²⁺) in aqueous solution and their ESCA intensities after immobilization on the activated silicagel surface are linearily correlated with each other in the ppm region.Professor Dr. Carl Mahr zum 80. Geburtstag in Dankbarkeit gewidmet.     

The effect of thermal annealing on luminescence centres in Ge-silica fibres

The radioluminescence spectrum of Ge-silica fibres doped with Nd is found to change by the effect of pre-irradiation and thermal annealing. Originally the spectrum consists of a gaussian band centred near 3.1 eV (400 nm). Following the irradiation and heating an additional asymmetric band appears near 2.4 eV (520 nm). On top of this band there is a line spectrum, which can be ascribed to internal transitions of the Nd³⁺. On the basis of the spectroscopic data and previous results of thermoluminescence measurements, a model is suggested for the luminescence and the effect of the thermal annealing. The blue and green bands are ascribed to an O₂ ^– molecular ion and a hole centre near the Nd³⁺ ion, respectively.

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Zusammenfassung Das Radiolumineszenzspektrum von mit Nd versetzten Ge-Siliziumoxidfasern ändert sich durch den Einfluß von vorheriger Bestrahlung und thermischem Tempern. Ursprünglich besteht das Spektrum aus einer Gaußschen Bande mit dem Mittelpunkt bei etwa 3.1 eV (400 nm). Nach Bestrahlung und Erhitzen zeigt sich in der Nähe von 2.4 eV (520 nm) eine zusätzliche, asymmetrische Bande. An der Spitze dieser Bande befindet sich ein Linienspektrum, was internen Übergängen von Nd³⁺ zugeschrieben werden kann. Auf der Grundlage der spektroskopischen Angaben und vorangehender Resultate aus Thermolumineszenzuntersuchungen wurde für die Lumineszenz und den Einfluß des thermischen Temperas ein Modell entwickelt. Blaue bzw. grüne Banden werden O₂ ^– Molekülionen bzw. Leerstellenzentren in der Nähe von Nd³⁺-Ionen zugeschrieben.

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Dedicated to Professor Dr. H. J. Seifert on the occasion of his 60^th birthday     

Robert Havemann. Chemiker im Widerstand

In the uncommon course of life of the German physical chemist and philosopher Robert Havemann resistance activities against National Socialism – for what he was sentenced to death in December 1943 – play a special role. Superiors, friends and Havemann himself led a successful struggle to prevent the execution. By declaring his research work to be highly essential to the war a research laboratory was established solely for Robert Havemann to continue his work from within the prison of Brandenburg‐Görden. In April 1945 he was liberated by the Red Army.     

Infrared characteristic bands of highly dispersed silica

Summary Infrared studies were carried out for several silica modifications. On powdering bulk silica in air, new bands were observed to appear at 3400 cm⁻¹ and 950 cm⁻¹ irrespective of its inner crystallographic structure. In addition to the bands observed for bulk silica, bands were observed for silica gel at the following frequencies: 3400, 1650, 1120, 950, and 870 cm⁻¹. Assignment of these band was made by using a deuteration technique and by preparing a transparent film of silica gel on a rock salt plate from tetramethoxy-silane and water vapor. The band at 3400 cm⁻¹ is νOH of silanol or sorbed water; 1650 cm⁻¹, δOH of sorbed water; 1120 cm⁻¹, δOH of silanol; 950 cm⁻¹,ν SiO of slanol; 870 cm⁻¹, νSiOSi of bridged ≡SiOSi≡ link on the surface.

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Zusammenfassung Es wurden Infrarot-Untersuchungen an verschiedenen Silica-Modifikationen ausgeführt. Wenn man festes Silica an Luft pulvert, werden neue Banden bei 3400 cm⁻¹ und 950 cm⁻¹ unabh?ngig von der inneren Kristallstruktur beobachtet. Zus?tzlich zu diesen Banden ergeben sich weitere in Silica-Gel bei den Frequenzen 3400, 1650, 1120, 950 und 870 cm⁻¹. Die Zuordnung dieser Banden lie? sich mit Deuterierungs-methode und durch Herstellung transparenter Filme von Silica-Gel auf Steinsalzplatten aus Tetramethoxysilan und Wasserdampf erreichen. Die Bande bei 3400 cm⁻¹ entspricht dem νOH von Silanol oder sorbiertem Wasser. 1650 cm⁻¹ dem δOH von sorbiertem Wasser, 1120 cm⁻¹ dem δOH von Silanol, 950 cm⁻¹ den δSiO vom Silanol, 870 cm⁻¹ dem νSiOSi der Brückenbindung an der Oberfl?che.

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The authors wish to express their thanks to Dr.Y. Miura, a chief of this Laboratory, for his encouragement in the course of this study, to Dr.I. Teraoka, a researcher of this Laboratory, for the preparation of sample and to Dr.R. Soda of the National Institute of Industrial Health, for his valuable discussions.     

Investigation of alumina-based ceramic materials using ICP-OES with external electrothermal vaporization

Summary The aim of this work was to develop a method based on ICP-OES for the determination of trace elements in alumina-based ceramic powders containing SiO₂ and MgO, respectively, and to study the evaporation and excitation of several elements by using external electrothermal vaporization. This method has the advantage of easy preparation, no dilution and short experiment durations. The evaporation mechanism was investigated separately from the excitation processes by means of radioactive⁵⁹Fe and¹¹⁵Cd isotopes. The influence of different thermochemical additives, as well as third elements and matrix compositions was determined.

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Untersuchung von Aluminiumoxid-haltigem keramischem Material mit Hilfe der ICP-OES mit externer elektrothermischer Verdampfung

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Dedicated to Prof. Dr. G. Tölg on the occasion of his 60th birthday     

Decomposition of methanol vapour over solid catalyst,measured by DSC

The activity of copper containing catalysts for the formation of methanol from CO and H₂ is investigated by DSC measurement of the methanol decomposition. Calibration of the DSC signal can be performed by melting experiments with tin under reaction conditions. Comparison of catalysts is well possible by measurement of the standard activity at 240°, the apparent activation energy for the methanol decomposition reaction and the aging of the catalyst samples.

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Zusammenfassung In DSC-Messungen an der Zersetzung von Methanol wurde die Aktivität von kupferhaltigen Katalysatoren für die Bildung von Methanol aus CO und H₂ untersucht. Das DSC-Signal kann mittels Zinn-Schmelzexperimenten unter Reaktionsbedingungen kalibriert werden. Ein Vergleich der Katalysatoren ist ohne weiteres durch die Messung der Standardaktivität bei 240°C, der scheinbaren Aktivierungsenergie der Methanol-Zersetzungsreaktion und des Alterns der Katalysatorproben möglich.

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Dedicated to Professor Dr. H. J. Seifert on the occasion of his 60^th birthday     

Explosive thermal dehydration of solids

Selected examples of dehydration, accompanied by violent disintegration or bloating of the decomposing solid substance are presented. This phenomenon has been explained as a specific case of internal decomposition of solids. A sealed box with compressed gaseous products is proposed as a model of the process. The practical applications of this phenomenon are discussed.

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Zusammenfassung Es werden ausgewählte Beispiele für die Dehydratation, begleitet von heftiger Zersetzung oder Aufblähen der zersetzten Feststoffe dargelegt. Diese Erscheinung wird als ein Spezialfall der internen Zersetzung von Feststoffen beschrieben. Als Modell für diesen Prozeß wird ein abgeschlossener Behälter mit unter Druck stehenden gasförmigen Produkten vorgeschlagen. Praktische Anwendungen dieser Erscheinung werden diskutiert.

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Dedicated to Professor Dr. H. J. Seifert on the occasion of his 60^th birthday

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The work was financially supported by the Ministry of National Education, grant No P/03/257/90-z. The authors wishes to express his thanks to all who contributed to this support.     

1H and 13C NMR spectral analysis of some necines of toxic pyrrolizidine alkaloids

Summary The total assignment of the ¹H and ¹³C NMR spectra of the necines of toxic pyrrolizidine alkaloids (retronecine, heliotridine, crotanecine, otonecine), their hydrochlorides and their N-oxides has been performed. The characteristic chemical shift differences between retronecine and heliotridine, as well as the protonation and N-oxidation shift effects in NMR studies of necines at the corresponding position are proposed to be an additional assignment aid. The assignment of the spectra was achieved by the concerted use of 2D correlation spectroscopy.Dedicated to Prof. Dr. Dr. Dres. h. c. Herbert Oelschläger, Frankfurt/Main, on the occasion of his 70th birthday     

In memoriam

Prof. Dr. GüNTER SAUERBREY, 1933–2003 Günter Sauerbrey died on 15 May, 2003, a few days after his 70^th birthday. For 24 years he was responsible for the Laboratory of Medical Techniques and Dosimetry of the Physikalisch-Technische Bundesanstalt, Berlin and he also taught at Universities. His important invention was the use of a quartz oscillator as a mass sensor, the quartz crystal microbalance (QCM), which he developed in his research for his doctoral thesis at the Technical University at Berlin. He described that method in two often cited papers: Phys. Verhandl., 1957. 8: p. 193 and Z. Physik, 1959. 155: p. 206–222. With the QCM, Sauerbrey introduced a new class of mass measuring devices: inertial balances. The Sauerbrey equations are the basis of all vibrational weighing systems. His experiments on QCM allowed the extension of Einstein’s equivalence principle from uniform fields to time-dependent fields. Further work was on radiometry, thermometry, medical measuring techniques, high-temperature and vacuum physics. Günter Sauerbrey participated at several Conferences on Vacuum Microbalance Techniques and discussed at these events, in particular, applications of the QCM. Requiescat in pace. Erich Robens, Vasile Mecea     

Characterization of alcohols, thiols and carboxylic acids in mixtures using the 119Sn-chemical shift of their tri-n-butyltin derivatives

Summary Mixtures of tri-n-butyltin thiolates, -alcoholates and -carboxylates were investigated. A characterization of diastereomeric compounds using their ¹¹⁹Sn-NMR-spectra was of special interest. It is shown that ¹¹⁹Sn-NMR spectroscopy is a useful method for the analysis of these mixtures.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

Thermoanalytical study of electrically aged polyethylene

Thermal analysis is found to be suitable methods to investigate the electrical aging of polyethylene.Measurements by means of the derivatograph and isothermal thermogravimetric analysis as well as differential scanning calorimetry (DSC) were applied to measure the induced changes of the properties due to electrical aging.The influences of the elctrical aging on the thermal analytical curves are discussed. New effects in the starting phase were also observed.

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Zusammenfassung Thermoanalyse erwies sich als geeignet, um das elektrische Altern von Polyethylen zu untersuchen.Mittels derivatografischer und isothermer thermogravimetrischer Analyse und DSC wurden die durch elektrisches Altern verursachten Veränderungen der Eigenschaften untersucht.Der Einfluß von elektrischem Altern auf die thermoanalytischen Kurven wurde diskutiert. Weiterhin konnten neue Effekte in der Startphase beobachtet werden.

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The authors wish to express theirs gratitude to Dr. Werner Ludwig (Department of Chemistry, Friedrich Schiller University, Jena) for the DSC measurements and for valuable discussions.

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Dedicated to Professor Dr. H. J. Seifert on the occasion of his 60^th birthday     

FTIR-ATR-spectroscopic analysis of Bis-Crown ether based PVC-membranes

Summary To get more information on the phase boundary and bulk membrane processes, the short and long time behaviour of potassium selective solvent polymeric membranes was studied. In parallel with the measurement of the dynamic response of model membranes, in situ spectroscopic measurements applying the Attenuated Total Reflection (ATR) technique in the infrared region, were carried out in solutions containing anions of different lipophilicity (Cl^– and SCN^–). Thin membranes (thinner than the penetration depth of IR beam) coated on the germanium reflection element by the dipping technique show no time dependence of the SCN bands in contact with KSCN solution of different concentrations, while the diffusion process of species can be monitored in thick membranes as it was shown in a time resolved study. The extremely short response times of ionophore based solvent polymeric membranes (determined under appropriate experimental conditions in this work) imply that the fundamental potential determining step of the overall response of this type of electrodes is a phase boundary process. Thus the slow inner membrane diffusion process followed by IR spectroscopy on the molecular level may affect only the long-term membrane behaviour.

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FTIR-ATR-spektroskopische Analyse von Bis-Kronenether-PVC-MembranenIII. Spektroskopische und elektrochemische in situ-Methoden zur Untersuchung von OberflÄchen- und Bulk-Membran-Prozessen

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Part II: see [4]

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Dedicated to Prof. Dr. W. Fresenius on the occasion of his 75th birthday     

Thin-layer chromatography of radioactively labelled cholesterol and precursors from biological material

Summary The investigation methods of the action of xenobiotics on sterol biosynthesis from ¹⁴C-acetate in rat hepatocyte cultures can be developed, with regard to extraction using Extrelut and the separation of the sterol pattern by thin-layer chromatography, in such a way that they are suitable for wider application, e.g., screening. Good visualisation and recognition of changes in the sterol pattern are possible using autoradiography of the thin-layer chromatogram.

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Dünnschicht-Chromatographie von radioaktiv markiertem Cholesterin und Vorstufen aus biologischem Material. Eine einfache und empfindliche Methode zur Untersuchung einer Beeinflussung des Sterolbiosynthesewegs

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Dedicated to Dr. E. Roesch on occasion of his 65th birthday     

Über die Wertigkeit des Kobalts in Azofarbstoffkomplexen

The Co^II-azocomplexes (1:2) have been prepared and the conditions for their existence are defined. The oxidation to the Co^III-complex by either oxygen or by the dyestuff itself is described. In the case of dyestuff-oxidation, the azo group is reduced to the respective amines. The formation of Co^III-azocomplexes in a technical scale by metallizing with Co^II-salts is discussed.