Showing papers by "Technical University of Berlin published in 1971"
378 citations
TL;DR: In this paper, a cucumber homogenates were incubated with 14C-linolenic and 14Clinoleic acid and the radioactivity of 0.3% was recovered in the fraction of flavor active aldehydes.
Abstract: Cucumber homogenates were incubated with14C-linolenic and14C-linoleic acid. Of the radioactivity, 0.3% was recovered in the fraction of flavor active aldehydes. The distribution of the specific racioactivity indicated that propanal,trans-2-hexenal andtrans-2,cis-6-nonadienal are related to 18∶3 and hexanal andtrans-2-nonenal to 18∶2. A pathway for the development of these compounds is discussed.
78 citations
TL;DR: Primary polycrystalline calcite in Echinoderms is shown in the cortex of primary spines of Cidaridae, in the secondary tooth skeleton of Clypeaster and in the accessory calcareous structures filling the crevice fold in the chewing areas of Diadematoidae teeth.
Abstract: Es wurde erstmals fur Echinodermen primar polykristalliner Calcit nachgewiesen, und zwar im Cortex der Primarstacheln der Cidaridae, dem sekundaren Zahnskelet von Clypeaster und in den akzessorischen Kalkstrukturen, die im Kauabschnitt die Furche der Diadematiden-Zahne ausfullen. Es gibt bei anderen Seeigelfamilien keine Bildungen, die dem Cidariden-Cortex oder den akzessorischen Kalkstrukturen der Diadematiden homolog sind. Das polykristalline sekundare Zahnskelet von Clypeaster ist dagegen dem monokristallinen sekundaren Zahnskelet anderer Seeigel homolog.
48 citations
TL;DR: In this paper, all the factors in the Claisen rearrangement of the ketene O.N-acetal contribute to the stereospecific formation of the sterol amides (24S,25R)-3, (24R.25S)-3 and (24 S, 25S)-4.
Abstract: Es werden alle Faktoren untersucht, die bei der Claisen-Umlagerung des Keten-O.N-acetals 2 zur stereospezifischen Bildung der Sterin-amide (24S,25R)-3, (24R.25S)-3, (24R.25R)-3 und (24S,25S)-3 und daraus der Sterine (24S)- und (24R)-4 beitragen. Durch Abbau der Amide 3 wird deren Konfiguration bestimmt und damit auf chemischem Wege bewiesen. das dem in Cucurbitaceen vorkommenden Sterin 4 die ungewohnliche (24S)-Konfiguration zukommt.
Stereochemistry of a Claisen Rearrangement in the Sterol Side Chain
All the factors are examined which in the Claisen rearrangement of the ketene O.N-acetal 2 contribute to the stereospecific formation of the sterol amides (24S,25R)-3, (24R.25S)-3, (24R.25R)-3 and (24S,25S)-3 and further to that of the sterols (24S)- and (24R)-4. The configuration of the amides 3 is determined by degradation, which gives a chemical proof for the unusual (24S)-configuration of the sterol 4, which occurs in Cucurbitaceae.
46 citations
TL;DR: A nonelectrochemical method for measuring both the voltage and the current across the inner chloroplast membrane (or thylakoid membrane) is established in extension of earlier work and is used to characterize the mode of action of valinomycin on the thylkoid membrane.
Abstract: Most of the studies devoted to the mechanism by which certain antibiotics increase the ion permeability ofbiological membranes have been carried out on artificialmodel systems. Undoubtedly one of the major reasons for this was that some of the most relevant biological membrane systems are of submicroscopic dimensions and thus inaccessible to the common electrochemical measuring techniques. This holds for the inner membrane systems of chloroplasts, mitochondria, and retinal rods.Since it is not trivial that a mechanism of action found for a model membrane works as well in a biological one with a much higher structural complexity, it seemed worth-while to study the mechanism of action of ionophorous antibiotics on the above-mentioned biological membranes.In this paper, a nonelectrochemical method for measuring both the voltage and the current across the inner chloroplast membrane (or thylakoid membrane) is established in extension of earlier work. This method is used to characterize the mode of action of valinomycin on the thylakoid membrane.
45 citations
TL;DR: In this article, the authors extended the black box theory of communications engineers to treat some problems of aerodynamically generated noise, such as the noise of ducted fans, and showed that axial and centrifugal fans act like momentum sources.
42 citations
TL;DR: In this paper, the screw-sense of the cholesteric arrangement is determined by the chirality of the optically active solute, and a circular dichroism is induced which causes temperature-dependent selective reflection colours characteristic of CHs.
Abstract: Addition of chiralic non-mesomorphic molecules to a nematic mesophase produces an optical rotatory power which exceeds the specific rotation of the optically active solutes by a factor of several orders of magnitude. Further, a circular dichroism is induced which causes temperature-dependent selective reflection colours characteristic of cholesteric phases. From this, it may be deduced that chiralic molecules transform nematic into cholesteric phases. The screw-sense of the cholesteric arrangement is determined by the chirality of the optically active solute.
35 citations
TL;DR: In this article, laser emission from Rhodamine 6G and Rhodamine B both dissolved in ethanol has been observed using the focused 6943 A output of a giant-pulse ruby laser as a pumping source.
35 citations
TL;DR: In this article, a chair-like transition state with Z-configuration of the ketene O.N-acetal double bond was observed, which cannot be observed directly.
Abstract: Bei der Umsetzung der Allylalkohole 2, 7 und 11 mit dem Titelreagens (1) erhalt man mit hoher Stereoselektivitat aus den trans-Formen die erythro-Amide 3, 8 und 12 und aus den cis-Formen die entsprechenden threo-Amide. Mit diesen Befunden last sich ein sesselformiger Ubergangszustand (6a, b) beschreiben und die direkt nicht erfasbare Z-Konfiguration der Keten-O.N-acetal-Doppelbindung beweisen.
Stereochemistry of the Claisen Rearrangement with 1-Dimethylamino-1-methoxy-1-propene
Reaction of the allylic alcohols 2, 7 and 11 with the title reagent (1) gives the erythro amides 3, 8 and 12 from the trans-forms and the corresponding threo amides from the cis allylic alcohols with high stereo-selectivity. These results indicate a chair-like transition state (6a, b) with Z-configuration of the ketene O.N-acetal double bond, which cannot be observed directly.
35 citations
TL;DR: A negative temperature dependence of elution volume was established so that the distribution coefficients decreased with increasing temperature, which gives rise to a negative enthalpy for the interacting effects between solute and the gel matrix.
33 citations
TL;DR: The reaction of hexacarbonylchromium with tri(tert-butyl)phosphine, tris(trimethylsilyl)-diphenylphosphines, and bis(trimmermyl)phenyl-phosphINE results in the elimination of one CO ligand and the formation of the corresponding organometalphosphinepentacaronyl-chromium(O) complexes as mentioned in this paper.
Abstract: Hexacarbonylchrom reagiert 1. mit Tri(tert.-butyl)-phosphin, Tris(trimethylsilyl)-, Tris(trimethylgermyl)- und Tris(trimethylstannyl)-phosphin sowie 2. mit Trimethylsilyl-diphenylphosphin, Bis(trimethylsilyl)-phenyl-phosphin und Bis(trimethylstannyl)-phenyl-phosphin unter Abspaltung eines CO-Liganden und Bildung entsprechender Organometallphosphin-pentacarbonyl-chrom(O)-Komplexe. Analog zu 1. reagieren Hexacarbonylmolybdan und Hexacarbonylwolfram mit Tri(tert.-butyl)-phosphin, Tris(trimethylgermyl)- und Tris(trimethylstannyl)-phosphin unter Bildung entsprechender Komplexe. Die Infrarot-, UV-, 1H-NMR- und 31P-NMR-Spektren werden mitgeteilt und diskutiert.
Organometalphosphine Substituted Transition Metal Complexes, XII. Organometalphosphinepentacarbonylchromium(O), -molybdenum(O), and -tungsten(O) Complexes
The reaction of hexacarbonylchromium with 1. tri(tert-butyl)phosphine, tris(trimethylsilyl)-, tris(trimethylgermyl)-, and tris(trimethylstannyl)phosphine as well as 2. with (trimethylsilyl)-diphenylphosphine, bis(trimethylsilyl)phenylphosphine, and bis(trimethylstannyl)phenyl-phosphine results in the elimination of one CO ligand and the formation of the corresponding organometalphosphinepentacarbonylchromium(O) complexes. In analogy to 1. hexacarbonyl molybdenum and hexacarbonyltungsten react with tri(tert-butyl)phosphine, tris(trimethylgermyl)phosphine, and tris(trimethylstannyl)phosphine to form the corresponding complexes. The i.r., u.v., 1H n.m.r., and 31P n.m.r. spectra are reported and discussed.
TL;DR: In this paper, the root extract of different Eryngium species together with the widespread falcarinone and its derivatives (2-4) have been isolated, the structures of which are elucidated by spectral and chemical methods.
Abstract: Aus den Wurzelextrakten verschiedener Eryngium-Arten werden neben dem weitverbreiteten Falcarinon (1) und seinen Derivaten (2–4) mehrere Terpenester (8–12) isoliert, deren Strukturen durch spektroskopische und chemische Methoden geklart werden.
Terpene Derivatives from Higher Plants, XII. On new Terpene Aldehyde Esters from Eryngium Species
From the root extract of different Eryngium species together with the widespread falcarinone (1) and its derivatives (2–4) several terpene esters (8–12) have been isolated, the structures of which are elucidated by spectral and chemical methods.
TL;DR: In this paper, anodische Verhalten von Nickel in luft-, N2-and H2-gesattigter Schwefelsaure untersucht.
01 Sep 1971
TL;DR: In this paper, a simple kinetic model is presented that describes the frequency-time-behaviour of the fluorescence of molecules showing an anomalous Stokes shift, and a discrete and a continuous description of this model are given.
Abstract: A simple kinetic model is presented that describes the frequency-time-behaviour of the fluorescence of molecules showing an anomalous Stokes shift A discrete and a continuous description of this model are given Results are compared with an earlier formulation given by Bakhshiev [4]
Vermittels eines einfachen kinetischen Modells wird das Frequenz-Zeit-Verhalten der Fluoreszenz von Molekulen untersucht, deren Fluoreszenzspektrum anomal stark rot verschoben ist Es wird ein diskretes und kontinuierliches Modell erortert Die gewonnenen Resultate werden mit einer fruheren Formulierung von Bakhshiev [4] verglichen
TL;DR: In this article, a correlation between stability constants and copolymerization parameters is found, and it is not the strength of hydrogen bonding between acrylic acid and solvent which is responsible for the variation of the relative reactivity ratios but rather the amount of dimerization of acrylic acid.
Abstract: Es werden Ergebnisse der Copolymerisation von Acrylsaure mit Methylmethacrylat in verschiedenen Losungsmitteln mitgeteilt und Vergleiche mit fruheren Untersuchungen am System Acrylsaure/Styrol durchgefuhrt. Zum Nachweis der vermuteten Wasserstoffbrucken zwischen Acrylsaure und den als Losungsmittel benutzten Protonenakzeptoren wurden die Gleichgewichtskonstanten fur die Mischassoziation IR-spektrometrisch in CCl4 bestimmt. Es ergab sich eine eindeutige Korrelation zwischen den Mischassoziationskonstanten und den Copolymerisationsparametern. Durch weitere Experimente konnte gezeigt werden, das nicht die jeweilige Starke der Wasserstoffbruckenbindung zwischen Acrylsaure und Protonenakzeptor uber die Verschiebung der r-Werte entscheidet, sondern das Ausmas der Dimerisierung der Acrylsaure.
Relative reactivity ratios are given for the system acrylic acid/methyl methacrylate in several solvents in comparison with results for the system acrylic acid/styrene which have been reported earlier. Association of acrylic acid with the proton accepting solvents was shown to occur by infrared spectroscopy using CCl4 as diluent. A correlation between stability constants and copolymerization parameters is obvious. According to further experiments it is not the strength of hydrogen bonding between acrylic acid and solvent which is responsible for the variation of the relative reactivity ratios but rather the amount of dimerization of acrylic acid.
TL;DR: In this paper, the 1.3-tricarbonyl compounds react as dienophiles and add isoprene or 2.2.3dimethylbuta-1.3diene to yield the spiro-dihydropyranes 9−16.
Abstract: Cyclische 1.2.3-Tricarbonylverbindungen (vgl. 5–8) reagieren als Dienophile mit Isopren und 2.3-Dimethyl-butadien-(1.3) unter Bildung der Spiro-dihydropyrane 9–16. Die IR- und Massenspektren der Reaktionsprodukte sowie die NMR-Spektren von 9 und 10 werden diskutiert.
1.2.3-Tricarbonyl Compounds, V. Hydrate-forming 1.2.3-Tricarbonyl Compounds as Dienophiles in Diels-Alder Reactions
The 1.2.3-tricarbonyl compounds 5–8 react as dienophiles and add isoprene or 2.3-dimethylbuta-1.3-diene to yield the spiro-dihydropyranes 9–16. I.r., mass, and n.m.r. spectra are discussed.
TL;DR: In this paper the coumarins 3, 4 and 7 have been prepared in an unequivocal manner, and a synthesis of samidin (12) is described, which is also a mixture of coumarin derivatives, Columbianetin, Angenomalin and Samidin.
Abstract: Ausgehend von Osthenol (1) werden die Cumarine 3, 4 und 7 auf eindeutige Weise dargestellt. Weiterhin wird eine Synthese des Samidins (12) beschrieben.
Naturally Occuring Coumarin Derivatives, VII Synthesis of Racemic Lomatin, Columbianetin, Angenomalin and Samidin
Starting with osthenol (1) the coumarins 3, 4 and 7 have been prepared in an unequivocal manner. Furtheron a synthesis of samidin (12) is described.
TL;DR: In this paper, it was shown that adding a chiralic eight-membered ring derivative of 1, 1′-dinaphthyl (I) to a nematic mesophase produces an optical rotatory power Φ which exceeds the optical rotation of the solute I by a factor of several orders of magnitude.
TL;DR: In this article, the reaction of diphenylgermanium dichloride and phenylphosphine in the presence of triethylamine yields only bis(diphenylchlorgermyl)-phenyl-phosphin (3), wahrend man aus Dimethyl-, Dibutyl- und Diphenylzinndichlorid und Phenylphophosphine (5-7) erhalt.
Abstract: Diphenyldichlorsilan und Diphenylgermaniumdichlorid reagieren sowohl mit Dikaliumphenylphosphid als auch mit Kalium-hydrogenphenylphosphid unter Bildung von dimerem und trimerem Diphenylsilyl-phenyl-phosphin (1a, 1b) bzw. Diphenylgermyl-phenyl-phosphin (4a, 4b). Die Reaktion von Diphenylgermaniumdichlorid und Phenylphosphin in Gegenwart von Triathylamin liefert dagegen nur Bis(diphenylchlorgermyl)-phenyl-phosphin (3), wahrend man aus Dimethyl-, Dibutyl- und Diphenylzinndichlorid und Phenylphosphin die cyclischen trimeren Dimethyl-, Dibutyl- und Diphenylstannyl-phenyl-phosphine (5-7) erhalt.
Cyclic Organosilyl-, Organogermyl- and Organostannyl-phosphines.
Diphenyldichlorosilane and diphenylgermanium dichloride react with dipotassium phenylphosphide as well as with potassium hydrogen phenylphosphide to form dimeric and trimeric (diphenylsilyl)phenylphosphine (1a, 1b) and (diphenylgermyl)phenylphosphine (4a, 4b), respectively. On the other hand the reaction of diphenylgermanium dichloride and phenylphosphine in the presence of triethylamine yields only bis(diphenylchlorogermyl)phenylphosphine (3), while dimethyl-, dibutyl-, and diphenyltin dichloride and phenylphosphine form the cyclic trimeric (dimethylstannyl)-, (dibutylstannyl)-, and (diphenylstannyl)phenylphosphines (5–7).
TL;DR: In this article, energy losses of 37 keV electrons in solid Ar, Ne and H 2 were measured with a resolution better than 0.08 eV and compared with optical results.
TL;DR: In this article, high-resolved electron energy loss spectra of graphite and of evaporated carbon films have been measured in the energy loss range between 20 and 400 meV, where the primary energy was 25 keV, the energy resolution between 4 and 7 meV.
Abstract: High-resolved electron energy loss spectra of graphite and of evaporated carbon films have been measured in the energy loss range between 20 and 400 meV. The primary energy was 25 keV, the energy resolution between 4 and 7 meV. The energy loss spectrum of graphite is characterized by a strong continuum due to the free charge carriers. Two weak and broad bands at 45 and 128 meV superimposed on this continuum are probably due to electronic excitations. In the energy loss spectrum of evaporated carbon films phonon creations predominate below 160 meV, where several well-separated peaks are observed. An energy loss at 370 meV is caused by a longitudinal band transition.
TL;DR: In this article, the reaction of π-cyclopentadienylmanganese tricarbonyl with tri(tert-butyl)phosphine, tris(trimethylsilyl)-, trimethylgermyl-, and tris-trimmethylstannyl-phosphines was studied.
TL;DR: Fluorescence spectra and quantum yields of the two 1-phenyl-2-naphthyl ethylenes and the three 1,2-dinaphthy ethylene were studied between +25° and -180°, both of the trans and cis isomers as discussed by the authors.
TL;DR: The Preparation of Symmetric Sulfones by Addition of Derivatives of Sulfoxylic Acid to Activated Double Bonds is described in this paper, where the olefinic bond is polarized by carbonyl, pyridyl, nitrile or sulfonyl groups with derivatives of sulfoxylic acid such as hydroxymethanesulfinate, formamidine sulfinic acid and dithionite.
Abstract: Aus Sulfoxylsaurederivaten wie Hydroxymethansulfinat, Formamidinsulfinsaure sowie aus Dithionit lassen sich durch Umsetzung mit Vinylverbindungen, deren Doppelbindung durch Carbonyl-, Pyridyl-, Nitril- oder Sulfongruppen polarisiert ist, β.β′-disubstituierte Diathylsulfone darstellen.
The Preparation of Symmetric Sulfones by Addition of Derivatives of Sulfoxylic Acid to Activated Double Bonds
β,β′-Disubstituted diethyl sulfones can be obtained by reaction of vinyl compounds in which the olefinic bond is polarized by carbonyl, pyridyl, nitrile or sulfonyl groups with derivatives of sulfoxylic acid such as hydroxymethanesulfinate, formamidine sulfinic acid and dithionite.
01 Nov 1971
TL;DR: The lowest energy conformation of sterically hindered arylethylenes has been calculated by a simple quantummechanical treatment involving interaction of non-bonded atoms as mentioned in this paper.
Abstract: Fur eine Reihe sterisch gehinderter Arylathylene wurde die energetisch gunstigste Konformation mit Hilfe einer HMO-Rechnung unter Berucksichtigung der Wechselwirkungspotentiale nicht gebundener Atome im Molekul ermittelt. In den Gleichgewichtskonfonnationen von cis-Stilben, 1.1-Diphenylathylen und Tetraphenylathylen sind die Phenylringe betrachtlich gegen die Ebene der athylenbindung verdrillt. Beim Tetraphenylathylen resultieren zwei Konformationen der Symmetrie D2 und Ci, von denen die D2-Form energetisch bevorzugt ist. Die berechneten Werte ergeben eine gute ubereinstimmung mit experimentellen Daten.
The lowest energy conformation of sterically hindered arylethylenes has been calculated by a simple quantummechanical treatment involving interaction of non bonded atoms. The resulting conformation of cis-stilbene, 1.1-diphenylethylene and tetraphenylethylene deviate remarkably from planarity by twisting the phenylethylene bond. In tetraphenylethylene two conformations of symmetry D2 and Ci, respectively, are possible but D2 is energetically preferred. The calculated values are in good agreement with experimental data.