Showing papers in "Helvetica Chimica Acta in 1956"
TL;DR: The relation between the simple form of MO-theory (two parameter theory) and the theory of spectra of graphs is investigated in this article by the use of some theorems of graph theory.
Abstract: Relations between the simple form of MO-theory (two parameter theory) and the theory of spectra of graphs are investigated. By the use of some theorems of graph theory it is shown that the spectra of energy eigenvalues given by the simple MO-theory are determined besides of scale factors by the topology of the conjugated systems. Furthermore bond orders and charge orders are completely determined by the topology. A procedure for the calculation of the characteristic polynom and the characteristic vectors directly from the graph is given.
219 citations
TL;DR: In this paper, the stability constants of calcium and magnesium complexes with adenosin-monophosphate and inorganic triphosphate have been determined and the possible structure of these complexes is discussed.
Abstract: Stability constants of calcium and magnesium complexes with adenosin-monophosphate, adenosin-diphosphate, adenosin-triphosphate and inorganic triphosphate (often called tripolyphosphate) have been determined. The possible structure of these complexes is discussed. Adenosin itself is unable to bind alcaline earth cations.
188 citations
TL;DR: The industrial β-carotene manufacturing procedure based on Inhoffen's synthesis C19 + C2 + C19 = C40 is described in this paper, where β-Ionone is first lengthened to β-C14-aldehyde as in our vitamin A-synthesis.
Abstract: The industrial β-carotene manufacturing procedure based on Inhoffen's synthesis C19 + C2 + C19 = C40 is described. β-Ionone is first lengthened to β-C14-aldehyde as in our vitamin A-synthesis. By acetalisation, condensation with vinyl ether and treatment with acid the new β-C16-aldehyde is obtained. Repetition of the same reactions with propenyl ether leads to the β-C19-aldehyde. For the final steps simple methods were developed giving high yields. All the chemical, physical and biological constants of synthetic β-carotene are identical with those of the natural compound. Exact data on light absorption are given. Extensive experiments with the synthetic β-carotene on rats and rabbits show that even very large doses have no toxic effects.
131 citations
TL;DR: In this paper, the synthesis of 4- and 6-substituted 1-H- and 1-phenyl-pyrazolo-(3,4-d)-pyrimidines is described.
Abstract: The synthesis of 4- and 6-substituted 1-H- and 1-phenyl-pyrazolo-(3,4-d)-pyrimidines is described. It starts from ethyl ethoxymethylene cyanoacetate from which the 4-hydroxy-pyrazolo-(3,4-d)- pyrimidines can be obtained in two steps through the corresponding 2-substituted 3-amino-4-carbethoxy-pyrazoles.
109 citations
TL;DR: The syntheses of four analogues of oxytocine are described and one with a phenylalanyl residue replacing the isoleucyl residue is synthesised.
Abstract: The syntheses of four analogues of oxytocine are described: one with a phenylalanyl residue replacing the isoleucyl residue, one with a leucyl residue replacing the isoleucyl residue, one with a valyl residue replacing the isoleucyl residue, and one with a glutaminyl residue replacing the asparaginyl residue.
101 citations
TL;DR: In this paper, a 2,4,6-triarylpyrylium-salze is introduced, which is a new Methode for the Triarylpyricrylliumsalze anwendbar.
Abstract: 2,4,6-Triarylpyryliumsalze lassen sich mit Natriumsulfid in Aceton leicht in Triarylthiopyryliumsalze uberfuhren Diese sind noch tieferfarbig als die analogen Pyryliumsalze Die Beziehungen zwischen Konstitution und Farbe werden kurz besprochen Die neue Methode ist auch auf die Vinylenhomologen der Triarylpyryliumsalze anwendbar
86 citations
TL;DR: In this article, the stability constants of the complexes of nitrilotriacetic acid with La, Ce, Pr, Nd, Sm, Gd, Dy, Yb and Y have been defermined and the polarographic method applied was proved to give good results by a redetermination of the stabilities of the complex of Cd, Pb, Zn, Co and Ni.
Abstract: The stability constants of the complexes of nitrilotriacetic acid with La, Ce, Pr, Nd, Sm, Gd, Dy, Yb and Y have been defermined and the polarographic method applied was proved to give good results by a redetermination of the stabilities of the complexes of Cd, Pb, Zn, Co and Ni. There again is a break at Gadolinium in the curve obtained by plotting stability constants versus atomic number of the rare earths.
84 citations
TL;DR: In this article, the adjectives homodetic and heterodetic are proposed to differentiate these two types of cyclo-polypeptides, i.e., whether the rings contain only peptide linkages or not.
Abstract: Naturally occurring cyclo-polypeptides may be subdivided into two groups, according t o whether the rings contain only peptide linkages or not. The adjectives homodetic and heterodetic are proposed to differentiate these two types of cyclo-polypeptides.
82 citations
TL;DR: In this article, a simple and efficient synthesis of lycopene is described based on stepwise lengthening of a symmetrical C10-dialdehyde as central component, leading to a 20-dial dehyde which is transformed into crocetin dialdehyde by partial hydrogenation of the central triple bond.
Abstract: A simple and efficient synthesis of lycopene is described based on stepwise lengthening of a symmetrical C10-dialdehyde as central component. This C10-dialdehyde is lengthened at both ends, first with vinyl ether and then with propenyl ether, leading to a C20-dialdehyde which is transformed into crocetin dialdehyde by partial hydrogenation of the central triple bond. By means of a new reaction devised by Wittig, crocetin dialdehyde is condensed at both ends with geranylidene-triphenylphosphorane and lycopene is obtained according to the scheme C10 + C20 + C10 = C40. This synthetic pigment is identical with pure natural lycopene isolated from tomato juice. The Wittig reaction also allows a new β-carotene synthesis using the components cyclogeranylidene-triphenylphosphorane and 8,8′-dehydro-crocetin dialdehyde.
76 citations
TL;DR: In this paper, einige neue Hilfsmittel fur die rationelle Durchfuhrung und Auswertung von analytischen und insbesondere praparativen Papierchromatogrammen are beschrieben.
Abstract: Es werden einige neue Hilfsmittel fur die rationelle Durchfuhrung und Auswertung von analytischen und insbesondere praparativen Papierchromatogrammen beschrieben.
76 citations
TL;DR: In this article, a method was described which enables the production in only one chemical step of 1,4-bisdehydro-3-oxo-steroids inter alia from 3-oxO- steroids saturated in ring A or from α β-mono-unsaturated 3-ketones.
Abstract: A method is described which enables the production in only one chemical step of 1,4-bisdehydro-3-oxo-steroids inter alia from 3-oxo- steroids saturated in ring A or from the α β-mono-unsaturated 3-ketones. The dehydrogenating agent is selenium dioxide and the solvent a tertiary alcohol preferably containing some acid.
TL;DR: The reduktive Methylierung des (−)-N-Nor-laudanosins gab rlatiirliches (+)-Laudanosin, wahrend der Abbau mit Ozon und Perameisensaure zu einem L-Asparaginssure-Derivat fuhrte as mentioned in this paper.
Abstract: Das aus Papaverin leicht zugangliche d, l-N-Norlaudanosin (Tetrahydro-papaverin) wurde in die optischen Antipoden gespalten. Die reduktive Methylierung des (−)-N-Nor-laudanosins gab rlatiirliches (+)-Laudanosin, wahrend der Abbau mit Ozon und Perameisensaure zu einem L-Asparaginssure-Derivat fuhrte. Damit ist die fruher nur auf Grund der Clough'schen Regel abgeleitete Konfiguration des naturlichen (+)-Laudanosins streng bewiesen. Aus unserer Beweisfuhrung ergibt sich auch die Konfiguration einer Anzahl weiterer Alkaloide der Tetrahydro-isochinolin-, der Aporphin- und der Tetrahydro-berberin-Reihe.
TL;DR: In this article, ein einfaches Verfahren zur Darstellung von 2,4,6-Triarylpyryliumsalzen mitgeteilt.
Abstract: Es wird ein einfaches Verfahren zur Darstellung von 2,4,6-Triarylpyryliumsalzen mitgeteilt. Der Einfluss von Auxochromen, insbesondere von Dimethylaminogruppen, auf die Farbe der Pyryliumsalze und der analogen N- Methyl- pyridiniumsalze wird besprochen. Auxochrome wirken in Verbindung mit dem Triphenylpyryliumion sehr viel starker bathochrom als in Verbindung mit dem Triphenyl-pyridiniumion. In der Pyridiniumreihe liegen die Maxima isomerer Farbsalze sehr nahe beieinander, wahrend in der Pyryliumreihe beachtliche Unterschiede vorhanden sind. Ein Deutungsversuch fur diese Erscheinung wird ausgesprochen.
TL;DR: Nine additional compounds of the pregnane series have been isolated from adrenals and elucidation of their constitution showed that four are known compounds, but five are new.
Abstract: Nine additional compounds of the pregnane series have been isolated from adrenals. Elucidation of their constitution showed that four are known compounds, but five are new. They are derived from the classical corticoids by hydroxylation in the 6β- or 19-positions, by reduction of the 4,5-double bond or 20-keto group, and by oxydation of the angular 18-methyl group not merely to an aldehyde, as in aldosterone, but to a carboxyl group. The latter derivative is of special biochemical interest.
TL;DR: In this article, the same authors synthesize Zeaxanthin and physalien from acetoxy-iso-C19-aldehyde and acetylene following the scheme C19+C2+C19 = C40.
Abstract: Zeaxanthin and physalien have been synthesized from acetoxyiso-C19-aldehyde and acetylene following the scheme C19+ C2+ C19 = C40. The acetoxy-iso-C19-aldehyde was obtained from isophorone via keto-iso-C19-aldehyde to which the chain lengthening procedure of our β-carotene synthesis was applied, using vinyl ether and propenyl ether. The optically inactive synthetic compounds have the same melting points as the natural products, the absorption spectra of the solutions are identical, and the mixed melting points show no depression.
TL;DR: Starting from lumiflavine and its 2-thio-analogue, the leukoflavine nucleus was obtained and stabilized by reductive acylation, and the acyl-leuko-compounds seem to exhibit the possibility of substitution reactions in 2- and 4-positions.
Abstract: Starting from lumiflavine and its 2-thio-analogue, the leukoflavine nucleus was obtained and stabilized by reductive acylation. The acyl-leuko-compounds seem to exhibit the possibility of substitution reactions in 2- and 4-positions. Several new lumiflavines were obtained, e. g. 4-thiolumiflavine and 2-desoxylumiflavine. The latter shows rather peculiar oxido-reductive properties which are discussed.
TL;DR: Theodorakopoulos et al. as discussed by the authors wurde auf Grund seiner Eigenschaften und Abbauergebnisse die Konstitution I zugewiesen.
Abstract: Dem Carboxy-lacton, C10H16O4, das dureh Oxydation der Antibiotica Narbomycin, Pikromycin urid Methymycin mit Kaliumpermanganat entsteht, wurde auf Grund seiner Eigenschaften und Abbauergebnisse die Konstitution I zugewiesen.
TL;DR: In this article, a method for chain-lengthening and rearrangement of double bonds was developed for carotenoid intermediates, starting from β-ionone, 2,6,6-trimethyl-cyclohexanone-(1) and 2, 6, 6-trIMEHENENE-(2)-one.
Abstract: Starting from β-ionone, 2,6,6-trimethyl-cyclohexanone-(1) and 2,6,6-trimethyl-cyclohexene-(2)-one-(1), intermediates for carotenoids are synthesized. New methods for chain-lengthening and rearrangement of double bonds are developed. 16 different ring compounds are characterised by their phenyl semicarbazones.
TL;DR: In this paper, the absorption spectra of 1-acetylazulene, 1-methyl-3-acetylamine, 2-methyl 1,3-dimethyl-1,3 diacetyl-diacetyl-acidamide (D2DIAE) have been determined.
Abstract: The absorption spectra of 1-acetylazulene, 1-methyl-3-acetylazulene, 2-methyl-1-acetylazulene, 3-acetylguayazulene 1,3-benzoylguayazulene, 1,3-diace t ylazulene and of 2-methyl- 1,3-diacetylazulene have been determined.
TL;DR: In this article, the papierchromatographische Trennung and sichere Unterscheidung der naturlichen 2-Desoxyhexamethylosen and deren 3-Methylather durch Renutzung von 2 verschiedenen Losungsmittelsystemen wird beschrieben.
Abstract: Die papierchromatographische Trennung und sichere Unterscheidung der naturlichen 2-Desoxyhexamethylosen und deren 3-Methylather durch Renutzung von 2 verschiedenen Losungsmittelsystemen wird beschrieben.
TL;DR: Squalene was synthesized in a modified procedure according to P. Karrer and A. Helfensteiqa starting from naturel and from synthetic nerolidol as mentioned in this paper.
Abstract: Squalene was synthesized in a modified procedure according to P. Karrer & A. Helfensteiqa starting from naturel and from synthetic nerolidol. After purification through the thio-urea adduct the synthetic products were found to be identical with pure natural squalene in their chemical and physical properties as well as in their biological behaviour.
TL;DR: In this article, it was shown that the matrix elements of the deterministic deterministic matrix can be computed in closed form as functions of n without involving further approximations, and that the corresponding wave function ψ(x) is approximated by a linear combination of hermitean orthogonal functions.
Abstract: If a particle moves in a one-dimensional field V(x) given as a polynomial of even order (V (x) = v0 + v1x + v2x2 + vkzk; k even) and if the corresponding wave-function ψ(x) is approximated by a linear combination Φ(x) of hermitean orthogonal functions
then it can be shown that the matrix elements of the secular determi- nant can be easily calculated in closed form as functions of n without involving further approximations.
TL;DR: In this article, the preparation of pure 4,5-benzo-azulene is described and some of its spectroscopic properties are compared with those of its isomers 1,2-and 5,6-benzosulene as well as the parent compound azulene.
Abstract: The preparation of pure 4,5-benzo-azulene is described and some of its spectroscopic properties are compared with those of its isomers 1,2-benzo-azulene and 5,6-benzo-azulene as well as with those of the parent compound azulene.
TL;DR: In Gegenwart von Luft mit guter Ausbeute ein Gemisch von diastereomeren Δ4-9-Methyl-8-hydroxy-octalonen-(3,8) gab beim Schutteln mit Kulturen von Curvularia fakata (Tehon) Boedijn as discussed by the authors.
Abstract: (±)-Δ4-9-Methyl-octalindion-(3,8) gab beim Schutteln mit Kulturen von Curvularia fakata (Tehon) Boedijn. in Gegenwart von Luft mit guter Ausbeute ein Gemisch von diastereomeren Δ4-9-Methyl-8-hydroxy-octalonen-(3). Diese gaben bei der Oxydation mit Chrom-(V1)-oxyd-Pyridin-Komplex die enantiomeren Δ4-9-Methyl-octalin- dione-(3,8). Auf Grund der Vergleiche der Drehungen und der Oxydationsgeschwindigkeiten mit Chrom(VI)-oxyd mit denjenigen der analogen D-Homo-steroide konnte dem erhaltenen rechtsdrehenden Δ4-9-Methyl-8-hydroxy-octalon-(3) die Konfiguration III und dem linksdrehenden die Konfiguration IV zugeteilt werden.
TL;DR: In this article, the 2-aminoindolenine structure of a base has been shown to have the same structure as that of an acyclic acid base in alkylations and acylations.
Abstract: On the basis of the physical constants (pKa, UV. and IR. absorption spectra) of the so-called “2-aminoindole” and its substitution products, and by interpretation of the course of the chemical reaction in alkylations and acylations, this base has been shown actually to have the 2-aminoindolenine structure.
TL;DR: In this article, the ionic strength of substituted benzenesulfonamides and two series of substituted Benzenes-Sulfonanilides were determined. But the ionicity of the reaction was not analyzed in terms of electrostatic field effects.
Abstract: Acidity constants at 20° and the ionic strength μ = 0,1 were determined for substituted benzenesulfonamides and two series of substituted benzenesulfonanilides. pK values are plotted versus Hammett's σ constants and ϱ values are calculated. ϱ = 1,06 is obtained for benzenesulfonamides, ϱ = 1,16 for benzenesulfonanilides substituted on the S side, and ϱ = 1,74 for benzenesulfonanilides substituted on the N side. In the latter series, σ values must be applied for p-NO2 and p-CH3CO. ϱ values found in this work are compared with those for other reactions, and they are discussed in terms of electrostatic field effects, inductive and mesomeric effects. It is concluded that direct field effects and electronic effects transmitted through the atom chain equally contribute to the free energy change caused by a substituent.
TL;DR: Aus dem Kulturfiltrat von zwei Streptomyceten, welche Strobacter ambofaciens Pinnert-Sindico nahestehen, wurden 4 lipophile, basische Antibiotica (Foromacidine A, B, C and D) isoliert.
Abstract: Aus dem Kulturfiltrat von zwei Streptomyceten, welche Streptomyces ambofaciens Pinnert-Sindico nahestehen, wurden 4 lipophile, basische Antibiotica – die Foromacidine A, B, C und D – isoliert. Die Foromaeidine A, B und C liefern durch milde saure Hydrolyse Nycarose, einen Dimethylamino–zucker und Forocidin A, B bzw. C. Durch alkalische Hydrolyse wird aus Foromacidin B und Forocidin B 1 Mol Essigsaure, und aus Foromacidin C und Forocidin C 1 Mol Propionsaure abgespalten. Die Zusammensetzung und die analytisch nachgewiesenen funktionellen Gruppen deuten auf eine Verwandtschaft der Foromacidine mit den Antibiotica der Carbomycin–Erythromycin–Gruppe hin. Die Foromacidine zeichnen sich durch bemerkenswerte antibiotische Wirksamkeit in vitro und in vivo aus und besitzen eine geringe Toxizitat.
TL;DR: In this paper, the preparation and spectroscopic properties of 2,7-polymethylene-4, 5-benzotropones are described and the trends in these properties with decreasing number of methylene groups in the polymethylene ring are due to steric inhibition of the benzotropylium resonance.
Abstract: The preparation and the spectroscopic properties of 2,7-polymethylene-4, 5-benzotropones are described. The trends in these properties with decreasing number of methylene groups in the polymethylene ring are due to the steric inhibition of the benzotropylium resonance.
TL;DR: Aus Fliegenpilzen wurde das quaternare Alkaloid Muscarin in reiner, kristallisierter Form isoliert (Chlorid, Chloroaurat, Reineckat).
Abstract: Aus Fliegenpilzen wurde das quaternare Alkaloid Muscarin in reiner, kristallisierter Form isoliert (Chlorid, Chloroaurat, Reineckat). Analysen fuhrten zur Formel C9H20O2N+. Die Strukturen I und II wurden durch Abbauversuche uberpruft und widerlegt.
TL;DR: In this article, an investigation has been made of some properties of faujasite-like crystals and it appears that, isomorphous replacements of the type Na+Al+++ Si++++ are possible.
Abstract: An investigation has been made of some properties of faujasite-like crystals. This rare zeolite has cubic symmetry and is based upon a remarkably open but sturdy aluminosilicate framework. From the compositions of natural and synthetic crystals it appears that, isomorphous replacements of the type Na+Al+++ Si++++ are possible. In addition replacements by ion exchange were readily effected involving the ions Na+, K+, TI+, Ag+, Mg++, Ca++, Sr++, Ba++, Co++, and Ni++, and the ions NH4+, NH3Et+34, NH2Et+34, NH2Me2+, NH2Me3+, NMe4+. In this latter series the extent of exchange diminishes with increasing alkyl content in the order given. NEt4+ ions did not exchange.