Showing papers in "Helvetica Chimica Acta in 1967"
TL;DR: In this paper, the synthesis of the new complexing agents tris-(2-pyridylmethyl)-amine and N,N,N′, N′-tetrakis-( 2pyridine methylenediamine) is described, and their protonation constants given.
Abstract: The synthesis of the new complexing agents tris-(2-pyridylmethyl)-amine and N,N,N′,N′-tetrakis-(2-pyridylmethyl)-ethylenediamine is described, and their protonation constants are given.
175 citations
TL;DR: The conversion of bicyclo[10.3.0]-1,12-epoxy-13-pentadecanone into 4-cyclopenta-decyne-1-one, effected by p-tolylsulfonylhydrazine under mild conditions and in high yield, provides an example of a new fragmentation reaction as mentioned in this paper.
Abstract: The conversion of bicyclo[10.3.0]-1,12-epoxy-13-pentadecanone into 4-cyclopenta-decyne-1-one, effected by p-tolylsulfonylhydrazine under mild conditions and in high yield, provides an example of a new fragmentation reaction.
161 citations
TL;DR: The analysis of a coffee concentrate is described: 202 constituents have been identified, 154 of which for the first time as mentioned in this paper, some of these compounds are new chemicals; their synthesis is described.
Abstract: The analysis of a coffee concentrate is described: 202 constituents have been identified, 154 of which for the first time. Some of these compounds are new chemicals; their synthesis is described. Most identifications are based upon mass spectrometry combined in many cases with IR. spectrometry and comparison with reference compounds. MS. and IR. data are given in detail. The analysis shows that a large number of minor constituents is present, many of which could not be identified.
144 citations
126 citations
TL;DR: Heterocyclische ringsystems as discussed by the authors are a family of Charakters with mindestens einem ring-Stickstoffatom, e.g., a ring-stoffat, which can be found in an Noder NC-Gruppe des Heterocyclus.
Abstract: Heterocyclische Ringsysteme aromatischen Charakters mit mindestens einem Ring-Stickstoffatom, die eine oder mehrere p-Tolylgruppen oder in einem an den Heterocyclus ankondensierten Benzolring eine Methylgruppe in p-Stellung zu einer CN-oder NC-Gruppe des Heterocyclus enthalten, konnen in Dimethylformamid in Gegenwart von Kaliumhydroxid oder Kalium-t-butylat mit aromatischen Aldehydanilen zu heterocyclisch substituierten Stilbenverbindungen umgesetzt werden.
111 citations
TL;DR: In this article, the acid-catalysed reaction of isopropenyl ether with tertiary acetylenic carbinols to give β-ketoallenes in high yields is described.
Abstract: The novel acid-catalysed reaction of isopropenyl ether with tertiary acetylenic carbinols to give β-ketoallenes in high yields is described. Upon treatment with bases, these allenes readily undergo isomerization to conjugated dienones. This reaction sequence results in an economic synthesis of pseudo-ionones and pseudo-irones from dehydrolinalool and its homologs.
99 citations
TL;DR: A new strain of Streptomyces antibioticus (WAKSMANet WOODRUFF), ETH 28829, produces a novel antibiotic, boromycin, which appears to be the first well defined boron containing organic compound to have been found in nature.
Abstract: A new strain of Streptomyces antibioticus (WAKSMANet WOODRUFF), ETH 28829, produces a novel antibiotic, boromycin, which appears to be the first well defined boron containing organic compound to have been found in nature. Boromycin is a complex of boric acid with a tetradentate organic complexing agent, that yields by hydrolysis D-valine, boric acid, and a polyhydroxy compound of macrolide type.
97 citations
TL;DR: In this paper, the 1:1-complexes between nonactin and monactin, and sodium, potassium, and ammonium thiocyanate are described.
Abstract: 1:1-Complexes between nonactin and monactin, and sodium, potassium, and ammonium thiocyanate are described.
87 citations
TL;DR: In this article, the protonation constants of polyaminocarboxylic acids have been determined in solutions containing different inert salts: KNO3, NaClO4 and N(CH3)4Cl.
Abstract: The protonation constants of the anions of thirteen polyaminocarboxylic acids have been determined in solutions containing different inert salts: KNO3, NaClO4 and N(CH3)4Cl. The formation constants of the following species: H5EDTA+, H6EDTA2+, H5CDTA+ and H4NTA+ have been obtained from solubility measurements with ethylenediamine tetraacetic acid (H4EDTA), 1,2-diaminocyclohexane tetraacetic acid (H4CDTA) and nitrilotriacetic acid (H3NTA) in acid solutions between pH = 3 and 0 at ionic strength 1M (NaClO4 + HClO4).
80 citations
TL;DR: In this article, the formation of polyaminocarboxylate ion complexes was investigated using potentiometric measurements with the redox couples Fe3+/Fe2+ and Tl3++/Tl+.
Abstract: The formation of complexes of GaIII, InIII, BiIII, ScIII, ZrIV, and ThIV with polyaminocarboxylate ions was investigated using potentiometric measurements with the redox couples Fe3+/Fe2+ and Tl3+/Tl+. Some data concerning the formation of related hydroxo and hydrogen complexes are reported.
79 citations
TL;DR: More than twenty examples illustrate the recently developed oxidoketone-alkynone-fragmentation, whereby α,β-epoxy-ketones are cleaved under mild conditions with p-toluenesulfonyl-hydrazine to give acetylenic ketones or aldehydes as discussed by the authors.
Abstract: More than twenty examples illustrate the recently developed oxidoketone-alkynone-fragmentation, whereby α,β-epoxy-ketones are cleaved under mild conditions with p-toluenesulfonyl-hydrazine to give acetylenic ketones or aldehydes.
TL;DR: The N-Oxide aliphatischer Amine hingegen zeigen zusatzlich zu diesen beiden Zerfallsmoglichkeiten noch M+-18-Pike as discussed by the authors.
Abstract: Beim Vergleich der Massenspektren verschiedener N-Oxide ergeben sich bezuglich der Pike M+-16 und M+-17 bei denjenigen aromatischer Amine allgemein gultige Verhaltensweisen. Die N-Oxide aliphatischer Amine hingegen zeigen zusatzlich zu diesen beiden Zerfallsmoglichkeiten noch M+-18-Pike. Wenig intensive Molekular-Ionenpike, thermische Abspaltung von O und H2O und das ganzliche Fehlen von M+-16-, M+-17- und M+-18-Piken konnen neben den beiden Folgeprodukten der Cope-Reaktion in hohem Masse den massenspektrometrischen Nachweis dieser Verbindungsklasse erschweren.
TL;DR: The different types of bonding in complexes formed in aqueous solution are clearly reflected in the values of ΔH0 and ΔS0 for the complex formation reaction as mentioned in this paper, which is the most common type of bonding.
Abstract: The different types of bonding in complexes formed in aqueous solution are clearly reflected in the values of ΔH0 and ΔS0 for the complex formation reaction.
TL;DR: The structure and properties of leucoflavin derivatives obtained through flavinsensitized photodecarboxylation of phenylacetate ions were described in this paper, where the photoreduction of flavin was shown to be a quantitative photoalkylation, the benzyl residue entering either position 5 (nitrogen) or the bridge position 4a (carbon), depending on the conditions.
Abstract: Structure and properties of leucoflavin derivatives obtained through flavinsensitized photodecarboxylation of phenylacetate ions are described. The photoreduction of flavin with phenylacetate as donor is shown to be a quantitative photoalkylation, the benzyl residue entering either position 5 (nitrogen) or the bridge position 4a (carbon) of the flavin nucleus, depending on the conditions. The isomers were isolated, and identified by IR., NMR., and elementary analysis. The benzyl residue migrates from N(5) to C(4a) upon heating.
TL;DR: The crystal structures of Mn5O8 and Cd2Mn3O8 were determined from single crystal and high-resolution X-ray powder data as discussed by the authors, and they have very similar monoclinic unit cells.
Abstract: The crystal structures of Mn5O8 and Cd2Mn3O8 are determined from single crystal and high resolution X-ray powder data. Both structures have very similar monoclinic unit cells, space group C–C2/m, and are isotypic:
Hence, the true formula of Mn5O8 is MnMnO8. The crystal structure consists of pseudohexagonal MnIV sheets (bc) with similar oxygen sheets on either side, giving a distorted octahedral coordination to the MnIV. As every fourth MnIV is missing in these “main layers”, their composition becomes Mn3O8, and chains of coordination octahedra linked by common edges become distinct. Above and below the empty MnIV sites are either MnII or CdII completing the composition MnMnO8 or Cd2Mn3O8 respectively. Examples of similar “double layer” structures are given.
TL;DR: The Umsetzung der stereoisomeren Isopulegole 1−4 with Diboran erfolgt unter hoher Stereospezifitat as mentioned in this paper.
Abstract: Die Umsetzung der stereoisomeren Isopulegole 1–4 mit Diboran erfolgt unter hoher Stereospezifitat. Aus der nachfolgenden oxydativen Aufarbeitung resultieren die Gemische der 9-Hydroxymenthole, in denen eines der Diastereomeren stark uberwiegt. Die Konstitution von 7 Diolen (5–11) wurde ermittelt und zum Teil unabhangige Wege zu ihrer Synthese entwickelt.
TL;DR: In this article, a 3d-Patterson-Synthese, gefolgt von mehreren 3D-Fourier-und -Differenz-fourier synthesen und Kleinste-Quadrate-Verfeinerungen, was bestimmt (R=8,5%).
Abstract: Naphtalin-chromtricarbonyl kristallisiert in 2 Modifikationen: (a) als Schindeln mit a=12,37, b=6,58, c=7,36 A, α=107°22′, β=96°44′, γ=92°50′, P1 oder P, Z=2, und (b) als Nadeln mit a=13,98, b=11,71, c=6,87 α, P212121, Z=4. Von letzterer wurde mittels einer 3d-Patterson-Synthese, gefolgt von mehreren 3d-Fourier-und -Differenz-Fourier-Synthesen und Kleinste-Quadrate-Verfeinerungen die vollstandige Struktur bestimmt (R=8,5%). Die C-C-Abstande im ebenen Naphtalinring von 1,375-1,447 α weisen gegenuber denjenigen im Naphtalin selber (1,364-1,427 A) keine wesentliche, durch den Cr(CO)3-Komplex bedingte Auflockerung auf. Keine Carbonylgruppe liegt in der «langen» Spiegelebene der Naphtalinmolekel, sondern jede ist aus ihr herausgedreht. Die zwischenmolekularen Abstande von 3,34-3,71 A fallen in den Bereich schwacher (CH…O)-Wechselwirkungen.
TL;DR: A novel acid-catalysed reaction of isopropenyl ether with tertiary vinyl carbinols giving γ, δ-unsaturated ketones in high yields is described in this article.
Abstract: A novel acid-catalysed reaction of isopropenyl ether with tertiary vinyl carbinols giving γ, δ-unsaturated ketones in high yields is described. Methylheptenone, geranylacetone, farnesylacetone and analogous ketones were prepared by this convenient and efficient new method, which involves a Claisen-rearrangement step.
TL;DR: In this paper, N-Dimethylformamide-dineopentylacetal mediates the direct formation of (-)-cannabidiol from (+)-trans- or (+)-cis-p-menthadiene-(2,8)-ol-(1) and olivetol.
Abstract: N, N-Dimethylformamide-dineopentylacetal mediates the direct formation of (-)-cannabidiol from (+)-trans- or (+)-cis-p-menthadiene-(2,8)-ol-(1) and olivetol. This reaction provides a simple synthetic entry into the series of optically active constituents of haschisch and defines at the same time the chirality of these compounds.
TL;DR: In this paper, new lines for the preparation of cyclopentadecanone (exaltone) and racemic muscon starting from cyclododecanone via bicyclic intermediate steps are described.
Abstract: New lines for the preparation of cyclopentadecanone (exaltone) and racemic muscon starting from cyclododecanone via bicyclic intermediate steps are described.
TL;DR: In this article, the hydration of different forms of magnesium oxide by water vapour was studied at room temperature using gravimetric, X-ray and electron microscopic methods, and it takes place in four steps; formation of a layer of chemi- and physisorbed water, transition of magnesium and hydroxide ions in the layer of physi-bed water.
Abstract: The hydration of different forms of magnesium oxide by water vapour was studied at room temperature using gravimetric, X-ray and electron microscopic methods. It takes place in four steps; formation of a layer of chemi- and physisorbed water, transition of magnesium and hydroxide ions in the layer of physisorbed water, nucleation of the hydroxide and growth of the hydroxide crystals.
TL;DR: A series of 2-allyl-phenols and 2-but-3′-enyl-phenol were photochemically rearranged to the corresponding cyclic ethers.
Abstract: A series of 2-allyl-phenols and 2-but-3′-enyl-phenol were photochemically rearranged to the corresponding cyclic ethers. The isomer distribution was shown to be similar to that observed for the acid catalysed cyclisation.
TL;DR: In this article, Ringoffnungen der Aziridine wurden untersucht von Dip1.-Chem. RAAB, Dip1-Chem. SZEIMIES, Dr. J. SCHEER, Dr G. SZABO and Herrn H. HUBER.
Abstract: Em Wort aufrichtigen Dankes gilt tuchtigen und begeisterten jungen Wissenschaftlern, die an den skizzierten Arbeiten mitwirkten. Mit der Chemie der Nitril-ylide befassten sich die Herren Dr. H. STANGL, Dr. H. J. STURM, Dr. R. RAAB, Dip1.-Chem. K.BUNGE und Dr. R. SUSTMANN, Die Ringoffnungen der Aziridine wurden untersucht von Dip1.-Chem. W. SCHEER, Dr. G. SZEIMIES, Dr. L. SZABO und Herrn H. HUBER.
TL;DR: The HNMR spectra of phenalene, phenalenone, of some protonated and alkylated derivatives and some substituted phenafulvenes are discussed and very qualitatively correlated with the π-electron distribution in some of these systems.
Abstract: The HNMR. spectra of phenalene, phenalenone, of some protonated and alkylated derivatives and the spectra of some substituted phenafulvenes are discussed and very qualitatively correlated with the π-electron distribution in some of these systems.
TL;DR: Cacao flavour has been extracted from the beans and analysed by classical methods as discussed by the authors, and 29 new components have been isolated, including new components from beans' texture, texture, and texture.
Abstract: Cacao flavour has been extracted from the beans and analysed by classical methods. 29 new components have been isolated.
TL;DR: In this paper, 17 substances were shown to be present in the aroma of black tea and the total number of substances now identified to 187 was brought up to 187, with many of these new aromatic constituents present only in traces.
Abstract: 17 substances were shown to be present in the aroma of black tea. This brings the total number of substances now identified to 187. Many of these new aromatic constituents are present only in traces. Nevertheless they possess an appreciable olfactive intensity whose flowery and/or fruity characteristics are found in many perfumed black teas such as: Kenya, Darjeeling, Ceylan, China and Oolong.
The components were identified by GC/MS. and their presence in the aroma verified by GC.
TL;DR: In this paper, a flameless atomic absorption method for the determination of small amounts of mercury in solutions is described, where the mercury is amalgamated quantitatively on a copper wire and subsequently vaporized in an absorption cell which is placed in the light path of a commercial atomic absorption instrument.
Abstract: A flameless atomic absorption method for the determination of small amounts of mercury in solutions is described. The mercury is amalgamated quantitatively on a copper wire and subsequently vaporized in an absorption cell which is placed in the light path of a commercial atomic absorption instrument. The mercury vapor can be quantitatively determined by its absorption of the 253.7 nm mercury line. The method has a detection limit of 0.2 ng and is therefore about 10000 times more sensitive than atomic absorption analysis using flame atomization.
TL;DR: A gas-chromatographic separation of cocoa aroma, followed by infra-red and mass-spectrometric identification, has yielded, besides 22 of the 91 previously described constituents, 35 new substances (8 aliphatic, 1 alicyclic, 7 aromatic, 9 o-heterocyclic and 4 pyrrolic, and 6 pyrazinic).
Abstract: A gas-chromatographic separation of cocoa aroma, followed by infra-red and mass-spectrometric identification, has yielded, besides 22 of the 91 previously described constituents, 35 new substances (8 aliphatic, 1 alicyclic, 7 aromatic, 9 o-heterocyclic, 4 pyrrolic, and 6 pyrazinic).
TL;DR: In this paper, the neuroleptic properties of 4-diazepines have been prepared using three methods: Aminolysis of either iminothioethers IV (X = methyl or an activating group such as cyanomethyl and p-nitrobenzyl) or the iminochlorides III.
Abstract: 11-Amino-5H-dibenzo[b,e]-1, 4-diazepines V, several of which possess neuroleptic properties, have been prepared using three methods:
1
Aminolysis of either iminothioethers IV (X = methyl or an activating group such as cyanomethyl and p-nitrobenzyl) or the iminochlorides III.
2
Bischler-Napieralski type cyclodehydration of o-anilinophenyl-ureas IX (only applicable for the synthesis of compounds V where R is other than hydrogen).
3
Cyclodehydration of amino-amides VII by various condensing agents.