The structure of α-(1,2-dithiole-3-ylidene) ketones and α-(1,2-dithiole-3-ylidene) aldehydes studied by means of n.m.r. spectroscopy

1H and ¹³C n.m.r. studies of a series of twelve 1,2-dithiole-3-ylidene ketones and aldehydes have shown that the geometry of the carbon backbone is the same as found in 1,6,6aλ⁴-trithiapentalenes. No evidence has been found which favours a bicyclic structure for the system. A linear correlation of observed ¹³C chemical shifts with calculated charge densities is found to be valid. The observations are in agreement with a structure which is a hybrid between a true ketonic structure and a true mesoionic structure. By using the difference in the ¹³C chemical shifts of ortho and meta carbon atoms in substituent phenyl groups it is possible to qualify the degree of coplanarity of the phenyl groups with the backbone of the molecule.     

Mass spectrometry in structural and stereochemical problems–CXCIII: On the combined hydroxyl and water loss in nitrophenylhydrazones

The mass spectrum of valeraldehyde o-nitrophenylhydrazone displays only a low intensity peak (3% relative abundance) corresponding to the loss of 35 mass units from its molecular ion contrary to data previously published. Mention is also made of the fragmentation of 5-nonanone 2,4-dinitrophenylhydrazone in view of a recent challenge to a published rationalization for the electron impact promoted fragmentation for this compound.     

Applications of artificial intelligence for chemical inference—XXI: Chemical studies of marine invertebrates—XVII. The computer-assisted identification of [+]-palustrol in the marine organism Cespitularia sp., aff. subviridis

In order to demonstrate the power utility of the interactive computer program CONGEN,⁵ an example describing its use in the identification of the tricyclic sesquiterpene alcohol, [+]-palustrol, in extracts of a marine Xeniid (Cespitularia sp., aff subviridis) is provided. The rotation of [+]-palustrol further supports the remarkable antipodal relationiship between sesquiterpenes from marine Coelenterates and their corresponding terrestrial forms.⁶     

Computer-assisted structure manipulation : Studies in the biosynthesis of natural products

A computer program (“REACT”) that simulates chemical reactions by manipulating representations of structures has been utilized to study biochemical reactions. Biosynthetically plausible sterol side chains were generated and the number of plausible isomeric sterols were calculated. Possible label distributions in structures resulting from the biochemical conversion of a humulene precursor to some known fungal metabolites were followed by studying different biochemical pathways.     

Rectilinear laminar flow of a visco-elastic fluid

Zusammenfassung Eine inkompressible viskoelastische Flüssigkeit fliesst zwischen zwei parallelen, starren, unendlichen Wänden. Es wird unter der Voraussetzung, dass die eine Wand fest ist und die andere sich mit einer exponentiell abklingenden Geschwindigkeit bewegt, das zur Aufrechterhaltung einer speziellen laminaren Strömung nötige Kraftfeld bestimmt.     

An electron spectroscopic determination of theL I energy in the elements Sodium (Z=11) to Copper (Z=29)

Energies of atomic electrons in theK andL shells of eighteen elements of low atomic numbers have been measured by electron spectroscopy. Tabulated values for theL _I energies are shown to be in need of considerable revision. AluminumKα radiation is shown to have high potentialities for ESCA studies.     

Mass spectrometry in structural and stereochemical problems—CLXXII: The electron-impact promoted fragmentation of 1,2-cyclohexanediol

The mass spectra of 1,2-cyclohexanediol and important data from the spectra of four deuterium labeled analogs have been recorded and mechanistic rationalizations are given for the most important degradation processes observed. Multiple mechanisms are required to explain the indicated peak shifts in the labeled analogs. Particularly relevant is the initial loss of water from the molecular ion, which involves at least four distinct processes.     

Beiträge zur Chemie der Silicium-Stickstoff-Verbindungen, 17. Mitt.: Silylsubstituierte Semicarbazide und Hydrazindicarbonsäurederivate

Zusammenfassung Semicarbazide lassen sich durch Chlorsilane nicht, durch Aminosilane nur unzulänglich substituieren. Man erhält aber Zugang zu der Verbindungsklasse der Silylsemicarbazide wie auch zu Silylhydrazindicarbonsäurederivaten über die Umsetzung von Silylhydrazinen mit Trimethylsilyl-N-cyanat oder mit Phenylisocyanat. Die Verbindungen sind in der Regel außerordentlich hydrolyseempfindlich, sie spalten die Silylgruppen leicht ab und sind nur schwer in völlig reinem Zustand zu fassen. Die Hydrolyseprodukte ermöglichen eine Zuordnung der Struktur der eingesetzten Silylhydrazine im Hinblick auf die Stellung der Silylgruppe am N- oder N-Atom der Hydrazine, da Phenylisocyanat stets nur mit einem an das Stickstoffatom gebundenen H-Atom reagiert.Zugleich 6. Mitt. über Hydrazin-Silicium-verbindungen; 5. Mitt. vgl.⁷.16. Mitt.:J. Pump undU. Wannagat, Mh. Chem.93, 352 (1962).Auszug aus der DiplomarbeitC. Krüger, T. H. Aachen 1960.