Synthesis of racemic and optically active Δ1- and Δ6-3,4-cis-tetrahydrocannabinols1

Three syntheses of the hitherto unknown (±)-Δ⁶-3,4-cis-THC 4a and the first total synthesis of optically active Δ¹- and Δ⁶-cis-THC's are described. These syntheses utilize a stereospecific intramolecular epoxide opening by phenolate anion; an acid catalyzed equilibration of Δ¹- and Δ⁶-cis-THC acetates; and a kinetically controlled dehydration. The use of HPLC, GLC and NMR for the separation and identification of closely related THC's is discussed.     

Anordnung und Orientierung kationischer Tenside auf ebenen Silicatoberflächen

Zusammenfassung Die n-Alkylammoniumderivate der glimmerartigen Schichtsilicate können als Modellsubstanzen für die Anordnung kationischer Tenside an Festkörpergrenzflächen herangezogen werden. Im ersten Teil der Arbeit wird die Darstellung durch Kationenaustausch aus den natürlichen Schichtsilicaten beschrieben. Es wird ausführlich auf die Fehlerquellen hingewiesen, die reproduzierbare Messungen erschweren.

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Summary The n-alkylammonium derivatives of mica-type layer silicates are suitable models for studies about the arrangement of cationic tensides at solid interfaces. Part I of the paper deals with the preparation of these compounds by a simple cation exchange reaction. Sources for errors in obtaining reproducible data are discussed in detail.

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Mit 1 Abbildung in 3 Einzeldarstellungen und 3 Tabellen     

Chemistry of thienopyridines. VII. Mechanistic studies on the synthesis of thieno[2,3-c] pyridine by thermolytic cyclization

A study was made of the formation of thieno[2,3-c]pyridine (1) from hydrogen sulfide and 4-vinylpyridine in a flow system at 630°. 2-(4-Pyridyl)ethanethiol and bis-2-(4-pyridyl)ethyl sulfide were found to be likely intermediates. Based on these studies, there was devised a two-step practical preparative method for I (optimum overall yield 58%) which consists of preliminary conversion of 4-vinylpyridine to benzyl 2-(4-pyridyl)ethyl sulfide and subsequent thermolysis (at 605°) of this substance.     

Vernetzung von Polyolefinen mit ultraviolettem Licht

Zusammenfassung Es wird gezeigt, daß sich neben verschiedenen Polyäthylen-Typen auch Äthylen-Propylen-Copolymerisate, Polypropylen und Polybuten-(1) durch ultraviolettes Licht vernetzen lassen, wenn man als Sensibilisatoren bestimmte Chlorkohlenwasserstoffe oder Dischwefeldichlorid verwendet. Die Festigkeit der vernetzten Produkte oberhalb ihres Schmelzpunktes wird mit dem ZST-Versuch gemessen. Die erreichten Reißzeiten unter Belastung sind z. T. recht hoch; die entsprechenden Vernetzungsgrade werden aus Bestimmungen des Gelanteils berechnet.     

Translational energy disposal in molecular collisions: The transfer of momentum constraint

A Franck—Condon type argument, which requires the least transfer of momenta to the nuclei during a collision is outlined and applied to the analysis of translational energy disposal and its dependence on the initial translational energy. Using the maximal entropy procedure of information theory we are able to proceed directly from the assumed (model) constraint to the product state distribution.     

An investigation of some experimental parameters in atomic fluorescence spectrophotometry

Atomic fluorescence in flames is measured by an adaptation of a commercially available flame spectrophotometer. A study is reported of the effect of background radiation and source scattering on 3 flames, air-propane, air-hydrogen and air-acetylene, and of the effects of variation of fuel gas pressure, zone of measurement in the flame, analysing monochromator slit-width and wavelength of measurement. The air-propane flame appears to offer several advantages. The atomic fluorescence of 10 metals is described; those of Co, Fe and Mn have not been previously reported. Excitation of spectra is achieved by means of an a.c. xenon arc lamp or individual discharge lamps.     

Quantum solvation of phthalocyanine in superfluid helium droplets

We have measured quantum states of the solvent-solute system of phthalocyanine in superfluid helium droplets in a high resolution pump-probe experiment. This provides evidence for the attribution of a splitting effect in the emission spectra of phthalocyanine in helium droplets to the relaxation of the first helium layer upon electronic excitation, measured recently by us. Our experimental results are a strong indication for the first helium layer playing a key roll for the solvation of molecules in helium droplets and, thus, for their spectroscopic features.     

Interfacial electron transfer in FeII(CN)6 4- -sensitized TiO2 nanoparticles: a study of direct charge injection by electroabsorption spectroscopy

Electroabsorption (Stark) spectroscopy has been used to study the dye sensitized interfacial electron transfer in an Fe(II)(CN)(6)(4)(-) donor complex bound to a TiO(2) nanoparticle. The average charge-transfer distance determined from the Stark spectra is 5.3 A. This value is similar to the estimated distance between the Fe(II) center of the complex and the Ti(IV) surface site coordinated to the nitrogen end of a bridging CN ligand in (CN)(5)Fe(II)-CN-Ti(IV)(particle). This finding suggests that the electron injection is to either an individual titanium surface site or a small number of Ti centers localized around the point of ferrocyanide coordination to the particle and not into a conduction band orbital delocalized over the nanoparticle. The polarizability change, Tr(Deltaalpha), between the ground and the excited states of the Fe(II)(CN)(6)(4)(-)-TiO(2)(particle) system is approximately 3 time larger than normally observed in mixed-valence dinuclear metal complexes. It is proposed that the large polarizability of the excited state increases the dipole-moment changes measured by Stark spectroscopy.     

Asymmetric hydrogenation of aromatic olefins catalyzed by iridium complexes of proline derived phosphine-oxazoline ligands

The synthesis of a series of phosphine-oxazoline ligands is reported. This ligands are synthesized by reaction of a phosphine chloride with the secondary nitrogen of proline. Upon coordination to iridium the resulting complexes can be used in the asymmetric hydrogenation of simple olefins. The effect of different counter ions and substitution at the oxazoline and the phosphine is reported.