Thermal Reactions of Epoxyenones and Epoxydienes in the Ionone Series

On flash vaccum thermolysis at temperatures between 390 and 585°, the epoxyenones 1 – 9 and the epoxydienes 10 – 12 undergo various types of reactions involving C? C and/or C? O bond cleavage in the oxirane ring. Thus, the compounds 1 , 4 – 9 , 11 , and 12 were transformed to the divinyl ethers 13 , 20 , 21 , 24 , 25 , 29 , and 38 by a reversible [1,5] homosigmatropic H-shift. On thermolysis of the epoxides 1 – 12 , several products formed via carbonyl-ylide intermediates were also isolated. The extent of the formation of ylide products is clearly related to the conjugating ability of the functional groups neighboring the oxirane. Thus, the epoxides 3 , 5 , and 7 – 10 , bearing a C(3)?C(4) bond, a 5-oxo function, a 3,4-epoxy or a 3,4-methano group, preferentially underwent reactions via a carbonyl-ylide intermediate. As a further reaction pathway, the epoxides 1 – 12 undergo cleavage of the C–O bonds of the oxirane, which, however, is presumably an acid-catalyzed rather than a thermal reaction.     

Photochemische Reaktionen. 85. Mitteilung [1]. Zur Photochemie von α, β-Epoxy-eucarvon

Photochemistry of α,β-epoxy-eucarvone . On π,π^*-excitation (λ = 254 nm) 4 isomerizes to the bicyclic ketoaldehyde 5 ; on n,π^*-excitation (λ ? 280 nm) 4 gives 5 , the β,γ-unsaturated ketone 6 , the enone 7 and the cyclobutanone 8 . Scission of the (C—C)-bond of the oxirane 4 would give the dihydrofurane e , which could isomerize to the ketoaldehyde 5 . On the other hand, 4 is assumed to isomerize to the β,γ-unsaturated aldehyde c , which could yield 6 and 7 by photodecarbonylation. The cyclo-butanone 8 is shown to be a photoisomer of the ketone 6 . Furthermore, eucarvol ( 18 ) rearranges by a thermal [1,5]-H-shift to dihydro-eucarvone ( 20 ); on UV.-irradiation 18 gives the bicyclic isomers 27 and 28 .     

Photochemical reactions. 145th Communication. Carbonyl vs. epoxyketone photochemistry: Photolysis of 1,2;3,4-diepoxy-2,6,6-trimethyl-1-cyclohexyl methyl ketone

The synthesis and photolysis of the title compound 3 is described. Irradiation (λ > 280 nm, MeCN) of the di-epoxyketone 3 leads predominantly to γ–H abstraction. Cyclization furnishes the cyclobutanols 22 – 24 , while cleavage gives compound 25 , presumably via the allene-oxide intermediate 36 . Further, products 27 and 28 are formed by Norrish fragmentation and by initial cleavage of the C(α)? O bond of the oxirane, respectively. The structures of the products 22 – 25 , 27 , and 28 were assigned on the basis of the spectral data of the photolysis products of the ¹³C-labelled diepoxyketone[6,6-dimethyl-¹³C₂]- 3 and by X-ray analysis of the compounds 24 and 35 , the latter being the p-nitrobenzoate of 22 .     

A post-column extraction system for the determination of tertiary amines by liquid chromatography with chemiluminescence detection

Summary The combination of an ion-pair extraction detection system with peroxyoxalate chemiluminescence detection has been investigated. Ion-pairs of protonated tertiary amines with a chemiluminescent counter ion are on-line post-column extracted to 1,2-dichloroethane containing bis(2,4,6-trichlorophenyl)oxalate (TCPO). Hydrogen peroxide is added to the organic phase by means of a solid-state perhydrit reactor. The influence of the base catalyst (imidazole) on the chemiluminescence reaction in apolar solvents was studied. Some sulfonated chemiluminophores were compared with respect to their chemiluminescence, ion-pairing and extraction properties, and 5-dimethylaminonaphthalene-1-sulfonate was found to be the most suitable reagent. The detection limit of the potential drug secoverine is in the sub-nanogram range.     

A combination of ring-oven and circular chromatography for trace metal analysis

Summary A chromatographic method for metal chelates of pyridine-2-aldehyde-2-quinolylhydrazone (PA QH) has been adapted to the ring-oven technique Advantage has been taken of the large difference inR _f -values of the cobalt, copper, nickel and iron(III) chelates on alumina, the acid stability of the cobalt PA QH complex, selective formation of chloride complexes of these metals and the use of specific spray reagents for copper and iron, such as rubeanic acid and KSCN to develop a simple and rapid field method for trace metal analysis. Quantitative estimation of these four metals with an accuracy ranging from 5.0 to 12% has been carried out in less than 30 minutes. Detection limits were found to be about 0.010g for nickel, 0.008g for copper and iron and 0.005g for cobalt. Other ions did not interfere in up to 10-fold excess. The suitability of this method for field work was tested by monitoring trace metals in fresh and sea water supplies and in algae.

---

Zusammenfassung Ein chromatographisches Verfahren für die Trennung von Metallchelaten des Pyridin-2-aldehyd-2-chinolylhydrazons wurde den Bedingungen der Ringofentechnik angepaßt. Dabei kommt der große Unterschied derR _f -Werte der Chelate des Kobalts, des Kupfers, des Nickels und des Eisens(III) auf Aluminiumoxid vorteilhaft zur Geltung. Die Säurebeständigkeit des Kobaltkomplexes, die selektive Bildung von Chloridkomplexen der angeführten Metalle, die Verwendung spezifischer Sprühreagenzien für Cu und Fe wie Rubeanwasserstoffsäure und Kaliumrhodanid führten zu einer einfachen und raschen Feldmethode für die Spurenmetallanalyse. Die Mengenschätzung dieser vier Metalle auf 5 bis 12% Genauigkeit ist in weniger als 30 Minuten durchführbar. Die Erfassungsgrenze liegt für Ni bei 0,01g, für Cu und Fe bei 0,008g und für Co bei 0,005g. Andere Ionen stören nicht bis zum zehnfachen Überschuß. Die Eignung der Methode wurde an Süß- und Seewasserproben sowie an Algen geprüft.

---

---

Presented at the International Symposium on Analytical Chemistry, July 1969, Birmingham, England.     

Ethylene glycol: Infrared spectra,AB initio calculations,vibrational analysis and conformations of 5 matrix isolated isotopic modifications

An extension of earlier ab initio calculations is reported which consists in a more detailed structure optimization of conformations investigated earlier, using the previously described as well as a more flexible basis set. The measurement and analysis of infrared spectra of five isotopic modifications, isolated in Ar and Xe matrices, are described. The analysis of the spectra, carried out within the framework of two H-bonded conformations r_e1 and r_e2 predicted by ab initio calculations to be the most stable ones, is complicated by the occurrence of unusually large matrix splittings and irreversible changes of the spectra under irradiation by infrared light. The spectra are interpreted in terms of essentially two slightly different conformers of type r_e1, deformed by the matrix field. The ¹⁸O isotope shifts prove to be important for correct assignment and the least squares fit. A valence force field is given, whose dependence on the conformation of the OH groups and especially on H-bonding is discussed. According to normal coordinate analysis, the effect of the internal H-bond is most pronounced in the COH bend and OH torsion region. The differences of the potential constants of free and bonded OH groups are responsible for a zero point energy differences of about 20 cm^?1 of two isomers of the modification CH₂ODCH₂OH. From experimental evidence for at least a partial equilibration of these two isomers at liquid helium temperature, internal rotation of the OH groups in an Ar matrix may be deduced. Thermodynamic functions of the r_e1 conformation of glycol in the rigid rotor-harmonic oscillator approximation are reported.     

Miniaturization of solid-phase reactors for on-line post-column derivatization in narrow-bore liquid chromatography

Summary The use of solid-phase reactors for post-column derivatization in narrow-bore HPLC (1.0mm i.d. analytical columns) is evaluated. Two systems are described, viz. for the determination of N-methylcarbamate pesticides and for that of urea and ammonia. The solid-phase reactor is packed with a strong anion exchange resin and urease immobilized on silica, respectively, to effect the catalytic hydrolysis of the solutes eluting from the analytical column. In both systems, the hydrolysis product is reacted with o-phthalaldehyde followed by fluorescence monitoring. Analytical data are presented and band broadening from various parts of the reaction detector system is discussed. An on-line trace enrichment procedure via a micro precolumn is descried for the trace level determination of N-methylcaramates in surface water samples.     

Transient observation of H labeled species in an operating PEFC using neutron radiography

High resolution neutron radiography was used to observe the time resolved distribution of ²H nuclei in the membrane of an operating polymer electrolyte fuel cell (PEFC) after changing the anode gas from ¹H₂ to ²H₂. The rate of replacement and the distribution of ²H nuclei shortly after the change of the anode gas were found to be independent of the applied current density. This behavior can be explained by a high exchange current density of the hydrogen oxidation reaction (HOR), the uptake of ²H nuclei in the membrane being limited by diffusive transport. A simple calculation as well as qualitative analysis is given to support this explanation.     

Über die subnormalen Lösungen der Differentialgleichungw″+e −z ·w′+konst.·w=0

Ohne Zusammenfassung Herrn Rektor Dr. W. Rotach zum 60. Geburtstag gewidmet