Photochemische Reaktionen. 116. Mitteilung [1]. Notiz zur 1γ, δ*-induzierten Photospaltung von γ, δ-Epoxy-eucarvon

π, π*-Induced Photocleavage of γ, δ-Epoxy-eucarvone . On ¹π, π*-excitation 1 undergoes cleavage of the C, C-oxirane bond ( 1 → c ) and isomerizes to the bicyclic dihydrofurane compound 5 . In addition, 1 shows photocleavage of the C (γ), O-oxirane bond ( 1 → d ) and gives the isomers 2, 3, 6, 7 and 8. Furthermore, the cyclohexenone 9 and the cyclohexene-1, 4-dione 10 are formed presumably via an intermediate 13 , which could also arise from d. Besides these products the compounds 11 and 12 are obtained, which are photoproducts of 2 .     

Laser-induced multiphoton dissociation ofn-butyl ether

The pulsed CO₂-laser-induced multiphoton dissociation of n-butyl vinyl ether is studied. Comprehensive measurements have been performed for 9.6.μm and 10.6 μm irradiation. The corresponding dissociation product distributions show distinct differences for the two irradiation wavelengths, the most important finding being that acetylene is only produced at 9.6 μm.     

15N-NMR spectroscopy 32. Synthesis and characterization of polyelectrolytes based on polyaminamides

The titrations of the polyammamides prepared from adipic acid and diethylenetriamine or di(3-aminopropyl)methylamine were monitored by means of natural-abundance ¹⁵N-(NMR) nuclear magnetic resonance spectra. Opposite shift effects were found for amine and amide nitrogens upon protonation of the amino groups. These shift effects allow one to distinguish substitutions involving exchange of electric charges from other substitutions without isolation of the polymers. Reactions of the polyaminamides with β-propiolactone, γ-butyroslution, methyl-methane sulfonate, prolyleneoxide, epichlorohydrine, maleic acid anhydride, succinic acid anhydride, carbon dioxide, ethylchloroformate, and methyne sulfonylchloride were carried out in water, and the resulting polyelectrolytes were characterized by means of ¹⁵N-NMR spectra.     

Xanthone. II. Vibronic coupling analysis from high resolution phosphorescence spectra

High resolved phosphorescence spectra of xanthone have been recorded in four host matrices in order to study vibronic coupling between the lowest tripl origin in all hosts, and the energetically close-lying second triplet state T₂, which is of nπ* orbital origin. In three hosts, there is thermall to phosphorescence from T₁. Vibrational analyses of the two emissions are reported. The vibrational structure of both emissions depends little on t vibronic mixing between the lowest two triplet states is weak, in spite of the small energy separation in some hosts. The importance of the different i ₁ and its sublevels is discussed, and it is concluded that across energy separations smaller than about 200 cm^?1 spin—orbit mixing is more orbital mixing between the ³ππ* and ³nπ* configurations of xanthone.