Both benzocarbazoles and quinolines can be synthesized from enyne ketenimines 1 generated in situ via biradical intermediates (see reaction below). Which of the heterocyclic ring systems is formed depends on the choice of the substituent R at the alkyne terminus.
Rod‐like micelles of perfluorosurfactants in aqueous solution were examined by using the transient and dynamic electric birefringence method. Tetraethylammoniumperfluoroctanesulfonat shows in the overlap region of the rods between 5 mM and 15 mM up to three different relaxation times τ1, τ2 and τ3 between a few μs and several ms. A forth very long relaxation time τ4 (seconds) appears at higher concentrations. The relaxation processes with the time constants τ1, τ3 and τ4 have a negative birefringence, while τ2 has a positive sign. In the anomaly region the total birefringence can change sign as a function of the total surfactant concentration and of the field strength. The anomalous behaviour of the time and frequence dependence of the electric birefringence is explained on the basis of intermicellar interaction. It is assumed, that the external electric field induces an additional anisotropic Lorentz‐field, which changes dramatically the local Lorentz‐field around the micelles. As a result both the correlation of the center of masses and the correlation of the rodlike micelles changes. This gives rise to the processes τ1, τ2 and τ3. The largest relaxation time τ4 seems to be due to a deformation and relaxation of a temporary network, which is built by the rodlike micelles.
Sowohl Benzocarbazole als auch Chinoline lassen sich aus den in situ gebildeten Eninketeniminen 1 über Diradikalzwischenstufen herstellen (siehe unten). Welches der beiden heterocyclischen Ringsysteme bei der Reaktion entsteht, wird durch die Wahl des Substituenten R1 am Alkinterminus entschieden.
Col/aides / Electric Birefringence / Flow Birefringence / Rods / ViscosityElectro-optic and rheological measurements were carried out on PTFE-fibrilles. The crystalline fibrilles had an axial ratio of about 100 and a thickness of 200 A.The dispersions were stabilized by ionic Perl1uorosurfactants and could be kept for months without precipitation.-The rotational diffusion constant of the fibrilles was determined as a function of the volume fraction. Both electric birefringence and rheological measurements gave identical results for the orientation times. In the dilute and semidilute concentration range the rotational diffusion constant was the same and did not change at the overlap concentration. The shear modulus was found to increase in the semidilute concentration with the square of the volume fraction of the PTFE fibrilles. -Electric birefringence measurements with ACpulses showed a remarkable result. The stationary birefringence changed sign as a function of the frequency. It is concluded that this phenomenon is related to the adsorption/desorption equilibrium of the surfactant ions on the PTFE fibrilles. The equilibrium is shifted by the electric field. These conclusions could be confirmed by light scattering measurements in AC-fields.Ber. Bunsenges. Phys. Chern. 92, 10-16 (1988) -
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