Bildung siliciumorganischer Verbindungen. XXXIII. Reaktion des 1,1,3,3-Tetramethyl-1,3-disila-4-trimethylsilyl-cyclopentens mit HBr

The ring system of (a), defined in “Inhaltsübersicht”, is cleaved by one mole of HBr already at ?78°C, forming mainly (b) besides (c) and (d). At 80°C (b) reacts by β-elimination completely to (e), (f), (g) and (h). As one of the products by the reaction of (a) with 4 moles of HBr (i) is formed by cleavage of (b) with HBr. The course of the reaction at —78°C is determined by ring cleavage and following HBr addition. With increasing temperature β-elimination of the addition products becomes the preferred reaction. To explain the reaction course the intermediate product (c) has been synthetized and its decomposition with HBr has been investigated. The reaction products have been identified by n.m.r. spectra.     

Pyridazines with heteroatom substituents in positions 3 and 5. 6. SN reactions in position 5 of 2-aryl-5-hydroxypyridazin-3(2H)-ones

The nucleophilic introduction of chloro- ( 2 ), azido- ( 4 ), (substituted) amino ( 3, 6 ), mercapto ( 10 ) and hydrazino-groups ( 13 ) into 2-aryl-5-hydroxypyridazin-3(2H)-ones [3] is described. The 5-aminopyridazin-3(2H)-one ( 6 ) also reacts with activated malonates 8 [4] to give pyrido[2,3-d]pyridazines 9 . Hydrazino compounds 13 can be treated with aldehydes to yield compounds 14 . Iodine can be introduced into position 4 of 5 -amino -(15 ) and 5-hydroxypyridazin-3(2H)-ones ( 17 ) by electrophilic substitution to afford compounds 18 .     

Lattice dynamics of sapphire (Al2O3)

Using inelastic neutron scattering we have determined all the dispersion branches of the ₁, ₂ and ₃ representations along the three-fold axis as well as the 2 times 15 branches of ₁ and ₂ symmetry along the -A-direction plus some branches along the -D-direction. The experimental data are analyzed using various rigid ion, polarizable ion and shell models. The shell models give a very satisfactory account of the dispersion curves as well as the scattering intensities. Special attention is given to the investigation of dielectric constants and equilibrium conditions.     

Neue Gas-Gebl?selampe

Ohne Zusammenfassung     

Ueber Verbesserungen an Verbrennungs?fen

Ohne ZusammenfassungHerr J. Schober hat uns je ein Exemplar seiner beiden verbesserten Verbrennungsöfen zur Prüfung übersandt. Wir haben dieselben in Gebrauch genommen und können hier mittheilen, dass sich dieselben als leistungsfähig und bequem in der Handhabung erwiesen haben. D. Red.