Values for the physical solubility of nitrogen as well as for the content of chemically dissolved nitrogen in glass melts are given. The form in which the nitrogen is present in the glass melts is discussed and an attempt is made to explain chemical interaction between nitrogen and the glass melt. The dependence of the amount of physically or chemically absorbed nitrogen on the nature of the furnace atmosphere is shown. The results offer an explanation for the presence of nitrogen often observed in bubbles of commercial glasses.
Im Fall von Trimethincyaninen, die in einer halb-cis-Konfiguration fixiert sind, haben Scheibe et al. f-Werte zwischen 0,45 bis 0,55 festgestellt. Nach dem zweidimensionalen Elektronengasmodell finden wir bei Mitberiicksichtigung des Elektronegativitatsunterschiedes von N und C den Wert 0,81. Die noch bestehenden Differenzen zwischen thcoretischen und experimentellen f-Werten diirften zum Teil darauf beruhen, daR die Losungsmittelkorrektur der empirischen f -Werte nach Onsnger nur eine grobe Nlherung darstcllt [ 6 ] ; zum Teil werden sic auf das Vorhandensein aromatischer Ringe an den Enden der Cyaninkette zuriickzufiihren sein, die in der theoretischen Betrachtung vernachlassigt sind. Im Fall der von Scheibe et al. diskutierten Verbindung 111, in der solche Gruppen fehlen, stimmt der beobachtete f-Wert (1,OO)
V [4] (Hg salt: m.p. 128 to 129 "C.) with n-butyllithium [3]. Thus, it is easier to remove a bromine cation from compound 11 than a proton [5]:GHsLi I1 ---+
(%H&P=CHz + (CnHs)P=CHBrThe desired bromomethylenation can be realized with lithium piperidide 161 which predominantly removes protons from 11; subsequent reaction with p-ionone (VI) gives, after chromatographic purification, the very unstable compound VII in 70 % yield (Amax = 269 mp; log E = 4.18).I thank Prof. G. Wiffig for his assistance in this work. [5] D . Seyferfh et al. have made the same observation. (Private communication by Prof. Seyferth.) [6] This also gives the best yields in chloromethylenation: G. Wittig and M. Schlosser, unpublished. I thank Dr. M. Schlosser for this communication.
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