MARCH 196lO-IODO-p'-NITROBENZOYL PEROXIDE 733 distilling head.. The product was analyzed by gas chromatography without further purification. Yields were generally between 30 and 60%. Table III summarizes the analyses and melting points of the biphenyl products.Vapor phase chromatographic method. The gas chromatography was carried out with either a Perkin-Elmer Model 154C or a Pye Argon instrument. The Perkin-Elmer was equipped with a 2-m. stainless steel column packed with fire brick C-22 (mesh 40-60) impregnated with Dow Corning Silicone Fluid 550 (10%). The eluent was helium and the column temperature was in the range of 180-200°. The Pye Argon was equipped with a 4.5-foot column packed with Celite (mesh 80-100) impregnated with Dow Corning Silicone Fluid 550 (5%). The eluent was argon and the column temperature was in the range of 150-160°. Oxidation of biphenyl derivatives. General method. One gram of biphenyl derivative was dissolved in 20 ml. of acetic acid (gl.). Three grams of chromic anhydride was added to a solution of 1 ml. of water in 20 ml. of acetic acid. The two preparations were combined and heated on a steam bath for 2 hr. The reaction mixture was then poured into excess ice water and the precipitate collected and recrystallized from benzene. The benzoic acid product was then identified by mixed melting point with authentic sample or by infrared analysis.
COMMUNICATIONS TO THE EDITOR 2873 system VI, as was easily determined by the mass spectral f r a g m e n t a t i~n ,~ which in both cases showed a major peak a t mle 173, corresponding to the expected formation of the dimethylene indole VII. The rest of the fragmentation patterns was almost identical for the two substances.
Die UR‐Spektren der Verbindungen AlH3·N(CH3)3, AlH3·2N(CH3)3 und AlH3·1 Tetrahydrofuran wurden im Bereich von 1–15μ in verschiedenen Lösungsmitteln sowie im festen Zustand aufgenommen. Die Zuordnung der beobachteten Banden wird an Hand von Modellberechnungen durchgeführt. Für die Verbindung AlH3·2N(CH3)3 wird ein bipyramidales Modell der Symmetrie D3h wahrscheinlich gemacht. Die Änderung der Kraftkonstanten der Al‐H‐Valenzschwingungen in Abhängigkeit von der Anzahl der angelagerten Donatormoleküle wird diskutiert. Nach Siebert ergibt sich ein Bindungsgrad von etwa 0,5 für die Al‐H‐Bindung.
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