Mass spectral study on thiazolo[3,2-a]benzimidazoles. Studies on heterocyclic compounds. IV

Condensation of α-halocarbonyl compounds and 2-mercaptobenzimidazole gives thiazolo-[3,2-a]benzimidazoles. This condensation occurred at the mercapto group of the benzimidazole followed by cyclization to form the thiazole ring. This was confirmed by the examination of the mass spectra of 2- and 3-methylthiazolo[3,2-a]benzimidazoles, 2- and 3-phenylthiazolo[3,2-a]-benzimidazoles, and their derivatives.     

Theoretische Betrachtung der Diels-Alderschen Reaktion auf Grund der LCAO-MO-Theorie

Zusammenfassung Vorliegende Arbeit bietet eine theoretische Betrachtung derDiels-Alderschen Reaktion mit Hilfe der LCAO-MO-Methode in derHückelschen Näherung unter der grundsätzlichen Voraussetzung der dem aktiven Komplex vorausgehenden -Komplexbildung zwischen dem Dien und Dienophil. Die als Resultat der Wechselwirkung zwischen Dien und Dienophil auftretende, im Bereich des Energieminimums berechnete Delokalisationsenergie steht in linearer Korrelation zur Aktivierungsenergie.Am Beispiel der Wechselwirkung des Cyclopentadiens mit unterschiedlichen Dienophilen wird gezeigt, daß die Delokalisationsenergie inendo-Stellung des Diens und Dienophils stets kleiner ist als inexo-Stellung, was den Satz vonAlder erklärt.

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TheDiels-Alders reaction has been studied theoretically using the conventionalHückel LCAO-MO method. The investigation is based on regarding the formation of a -complex from the diene and dienophil as a forerunner of the transition state. A linear correlation exists between the energy of delocalization resulting from the diene—dienophil interaction and calculated for the region of the energy minimum and the energy of activation. The interaction of cyclopentadiene with various dienophils is used as an example showing that the delocalization energy of theendo situated diene and dienophil is always lower than the delocalization energy of theexo oriented ones, a fact that explainsAlders rule.

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Mit 5 Abbildungen     

The role of metallic palladium in the reductive decomposition of π-allyl palladium chloride in aqueous alkaline solutions

Russian Chemical Bulletin -     

Synthesis and electrochemical applications of fluorinated vinylazole copolymers for monitoring NO in model and biological systems

Copolymers of 1-vinyl-1,2,4-triazole and 5-vinyltetrazole with 1,1,5-trihydrooctafluoropentyl methacrylate and 1,1,7-trihydrododecafluoroheptyl methacrylate were prepared under the conditions of radical initiation. These copolymers were used for modification of the surface of a glassy carbon electrode, and the effect of the modification on the electrochemical behavior of the electrode in anodic oxidation of dopamine and NO was studied. The possibility of enhancing the selectivity of the electrochemical sensor for monitoring NO in biological media was demonstrated.