Alkaloids of Arundo donax. XIV. Crystal and Molecular Structure of N-Methyl-tetrahydro- β-carboline

An indole alkaloid of the N-methyl-tetrahydro--carboline series was isolated for the first time from Arundo donax, Poaceae. Its structure was solved by X-ray structure analysis.     

Uronic (hexenuronic) acid profile of ethanol–alkali delignification of giant reed Arundo donax L.

The effect of process variables on uronic acids (UAs) and hexenuronic acids (HexAs) in the annual crop Arundo donax L. during ethanol–alkali pulping has been examined. A substantial loss of UA moieties (up to 90%) was observed by the end of pulping (target kappa number 18) performed with 25% NaOH and 40% EtOH (by volume) within the temperature range of 130–150 °C. At the same time, the progressive formation of HexA in pulp was detected from the early phases of delignification. The proportion of HexA in the residual UA of the final pulp was found to be 84%, indicating almost complete conversion of 4-O-methylglucuronic acid side groups (MeGlcA) of heteroxylan into HexA. The kinetics of UA degradation and HexA formation has been described in terms of three consecutive first-order reaction stages. The overall rate of UA degradation was one order higher than the rate of UA conversion into HexA. The values of apparent activation energy were estimated as 68.6 and 94.7 kJ mol^–1, respectively. The reaction medium alkalinity was shown to be the controlling factor for UA and HexA stability during ethanol–alkali pulping. An increase in alkali charge from 5% to 35% (as NaOH) led to UA loss of 40%, but promoted HexA formation from 11.8 to 20.1 mol g^–1. The addition of organic solvent to the alkaline pulping solution had a similar effect, and about 10% of UA was lost and the content of HexA increased from 6.9 to 10.9 mol g^–1 with an increase in ethanol proportion in the liquor from 20% to 60%.     

Condensed aromatics—XXIV. Cyclo[d.e.d.e.e.d.e.d.e.e]decakisbenzene

The macrocyclic condensed aromatic hydrocarbon C₄₀H₂₀ cyclo[d.e.d.e.e.d.e.d.e.e] decakisbenzene is treated. It belongs to the class of cycloarenes. The simple Hückel molecular orbital analysis has been performed and employed in the construction of a harmonic force field. The set of calculated vibrational frequencies is reported.     

Condensed aromatics—XXIII. Cyclo[d.e.d.e.d.e.d.e.d.e.d.e]dodecakisbenzene (kekulene)

Some topological properties of coronoids are given. These systems have chemical counterparts in cycloarenes. For one of these molecules, viz. C₄₈H₂₄ kekulene, the simple Hückel molecular orbital analysis has been performed and employed in the construction of a harmonic force field. Finally the set of calculated vibrational frequencies is reported.     

Prof. Dr. E. Gorter, 19. Februar 1881 –17. Februar 1954

Ohne Zusammenfassung     

Über die roten Anile. 2. Mitt.

Zusammenfassung Bei der Spaltung des -(p-Dimethylaminophenylimino)--keto--(3,4,5-trimethoxyphenyl)-valeriansäurenitrils (V) mit Chlorwasserstoffsäure entsteht die -Keto--(3,4,5-trimethoxyphenyl)-buttersäure (VII) und nicht, wie infolge des Versagens einiger typischen -Ketocarbonsäurereaktionen vermutet wurde, die 3-Hydroxy-4,5,6-trimethoxy-indan-3-carbonsäure.1. Mitt.:J. Michalský undL. Sadílek, Mh. Chem.90, 171 (1959).     

Über die roten Anile. 1. Mitt.

Zusammenfassung Durch Anwendung der vonF. Kröhnke ¹ ausgearbeiteten Methode zur Darstellung von -Keto-carbonsäuren konnte man über die roten Anile VIII die entsprechenden -Keto-(3,4,5-trimethoxyphenyl)-alkancarbonsäuren (IX, XI) gewinnen. Die erfolgreich durchgeführte Synthese des -(p-Dimethylaminophenylimino)--keto--(3,4,5-trimethoxyphenyl)-valeriansäurenitrils (VIIIc) läßt auch die geplante Synthese von -(p-Dimethylaminophenylimino)--keto--[2,3,4,4-tetramethoxydiphenylyl-(6)]-valeriansäurenitril und der entsprechenden -Keto-säure (V, [H statt Br]) als hoffnungsvoll erscheinen.     

Correctionto Chin .J .Chem .2002,20,851— 857

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RECIPROCAL A.C.OSCILLOPOLAROGRAM

In this paper a new electrochemical method“Reciprocal a.c.oscillololarography”is discussed.Both principle and experimental work aredescribed.