A simple and expedient method for the preparation of N-chlorohydantoins

A simple and efficient methodology for the preparation of N-chlorinated hydantoins is presented. These versatile chlorenium sources were isolated in high yield after a simple recrystallization. Among the ten examples are the first chiral N-chlorohydantoins.     

A composite chiral pair of rotational bands in the odd-A nucleus 135Nd

High-spin states in 135Nd were populated with the 110Pd(30Si,5n)135Nd reaction at a 30Si bombarding energy of 133 MeV. Two DeltaI=1 bands with close excitation energies and the same parity were observed. These bands are directly linked by DeltaI=1 and DeltaI=2 transitions. The chiral nature of these two bands is confirmed by comparison with three-dimensional tilted axis cranking calculations. This is the first observation of a three-quasiparticle chiral structure and establishes the primarily geometric nature of this phenomenon.     

The excitation of acoustic resonances by vortex shedding

A single acoustic resonance, excited by vortex shedding from the trailing edge of a flat plate, has been studied in detail. The resonance was generated in the working section of a low-speed wind tunnel and the scale was large enough for accurate measurements to be made. The trailing edge was designed so that it could be made to oscillate slightly to simulate the correlating effect of the resonance on the vortex shedding.     

Verteilung der Translationsenergie auf die Produkte von Methylradikalreaktionen

Ohne Zusammenfassung     

Charge density distributions and sigma bond inductive effects in hydrocarbons and hydrocarbon ions

Atomic orbital charge densities have been calculated for the electron systems of a number of hydrocarbon molecules, by an electronegativity equalization method. These electron distributions have been used to analyze the relative inductive effects of alkyl groups, the transmission of electronic effects through localized bonds, the inductive stabilization of simple hydrocarbon ions, and the dependence of the ¹H and ¹³C chemical shifts on the corresponding partial charges of the atoms. The charge densities calculated by electronegativity equalization were compared to those predicted by various molecular orbital methods.

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Zusammenfassung Mit Hilfe einer Methode, die auf der Angleichung von Elektronegativitäten beruht (electronegativity equalization), sind atomare Orbitalladungsdichten für -Elektronensysteme einer Reihe von Kohlenwasserstoffmolekülen berechnet worden. Die Ladungsdichten werden mit den Voraussagen verschiedener MO-Methoden verglichen.Diese Elektronenverteilungen werden zur Analyse der relativen induktiven Effekte von Alkylgruppen, der Weiterleitung elektronischer Effekte durch lokalisierte Bindungen, der induktiven Stabilisierung einfacher Kohlenwasserstoffionen und der Abhängigkeit der chemischen Verschiebung von ¹H und ¹³C von den partiellen Ladungen der Atome benutzt.

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Résumé Les densités de charge dans les orbitales atomiques ont été calculées pour les systèmes d'électrons d'un certain nombre de molécules d'hydrocarbure à l'aide d'une méthode d'égalisation des électronégativités. Ces distributions électroniques ont été utilisées pour analyser les effects inductifs relatifs des groupements alkyles, la transmission des effets électroniques à travers les liaisons localisées, la stabilisation par effet inductif des ions hydrocarbures simples, et la relation entre les déplacements chimiques de ¹H et ¹³C et les charges atomiques partielles correspondantes. Les densités de charges calculées ici ont été comparées à celles obtenues par différentes méthodes d'orbitales moléculaires.

     

Configurational analysis of rotational states in the SD shell

It is shown that the shell-model states belonging to a given rotational band in ²³Na and ²⁴Mg have very similar subshell occupancies, different bands being characterised by different occupancies. On the one hand this establishes a connection, somewhat different from that provided by the SU (3) scheme, between the spherical shell model and the idea of an intrinsic state, and on the other hand helps discriminate between possible candidates for membership of a band and imposes limits on the lengths of the bands.     

Unexpected formation of a 10H-Pyrido[2,3-h]pyrazolo[3,4-b]quinoline derivative,a new ring system

Treatment of N-(1,3-dimethylpyrazol-5-yl)-4-anthranilic acid with phosphorus oxychloride gave an intermediate which was condensed with 3-dimethylaminopropylamine to yield 10,8-dimethyl-7-(3-dimethylaminopropylamino)-10H-pyrido[2,3-h]pyrazolo[3,4-b]quinoline (IV). The structure of IV, which represents a previously undescribed ring system, was confirmed by an independent synthesis.     

Arylene-modified siloxanes

Polyarylenepolysiloxanes with varied structure can be obtained in condensation reactions of arylenedisilanols and N-methylsiloxazanes. Molecular weights, viscometric properties, glass transition temperatures, and thermogravimetric analysis data are reported.