Quantitative behandlung kinetischer racematspaltungen bei der umsetzung optisch aktiver 1,1-diphenyl-alkan-2-ole mit racemischem 2-phenylbuttersäureanhydrid

The absolute configurations have been determined of a series of 1,1-diphenyl-alkane-2-ols by kinetic resolution in the reaction with 2-phenylbutyric anhydride (Horeau's method). There is an agreement with the results obtained in a quantitative interpretation of this reaction by the stereochemical analogy model of Ruch and Ugi. The (?)-carbinols have S-configuration. In this special reaction, the effective bulk of the isopropyl substituent must be more important than of the diphenylmethyl group.     

Recent studies of phase equilibria at high pressures

In its first part the present review considers the dependence of phase transition temperatures of some selected liquid crystals on pressure up to 300 MPa with differential thermal analysis (DTA) and diamond anvil techniques; here also pressure-induced phases as well as tricritical and reentrant phenomena will be discussed. In the second part the most important types of high-pressure phase diagrams of fluid mixtures are shortly reviewed. Here recent results on binary systems (containing trifluoromethane, tetrafluoromethane, nitrogen etc) will be presented and compared with data that are calculated from an equation of state. The results will be discussed in relation to some applications e.g. in fluid extraction and supercritical fluid chromatography (SFC).     

Sodium dispersions in the preparation of 3,5-dinitrobenzoates of alcohols

Summary The 3,5-dinitrobenzoates of alcohols can easily be prepared on a small scale by first forming the sodium alcoholates by the use of a sodium dispersion.

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Zusammenfassung Alkohol-3,5-dinitrobenzoate lassen sich in kleinem Maßstab leicht herstellen, indem man mit Hilfe einer Natriumdispersion zunächst das betreffende Natriumalkoholat bildet.

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Résumé On peut préparer facilement et sur une petite échelle, les dinitro-3,5-benzoates d'alcools en formant d'abord les alcoolates de sodium à l'aide de sodium dispersé.

     

?therische ?le

Ohne Zusammenfassung