Submicro methods for the analysis of organic compounds : The determination of hydroxyl groups

Various procedures were examined for the determination of organic hydroxyl groups. Conventional acetylation methods could not be used on the submicro scale, but the spectrophotometric method based on esterification with 3,5-dinitrobenzoyl chloride followed by extraction of the ester and colour development with alkaline acetone proved reasonably satisfactory for aliphatic alcohols. Acidic hydroxyl groups e.g. in phenolic compounds, were titrated accurately with 0.01 M tetrabutylammonium hydroxide in benzene-methanol solution in a pyridine medium ; visual end-points or potentiometricend-points with glass-silver or glass-in-stream platinum electrode pairs were used depending on the strength of the acidic group. Some differentiating titrations were possible. A general submicro bromination method for phenols was not feasible.     

Buchbesprechungen

Ohne Zusammenfassung     

Heat of formation of yttrium-bismuth alloys

In the Y—Bi system the formation heats were measured using a direct isoperibol calorimeter. The following values were found for the two known compounds:

     

Darstellung,Schwingungsspektren und Struktur von Oxotetrafluorovanadaten MIVOF4 (MI = Na,K, Rb,Cs, Tl, (CH3)4N)

Preparation, Vibrational Spectra, and Structure of Oxotetrafluorovanadates M^IVOF₄ (M^I = Na, K, Rb, Cs, Tl, (CH₃)₄N) The compounds M^IVOF₄ (M^I = K, Rb, Cs, Tl) and M^IVOF₄ · H₂O (M^I = Na, (CH₃)₄N) have been prepared. The crystal structure of KVOF₄ has been determined by single crystal X-ray diffraction. The VOF-ions form endless chains by fluorine bridges. The lengths of the bridge bonds are 1.875(7) and 2.333(7) Å. The terminal V? O- and V? F-distances are 1.572(8) and 1.793 Å (mean value), respectively. The vibrational spectra have been registered and assigned.     

Hydrocarbomethoxylation of 1-hexene with formic acid and methanol under conditions of phosphoric acid catalysis

Conclusions When the hydrocarbomethoxylation of 1-hexene with formic acid is run at atmospheric pressure and temperatures close to room temperature, in the presence of conc. H₃PO₄, an increase in the relative amount of the latter, as well as an increase in the reaction temperature in the investigated range, both favor an increase in the yields of the methyl esters of the C₇ acids, in particular, those containing two methyl groups on the quaternary carbon atom in the -position. An increase in the relative amount of formic acid also favors an increase in the amounts of these esters in the obtained mixtures of esters.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1116–1118, May, 1971.     

Biochemisches Verhalten von Desoxyribonucleinsäure

Zusammenfassung Es wird eine durch DNS ausgel?ste biologische Wirkkette diskutiert. Durch DNS-Injektion lassen sich beim Warmblüter DNase-Aktivit?tserscheinungen hervorrufen. DNasen bewirken in niedrigen Konzentrationsbereichen 10⁻¹³-10⁻⁵ g/ml eine Steigerung der Zellzahl. In h?heren Konzentrationen wirken sie hemmend auf die Lebenst?tigkeit. Aufgrund dieser experimentellen Befunde ergibt sich ein selbstregelnder Mechanismus. Ausgeführt mit Mitteln der Deutschen Forschungsgemeinschaft.