St. Rüdiger

Fluorocarbons as blood substitutes: critical solution temperatures of some perfluorocarbons and their mixtures

Abstract The exhalation of perfluorocarbons (PFCs) from the organism after administration of perfluorocarbon-based blood substitutes is discussed in terms of their lipid solubilities, which may be correlated with their critical solution temperatures (CSTs) with n-hexane, of which a number of measurements are reported here. The critical solution temperatures of some binary mixtures of PFCs with n-hexane are also reported. These are linearly dependent on the compositions of the mixtures of perfluorocarbons. The application of this simple relationship enables the extrapolation of the CST of the pure component (such as perfluoro-n-octyl bromide) for which the CST may not otherwise be easily determined. The observed CSTs of derivatives of PFCs, in which a fluorine atom has been replaced by a more polarizable atom, are strongly dependent upon the respective molar refraction.

Aliovalent-substituted chromium-based catalysts for the hydrofluorination of tetrachloroethylene

New aliovalent-doped chromium oxide and fluoride catalysts have been prepared by coprecipitation techniques to obtain solid solutions. The catalysts have been characterized by, e.g., X-ray, BET, and pyridine adsorption analysis, and tested for their catalytic activity in the gas-phase reaction of C2Cl4 with HF. The latter reaction involves several consecutive steps and produces the expected C2HClxFy (x+y=5) compounds, but also some perhalogenated compounds the formation of which needs further explanation. Reaction data obtained with a (Cr,Mg)(F,OH)x catalyst were used to calculate reaction rates and activation energies of all the consecutive steps which could be successfully used to predict the reaction outcomes under varying experimental conditions.

Current balance of the electrochemical fluorination of a trialkylamine

Abstract The electrochemical fluorination of dibutylmethylamine was studied. All the fluorination products formed, liquid, gaseous, and dissolved in HF, and also the hydrogen evolved were quantitatively determined. From either their formulae or their relative fluorine contents the amount of current necessary for their formation was estimated. Altogether, the fluorination products determined cover about 86 – 92 % of the current applied. A major part of the current was consumed by production of polyfluorinated compounds, which remained dissolved in the hydrogen fluoride.

Investigations on the electrochemical fluorination of amines

Abstract Electrochemical investigations of dibutylmethylamine (DBMA) and of polyfluorinated amines derived from DBMA by electrochemical fluorination in anhydrous HF (ECF) were carried out. From the results of these investigations, which gave no evidence of a direct involvement of the organic compounds in the anodic process, and from other experimental facts discussed, it follows that the formation of an ‘active fluorine’ at the anode is very probably the primary step in the ECF of amines.

On the electrochemical fluorination of aminoethers to give perfluoroaminoethers : possible candidates for blood substitutes

Abstract Aminoethers, ROC 2 H 4 NCH 2 CH 2 OCH 2 C H 2 (R = C 6 H 5 , C 6 F 5 , C 2 H 5 ), C 6 F 5 OC 2 H 4 N[CH 2 ] 5 , were electrofluorinated in anhydrous hydrogen fluoride, the corresponding saturated perfluoroaminoethers being the largest individual substances in each case. One of them, F-[4-(2-cyclohexyloxyethyl)morpholine], has promising properties as a blood substitute.

On polyfluorinated, HF soluble compounds formed during the electrochemical fluorination of dibutylmethylamine

Abstract The electrochemicaI fluorination of dibutylmethylamine yields, besides other products, considerable amounts of polyfluorinated compounds which remain dissolved in HF. Since the occurrence of such compounds is a widespread phenomenon in ECF, their formation as well as their composition was studied. Whereas some partially fluorinated compounds are likely to be intermediates in the fluorination process, others remain inert toward further ECF. The latter have on average about 9 of the 21 H-atoms replaced by F, with almost no F at C-atoms adjacent to the N-atom.

Perfluorocarbons: chemically inert but biologically active?

Abstract One of the most striking properties of perfluorocarbons is their chemical inertness. Due to this, these compounds are said to be physiobiologically compatible. Therefore, they are suggested for a variety of medical uses including the one as component of blood substitutes. However, it was the blood substitute research, which revealed biological activities of perfluorocarbons. Some of these biological effects are described shortly.

On the electrochemical fluorination of quaternary ammonium compounds. Part 1. Tetraalkyl ammonium salts

Abstract Tetraalkylated ammonium compounds, which are known to be very stable towards oxidative attack, can be electrofluorinated readily to yield perfluoro tertiary amines. Other than the enhanced formation of gaseous cleavage products, the electrofluorination proceeds similarly to that of other tertiary amines.

Über synthesen von difluoraminopyrimidinen

Zusammenfassung Es wird uber Synthesen von Difluoraminopyrimidinen berichtet. Bei der Direktfluorierung der Aminoderivate worden die entsprechenden Difluoraminoverbindungen neben weiteren Fluorierungsprodukten erhalten. Im Falle der Alkylierung von Difluoramin durch protonierte Pyrimidine wird die Bildung der Difluoraminoverbindungen diskutiert.

On the interactions of perfluorochemical emulsions with liver microsomal membranes

Abstract The interactions of rat liver microsomal membranes with various emulsified perfluorochemicals (PFCs) have been studied. The percentage of microsomal cytochrome P 450 forming a complex with a PFC decreased with increasing critical solution temperature (CST) of the PFC. The complex was apparently not formed with lipophobic PFCs whose CSTs were higher than 46 °C, e.g. perfluorotributylamine. The complex was destroyed by an excess of a lipophobic PFC emulsion. The rate of complex formation depended on the solubility of the PFC in water and on the dispersity of the emulsion. The results obtained have been used for an analysis of liver cytochrome P 450 induction after intravenous administration of fluorocarbon emulsions to rats. It is suggested that the membrane-related biological activities of PFCs depend mainly on the solubility of PFCs in lipids and water.