Vom Rohöl zu Energie‐ und Chemierohstoffen. Erdölverarbeitung in der Mineralölraffinerie

Crude oil still is one of the most important sources of primary energy. With an annual consumption of nearly four billion metric tons it is also the most important raw material for the chemical industry. The complex process network of a modern oil refinery is used to upgrade crude oil into a wide variety of intermediates and products.     

Untersuchungen über die Löslichkeit von Molybdatophosphaten. I. Löslichkeit von Chinoliniummolybdatophosphat

Studies on the Solubility of Molybdatophosphates. I. Solubility of Quinolinium Molybdatophosphate The solubility of quinolinium molybdatophosphate was determined radiochemically under conditions of the gravimetric determination of phosphate in hydrochloric acid as well as in nitric acid media. The residue concentration of phosphate variies in the range of 10^?8 to 10^?9 mol/I. The dependence of the solubility on the reagent concentration and on the concentration of solution components was investigated and discussed variing the pore width of the filters used for separating the precipitate. The accuracy and the precision of the determination of phosphate was not influenced in practice by the solubility.     

Hochauflösende Festkörper-NMR-Untersuchungen an Kieselsäuren. III Hochauflösende 29 Si-Festkörper-NMR-Untersuchungen an synthetischen siliciumreichen Kieselsäurehydraten

Solid-State High-Resolution N.M.R. Studies of Silicic Acids. III. Solid-State High-Resolution ²⁹Si-N.M.R. Studies of Synthetic Highly Siliceous Silicic Acid Hydrates Solid-state high-resolution ²⁹Si-N.M.R. experiments were used to study the structure of the silicate layers in three synthetic highly siliceous silicic acid hydrates obtained by cation exchange reactions from the synthetic sodium silicate hydrates ilerite, magadiite and kenyaite. For each of the studied samples two well-separated N.M.R. signals have been recorded which could be assigned to Q³ - (O?Si(OSi?)₃–) and Q⁴-(?Si(OSi?)₄–) units of the silicate layers of the corresponding silicic acid hydrate. On the basis of these results the same model was used to describe the structure of the silicate layers in the studied compounds which has been already used for the interpretation of the N.M.R. results in case of the synthetic sodium silicate hydrates. Compared with the sodium silicate hydrates in the studied silicic acid hydrates a somewhat large Q⁴/Q³-ratio and a high-field shifted Q³signal have been detected. These observations were attributed to structural changes which appeared as a result of the cation exchange reactions.     

12. Österreichische Chemietage

Joint Meeting of the Slovenian & Austrian Chemical Societies, September 10 – 13, 2007, Alpen‐Adria‐Universität Klagenfurt     

Organic Stereochemistry. Part 6

Following the previous Part on the mechanisms of chiral recognition in pharmacology, the road was open to cover one aspect of stereoselectivity that had been evoked in Part 5 but not discussed explicitly, namely the pharmacological significance of the conformational behavior of active molecules. There, we saw how ligands and binding sites adapt to each other, but these results were not related explicitly to the conformational behavior of the ligand. The focus of the present Part is to use a few well‐known drugs, examine their conformational behavior, compare the 3D geometry of probable conformers with rigid analogs acting at the same receptor, and reflect on the concept of ‘active conformation’.     

Über basische Aluminiumsalze und ihre Lösungen. XVI. Kinetische Untersuchungen an niederbasischen Aluminiumchloridlösungen

Basic Aluminum Salts and their Solutions. XVI. Kinetic Studies on Low Basic Aluminum Chloride Solutions Basic aluminum chloride solutions of low basicity were prepared by different methods and investigated by means of the ferrone kinetics. In solutions prepared by expulsion of hydrogen chloride or addition of solid sodium carbonate preferably dimeric cations are formed. In solutions prepared by addition of sodium hydroxide solution or sodium carbonate solution only at very low basicity small quantities of dimeric ions are formed, at increasing basicity tridecameric ions arise. An explanation of this behaviour is given, involving the action of hydroxide ions and a possible formation of the dihydroxy-aluminum complex. The rate constant for the reaction of the dimeric ions with the ferrone reagent was determined to be k = 0.97 ± 0.06 min^?1.     

PHOTOCHEMIE ANOMALER NUCLEINSÄUREBAUSTEINE-VIII. ZUR PHOTOCHEMIE DES 6–AZACYTOSINS UND 6–AZACYTIDINS

Abstract— The photochemical behavior of 6–azacytosine and 6–azacytidine has been investigated by spectrophotometric, polarographic, and chromatographic methods. Both compounds form photohydration products, similar to cytosine and cytidine, but their photosensitivity is about ten fold higher. The greatest stability against u.v. light was found in strong acid and alkaline medium, indicating that under these conditions the electronic density at the reaction center is decreased.
For estimation of the photochemically active excited state triplet-triplet-transfer, experiments and measurements in the presence of paramagnetic metal ions were done. The results show that the photohydration reaction involves the first excited singlet state and the corresponding triplet state probably as well.
The photoproducts of both substances can be reactivated by heat. This reaction in acidic medium is strongly overlapped by a deamination reaction which yields 6–azauracil as a final product. In alkaline solution the ring system of the photohydration product is disrupted in the dark. The kinetic parameters of the heat-reversible reaction of 6–azacytosine and 6–azacytidine are completely identical. This is in contrast to the published results with cytosine and cytidine where the back reaction is lowered for the latter. The differences in the behavior of the normal bases and their azaanalogues can be explained by means of an intramolecular hydrogen bond stabilization of the cytidine photoproduct. An analogous stabilization effect in the case of the 6–azacytidine photoproduct seems to be improbable for sterical reasons.