Zur Synthese von Polyfluoralkylestern der Fluorsulfonyl-difluoressigsäure und der α-Trifluormethylfluoressigsäure

On the Synthesis of Polyfluoroalkylesters of Fluorosulfonyl-difluoroacetic Acid and α-Trifluoromethylfluoroacetic Acid .     

Einige Aspekte der Bioverfügbarkeit von α-Tocopherol

Some Aspects of α-Tocopherol Bioavailability The bioavailability of α-tocopherol depends on various factors. The ingested esterified form is almost completely hydrolyzed in intestinal tract by esterases prior to absorption. Bile and pancreatic juice are necessary for optimal hydrolyzation, emulgation and absorption of vitamin E. An acid pH- value is required for tocopherol-absorption. Polyunsaturated longchain fatty acids in the diet inhibit whereas medium-chain triglycerides (MCT) enhance the absorption. Moreover, consumption of polyunsaturated fatty acids increases the requirement for antioxidants. Therefore long time consumption of polyunsaturated fatty acids (e. g. fish oil) shouldn't be used without an adequate compensation with antioxidants as well as control of α-tocopherol status. The dosis dependant absorption rate (average = 40%) can't be improved significantly by emulsifiers like Tween 80 or lecithin. Lipoprotein fractions are responsible for transport and distribution oif α-tocopherol with different efficiency: LDL 64%, VLDL 8%, HDL 24%. Vitamin E is rapidely taken up by tissues especially in liver, muscle, adrenal glands and adipose tissue. Beside free α-tocopherol as the typical storage from α-tocopheryl acetate is also detectable. The bioavailability of intravenous administered dl-α-tocopheryl acetate is good. The vitamin E-ester is rapidely eliminated and mainly hydrolyzed. This can be confirmed by a significant increase in the content of free α-tocopherol in plasma.     

Zur Herstellung von Säurederivaten der Oxalsäure-N1-acylamidrazone

Preparation of Carboxylic Acid Derivatives of Oxalic Acid-N¹-acyl Amidrazones The synthesis of oxalic acid ethylester-N¹-acyl amidrazones 1 is described. The amidrazonecarboxylates 1 were converted to the oxalic acid-N¹-acyl amidrazones 2 and to the corresponding carboxamides 3 and hydrazides 4 , which yield [5-amino-1,3,4-oxadiazol-2-yl]-N¹-acylamidrazones 5 .     

Simulation der Strömung in Fermentern von Biogasanlagen1

The performance of the stirring equipment in biogas plants is an essential prerequisite for optimal fermentation and high biogas yield. With the help of Computational Fluid Dynamics, a three‐stage central stirrer is evaluated by use of the criteria energy consumption, suitability for substantial and energetic homogenization, and prevention and destruction of particle agglomerations at the top and bottom of the tank. Analysis of the calculations with suitable performance numbers shows insufficient mixing in the upper part of the vessel and a non‐uniform impact on the shaft. Modifications made to the construction and the arrangement of the blades lead to improved results.     

Untersuchungen zur Knüpfung der Peptidbindung mit α-trifluormethylsubstituierten α-Aminosäuren

Chemical Peptide Bond Formation with α-Trifluoromethyl Substituted α-Amino Acids The reaction of α-trifluoromethyl substituted N-^tbutoxycarbonyl amino acids (Boc-TFM-Xaa-OH) 1 with dicyclohexylcarbodiimide results in formation of 2-^tbutoxy-4-trifluoromethyl-5(4H)-oxazolones 2 within minutes. Compounds 2 react with amino acid esters to give Boc protected dipeptide esters 4. However, at room temperature compounds 2 decompose to give Leuchs anhydrides 3 , via retro ene reaction. Therefore, α-trifluoromethyl substituted N-^tbutoxycarbonyl amino acids (Boc-TFM-Xaa-OH) are of limited value for peptide synthesis.     

1H- und 13C -NMR-spektroskopische Untersuchungen an substituierten 1, 1-Dioxo-1, 2-thiazinen; Additivität der Substituenteneffekte

¹H- and ¹³C-N.M.R. Spectroscopic Investigations of Substituted 1, 1-Dioxo-1, 2-thiazines; Additivity of the Substituent Effects . The influence of various XCH₂ substituents (X: Cl, Br, I, SCN, SO₂CH₃, SC(NH₂)₂^⊕, Py^⊕) in the 3-, 5- and 3, 5-position of the 1, 1-dioxo-2-phenyl-1, 2-thiazine on the ¹H- and ¹³C-n.m.r. chemical shifts of the ring atoms is described. The substituent effects are additive. The ¹H- and ¹³C-n.m.r. chemical shifts of the 3, 5-substituted 1, 1-dioxo-1, 2-thiazines can be calculated from increments derived from the 3- and 5-substitued compounds.     

Produkte der Dimerisierung ungesättigter Fettsäuren II: Die Monomerfraktion der Dimerisierung reiner Linolsäure 1. Aromatenfraktion

Products of Dimerisation of Unsaturated Fatty Acids II: The Fraction of Monomeres Obtained by Dimerisation of Pure Linoleic Acid, 1st Fraction of Aromatics The monomeric fraction obtained by dimerisation of pure linoleic acid shows after methylation a much more complex gas chromatogram as the same fraction obtained by dimerisation of oleic acid. Main compounds are p-and m-disubstituted benzene derivatives carrying one alkyl- and one alkylcarboxylic group. Besides stearic acid and stearolactone the same monomethyl branched isostearic acids are produced as observed by dimerisation of oleic acid. In contrast to the latter reaction also isomers of oleic acid could be detected in considerable amounts.     

Kälteadaptation der Wachssynthese in der Harder'schen Drüse der Ratte

Adaptation to Coldness in the Synthesis of Wax Esters in the Harderian Gland of the Rat The Harderian gland of the rat has been shown to contain characteristic wax esters of [n-7] unsaturated alcohols and fatty acids. The change of the temperature in the surroundings from 25 to 4° C for six weeks does not change the pattern of exclusively [n-7] monoenoic fatty acids. The adaptation of this exocrine eye gland results in an increased synthesis of [n-5] monounsaturated alcohols and shortening of the chain length. Different pathways of unsaturation and/or chain modification and the regulation of lipid synthesis in this gland are discussed, as well as the biological role of these waxes.     

Die Geburt der Hochdruckchemie und das Leuna Werk: Ein Stück Geschichte der technischen Chemie – Teil 1

The onset of the technical high pressure chemistry can be traced back to the beginning of the 20th century. After resolving many technically completely new problems in an incredible short time, including the development of a suited catalyst, the first large scale plant to synthesize ammonia from nitrogen and hydrogen went on stream 100 years ago in Ludwigshafen (BASF). Since 1916 the BASF subsidiary in Leuna, the Ammoniakwerk Merseburg, was part of these successful developments. Within a short time further high pressure syntheses emerged – the synthesis of methanol and higher alcohols as well as the hydrogenation of coals into liquid hydrocarbons. This contribution acknowledges these very important developments that have revolutionized the area of technical chemistry.