DIELS-ALDER-Reaktionen. V. Kinetische Modellierung der bei der Mischdimerisierung von Cyclopentadien mit Butadien-(1,3) ablaufenden Reaktionen

Diels-Alder-Reactions. V. Kinetic Modelling of the Reactions Taking Place in the Codimerization of Cyclopentadiene with Butadiene With the aid of independently determined rate constants of the 11 reactions which must be considered, the dependence of concentration on time for the most important products of the reaction between cyclopentadiene and butadiene can be calculated only with unsufficient accuracy. Using optimization procedures (sequential simplex procedure and the procedure of SILLEN ) it is possible, however, to recalculate rate constants from the experimental dependence between concentrations and time. These recalculated rate constants permit a calculation of the dependence between the concentrations of all products and the reaction time, which very well agrees with the experiment.     

Untersuchungen über die basisch katalysierte reaktion von melamin mit formaldehyd

Reaction products of melamine and formaldehyde can be modified by treatment with N -diethyl-trimethylsilyl-amine to yield materials, which are soluble in organic solvents and can easily be fractionated by gel permeation chromatography. Moreover, gel permeation chromatography is used for the quantitative investigation of the course of the sodium-hydroxyde catalysed methylolation of melamine. For this purpose the differential refractometer is calibrated to the corresponding peak area in the chromatograms. In the quantitative determination of the methylolation reaction of melamine in alkaline aqueous solution a difference between the injected and the amount calculated from calibration data was observed. This difference is caused by the presence of polyoxymethylene glycols in the methylolmelamines. Polyoxymethylene glycols are also found in technical melamine-formaldehyde resins.     

Untersuchungen über die Lipide von Kartoffeln

Investigations on the Lipids of Potatoes Gas chromatographic investigations on the fatty acid composition of the total lipids of freeze-dried potato showed that 90% of the fatty acids consist of linolenic, linoleic, palmitic and stearic acids. In all, 31 different fatty acids were detected and identified. Noticeable amounts of odd-chain fatty acids and those having more than 20 C-atoms (up to C₃₀) were found. Eight different varieties of potato were investigated. Difference in the fatty acid composition of the individual varieties was not appreciable. Experiments on the group separation of lipids showed that they contain a large amount of phospholipids (especially lecithin and cephalin). Appreciable amounts of triglycerides were also found, however, the sterol esters, sterols and free fatty acids were present to a lesser extent.     

Untersuchungen über die Autoxydation von Margarine

Investigations on the Autoxidation of Margarine The authors investigated the influence of storage temperature, packing and of the quality of dispersion on the oxidative stability of margarine. The oxidative stability of margarine is improved with increasing fineness of the dispersion. The autoxidation can be prevented to a great extent by employing low storage temperature and suitable packing material. Packing materials containing traces of heavy metals promote the autoxidation in the upper layer of margarine.     

Untersuchungen zur Sulfochlorierung von Paraffinen. VIII. Untersuchungen über die Verseifung von definierten Alkansulfochloriden mit Natronlauge

Studies on Sulphochlorination of Paraffins. VIII. Studies on the Hydrolysis of Individual Alkane Sulphochlorides by Sodium Hydroxide The hydrolysis of individual C₁ C₅ alkane sulphochlorides by sodium hydroxide in dioxane/water (1:1) was kinetically studied at 25°C by means of stopped-flow technique, measuring the change of electric conductivity. The rate constants were influenced by steric hindrance, but in all cases were higher than the rate constant for alkaline hydrolysis of benzene sulphochloride, which cannot react according to the elimination-addition (sulphene) mechanism. The reaction enthalpy of the alkaline hydrolysis of four individual alkane sulphochlorides was determined by a simple calorimetric apparatus; the average value amounts to δ_RH = −239 kJ mol⁻¹.     

Untersuchungen zur Sulfochlorierung von Paraffinen. II. Untersuchungen über die Reaktion von aliphatischen Sulfochloriden mit Nucleophilen

Studies on the Sulphochlorination of Paraffins. II. Studies on the Reaction of Aliphatic Sulphochlorides with Nucleophiles The reaction of sterically pure cis- and trans-4-methyl-cyclohexyl sulphochlorides with dimethyl amine, natrium methylate, and natrium phenolate in each case gives mixtures of the cis- and trans-isomers of the corresponding derivatives of 4-methylcyclohexyl sulphonic acid, which could be separated by gas chromatography. Reaction of cis- and trans-4-methyl-cyclohexyl sulphochlorides with potassium fluoride in DMF/H₂O gives 4-methylcyclohexyl sulphofluoride; the cis- and trans-forms of this compound could not be separated by gas chromatography. If n-propyl or isopropyl sulphochloride react with potassium fluoride in DMF/D₂O; the sulphofluorides which are formed do not contain deuterium. Evidently the reaction of primary and secondary aliphatic sulphochlorides with basic nucleophiles proceeds by an elimination-addition-mechanisms with sulphenes as short-living intermediates, but the reaction with fluoride ions proceeds by an addition-elimination-mechanism.     

Untersuchungen über die toxikologischen Eigenschaften von Waschmittelenzymen

Investigations on the Toxicological Properties of Enzymes Used in Washing Agents Enzymes used in washing agents and enzyme-containing washing agents were tested in animal experiments for their general and local tolerance. The results of these investigations confirm that enzymes employed in washing agents are not toxic. The amounts of enzymes that are added to washing agents do not alter the local tolerance of such products. Similar observations were made in dermatological investigations on testpersons. From the results, it may be concluded that enzyme-containing washing agents do not present any hazard to the health of consumers. The same is also true for allergic reactions. Enzymes used in washing agents do have histamine-and kinin-liberating properties, however, only at such concentration-ranges that are insignificant for the practice.     

Kinetische Untersuchungen über die Autoxidation von Olefinen

Kinetic Studies on the Autoxidation of Olefins The oxidabilities \documentclass{article}\pagestyle{empty}\begin{document}$ {{{\rm k}_{\rm p} } \mathord{\left/ {\vphantom {{{\rm k}_{\rm p} } {\sqrt {2{\rm k}_{\rm t} } }}} \right.\kern-\nulldelimiterspace} {\sqrt {2{\rm k}_{\rm t} } }} $\end{document} at 50°C were determined for 37 olefins, using chlorobenzene as the solvent and azodiisobutyronitril as the initiator. In the group of acyclic aliphatic olefins the oxidability rises with increasing number of alkyl groups bound to the double bond. This is also true for cyclic olefins, but in this case the ring size has also a great influence on the oxidability. So the oxidability decreases from five-ring to eight-ring cycloolefins. Particularly high oxidabilities are found in the case of olefins in which a phenyl group is attached directly to the C C-double bond.     

Untersuchungen über die Kinetik des Bleichens mit Bleicherden

Investigations Concerning the Kinetics of Adsorptive Bleaching1 The mechanism of bleaching with clays was studied by means of the kinetics for the removal of carotene and chlorophyll. Experiments were made with a rapeseed oil. It was bleached under N₂. Samples were taken at different times and analyzed in terms of light absorbancy A at 445 and 660 nm. In the first period of bleaching the concentrations of remaining pigments were linearized by plotting log A/Ao against \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt {t\,} $\end{document}. The slope k was proportional to the added amount of bleaching clay, although the original amount of water in the system also had an influence. The rate formula found is characteristic of flocculation of colloids, as found from experimental data in the literature. Thus the pigments of rapeseed oil are particulate and colloidally dispersed in the oil. The stability of the colloid Then also pigment particles adhere to the clay. After the first period the stability of the colloid is broken, and the pigment particles aggregate in the bulk. These aggregates were visible in the microscope.     

Untersuchungen über die Verseifungsfarbzahl

Studies on the Saponification Colour Number Oxidized fats give yellow to brown solutions on saponification with alcoholic potassium hydroxide. Studies reported here were directed towards determining the causes of such reactions. The results indicate that at least two multiple bonds which are conjugated in relation to the carbonyl group, or a α,β-dicarbonyl group give a strong reaction on heating with alcoholic potassium hydroxide. It is shown that under certain conditions of reaction the saponification colour number is suitable as a measure for the degree of oxidation of heated fats. The method employed is described.     

Untersuchungen über die Haltbarkeit der Struktur von Margarine

Studies on the Structural Stability of Margarine In certain cases the stability of the structure of margarine is considerably impaired due to recrystallization of the solid phase. Microscopic studies, differential thermoanalysis and chemical methods were employed in order to gather an insight in the relationship between the composition of margarine fats and the occurrence of such structural alterations.     

Untersuchungen zur Sulfochlorierung von Paraffinen. VII. Untersuchungen über die Chlorierung von definierten Alkansulfochloriden

Studies on Sulphochlorination of Paraffins. VII. Studies on the Chlorination of Individual Alkane Sulphochlorides The products of the chlorination of individual C₂–C₆ alkane sulphochlorides were studied by means of ¹³C-n.m.r. spectroscopy. In no case a geminal chloro sulphochloride could be found, and only in very few cases chlorination at vicinal C H-bonds took place. As in the sulphochlorination of alkane sulphochlorides the C H-bonds geminal and vicinal to the sulphochloride group are strongly descativated. The results of ¹³C-n.m.r. analyses were confirmed by the results of gaschromatography of the sulphonic acid dimethyl amides, formed by the reaction of the chlorination mixtures with dimethyl amine.     

Untersuchungen zur Sulfochlorierung von Paraffinen. VI. Untersuchungen über die Sulfochlorierung von definierten Alkylchloriden

Studies on Sulphochlorination of Paraffins. VI. Studies on the Sulphochlorination of Individual Alkyl Chlorides The products of sulphochlorination of individual C₂–C₇ alkyl chlorides were studied by means of ¹H- and ¹³C-n.m.r. spectroscopy. Gaschromatographic determination of the isomers formed was possible after the reaction of the chloroalkane sulphochloride mixture with dimethyl amine in ether. In no case geminal chloroalkane sulphochlorides were formed. Vicinal chlorosulphochlorides are formed, but substitution in greater distance from the chlorine is preferred if possible. Thus higher alkyl chlorides yield only very little amounts of vicinal chloroalkane sulphochlorides. The relative rates of sulphochlorination of alkyl chlorides were determined by competitive reactions.     

Polymerisation von Butadien-(1,3) mit Tetrabenzyltitan-Verbindungen enthaltenden Systemen

Tetrabenzyltitanium and its o-halogenbenzyl derivates have only a small activity for polymerizing butadien. Aluminium trialkyls accelerate the catalytic activity. A very suitable system for preparing 1,4-cis or 1,4-trans polybutadien under normal pressure is formed by tetrabenzyl titanium and aluminium chloride as a co-catalyst.     

Kinetische Untersuchungen über die Addition von Halogenwasserstoffen an Olefine

Kinetic Studies on the Addition of Hydrogen Halides to Olefins The relative rates of the reactions of olefins with hydrogen bromide and iodide were determined in acetic acid solution. The kinetic data of the substituted styrenes were correlated by means of the Hammett equation, those of the open-chain aliphatic olefins were correlated by means of the three- and the five-parameter Taft equations. All correlations show the transition state to be similar to an open carbenium ion.     

Untersuchungen über die Verknäuelung von technischen Polyisobutylenen

With technical grade polyisobutylenes (Oppanole B of BASF), light scattering in n-hexane, osmotic pressure in toluene, and intrinsic viscosity in different solvents are measured. The data are used to derive polydispersity, degree of coiling, and coil expansion of the samples. The undisturbed dimensions are estimated.     

Biokinetische Untersuchungen über die Resorption von Aminosauren beim Menschen

Biocinetic Investigations of Resorption of Amino-Acids in Human Beings Biocinetics — as pharmacocinetics For years an unrenouncable part of the clinical pharmacology — is a procedure to gain quantitative statements about conversion factors and resorption processes by means of calculation models. For that purpose two basic requirements are necessary: 1. It should be possible to describe the elimination of the investigated compounds from blood by equations of first order, that means increase in concentration and velocity of elimination have to be proportional. This is given for most of the investigated substances, and for amino-acids, too. Key factor is a compound specific elimination constant (k₂) of the exponential equation. 2. The distribution volume of the substance must be known. It is to determine by intravenous infusion of known quantities of the compound. For aminoacids it ranges from 674 (PHE) to 212 (TRP) ml/kg body weight. By mathematical operations like eliminating the elimination processes from concentration/time curves after oral application qualitative and quantitative informations about the entry of resorbed amino-acids into the periphere circulation and by that about the biological use of the applicated amino-acids can be gained.