Untersuchungen zur Feinstruktur des PVC,V Herstellung von 1,2,6-Trichlor-n-hexan als Modellsubstanz für niedermolekulares PVC

The reaction of 1,2,6-trihydroxy-n-hexane (IV) with thionylchloride gives 1,2,6-trichloro-n-hexane (II) which is used as model substance for ¹H-NMR, ¹³C-NMR and mass spectrometry and can be compared with extracted and hydrogenated low molecular weight PVC, respectively.     

Untersuchungen zur Sulfochlorierung von Paraffinen. III. 1H- und 13C-NMR-Spektren aliphatischer und cycloaliphatischer Mono- und Disulfochloride

Studies on the Sulphochlorination of Paraffins. III. ¹H- and ¹³C-N.M.R. Spectra of Aliphatic and Cycloaliphatic Mono- and Disulphonylchlorides Isomeric monosulphonylchlorides of propane, butane, and heptane as well as disulphonylchlorides of propane, butane, and pentane are measured ¹H- and ¹³C-n.m.r.-spectroscopically. Including several other aliphatic and cycloaliphatic sulphonylchlorides, the use of n.m.r. spectroscopy to identification and estimation of the composition of mono- and disulphonylchloride mixtures is discussed.     

Stereochemische Untersuchungen mit der 13C-NMR-Spektroskopie. 2-Methoxycarbonyl-cyclohexanole und deren Acetate

Stereochemical Investigations by means of ¹³C NMR Spectroscopy. 2-Methoxycarbonyl-cyclohexanols and their Acetates The ¹³C NMR spectra of cis-( 1 ) and trans-( 2 ) 2-methoxycarbonyl-cyclohexanol and of cis-( 3 ) and trans-( 4 ) 2-methoxycarbonyl-cyclohexyl acetate are reported, and the signals are assigned by means of substituent shift increments. The so interpreted spectra allow conclusions concerning the configuration and predominant conformation of the compounds. It is shown that an upfield shift of the substituted carbon atom does not necessarily imply the axial position of the substituent.     

Stereochemische Untersuchungen mit der 13C-NMR-Spektroskopie. V. Methyl- und tert.-butylsubstituierte Cyclohexane

Stereochemical Investigations by Means of ¹³C-N.M.R.-Spectroscopy. V. Methyl- and tert.-Butyl-substituted Cyclohexanes The ¹³-chemical shifts of some cyclohexanes with methyl and tert. butyl as substituents in configurational different positions are discussed. The substituent effects of the methyl and t-butyl groups, respectively, on the C-atoms of the ring are different and can be explained with the aid of long range (γ and δ) steric interactions. It is shown, that in all investigated compounds a twisted conformation of the ring is prefered instead of an axial arrangement of a t-butyl group.     

Rheo-mechanische Untersuchungen der Netzwerkstruktur von Elektrodenkontaktgelen und HPLC-Methode zur Bestimmung des Restmonomergehaltes

Hydrogels were synthesized by photoinitiated copolymerization of acrylic acid and triethylene glycol dimethacrylate (TEGMA). In less than one minute an aqueous reaction mixture underwent UV-curing to yield transparent gels that retain their shape. The correlation between structure and properties makes them suitable for the use in medical electrodes. The viscoelastic properties and plateau moduli (G'_P) were determined as functions of the cross-linker concentration by means of rheo-mechanical oscillation measurements. The molecular weights between two entanglement points were calculated from the G'_P values and vary from 4.6·10⁵ to 1,7·10⁶ g mol^–1, depending on the concentration of TEGMA. The low cross-linking efficiency of 1% estimated from G'_P is probably caused by network defects and was not influenced by the degree of cross-linking. Thermal initiators were employed and time-dependent measurements of the storage modulus (G') were taken in order to study the kinetics of gel formation. It was thus possible to compare the effectiveness of different initiators and their influence on the elasticity of the hydrogels. In addition, the content of acrylic acid in the prepared gels was determined by selective extraction and HPLC separation of the monomer from the complex multicomponent mixture. It was found that the residual monomer content of about 0.40% w/w could be reduced to almost zero by increasing the duration of exposure. Finally, the effect of the cross-linker concentration on the monomer content in the hydrogels was also investigated.     

Untersuchungen zur kontinuierlichen Hydrierung von Ölen und Fettsäuren IV: Stoffübergang bei kontinuierlicher Hydrierung

Investigations of Continuous Hydrogenation of Oils and Fatty Acids IV: Migration of Material During Continuous Hydrogenation Material migration takes place more or less in the velocity of the process in every heterogeneously catalyzed reaction. Above all hydrogenation of free fatty acids or fatty acids bound in triglycerides in the three phase system can make material migration valid. The effect of material migration on the reaction kinetic, especially by using high-active catalysts, was verified in a continuous hydrogenation system according to the trickling procedure. The effect of pressure increase up to 0.5 MPa is much higher than in the range of 1-2 MPa. The values of the material migration figure k_m were found in the range of 1.3 to 4.9 · 10⁴ cm · s^?1.     

Untersuchungen zur kontinuierlichen Hydrierung von Ölen und Fettsäuren I: Verlauf des Austausches der Rohstoffe

Investigations of the Continuous Hydrogenation of Oils and Fatty Acids I: Course of Raw Material Exchange The authors investigated the speed of exchange from one raw material to another during continuously hydrogenation in the system of trickling procedure of a continuous current reactor with solid catalyst layer. Pelletted Ni-catalyst with a Ni-content of 48.1% and a degree of reduction of 49% was used. The nearly complete exchange of sunflower oil for oleic acid and vice versa was reached by use of 2.5 to 3 fold acid or oil volume referred to catalyst layer volume.     

Konformationsuntersuchungen mit Hilfe der 13C-NMR-Spektroskopie. II. Vorzugskonformationen,Substituenteneffekte und Barrieren der Ringinversion von Ketalen methylsubstituierter Cyclohexanone

Conformational Investigations by Means of ¹³C-N.M.R.-Spectroscopy. II. Conformational Preferences; Substituent Effects and Barriers to Ring Inversion in the Ketals of Methyl-substituted Cyclohexanones The comparison of the experimental determined ¹³C-NMR-chemical shifts of 8 ketal s with those, which were calculated by the well-known additivity rules allows some conclusions about the conformation of the compounds respectively about γ-gauche-effects and δ-syn-axial interactions in question. ¹³C-NMR-measurements at low temperatures make it possible to determine the barriers to ring inversion of some ketals. The obtained values are discussed in dependence of the substitution pattern.     

Untersuchungen zur kontinuierlichen Hydrierung von Ölen und Fettsäuren V: Grad der Ausnutzung der Ni-Katalysatoroberfläche bei der Hydrierung

Investigations of Continuous Hydrogenation of Oils and Fatty Acids V: Degree of Utilization of Ni-Catalyst Surface During Hydrogenation Hydrogenation of olive oil by Ni-catalyst according to the trickling process was investigated in a simplified reactor model. The tests were carried out by discontinuous proceeding on pelletted Ni-catalyst with elimination of the influences of the outer diffusion and by discontinuous proceeding with elimination of the outer and internal diffusion (powdery catalyst). The obtained values of the effective factor of the outer diffusion showed that the laminar film on the surface of the pellets causes a small resistance to mass transfer. The measurements of the effective factors of the internal diffusion showed that the degree of the exploit of the internal catalyst surface during hydrogenation of oils on pelletted Ni-catalyst is low.     

Struktur und Eigenschaften von ABS-Polymeren, 13. Einfluß der Polymerisationsbedingungen auf die Struktur von ABS-Polymeren bei der Pfropfung in Emulsion

By grafting styrene-acrylonitrile onto poly(butadiene) latex graft polymers of different structure are synthesized. During the graft reaction the monomer to poly(butadiene) ratio and the conversion were varied and the influence of these variations on the degree of grafting and the molecular weight of grafted chains was studied. By mixing these graft polymers of different graft structure (graft density) with styrene-acrylonitrile-copolymers, ABS-materials are formed with a rubber content of 17.5% by weight. Glass transition temperature (T_g) of the elastomer phase of these ABS materials as well as notched impact values correlate with graft density of the rubber component.     

Untersuchungen zur Sulfochlorierung von Paraffinen. X. Über die Anwendbarkeit additiver Inkremente bei der Auswertung der 13C-NMR-Spektren von Alkanmono- und -disulfochloriden und von Chloralkansulfochloriden

Studies on Sulphochlorination of Paraffins. X. The Application of Additive Increments for the Interpretation of ¹³C-N.M.R. Spectra of Alkane Mono- and Disulphochlorides and of Chloroalkane Sulphochlorides Increments which consider the influence of chlorine and sulphonylchloride substituents on the ¹³C-n.m.r. shifts of alkanes were calculated and discussed. The application of additive increments for the calculation of ¹³C-n.m.r. chemical shifts of alkane-1,2-disulphonylchlorides, branched alkane monosulphonylchlorides, sulphochlorinated 1-alkylchlorides and chlorinated 1-alkane sulphonylchlorides is demonstrated. The limitations of the method are discussed.     

Konformationsuntersuchungen mit Hilfe der 13C-NMR-Spektroskopie. IV. Additive Berechnung der 13C-chemischen Verschiebungen in 2-Brom-cycloalkanolen und 2-Brom-1-methoxy-cycloalkanen unterschiedlicher Ringgröße

Conformational Investigations by Means of ¹³C-N.M.R.Spectroscopy. IV. Additive Calculation of the ¹³C-N.M.R. Chemical Shifts in 2-Bromo-cycloalkanoles and 2-Bromo-1-methoxy-cycloalkanes of Different Ring Size The ¹³C-n.m.r. spectra of a series of bromo-cycloalkanes, cycloalkanoles, methoxy-cycloalkanes, trans-2-bromo-cycloalkanoles and trans-2-bromo-1-methoxy-cycloalkanes (ring size n = 5, 6, 7, 8, 12) as well as cis-2-bromo-cyclododecanol and cis-2-bromo-1-methoxycyclododecane are obtained and assigned. The ¹³C-chemical shifts of the monosubstituted compounds have been used to estimate the substituent effects of bromo, hydroxy and methoxy groups to the α-, β- and γ-position. Using these shift parameters, the ¹³C-chemical shifts of the vicinal disubstituted compounds are calculated in an additive incremental manner. These ¹³C-chemical shifts have been compared with the experimental values and the differences are discussed with respect to the magnitude of the deviations from additivity with the dimension of steric and electronic interaction of the vicinal substituents.     

Struktur und Eigenschaften von ABS-Polymeren. IV. Zum Einfluß der thermischen Vorbehandlung auf das Deformationsverhalten von ABS-Pfropfpolymerisaten

The influence of thermal history on the thermomechanical properties of a graft polymer (ABS) is investigated. The thermal pretreatments are: sharp quenching from above the glas-transition of the matrix resin, annealing below the glas transition. A first characterization of the influence of these two pretreatments is done by measuring density, probe length as function of temperature and by DTA. The less modulus in the region below the glas transition of the matrix resin is very sensitive to thermal pretreatment. Small but reproducible influences are observed in the glas transition region of the polybutadien particles. At room temperature stress-strain measurements are achieved until fracture happens. Crazing is observed (which is often called stress-whitening) in all cases, but the extent of craze growing is dependent on thermal history. The measurements are completed by scanning micrographs of the fracture surfaces. Annealing of the fracture surfaces gives additional informations. The results are discussed using the concept of free volume which is variated by thermal pretreatment. At room temperature the phase-boundary between polybutadion particle and matrix resin is considered as transition zone from high to small hole concentration. The sharpness of this zone is supposed to be a decisive parameter for the macroscopic deformation behaviour.     

Untersuchungen zur Thermischen Umsetzung von Phenylcyclopentan, -hexan, -heptan und -octan in der Gasphase

Studies on Thermal Conversion of Phenyleyclopentane, -hexane, -heptane, and -octane in the Gas Phase The title compounds were pyrolyzed from 700 to 780°C in a metallic laboratory tubular reactor in the presence of steam. The reaction products were analyzed by gas chromatography and by a combination of gas chromatography and mass spectrometry. From the phenylcyclanes tested, more than 65 hydrocarbons could be detected in the liquids, besides gaseous reaction products. In most cases unambiguous structures could be derived by using different analytical methods. As typical initial-step products phenylcyclenes, ω-phenyl-1-alkenes and 1-phenyl-1-alkenes are formed by dehydrogenation and isomerization of the title compounds. The detection of phenylalkenes corresponds well with the isomerization of unsubstituted cyclanes to the corresponding α-olefines described in former papers.