A study of the copper-catalysed direct arylation of β-dicarbonyl compounds with 2-bromobenzoic acids

The Cu-catalysed condensations of 2-bromobenzoic acids with β-dicarbonyl anions to give α-arylated-β-dicarbonyl compounds have been investigated in detail. Previously recommended experimental conditions for these reactions are shown to be in appropriate and the limited synthetic utility of these processes in the past is explained. Much superior conditions have now been developed by use of which a variety of β-dicarbonyl compounds can readily be arylated in good to excellent yield with A wide range of substituted 2-bromobenzoic acids and with certain other halo-aromatic acids. The scope and limitations of the synthetic method have been established, and a simple, high yield procedure for the preparation of homophthalic acids is described. It is shown that Cu(I) is almost certainly the effective catalyst, and information has been obtained on the probable mechanism of the substitution reaction by examination of steric and electronic effects in the halo-aromatic acids and by consideration of the structure and role of the β-dicarbonyl component.     

Analysis of carbohydrates by anion exchange chromatography and mass spectrometry

A versatile liquid chromatographic platform has been developed for analysing underivatized carbohydrates using high performance anion exchange chromatography (HPAEC) followed by an inert PEEK splitter that splits the effluent to the integrated pulsed amperometric detector (IPAD) and to an on-line single quadrupole mass spectrometer (MS). Common eluents for HPAEC such as sodium hydroxide and sodium acetate are beneficial for the amperometric detection but not compatible with electrospray ionisation (ESI). Therefore a membrane-desalting device was installed after the splitter and prior to the ESI interface converting sodium hydroxide into water and sodium acetate into acetic acid. To enhance the sensitivity for the MS detection, 0.5 mmol/l lithium chloride was added after the membrane desalter to form lithium adducts of the carbohydrates. To compare sensitivity of IPAD and MS detection glucose, fructose, and sucrose were used as analytes. A calibration with external standards from 2.5 to 1000 pmole was performed showing a linear range over three orders of magnitude. Minimum detection limits (MDL) with IPAD were determined at 5 pmole levels for glucose to be 0.12 pmole, fructose 0.22 pmole and sucrose 0.11 pmole. With MS detection in the selected ion mode (SIM) the lithium adducts of the carbohydrates were detected obtaining MDL's for glucose of 1.49 pmole, fructose 1.19 pmole, and sucrose 0.36 pmole showing that under these conditions IPAD is 3-10 times more sensitive for those carbohydrates. The applicability of the method was demonstrated analysing carbohydrates in real world samples such as chicory inulin where polyfructans up to a molecular mass of 7000 g/mol were detected as quadrupoly charged lithium adducts. Furthermore mono-, di-, tri-, and oligosaccharides were detected in chicory coffee, honey and beer samples.     

A Combined Experimental and Computational Study of Chrysanthemin as a Pigment for Dye-Sensitized Solar Cells

The theoretical study of chrysanthemin (cyanidin 3-glucoside) as a pigment for TiO₂-based dye-sensitized solar cells (DSSCs) was performed with the GAUSSSIAN 09 simulation. The electronic spectra of neutral and anionic chrysanthemin molecules were calculated by density functional theory with B3LYP functional and DGDZVP basis set. A better energy level alignment was found for partially deprotonated molecules of chrysanthemin, with the excited photoelectron having enough energy in order to be transferred to the conduction band of TiO₂ semiconductor in DSSCs. In addition, we used the raw aqueous extracts of roselle (Hibiscus sabdariffa) calyces as the source of chrysanthemin and the extracts with various pH values were tested in DSSCs. The extracts and photosensitized semiconductor layers were characterized by UV-Vis spectroscopy, and DSSCs based on raw extracts were characterized by current density-voltage measurements.     

A Novel Green Synthesis of Silver Nanoparticles Using Gum Karaya: Characterization,Antimicrobial and Catalytic Activity Studies

Stable silver nanoparticles have been synthesized using gum karaya acting as both reducing and stabilizing agent without using any synthetic reagent. The reaction is performed using water, which is an environmentally safe solvent. This reaction was carried out in an autoclave at a pressure of 15 psi and 120 °C temperature by varying the time. The influence of different parameters such as time, change of concentration of silver nitrate and concentration of gum karaya on the formation of silver nanoparticles has been studied. The synthesized silver nanoparticles are characterized by UV–Vis spectroscopy, FTIR, XRD and TEM. UV–Vis analysis of the sample confirmed the formation of silver nanoparticles exhibiting a sharp peak at a wavelength of 420 nm. TEM micrographs showed the formation of well-dispersed silver nanoparticles of size 2–4 nm. The antimicrobial activity of silver nanoparticles stabilized in gum karaya is tested against Escherichia coli, Micrococcus luteus and is found to be possessing inhibiting property. The silver nanoparticles stabilized in gum karaya exhibited very good catalytic activity and the kinetics of the reaction was found to be pseudo first order with respect to the 4-nitrophenol.     

Electric field assisted charge carrier photogeneration in poly(spirobifluorene-co-benzothiadiazole)

The dynamics of charge carrier generation in poly(spirobifluorene-co-benzothiadiazole) was investigated by electric field-induced fluorescence quenching and differential absorption measurements. Three different time domains of carrier generation have been identified: an ultrafast phase, a subnanosecond phase, and an entire lifetime phase. The charge generation efficiencies during the first and second phases were found to be almost independent of temperature, being about 25% and 10%, respectively, at an applied electric field of 1.3×10(6)?V/cm, while the generation efficiency during the third phase increases from 2% at 80 K to 10% at room temperature. The results of transient spectroscopy measurements and quantum chemical calculations suggest an intramolecular charge transfer for about 1 ps from the alkoxy-substituted fluorene side group to the benzothiadiazole subunit of the main chain. The formation and evolution of the resulting charge transfer states determine the way of charge carrier generation.     

Analysis of urinary oligosaccharides in lysosomal storage disorders by capillary high-performance anion-exchange chromatography–mass spectrometry

Many lysosomal storage diseases are characterized by an increased urinary excretion of glycoconjugates and oligosaccharides that are characteristic for the underlying enzymatic defect. Here, we have used capillary high-performance anion-exchange chromatography (HPAEC) hyphenated to mass spectrometry to analyze free oligosaccharides from urine samples of patients suffering from the lysosomal storage disorders fucosidosis, α-mannosidosis, G(M1)-gangliosidosis, G(M2)-gangliosidosis, and sialidosis. Glycan fingerprints were registered, and the patterns of accumulated oligosaccharides were found to reflect the specific blockages of the catabolic pathway. Our analytical approach allowed structural analysis of the excreted oligosaccharides and revealed several previously unpublished oligosaccharides. In conclusion, using online coupling of HPAEC with mass spectrometric detection, our study provides characteristic urinary oligosaccharide fingerprints with diagnostic potential for lysosomal storage disorders.     

New resolving bases for ibuprofen and mandelic acid: qualification by binary phase diagrams

New resolving bases for ibuprofen 1 and mandelic acid 2 were studied and qualified by their binary phase diagrams of the corresponding salts. It was shown that analysis of the binary phase diagrams gives a good prediction for a resolution process. A comparison of resolving bases revealed that (S)-phenylglycinol (S)-7 is the best resolving base for ibuprofen 1. By the same procedure, various resolving bases for mandelic acid 2 were studied. The known resolving base (S)-MBA 9 was found to be the best for this acid.     

Polypropylene and polyethylene blends

Summary The flow behaviour of blends of an isotactic polypropylene (PP) and a high density polyethylene (PE) in the molten state was studied as a function of composition, temperature and shear rate to examine the degree of compatibility under shear. PP and PE were melt blended in a laboratory single screw mixing extruder at the compositions 0, 25, 50, 75 and 100 percentage of PE by weight and shear stress versus shear rate data were obtained using an Instron capillary viscometer at different temperatures. Viscosity-shear rate data of PP-PE blends at different temperatures constitute master curves at constant blend composition, when plotted as /₀ versus ₀/T. This type of behaviour is commenly observed for homopolymer systems. Therefore these experimental findings indicate that the PP-PE system forms either a compatible blend in the molten state under shear flow conditions or a morphology which is independent of temperature.

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Zusammenfassung Es wurde das Fließverhalten von Mischungen eines isotaktischen Polypropylens (PP) und eines Polyäthylens mit hoher Dichte (PE) im Schmelzzustand untersucht in Abhängigkeit von der Zusammensetzung, der Temperatur und der Schergeschwindigkeit. Damit sollte der Grad der Kompatibilität unter Scherbeanspruchung geprüft werden. PP und PE wurden in einem Labor-Einschnecken-Misch-Extruder mit Anteilen von 0, 25, 50, 75 und 100 Gewichts-Prozent PE zusammengemischt. Die Fließkurven wurden bei verschiedenen Temperaturen in einem Instron-Kapillar-Rheometer gemessen. Die Viskositätsverläufe als Funktion der Schergeschwindigkeit bei verschiedenen Temperaturen lassen sich bei konstantem Mischungsverhältnis zu Masterkurven zusammenfassen, wenn man /₀ gegen ₀/T aufträgt. Dieses Verhalten findet man gewöhnlich nur für Homopolymerisate. Daher zeigen diese experimentellen Ergebnisse an, daß die PP-PE-Systeme im Schmelzzustand unter der Bedingung des Scherfließens entweder eine kompatible Mischung bilden oder aber eine temperaturunabhängige Morphologie aufweisen.

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In partial fulfilment of the Teknisk Licentiate degree (Ph.D.).

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With 11 figures and 3 tables