Determination of Isobaric Enthalpy Differences of Heat Transfer Fluids

The heat capacity of eutectic diphenyl oxide (DPO) and biphenyl (BP) was investigated with Calvet-type differential scanning calorimetry. Significant impact of the sample mass per crucible was found. With 82 mg per 130 µl lowest impact by heat of evaporation on the readings was achieved. With the linear data fit C (in J/(g*K)) = 0.00268 * T (in °C) + 1.4917 in the range of 130 – 409 °C the calculated enthalpy difference between 300 °C and 400 °C is 0.6 – 3.7% smaller in comparison to the projections based on manufacturer’s data sheets. The impact of pressure on the enthalpy difference was tested with a compression loop between 17 bar and 63 bar. It could be shown that additional mechanical pressure causes decreases of the enthalpy difference by -0.03% J/(g*bar)

Lignin-Depolymerisation via UV-Photolysis and Titanium Dioxide Photocatalysis

Today, more than 70 million tons of lignin are produced by the pulp and paper industry every year. However, the utilization of lignin as a source for chemical synthesis is still limited due to the complex and heterogeneous lignin structure. The purpose of this study was a selective photodegradation of industrially available kraft lignin in order to obtain appropriate fragments and building block chemicals for further utilization, e.g. polymerization. Thus, kraft lignin obtained from soft wood black liquor by acidification was dissolved in sodium hydroxide and irradiated at a wavelength of 254 nm with and without the presence of titanium dioxide in various concentrations. Analyses of the irradiated products via SEC showed decreasing molar masses and decreasing polydispersity indices over time. At the end of the irradiation period the lignin was depolymerised to form fragments as small as the lignin monomers. TOC analyses showed minimal mineralisation due to the depolymerisation process

The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

The synthesis of various 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones was realized following a simple three-step process. The protocol utilized the photodecarboxylative addition of readily available carboxylates to N-(bromoalkyl)phthalimides as a versatile and efficient key step. The initially obtained hydroxyphthalimidines were readily converted to the desired N-diaminoalkylated 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones via acid-catalyzed dehydration and subsequent nucleophilic substitution with the corresponding secondary amines. The procedure was successfully applied to the synthesis of known local anesthetics (AL-12, AL-12B and AL-5) in their neutral forms

Photochemischer Abbau von Ibuprofen mit Phosphorkonvertierten Xenon-Entladungslampen

Der Eintrag anthropogener Spurenstoffe in die Umwelt ist unerwünscht. Problematisch sind bspw. in Abwässern enthaltene Medi-kamentenrückstände. Die Reinigung gelingt mit UVC-Strahlung, die bisher bspw. mit Quecskilber-haltigen Amalgamstrahlern erzeugt wird. Xenon-Excimerlampen liefern UVC-Strahlung ohne toxisches Quecksilber. Die aus Xenon-Excimeren emittierte Strahlung ist mit 172nm extrem kurzwellig. Mit neuen speziellen Phosphoren kann sie in längere Wellenlängen konvertiert und somit effizienter zur Wasserbehandlung eingesetzt werden