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Search Results: 1 - 10 of 295 matches for " Herwig Schottenberger "
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Improved Synthesis and Crystal Structure of Dalcetrapib
Gerhard Laus,Volker Kahlenberg,Frank Richter,Sven Nerdinger,Herwig Schottenberger
Crystals , 2012, DOI: 10.3390/cryst2041455
Abstract: An improved synthesis of the Cholesteryl Ester Transfer Protein inhibitor dalcetrapib is reported. The precursor disulfide was reduced (a) by Mg/MeOH or (b) by EtSH/DBU/THF. The resulting thiol was acylated (a) by a known procedure or (b) in a one-pot process. Impurities were removed (a) by dithiothreitol (DTT) or (b) by oxidation using H 2O 2. Dalcetrapib crystallized in space group P2 1/ c.
Halogen Interactions in 2,4,5-Tribromoimidazolium Salts
Carmen Froschauer,Volker Kahlenberg,Gerhard Laus,Herwig Schottenberger
Crystals , 2012, DOI: 10.3390/cryst2031017
Abstract: The crystal structures of 2,4,5-tribromo-1-(prop-2-ynyl)imidazole and seven new 1,3-dialkyl-2,4,5-tribromoimidazolium salts ( R 1 = propenyl, propynyl, dibromopropenyl; R 2 = Me, Et) with halogen-containing anions (tetrafluoroborate, hexafluorophosphate, triflimide) were determined. The structures revealed halogen...halogen and anion...π interactions. Contacts of the type Br...Br, Br...F, Br...O, Br...N, F...F, H...Br, H...F, F...π and O...π were identified. Specific interactions were quantified by Hirshfeld surface analysis.
1,4-Diazabicyclo[2.2.2]octane (DABCO) 5-aminotetrazolates
Gerhard Laus,Volker Kahlenberg,Klaus Wurst,Michael Hummel,Herwig Schottenberger
Crystals , 2012, DOI: 10.3390/cryst2010096
Abstract: The crystal structures of four salts of 1,4-diazabicyclo[2.2.2]octane (DABCO) and 5-aminotetrazole are described. Anhydrous 1:1 ( Pbca, R gt = 0.041) and 1:2 ( P, R gt = 0.038) salts form hydrogen-bonded layers of anions and cations. The monohydrate of the 1:1 compound ( P2 1/ c, R gt = 0.038) shows infinite chains of DABCO cations and an undulated layer of anions and water molecules. The octahydrate of the 3:2 compound ( P2 1/ c, R gt = 0.042) features DABCO triples and clusters of four tetrazolate ions in a network of water molecules.
Syntheses and Crystal Structures of Ferrocenoindenes
Klaus Wurst,Gerhard Laus,Michael R. Buchmeiser,Herwig Schottenberger
Crystals , 2013, DOI: 10.3390/cryst3010141
Abstract: Ferrocenoindenes display planar chirality and thus represent valuable ligands for asymmetric catalysis. Here, we report on the synthesis of novel 3-(1,1-dibromomethylene)ferroceno[1,2-a]indene, ( Z)-3-(1-bromomethylene)-6-iodoferroceno[1,2-a]indene, and benzo[5,6-f]ferroceno[2,3,a]inden-1-one. Any application-oriented design of chiral catalysts requires fundamental knowledge about the ligands involved, not only in terms of atom-connectivity, but also in terms of their three-dimensional structure and steric demand. Therefore, the crystal structures of 2-ferrocenylbenzoic acid, ferroceno[1,2-a]indene, and ( Z)-3-(1-bromomethylene)-6-iodoferroceno[1,2-a]indene have been determined. The bond-lengths that can be retrieved therefrom also allow for an estimation of the reactivity of the aryl-iodo, bromo-methylidene and dibromomethylidene moieties.
Crystal Structure of 2-Ethylimidazole-1-sulfonyl Azide: A New Azidation Reagent
Gerhard Laus,Verena Adamer,Michael Hummel,Volker Kahlenberg,Klaus Wurst,Sven Nerdinger,Herwig Schottenberger
Crystals , 2012, DOI: 10.3390/cryst2010118
Abstract: Crystalline 2-ethylimidazole-1-sulfonyl azide was designed as a convenient reagent with improved thermal stability for electrophilic azidation of carbanions. The compound crystallized in the monoclinic space group P2 1/ c. The molecules are arranged into chains by short C–H...O contacts along a two-fold screw axis. The quaternary 1-azidosulfonyl-2-ethyl-3-methylimidazolium tetrafluoroborate crystallized in Fdd2 with two independent ion pairs which engage in C–H...F interactions.
M?ssbauer Spectroscopy and X-ray Diffraction Study of 57Fe-Labeled Tetrachloroferrate(III)-Based Magnetic Ionic Liquids
Rolfe H. Herber,Israel Nowik,Mirco E. Kostner,Volker Kahlenberg,Christoph Kreutz,Gerhard Laus,Herwig Schottenberger
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12106397
Abstract: Four 57Fe-labeled tetrachloroferrates(III) of organic cations (1-butyl-3-methyl-imidazolium, 1-allyl-3-methylimidazolium, 1-methyl-1-propylpyrrolidinium, tetraphenyl-phosphonium) were examined by temperature-dependent M?ssbauer spectroscopy. The hyperfine and dynamic parameters of the iron(III) site were determined. Single crystal X-ray diffraction data of [Ph 4P][FeCl 4] were collected at four temperatures (295, 223, 173, and 123 K), and the dynamics of the iron atom inferred from the M?ssbauer data and the single crystal U i,j parameters have been compared.
Iminium Salts by Meerwein Alkylation of Ehrlich’s Aldehyde
Carmen Froschauer,Hedda K. Weber,Volker Kahlenberg,Gerhard Laus,Herwig Schottenberger
Crystals , 2013, DOI: 10.3390/cryst3010248
Abstract: 4-(Dimethylamino)benzaldehyde is alkylated at the N atom by dialkyl sulfates, MeI, or Me 3O BF 4. In contrast, ethylation by Et 3O BF 4 occurs selectively at the O atom yielding a quinoid iminium ion. 4-(Diethylamino)benzaldehyde is alkylated only at O by either Et or Me oxonium reagent. The iminium salts are prone to hydrolysis giving the corresponding hydrotetrafluoroborates. Five crystal structures were determined.
Synthesis and Crystal Structures of New 5,5'-Azotetrazolates
Gerhard Laus,Volker Kahlenberg,Klaus Wurst,Herwig Schottenberger,Niko Fischer,J?rg Stierstorfer,Thomas M. Klap?tke
Crystals , 2012, DOI: 10.3390/cryst2010127
Abstract: Five new 5,5'-azotetrazolate salts (amminsilver, trimethylsulfonium, tetramethyl-phosphonium, trimethylsulfoxonium, 2-(hydroxyethyl)trimethylammonium) were prepared and characterized. The crystal structures were determined by X-ray diffraction. Interactions between the ions are identified and discussed. The sensitivities of the highly energetic silver salt were measured by BAM (Bundesanstalt für Materialforschung und-prüfung) methods.
The Misleading Use of “Enthalpy” in an Energy Conversion Analysis  [PDF]
Heinz Herwig
Natural Science (NS) , 2014, DOI: 10.4236/ns.2014.611085
Abstract: The frequently used thermodynamic state quantity enthalpy H turns out to be very problematic when applied in an energy conversion analysis. Due to the fact that H combines two terms, the internal energy U and the product pV, the interpretation of what H means in physical terms is often obscure and leads to various misinterpretations. Several examples are given and interpreted twice,i.e.with and without referring to enthalpy.
Risk management in patients with severe acute pancreatitis
Herwig Gerlach
Critical Care , 2004, DOI: 10.1186/cc3007
Abstract: Severe acute pancreatitis (SAP) can progress to a critical condition within a few hours or days after the onset of symptoms. Particularly during the early course of the disease, patients are at high risk for developing infections with subsequent multiple organ dysfunction syndrome. Therefore, early surgical intervention has been favoured, although evidence-based data are lacking. In this issue of Critical Care, De Waele and coworkers [1] present findings from a critical review conducted over nearly a decade. In contrast to many prior recommendations, the authors could not find any significant association between the timing of surgery and patient outcomes. Moreover, they identified patient age, severity of organ dysfunction at the time of surgery, and the presence of sterile necrosis as the main risk factors, and concluded that an early surgical intervention is not justified in the absence of proven infection when necrosis is detected after computed tomography (CT) scan [1]. These important findings once again raise the issue of risk assessment in the individual patient with SAP.A major problem in the treatment of patients with SAP is the lack of randomized trials. Recently, King and coworkers [2] reported results from the first pan-European survey conducted among specialists in hepato-pancreato-biliary surgery of surgical strategies for management of SAP, with the aim being to highlight areas of discordance and thus provide a rational focus for future research. A questionnaire survey of 866 surgeons was undertaken, and the response rate was 38%. Severity stratification was used by 324 respondents (99%), with the Ranson score being the most popular. Antibiotic prophylaxis was utilized by 73%, and fine needle aspiration biopsy (FNAB) was undertaken by 53% of respondents. Furthermore, the results show that there were further aspects of practice that were concordant among surgeons, such as use of early CT and agreement that infected necrosis should be treated surgically
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