bluuebunny/crossref_metadata_2025 huggingface dataset:
Die „Erweiterung”︁ des Redox‐Begriffs mit Stoffen aus dem Alltag
Authors: Rossow Marco , Flint Alfred
Published: April 2009

In so gut wie allen Bereichen des täglichen Lebens finden in kleinerem und größerem Umfang ständig Redoxreaktionen statt. Dabei handelt es sich teilweise um scheinbar sehr einfache und uns aus dem Alltag geläufige Reaktionen, wie das Verbrennen einer Kerze, das Verbrennen von Benzin, das Rosten eines Eisengegenstandes oder das Anlaufen von Kupferrohren und ‐dächern.

Weit weniger geläufig und dennoch von sehr großer Bedeutung sind die Redoxreaktionen, die in Batterien und Akkumulatoren ablaufen (vgl. [6]). Der Grund für den geringen Bekanntheitsgrad ist, dass man den Verlauf dieser Reaktionen nicht sehen kann. Während des Betriebes verändern sich die elektrochemischen Spannungsquellen rein äußerlich nicht. Ist eine Batterie oder ein Akkumulator entleert, so wird sie ersetzt bzw. man lädt ihn auf. Eine Stoffumwandlung ist in keinem der Fälle wahrnehmbar.

Weitere Bereiche des alltäglichen Lebens, in denen Redoxreaktionen eine große Rolle spielen, jedoch kaum wahrgenommen werden, sind sowohl Einfärbungs‐ als auch Entfärbungsprozesse. Dabei nimmt in einer Zeit, in der man günstig Kleidung kaufen kann, die Alltagsrelevanz der Färbeprozesse ab. Das Entfärben von unerwünschten Rotwein‐ oder Grasflecken ist jedoch nach wie vor im täglichen Leben von großer Bedeutung.

Nicht nur im Alltag, sondern auch in der Wissenschaft Chemie spielen die Redox‐Reaktionen eine ganz entscheidende Rolle. Sie sind neben den Säure‐Base‐Reaktionen die am häufigsten ablaufenden und ihnen liegt ein ganz wesentliches Donator‐Akzeptor‐Prinzip zu Grunde. Dieser Bedeutung tragen auch die derzeitigen Rahmen‐ und Lehrpläne Rechnung, Redox‐Reaktionen nehmen in der Schule einen großen Raum ein. Wir finden sie z.B. im Anfangsunterricht bei den Verbrennungs‐ bzw. Metall‐Metalloxid‐Reaktionen, später bei der Behandlung der Organischen Chemie und der Oxidation von Alkoholen und Aldehyden sowie in der Oberstufe im Bereich der Elektrochemie oder auch bei den Farbstoffen.
Vorstellungen deutscher Chemielehrkräfte über die Bedeutung und Ausrichtung des Chemielernens
Authors: Markic Silvija , Eilks Ingo , van Driel Jan , Ralle Bernd
Published: April 2009

In einer Fragebogenstudie wurden 1142 Chemielehrkräfte verschiedener Schulformen aus sieben Bundesländern über ihre Vorstellungen bzgl. des Lernens und Lehrens von Chemie befragt. Grundlage der Befragung ist das Konzept der ‚Curriculum Emphases’︁ von Roberts [1], also ein Konzept, nach dem jedem Curriculum neben dem Lernen von Inhalten auch eine bestimmte Anzahl von Botschaften inhärent ist. Benutzt wird eine Interpretation von van Berkel [2], die drei wesentliche Ausprägungen für den Chemieunterricht beschreibt: a) Reine Chemie, b) Chemie‐Technik‐Gesellschaft und c) Chemie als lebendige Wissenschaft. In diesem Aufsatz wird aufgezeigt, dass deutsche Chemielehrerinnen und ‐lehrer eine unterschiedliche Orientierung des Curriculums bzgl. verschiedener Schulformen und ‐stufen sehen. Teilweise konnten auch zwischen einzelnen Bundesländern signifikante Unterschiede festgestellt werden. Ausgewählte Ergebnisse aus der Studie werden diskutiert.
A Bilingual Teaching Material for the Chemical Elements
Authors: Franco‐Mariscal Antonio Joaquín , Cano‐Iglesias María José
Published: April 2009

The „Elemental Germany”︁ is an engaging activity for bilingual teaching that encourages high school chemistry students to match the names of the elements with their chemical symbols in order to spell out the names of the German states and their main cities. By completing the puzzle, students reinforce their knowledge of both chemical elements and the names of the German states.
Stable generation of serum‐ and feeder‐free embryonic stem cell‐derived mice with full germline‐competency by using a GSK3 specific inhibitor
Authors: Sato Hiromu , Amagai Keiko , Shimizukawa Rie , Tamai Yoshitaka
Published: April 2009

C57BL/6 (B6)‐derived embryonic stem (ES) cells are not widely used to generate knockout mice despite the advantage of a well‐defined genetic background because of poor developmental potential. We newly established serum‐ and feeder‐free B6 ES cells with full developmental potential by using leukemia inhibitory factor (LIF) and 6‐bromoindirubin‐3′‐oxime (BIO), a glycogen synthase kinase‐3 (GSK3) inhibitor. BIO treatment significantly increased the expression levels of 364 genes including pluripotency markers such as Nanog and Klf family. Unexpectedly, by aggregating or microinjecting those ES cells to each eight‐cell‐stage diploid embryo, we stably generated germline‐competent ES‐derived mice. Furthermore, founder mice completely derived from female XO, heterozygous, or homozygous mutant B6 ES cells were directly available for intercross breeding and phenotypic analysis. We hereby propose that serum‐ and feeder‐free B6 ES cells stimulated with LIF plus GSK3 inhibitor are valuable for generating mouse models on B6 background. genesis 47:414–422, 2009. © 2009 Wiley‐Liss, Inc.
Synthesis of Secondary, Tertiary and Quaternary 1,3,5‐Triazapenta‐1,3‐dienes and Their CoII, ZnII, PdII, CuII and BF2 Coordination Compounds
Authors: Häger Ina , Fröhlich Roland , Würthwein Ernst‐Ulrich
Published: April 2009

The secondary and tertiary 1,3,5‐triazapenta‐1,3‐dienes 2 and 3 are easily obtained by the reaction of N‐imidoyl chlorides with amidines or from ethyl N‐imidoylimidoates 5 and primary amines. In a new synthetic pathway the compounds 5 were prepared by the reaction of imidoates in their protonated or free form with N‐imidoyl chlorides. A quaternary 1,3,5‐triazapenta‐1,3‐diene 4a is obtained by the reaction of the imidoate 5b with pyrrolidine. X‐ray diffraction studies of the tertiary 1,3,5‐triazapenta‐1,3‐diene 3c and its protonated form 3c·HCl allow the comparison of different patterns of intermolecular hydrogen bonding in the solid state. Two equivalents of a secondary 1,3,5‐triazapenta‐1,3‐diene 2 were treated at room temperature after deprotonation with potassium tert‐butoxide with CuCl2, Ni(ClO4)2 or with Pd(ac)2 (without deprotonation) to give the corresponding neutral 2:1 chelate complexes (2a)2·Cu, (2a)2·Ni and (2b)2·Pd, respectively. A fluorescent boron complex 2b·BF2 was obtained by reacting 2b with boron trifluoride–diethyl ether. From the tertiary triazapentadiene 3c and CoCl2 or ZnCl2 the six‐membered 1:1 chelate complexes 3c·CoCl2 and 3c·ZnCl2, respectively, were obtained. In these cases a proton shift from the terminal nitrogen atom of the free ligand to the central nitrogen atom of the complex was observed. Two equivalents of 3c reacted at room temperature with Cu(ac)2 or Pd(ac)2 to form the neutral 2:1 chelate complexes (3c)2·Cu and (3c)2·Pd, respectively. A fluorescent 1:1 boron complex 3c·BF2 was obtained from 3c and boron trifluoride–diethyl ether. In all cases the triazapentadienes act as neutral or anionic bidentate ligands to form six‐membered chelates with the metal ion or the boron centre. Most of the complexes were completely characterized, which included X‐ray crystallography.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Supramolecular Architectures and Magnetic Properties of Self‐Assembled Windmill‐Like Dinuclear Copper(II) Complexes with Purine Ligands
Authors: Cepeda Javier , Castillo Oscar , García‐Terán Juan P. , Luque Antonio , Pérez‐Yáñez Sonia , Román Pascual
Published: April 2009

Three new CuII compounds, [Cu2(μ‐ade)4(H2O)2]·(bpa)·8H2O (1), [Cu2(μ‐Hade)4(H2O)2](NO3)4·2[Cu(pic)2(H2O)]·6H2O (2) and [Cu2(μ‐6Clpur)4(H2O)2]·~6H2O (3) [in which ade = adeninate anion, Hade = 7H‐adenine, 6Clpur = 6‐chloropurinate anion, bpa = 1,2‐bis(4‐pyridyl)ethane, pic = 2‐pyridinecarboxylate anion], are reported. Their crystal structures consist of dinuclear copper(II) units, in which four ligands arranged in a windmill‐like fashion bridge the metal ions through a nonlinear NCN group. Supramolecular crystal building of compound 1 is essentially maintained by an extensive network of hydrogen‐bonding interactions that involves direct contacts between the nucleobases. In contrast, in compound 2 there is no evidence for direct interactions between the nucleobases, but the hydrogen bonds among the nucleobases and nitrate counteranions are especially relevant. Compound 3 is mainly built up from T‐shaped noncovalent Cl···N interactions and hydrogen‐bonding interactions involving the crystallization solvent molecules. Magnetic susceptibility measurements indicate the presence of strong intradimeric antiferromagnetic interactions with large singlet–triplet splittings of –222 (for 1), –288 (for 2) and –255 (for 3) cm–1. DFT calculations were carried out to evaluate the dependence of the magnetic coupling value as a function of some key structural parameters: the Cu–N basal plane distance, the axial Cu–Ow distance and the Cu···Cu distance. DFT calculations also revealed that the nature of the bridging ligand is a crucial factor. In this way, the strength to transmit the magnetic interaction of the different bridging ligands is explained on the basis of the number of electron lone pairs.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
The development of a two‐leveled two cross interface for on‐line coupling solid‐phase extraction and capillary electrophoresis‐mass spectrometry
Authors: Lee Wei‐Han , Her Guor‐Rong
Published: April 2009

A two‐leveled, two cross PDMS‐based interface for on‐line coupling of SPE with CE‐MS was proposed. In this interface, the SPE column and the CE separation column were positioned orthogonally and two crosses were fabricated on the interface. With the two cross design, the operation of SPE could be performed independently without unexpected flow through leakage into the separation column. The performance of the interface was optimized using a peptide mixture. The position of the SPE column related to the CE separation channel was found to be critical to the performance of the system. Under the optimal position, the separation efficiency was similar to a CE‐MS experiment without SPE. The peptide signals were enhanced 50‐ to 100‐fold and the repeatability was within 4% RSD for migration time and 10% RSD for peak area. A tryptic digest of cytochrome c was used to demonstrate the feasibility of the interface in protein identification at a level of 1 ng/μL.
Multiresidue determination of penicillins in environmental waters and chicken muscle samples by means of capillary electrophoresis‐tandem mass spectrometry
Authors: Bailón‐Pérez M. Isabel , García‐Campaña Ana M. , del Olmo Iruela Monsalud , Cruces‐Blanco Carmen , Gracia Laura Gámiz
Published: April 2009

A new analytical method based on CZE coupled with tandem MS detection (CE‐MS/MS) has been developed for the simultaneous determination of nine penicillins of human and veterinary use (nafcillin, dicloxacillin, cloxacillin, oxacillin, ampicillin, penicillin G, amoxicillin, penicillin V and piperacillin), whose levels are regulated by the EU Council regulation No. 2377/90 in animal edible tissues. CE separation conditions, sheath liquid composition and electrospray parameters have been carefully optimized to reach high sensitivity and precision. Separation was carried out in a 96 cm total length fused‐silica capillary (50 μm id, 360 μm od) using 60 mM ammonium acetate at pH 6.0 as running buffer. Lomefloxacin was used as internal standard. MS/MS experiments were carried out using an IT as analyzer operating in multiple reaction monitoring mode to achieve the minimum number of identification points established by the 2002/657/EC European Decision. The use of an SPE procedure in two steps, combining Oasis hydrophilic–liphophilic balance and Alumina N cartridges provide a satisfactory preconcentration and clean up treatment for meat samples after extraction of the compounds with ACN. Only Oasis hydrophilic–liphophilic balance cartridges were necessary in water samples to obtain adequate recoveries. The method has been characterized for its use in meat and water samples, using matrix‐matched calibrations. For chicken muscle samples, LODs between 8 and 12 μg/kg have been obtained, in all cases lower than the maximum residue limits permitted. For water samples LODs from 0.18 to 0.26 μg/L could ensure its satisfactory application in aquatic samples.
Development and characterization of cIEF‐MALDI‐TOF MS for protein analysis
Authors: Silvertand Linda H. H. , Toraño Javier Sastre , de Jong Gerhardus J. , van Bennekom Wouter P.
Published: April 2009

This paper describes the hyphenation of cIEF and MALDI‐TOF MS via a fractionation or spotting device. After focusing in cIEF the compounds are hydrodynamically mobilized and deposited on a MALDI target plate using a sheath liquid interface, which provides the catholyte solution and the electrical ground. From previous experiments, sample conditions that resulted in a high resolution in cIEF and acceptable protein signal intensity in MS were selected [Silvertand et al., Electrophoresis, 2008, 29, 1985–1996]. Besides the mixture of test proteins, the sample solution contains 1% Pharmalyte, 0.3% hydroxyethyl cellulose and 0.1% Tween 20 and is used for both optimization as well as characterization of the cIEF‐MALDI‐TOF MS system. Hyphenation problems encountered are mainly due to transfer of the liquid from the needle to the MALDI target plate and are solved by choosing the proper sheath catholyte (200 mM NH4OH in 50% methanol with 0.1% Tween20). MS electropherograms were reconstructed by plotting the intensities of the m/z values corresponding to the proteins versus migration time (related to spot number). Reproducibility, peak width and signal intensity for different focusing and spotting (fractionation) times were calculated using these reconstructed MS electropherograms as well as the UV electropherograms. The best results were obtained with focusing time of 75 min (no under‐ or overfocusing) and a spotting time of 5 s (highest protein signal intensity in MS). The applicability of the system is demonstrated by the analysis of a biopharmaceutical (glucagon) and its deamidation product.
Full operator algorithm for hybrid simulation
Authors: Hung Chung‐Chan , El‐Tawil Sherif
Published: April 2009

One of the weaknesses of the operator splitting method (OSM) is that its corrector step employs the approximation that incremental forces are linearly related to the tested structure's initial stiffness matrix. This paper presents a new predictor–corrector technique in which the assumptions about the tested structure's response are shifted to the predictor step, which results in an enhancement in overall simulation accuracy, especially for nonlinear structures. Unlike OSM, which splits the displacement and velocity operators into explicit and implicit terms, the new method uses predicted accelerations to compute fully explicit displacement and velocity values in the predictor step. Another advantage of the proposed technique, termed the full operator method (FOM) is that its formulation makes it suitable for both quasi‐static and real‐time hybrid simulation. The effectiveness of FOM is first evaluated by investigating error propagation in an undamped single degree‐of‐freedom model. It is shown that the corrector step in FOM is able to significantly suppress aberrant simulation results caused by incorrect estimation of the structure's stiffness matrix. The performance of FOM is demonstrated by exercising two additional models, which exhibit significant inelastic behavior under the prescribed excitation. The simulation results show that the proposed FOM algorithm is capable of producing accurate solutions and that the corrector step is influential in effectively reducing simulation errors. It is also shown that FOM suppresses actuator displacement control errors because of its reliance on measured quantities in the corrector step. Copyright © 2009 John Wiley & Sons, Ltd.
Aroma‐active compounds of Beijing roast duck
Authors: Chen Gengjun , Song Huanlu , Ma Changwei
Published: April 2009

The aroma‐active compounds of Beijing roast duck were investigated by using aroma extract dilution analysis (AEDA), dynamic headspace dilution analysis (DHDA), gas chromatography–olfactometry–mass spectrometry (GC–O–MS) and odour activity values (OAVs; ratio of concentration to odour threshold). The following volatile components are the predominant odorants of Beijing roast duck: 3‐methylbutanal, hexanal, dimethyl trisulphide, methional, 2‐methylbutanal, octanal, heptanal, 2‐methyl‐3‐furanthiol, 2‐furfurylthiol, 2‐ethyl‐3,5‐dimethylpyrazine, (E,E)‐2,4‐nonadienal, 1‐octen‐3‐ol, nonanal, decanal, (E)‐2‐decenal, (E,E)‐2,4‐decadienal, (E)‐2‐nonenal, (E,Z)‐2,6‐nonadienal, (E,E)‐2,4‐octadienal (fatty, fried), etc. Due to abundant flavour precursors of Beijing crammed duck (raw material of Beijing roast duck), such as amino acids, esters, vitamins and carbohydrates, and the special process (e.g. roasting, drying, etc.), the identified compounds above were likely derived from different kinds of reactions, such as degradation of fatty acids and amino acids, Maillard/Strecker and other associated reactions, which were considered to account for the typical aroma of Beijing roast duck. Copyright © 2009 John Wiley & Sons, Ltd.
Effects of surface waves on hydrodynamic pressures on rigid dams with arbitrary upstream face
Authors: Avilés Javier , Suárez Martha
Published: April 2009

The effects of surface gravity waves on earthquake‐induced hydrodynamic pressures on rigid dams with nonvertical upstream face are examined, taking the compressibility and viscosity of water into account. A simple closed‐form solution is obtained by using the Trefftz numerical method. The boundary under study is reduced to the upstream face only and the degrees of freedom of the problem are restricted to the number of trial functions used for analysis. For harmonic base excitation, a number of numerical examples for various geometries of the upstream face are presented. The hydrodynamic pressure distribution, the resultant lateral force and its effective height of application are evaluated. The results are strongly influenced by the upstream shape and, in a lesser degree, by the consideration of surface waves. Copyright © 2009 John Wiley & Sons, Ltd.
Both DNA damage and mitochondrial dysfunction are involved in novel oxadiazolo[3,4‐d]pyrimidine nucleoside derivatives‐induced cancer cell death
Authors: Liu Hai‐liang , Xu Jing‐jing , Dai Xiao‐min , Shi Jing‐Bo , Xu Song , Gao Jing , Yao Qi‐zheng , Liu Feng
Published: April 2009

Eight novel oxdiazolo[3,4‐d]pyrimidine nucleoside derivatives (I‐VIII) were synthesized to investigate their anti‐tumor effects and possible mechanisms. Four human cancer cell lines including Hela, ECA109, HepG2 and A459 cells were used. Compounds VI and VIII showed significant inhibition on cancer cell proliferation by MTT assay and IC50 values were around 30–70 µmol l−1. Both compounds could release nitric oxide (NO), led to a significant intracellular free Ca2+ overloading and resulted in mitochondrial dysfunction, showing a decrease in mitochondrial membrane potential in HepG2 cells in a dose‐dependent manner. Furthermore, compound VIII induced obvious DNA damage on HepG2 cells. These data indicate that compounds VI and VIII are two active antitumor compounds, and both DNA damage and mitochondrial dysfunction are involved in the mechanisms underlying oxadiazolo[3,4‐d]pyrimidine nucleoside derivative‐induced cancer cell death, which might also be related to the released NO. Copyright © 2009 John Wiley & Sons, Ltd.
Differential developmental toxicities of di‐n‐hexyl phthalate and dicyclohexyl phthalate administered orally to rats
Authors: Saillenfait Anne‐Marie , Gallissot Frédéric , Sabaté Jean‐Philippe
Published: April 2009

The objective of this study was to evaluate the developmental toxic potential of di‐n‐hexyl phthalate (DnHP) and dicyclohexyl phthalate (DCHP) in rats. Pregnant Sprague–Dawley rats were exposed to DnHP or DCHP at doses of 0 (olive oil), 250, 500 and 750 mg kg–1 per day, by gavage, on gestational days (GD) 6–20. Maternal food consumption and body weight gain were significantly reduced at 750 mg kg–1 per day of DnHP and at the two high doses of DCHP. Slight changes in liver weight associated with peroxisomal enzyme induction were seen in dams treated with DnHP or DCHP. DnHP caused dose‐related developmental toxic effects, including marked embryo mortality at 750 mg kg–1 per day, and presence of malformations (mainly cleft palate, eye defects and axial skeleton abnormalities) and significant decreases in fetal weight at 500 and 750 mg kg–1 per day. Significant delay of ossification and increase in the incidence of skeletal variants (e.g. supernumerary lumbar ribs) also appeared at 250 mg kg–1 per day. DCHP produced fetal growth retardation at 750 mg kg–1 per day, as evidenced by significant reduction of fetal weight. DnHP and DCHP induced a significant and dose‐related decrease in the anogenital distance of male fetuses at all doses, and there was a significant increase in the incidence of male fetuses with undescended testis at 500 and 750 mg kg–1 per day of DnHP. In conclusion, DnHP showed clear embryolethality and teratogenicity, but not DCHP. There was evidence that both phthalates could alter the development of the male reproductive system after in utero exposure, DnHP being much more potent than DCHP. Copyright © 2009 John Wiley & Sons, Ltd.
S‐allylcysteine attenuates renal injury by altering the expressions of iNOS and matrix metallo proteinase‐2 during cyclosporine‐induced nephrotoxicity in Wistar rats
Authors: Magendiramani Vinayagam , Umesalma Syed , Kalayarasan Srinivasan , Nagendraprabhu Ponnuraj , Arunkumar Jagadeesan , Sudhandiran Ganapasam
Published: April 2009

Cyclosporine A (CsA) is the first choice immunosuppressant used for the prevention of allograft rejection in solid organ transplantation and immune‐mediated diseases. Reactive oxygen species‐induced oxidative stress and lipid peroxidation are implicated in the pathophysiology of CsA‐induced renal injury. In this work, we have studied the effect of a garlic‐derived compound, S‐allylcysteine (SAC) on CsA‐induced nephrotoxicity. CsA‐induced nephrotoxicity was assessed in terms of increased activities of serum marker enzymes and levels of kidney markers. CsA administration induced significant elevation in lipid peroxidation along with abnormal levels of enzymic and non‐enzymic antioxidants in the kidneys of the rats. SAC administration improved renal function by bringing about a significant decrease in peroxidative levels and increase in antioxidant status. Elevated expressions of inducible nitric oxide synthase (iNOS) and nuclear factor kappa B (NF‐κB) due to CsA administration were reduced by SAC treatment. An increase in the expression of matrix metalloproteinase‐2 (MMP‐2) was evident in CsA‐induced groups of rats, which was moderately reduced in SAC treated rats. An increase in the levels of serum constituent's urea, uric acid and creatinine was observed in the CsA‐induced rats, which was reduced upon treatment with SAC. These results indicate that SAC has a protective action against CsA‐induced nephrotoxicity which is also supported by histopathological studies. A comparative study of the antioxidant vitamin C and SAC is more valuable to assess the efficacy of the drug that can be used for the treatment of nephrotoxicity. Copyright © 2009 John Wiley & Sons, Ltd.
Kauren‐19‐oic acid induces DNA damage followed by apoptosis in human leukemia cells
Authors: Cavalcanti Bruno C. , Bezerra Daniel P. , Magalhães Hemerson I. F. , Moraes Manoel O. , Lima Mary Anne S. , Silveira Edilberto R. , Câmara Cláudio A. G. , Rao Vietla S. , Pessoa Cláudia , Costa‐Lotufo Letícia V.
Published: April 2009

This study evaluated the potential cytotoxicity of the natural diterpenoids kauren‐19‐oic acid (KA), 14‐hydroxy‐kaurane (1) and xylopic acid (2), and semi‐synthetic derivatives of KA (3–5) towards human cancer cell lines (K562, HL60, MDA‐MB435 and SF295) and lymphocytes. Mouse erythrocytes were used to verify a possible hemolytic activity Cytotoxicity mechanisms were investigated in HL60 cells. KA showed a moderate antiproliferative effect in MTT assay towards all cancer cells (IC50, 9.1–14.3 µg ml−1). However, KA appeared not selective to cancer cells, since it also inhibited the lymphocytes proliferation (IC50, 12.6 µg ml−1). Unlike KA, compounds 1–5 displayed no cytotoxicity and were also free from antiproliferative and hemolytic effects, suggesting that the exocyclic double bond (C16) unit may be the active pharmacophore of KA cytotoxicity. KA‐treated HL60 cells displayed decreased proliferation (5‐bromo‐2';‐deoxyuridine incorporation assay) and topoisomerase I activity (DNA relaxation assay). These assays revealed that KA primarily intercalates with DNA and not with topoisomerase I. Fluorescence microscopy using AO/EB (acridine orange/ethidium bromide) staining indicated that KA can induce both apoptosis and necrosis in HL‐60 cell cultures, which corroborate the findings with MTT. From these findings, we conclude that KA, although demonstrating cytotoxic potential, may have a limited or poor therapeutic potential due to lack of selectivity to tumor cells. Further studies on the structure modification of KA and the mechanism of the new derivatives are currently in progress. Copyright © 2009 John Wiley & Sons, Ltd.
Quantum chemical predictions concerning two unknown “mesoionic” compounds
Authors: Paoloni Leonello , Ciampi Antonio
Published: April 2009

The Pariser‐Parr‐Pople approximation was used to predict the properties of compounds I, 3‐oxo‐2H‐1,2,3‐triazolo[3,4‐a]pyridine, and II, 3‐oxoisoxazolo[2,3‐a]pyridine, originated by joining a pyridine ring to two sydnone‐like heterocyclic systems not yet reported in the literature. A parallel computation was carried out for two known compounds of similar structure, to give the predictions a better reliability through the comparison with observed spectral data and chemical behaviour. Compound I is expected to be stable, with an absorption spectrum similar to III, 2‐oxo‐1,3,4‐oxadiazolo[4,5‐a]pyridine, and chemical properties analogous to IV, 1‐methyl‐3‐oxo‐1,2,4‐triazolo‐[4,3‐a]pyridine. A reaction path is suggested for obtaining from I the unknown isomeric structure V, 3‐oxo‐1H‐1,2,3‐triazolo[3,4‐a]pyridine. Compound II is predicted as an unstable orange‐red substance which should be handled and kept at low temperatures.
The syntheses and thermal rearrangement of some methiodides of s‐triazolo[4,3‐a]pyridines
Authors: Paudler William W. , Brumbaugh Richard J.
Published: April 2009

It has been shown that the N‐methylation, with methyl iodide, of s‐triazolo[4,3‐a]pyridines affords a mixture of the N‐1 and the N‐2 methiodides. The N‐2 methiodides can be thermally rearranged to the N‐1 methiodides. The 8‐methyl N‐1 methiodides exhibit peri interaction between the two methyl groups. This interaction is reflected in greater stability of the N‐2 methiodide vs. the N‐1 compound.
2‐Isoxazoline derivatives. Part I. A base‐promoted fragmentation of 2‐isoxazolines
Authors: Bianchi Giorgio , Gandolfi Remo , Grünanger Paolo
Published: April 2009

The action of bases on 3‐aryl (or alkyl)‐5‐acyl‐2‐isoxazolines has been shown to give rise to the corresponding aromatic (or aliphatic) nitriles and α‐diketones by cleavage of the O‐N and C3C4 bonds of the heterocyclic ring. This fragmentation reaction has been extended to other 2‐isoxazolines substituted in the 5‐position with electron‐attracting groups.
The synthesis of pyridazino[4,5‐d] pyridazines, pyrazino [2,3‐d] pyridazines and a pyrimido [4,5‐d] pyridazine
Authors: DiStefano Lorraine , Castle Raymond N.
Published: April 2009

The synthetic chemistry of the relatively unknown pyridazino [4,5‐d]pyridazine ring system has been extended. 1,4‐Diaminopyridazino [4,5‐d]pyridazine (VIII) has been prepared by two routes, the most interesting of these being the one‐step conversion of 4,5‐dicyanopyridazine into VIII with hydrazine. Upon nitration VIII gave only the mononitramine (X). Attempts to prepare 1,4‐dichloropyridazino [4,5‐d]pyridazine gave only 4‐chloro‐2H‐pyridazino [4,5‐d]pyridazin‐1‐one (XII). Pyrimido [4,5‐d]pyridazine‐1,3‐dione (XIV) was prepared from pyridazine‐4,5‐dicarboxamide (IV). The hydrolysis of 5,8‐dichloropyrazino [2,3‐d]pyridazine (XV) gave 5‐chloropyrazino [2,3‐d]pyridazin‐8‐one (XVII) and likewise the ammonolysis of XV gave 5‐amino‐8‐chloropyrazino [2,3‐d]pyridazine (XX). As expected the hydrolysis of 5,8‐dibromo‐pyrazino [2,3‐d]pyridazine (XXI) gave 5‐bromopyrazino [2,3‐d]pyridazin‐8‐one (XXII). Attempted catalytic dechlorination of 5‐chloropyrazino [2,3‐d]pyridazin‐8‐one (XVII) gave 1,2,3,4‐tetrahydropyrazino [2,3‐d]pyridazin‐5‐one (XIX).
The mass spectra of 1,2,4‐oxadiazolines
Authors: Srivastava R. M. , Clapp Leallyn B.
Published: April 2009

The fragmentation patterns of seven oxadiazolines (compounds I‐VII) were obtained from mass spectral data. Fragmentations a and b (Figure 1) are more important than c. Some of the novel cracking pathways are discussed.
Aziridinyl ketones XVII. The hydrogenation of 2‐phenyl‐3‐aroylaziridines to aziridinylcarbinols
Authors: Wall Donald K. , Imbach Jean‐Louis , Pohland Albert E. , Badger Robert C. , Cromwell Norman H.
Published: April 2009

The sodium borohydride reduction of both cis and trans‐1‐cyclohexyl‐2‐phenyl‐3‐aroylaziridines provides in each case the corresponding carbinol as a mixture of the two possible diastereoisomeric racemates, whereas reduction of these ketones with lithium aluminum hydride or with lithium diisopropylamide provides only the racemate resulting from attack on the carbonyl group from the least hindered side. Catalytic hydrogenation of a cis aziridinyl ketone cleaved the aziridine ring and provided an amino carbinol.
Trifluoromethylfurans
Authors: Bambury R. E. , Yaktin H. K. , Wyckoff K. K.
Published: April 2009

The preparation of 5‐trifluoromethylfurfural and some of its derivatives is described. Biological activity of the derivatives is reported.
The synthesis of oximes containing the ferroin group
Authors: Case Francis H. , Mcmenamin Patrick J.
Published: April 2009

A series of oximes of substituted 2‐pyridylmethyl and phenyl ketones has been prepared. These all contain the ferroin group (NCCN). The 4‐substituted pyridyl‐syn‐methyl and phenyl ketoximes form chelates with Fe(II).
Ring closure reactions with nitriles. I. Formation of pyrrolo [2,1‐c] [1,2,4] benzothiadiazines and pyrrolo[1,2‐a] quinazolines
Authors: Bell Stanley C. , Conklin George
Published: April 2009

Pyrrolo[2,1‐c][1,2,4]benzothiadiazines have been prepared from the reactions of o‐amino‐benzenesulfonamides with γ‐cyanopropionaldehydes. Pyrrolo[1,2‐a]quinazolines have been prepared from the reaction of anthranilamides with either γ‐cyanopropionaldehyde or succinic anhydride. The cyclization of a 4‐oxo‐2‐quinazolinepropionic acid has produced a pyrrolo‐[1,2‐a]quinazoline and the isomeric pyrrolo[2,1‐b]quinazoline.
Pyrazoles. II. Reactions of 1‐methyl‐5‐amino‐4‐pyrazolecarboxamide and nitrous acid introduction of a nitro group at position 5 in the payrazole ring
Authors: Cheng C. C.
Published: April 2009

Addition of sodium nitrite to a mixture of hydrochloric acid and 1‐methyl‐5‐amino‐4‐pyrazolecarboxamide, at either high or low temperature, yielded 1‐methyl‐4‐hydroxypyrazolo‐[3,4‐d]‐v‐triazine. On the other hand, addition of hydrochloric acid to an aqueous mixture of sodium nitrite and 1‐methyl‐5‐amino‐4‐pyrazolecarboxamide gave, at high temperature (˜ 100°), 1‐methyl‐5‐nitro‐4‐pyrazolecarboxylic acid and at low temperature (˜ 0°), 1‐methyl‐5‐nitrosamino‐4‐pyrazolecarboxylic acid.
Picrylamino‐substituted heterocycles. III. 1,2,4‐triazoles
Authors: Coburn Michael D. , Jackson Thomas E.
Published: April 2009

This paper describes the synthesis of various picryl‐and picrylamino‐substituted 1,2,4‐triazoles and 3,3′‐bi‐1,2,4‐triazolyls. These compounds were prepared by condensing the appropriate 1,2,4‐triazole or amino‐1,2,4‐triazole with a picryl halide. The proton n.m.r. spectra, crystal densities, thermal stabilities, and drop‐weight impact sensitivities of the resulting compounds were determined.
Enazine chemistry II. The mechanism of formation of 1‐(cis‐3‐phenylpropenyl)‐5‐phenylpyrazole from the pyrolysis of cinnamaldehyde azine
Authors: Stern Robert L. , Krause Josef G.
Published: April 2009

The mechanism of pyrazole formation from the thermolysis of α,β‐unsaturated azines has been examined by both kinetic and non‐kinetic methods. The reaction exhibits a large negative entropy of activation, a large primary isotope effect and a positive slope in a Hammett study on cinnamaldehyde derivatives. The reaction was shown to be cleanly intramolecular and was also unaffected by radical traps. A mechanism involving intramolecular 1‐5 abstraction of a proton is presented, which accounts for all of the experimental data.
Thiazolo‐N‐hydroxyuracils
Authors: Bauer Ludwig , Mahajanshetti C. S.
Published: April 2009

The partial Lossen degradation of the hydroxamic acid group at C‐4 or C‐5 of sodium 4,5‐thiazoledicarbohydroxamate (IIIb) and its 2‐methyl analog (IIIe) initiated a multicoursed reaction which furnished a mixture of thiazolo[4,5‐d]‐ and thiazolo[5,4‐d]‐N‐hydroxyuracils. The isomer distribution was sensitive to the solvent systems in which these reactions were carried out. The structure of the isomers so obtained was established by chemical and spectral methods.
Friedel crafts reactions of three‐member heterocycles I. Reaction of propylene oxide with benzene
Authors: Milstein Norman
Published: April 2009

The Friedel Crafts reaction of propylene oxide with benzene has been reinvestigated, and under anhydrous conditions the product is 2‐phenylpropanol.
Friedel crafts reactions of three‐member ileterocycles II: Alkylation of aromatic compounds with aziridines
Authors: Milstein Norman
Published: April 2009

The Friedel Crafts reaction of propylenimine with symmetrical arenes in the presence of aluminum chloride was investigated. Electron donating substituents increase the α‐methyl‐β‐phenethylamine/ β‐methyl‐β‐phenethylaimine ratio, while increasing the temperature has the opposite effect. In the reaction of chlorobenzene or toluene with aziridine, the nature of the substituent has little effect on the ortho/para ratio.
Synthesis of pyridazine derivatives. XXI. Tetrazolo‐azido transformations in some fused azolopyridazines
Authors: Kovačič A. , Stanovnik B. , Tišler M.
Published: April 2009

6‐Azidotetrazolo[1,5‐b]pyridazine (III) has been prepared by two different routes and is easily transformed into the 6‐amino derivative (IV). The attempted cyclization of 6‐hydrazinotetrazolo[1,5‐b] pyridazine (II) into the postulated tricycle has been shown to result in the formation of 6‐azido‐s‐triazolo [4,3‐b]pyridazine (VI), obtained also in a separate experiment from VII. The azido structure of VI has been confirmed from spectroscopic data and from its conversion into 6‐amino‐s‐triazolo [4,3‐b]pyridazine (VIII), obtained in another experiment from VII. Similarly, cyclization of II with cyanogen bromide resulted in the simultaneous formation of the s‐triazolo ring and ring opening of the fused tetrazolo ring, giving IX. For 6‐azido‐2‐phenylimidazo[1,2‐b]pyridazine (XII) the expected azide structure proved to be correct.
4‐Thiazoline‐2‐thiones. V. Kineticvs.thermodynamic control of the conjugate addition at theS‐ vs. N‐positions to acrylonitrile and methyl acrylate
Authors: Humphlett W. J.
Published: April 2009

The basic catalyzed conjugate addition of the title system in methanol was found to occur at either theS‐orN‐atoms, or concurrently at theS‐andN‐atoms, of themagnified imagemoiety of the heterocycle. Evidence indicates that the formation of the two types of adducts depends on an equilibrium between the reactions of conjugate addition and reversal. Certain choice of isolation of the two types of products is allowed by control of the reaction conditions.
The synthesis of some ethyl 3‐(1,2‐dialkylhydrazino)propanoates and their cyclization to 1,2‐dialkyl‐3‐yrazolidinones
Authors: Kornet Milton J. , Ie Tan Sip
Published: April 2009

The preparation of several ethyl 3‐(1,2‐dialkylhydrazino)propanoates (III) by the reaction of 1,2‐dialkylhydrazines with acrylates is described. Compound III is accompanied by small amounts of the bis addition products (V) in the reactions of ethyl acrylate with a few of the hydrazines. Cyclization of III to 1,2‐dialkyl‐3‐pyrazolidinones (IV) was achieved with sodium methoxide. 1,2‐Dialkyl‐5‐methyl‐3‐pyrazolidinones were obtained directly from 1,2‐dialkylhydrazines and ethyl crotonate. A procedure for the preparation of 1,2‐di‐(2‐ethoxycarbonylethyl)hydrazines is also given.
Stereochemistry of epimeric 1‐hydroxy‐N‐methylquinolizidinium iodides
Authors: Temple Davis , Sam Joseph
Published: April 2009

The methiodides of epimeric 1‐hydroxy, 1‐hydroxy‐1‐phenyl, and 1‐hydroxy‐1‐methylquinolizidines were prepared from their respective bases. The previously described but not separated epimeric 1‐hydroxy‐1‐methylquinolizidines were prepared and their configurations elucidated by the use of nuclear magnetic resonance (NMR) and infrared data. Structural assignments of the quinolizidinium iodides were made on the basis of NMR data.
Studies in alkylation. I. Synthesis and reactions of spiro[oxirane‐2,4‐piperidines]
Authors: Fishman Morris , Cruickshank Philip A.
Published: April 2009

Spiro[oxirane‐2, 4′‐piperidines] have been prepared by the action of dimethyloxosulfonium methylide on 4‐piperidones. The spiro[oxirane‐2,4′‐piperidines] act as alkylating agents to introduce (4‐hydroxy‐4‐piperidyl) methyl moieties onto heteroaromatic compounds such as 4(3H)‐quinazolone.
The reaction of certain heterocyclic azides with triphenylphosphine
Authors: Vanallan J. A. , Reynolds G. A.
Published: April 2009

Azidobenzothiazole and azidobenzimidazole and certain of its derivatives react with triphenyl‐phosphine to give isolatable adducts which decompose thermally to give the corresponding phosphinimines. 2‐Azidobenzoxazole gives an adduct which loses nitrogen at 15–20° and gives the phosphinimine directly. Methylation of the phosphinimines occurs at the hetero nitrogen, whereas benzoylation occurs at the exo nitrogen atom. The structures of the alkylation and aroylation products of the phosphinimines were established.
The synthesis of 2‐chloro‐1‐(β‐D‐ribofuranosyl)benzimidazole and certain related derivatives
Authors: Revankar Ganapathi R. , Townsend Leroy B.
Published: April 2009

The synthesis of 2‐chloro‐1‐(β‐D‐ribofuranosyl)benzimidazole (4b) has been accomplished by a condensation of 2‐chloro‐1‐trimethylsilylbenzimidazole (1) with 2,3,5‐tri‐O‐acetyl‐D‐ribofuranosyl bromide (2) followed by subsequent deacetylation. Nucleophilic displacement of the 2‐chloro group has furnished several interesting 2‐substituted‐1‐(β‐D‐ribofuranosyl)benzimidazoles. 1‐(β‐D‐Ribofuranosyl)benzimidazole (5) and 1‐(β‐D‐ribofuranosyl)benzimidazole‐2‐thione (6) were prepared from 4b and 6 was also prepared by condensation of 2 with silylated benzimidazole‐ 2‐thione (3). Alkylation of 6 furnished certain 2‐alkylthio‐1‐(β‐D‐ribofuranosyl)benzimidazoles and oxidation of 6 with alkaline hydrogen peroxide produced 1‐(β‐D‐ribofuranosyl)benzimidazole‐2‐one (9). The assignment of anomeric configuration for all nucleosides reported is discussed.
1,2,4‐Triazoles. XX. Pyrolytic decomposition of ketone hydrazones derived from pyrid‐2‐ylhydrazine and related bases. Some further examples of the s‐triazolo[4, 3‐α]pyrazine and s‐triazolo[4, 3‐a]quinoxaline series
Authors: Potts K. T. , Schneller S. W.
Published: April 2009

Pyrolytic decomposition of ketone 2‐heterylhydrazones has been shown to be unsatisfactory for the preparation of fused s‐triazole derivatives. The introduction of more diversified substituents into the s‐triazolo[4, 3‐a]pyrazine and s‐triazolo[4,3‐a]quinoxaline systems has been accomplished and some reactions and spectral characteristics of these ring systems are reported. Isomerization of the s‐triazolo[4, 3‐a]pyrazine system to the s‐triazolo[1,5‐a]pyrazine system is described.
Heterocyclic tautomerisms. II. An investigation of the 2‐arylbenzothiazoline 2‐(benzylideneamino)thiophenol tautomerism. Part 2
Authors: Goetz Frederick J.
Published: April 2009

The reaction between 4‐mercaptoaniline and various aromatic aldehydes was studied as a model system in order to determine which type of substitution on the aryl group in 2‐arylbenzothiazolines (1) might give rise to the greatest possible stabilization of the hypothetical 2‐(benzylideneamino)thiophenol tautomer (II). Regardless of electronic effect of substituents, most aldehydes reacted with 4‐mercaptoaniline to form poly[4‐(benzylideneamino)thiophenols] (III). Aromatic aldehydes substituted in the 2 position with the hydroxyl function reacted to form the stable, monomeric 4‐(benzylideneamino)thiophenols (IV). This stabilization in the monomeric state is presumed to be due to the hydrogen‐bonded nature of these compounds (V). Both monomeric and polymeric compounds reacted with benzalacetophenone in the presence of a basic catalyst in the manner to be expected of the 4‐(benzylideneamino)thiophenol structure (IV) yielding correspondingly substituted 1,3‐diphenyl‐1‐[4‐(benzylideneamino)phenylthio]‐3‐propanones (VI).
The synthesis of pyrimido[4,5‐c]pyridazines and pyrimido[5,4‐c]pyridazines
Authors: Nakagome Takenari , Castle Raymond N. , Murakami Hirotaka
Published: April 2009

The Hofmann reaction on 6‐methylpyridazine‐3,4‐dicarboxamide (1) gave a mixture of 3‐methylpyrimido[4,5‐c]pyridazine‐5,7‐dione (2), 3‐methylpyrimido[5,4‐c]pyridazine‐6,8‐dione (3) and an acid (4) of unknown structure. The Hofmann reaction on pyridazine‐3,4‐dicarboxamide (9) gave a mixture of pyrimido[4,5‐c]pyridazine‐5,7‐dione (10) and an acid (11) of unknown structure. The reaction of 3‐amino‐6‐methylpyridazine‐4‐carboxamide (18) with ethyl orthoformate gave 3‐methylpyrimido[4,5‐c]pyridazin‐5‐one (21). 4‐Aminopyridazine‐3‐carboxamide (36) upon fusion with urea gave pyrimido[5,4‐c]pyridazine‐6,8‐dione (37) while with ethyl orthoformate 36 gave pyrimido[5,4‐c]pyridazin‐8‐one (38). Pyrimido[5,4‐c]‐pyridazine‐8‐thione (39) was obtained by the action of phosphorus pentasulfide on 38. 4‐Amino‐3‐cyanopyridazine (16) when treated with formamide produced 8‐aminopyrimido[5,4‐c]‐pyridazine (41). The synthesis of 4‐aminopyridazine‐3‐carboxamide (36) and 4‐amino‐3‐cyanopyridazine (16), both key intermediates in the synthesis of the novel pyrimido[5,4‐c]pyridazine ring system was accomplished by the Reissert reaction of 4‐aminopyridazine‐2‐oxides and subsequent conversion of the nitrile to the amide.
Tautomeric forms of Oxy‐ and Oxo‐derivatives of 1,3,5‐Triazine. Part VI. Isomerization mechanism and thermal stability of the methyl esters of cyanuric acid
Authors: Paoloni L. , Tosato M. L. , Cignitti M.
Published: April 2009

Previous investigations of the kinetics and the mechanism of the thermal isomerization C3N3(OMe)3 → C3(NMe)3O3 have been continued with a study of the isomerization mechanism of the mixed O,O,N‐ and O,N,N‐trimethyl esters of cyanuric acid. A full discussion of the overall process is given, in which it is assumed that the above mixed esters are intermediates.

It is shown that the tautomeric transformation occurs as the consequence of the attack of Me+ cations on the ring nitrogen of the neutral molecules. The presence of such cations in the melt was established by ionic exchange with the H+ of the molten acids. It is also shown that the tautomeric transformation in solution proceeds with the same mechanism.

An explanation is proposed for the thermal instability of the mixed esters (which isomerize even in the solid state, more than 20° below their melting point), which is based on the high polarity of these molecules. This property is discussed in terms of electronic structure calculations carried out with the Pariser‐Parr‐Pople approximation of the A.S.M.O., S.C.F., method.
Phthalonimides (1,3,4‐trioxo‐1,2,3,4‐tetrahydroisoquinolines) of potential biological interest
Authors: Buu‐Hoï N. P. , Saint‐Ruf G. , Bourgeade J. C.
Published: April 2009

A new simple method for the preparation of phthalonimides (1,3,4‐trioxo‐1,2,3,4‐tetrahydroisoquinolines), consisting of the selenium dioxide‐oxidation of the appropriate homophthalimides, has been devised; the thiosemicarbazones and other derivatives of phthalonimides of possible biological interest (as potential antibacterial, antiviral, or immunosuppressive agents) have been synthesized.
Crystal and molecular structure of 1‐benzyl‐1,2,2‐trimethyl azetidinium bromide
Authors: Moret C. L. , Trefonas L. M.
Published: April 2009

The structure of the compound, 1‐benzyl‐1,2,2‐trimethyl azetidinium bromide has been determined by a single crystal x‐ray diffraction study. The compound crystallizes in the space group Pnam with four formula weights in a unit cell of dimensions a = 14.36, b = 13.73, c = 6.906 Å. The compound is partially disordered with the benzyl part ordered and the remainder of the ring disordered about the mirror plane. The azetidinium ring bears a close resemblance in bond distances, bond angles and conformation to the β‐lactam ring found in penicillin. The disordering is discussed in detail and a comparison of the effects of fusing a second ring to the azetidinium moiety are explored. A final value of R = 0.094 for the 432 independent reflections was obtained.
A study of the synthesis and some reactions of perimidines
Authors: Paragamian V. , Baker M. B. , Puma B. M. , Reale J.
Published: April 2009

A study of the preparation of perimidines from 1,8‐diaminonaphthalene and carbonyl compounds is presented. The optimum conditions for the reaction of the above diamine with carboxylic acids and esters, acid chlorides, anhydrides and aldehydes are defined.

The chemical behavior and a number of previously unreported reactions of perimidines are presented. The latter includeN‐alkylations, reductions, oxidations and acylations.
Mass spectral and NMR studies of some cinnolines
Authors: Elkins John Rush , Brown Ellis V.
Published: April 2009

Fragmentation upon electron impact of cinnoline (1) occurs with the consecutive loss of N2 and C2H2. Fragmentation of 4,4′‐dicinnolyl (2) and 4‐styrylcinnoline (4) gives a series of ions leading to the “dibenzoladderene” ion (3) and the 1‐phenylbenzodibutylene ion (5) respectively. Fragmentation of 4‐styrylquinoline (6) also leads to 5, but of more interest is the loss of H. during ring rearrangement to give the highly resonance stabilized 3‐styrylbenzocyclo‐pentadieneoneimine ion (7) which then loses N. Fragmentation of various other substituted cinnolines follow different pathways: 4‐methylcinnoline (8) apparently fragments through the “1,2‐diazatropylium” ion (9); nitrocinnolines fragment with initial loss of the nitro substituent; aminocinnolines fragment with initial loss of N2; and 4‐cinnolone (17) fragments with the consecutive loss of two HCN's and CO.

The NMR spectra of cinnolines generally show the following order of deshielding: 3‐proton > 8‐proton > 4‐proton. The spectra of cinnolinum chloride (18) is interpreted in terms of protonation at N‐1 of 1, and the spectrum of 17 is interpreted in terms of strong intermolecular hydrogen bonding.