bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on ethylene‐propylene‐diene rubber modification by N‐chlorothio‐N‐butyl‐benzenesulfonamide
Authors: Zhang H. , Datta R. , Talma A. , Noordermeer J. W. M.
Published: April 2009

N‐Chlorothiosulfonamides have been used to modify ethylene‐propylene‐diene rubber (EPDM) to enhance the compatibility of EPDM in, e.g., natural rubber (NR)/butadiene rubber (BR)/EPDM blends for ozone resistance. N‐Chlorothio‐N‐butyl‐benzenesulfonamide (CTBBS) was selected as a representative for N‐chlorothiosulfonamides. In this study, we found that CTBBS behaves differently with various types of EPDM. Three types of EPDM were selected: ethylidene norbornene (ENB)‐EPDM, hexadiene (HD)‐EPDM, and dicyclopentadiene (DCPD)‐EPDM. HD‐EPDM showed the greatest effectiveness toward CTBBS‐modification. However, this EPDM is not commercially available anymore. On the opposite side, DCPD‐EPDM showed the lowest reactivity so that almost no modification could be realized. The result with ENB‐EPDM was, that upon application of CTBBS to ENB‐EPDM, gelation occurred and, therefore, a low amount of modification was achieved. With the limited modification efficiency for ENB‐EPDM, there is no significant improvement when applying the modified ENB‐EPDM into NR/BR/EPDM blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Pendent polyimides using mellitic acid dianhydride. III. The effect of pendent group functionality on polymer properties
Authors: Illingsworth Marvin L. , Wang Wei , McCarney Jonathan P. , Hughes Kenneth A. , Trotter Kari J. , Stapleton Russell A. , Chabot Jeffrey R. , Siochi Emilie J. , Kotlarchyk Michael
Published: April 2009

Methyl, methoxy, and nitrile (cyano) functional groups were incorporated into the metal–organic pendent group of a co‐polyamic acid, co‐PAA[(3,4′‐ODA/ODPA)0.9(3,4′‐ODA/{MADA‐p‐Zr(adsp)(Rdsp)})0.1], in various locations to investigate their effects on polymer chain interactions and film quality. Proton nuclear magnetic resonance and gel permeation chromatography (GPC) performed on solutions of these products were consistent with the expected 10% (mol) functionalized pendent polymeric structures. Thermogravimetric analysis performed on ether‐precipitated samples revealed little functional group effect on imidization temperature (decreases of 5–8°C), but showed a somewhat‐greater effect on decomposition temperature (decreases of 6°C for the 3‐methoxy derivative to 28°C for the methyl derivative). Differential scanning calorimetry performed on imidized powder samples showed that glass transition temperatures increased with the addition of the functional groups from 2°C for the methyl derivative to 19°C for the 3‐methoxy derivative. Imidized films were solvent resistant, transparent, and flexible, with the nitrile derivative least susceptible to crack formation. Light scattering results revealed that the nitrile derivative had the lowest second virial coefficient of the functional groups tested and formed aggregates at room temperature in NMP with n = 2, thus rationalizing its superior film forming properties. Results of contact angle measurements and atomic oxygen exposure of functionalized pendent co‐PI films are included. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of phenolic curative on crosslink density and other related properties of dynamically cured NR/HDPE blends
Authors: Pechurai Worawan , Sahakaro Kannika , Nakason Charoen
Published: April 2009

Dynamically cured 60/40 NR/HDPE blends with various amounts of phenolic curative were prepared in an internal mixer at 160°C. A simple blend (i.e., the blend without curative) was also prepared using the same materials and blend proportion for comparison purposes. Mechanical, dynamic, and morphological properties; swelling resistance and crosslink density of the blends were investigated. It was found that the thermoplastic vulcanizates (TPVs) gave superior mechanical and dynamic properties than the simple blend. Furthermore, the mechanical properties in terms of elongation at break, modulus and tensile strength and elastic response in dynamic test in terms of storage modulus increased with increased loading amount of the curative. The complex viscosity also increased but the tan δ and tension set decreased with increased loading level of the curative. The crosslink density of the TPVs was estimated based on the elastic shear modulus. It was found that the crosslink density of the blends increased with increased loading levels of the curative while the degree of swelling decreased. This correlated well with the trend of mechanical and dynamic properties. SEM micrographs were used to confirm the level of mechanical and dynamic properties. It was found that the simple blend at a given blend ratio exhibited co‐continuous phase morphology. However, the TPVs showed micron scale of vulcanized rubber domains dispersed in a continuous HDPE matrix. The size of vulcanized rubber domains decreased with increasing amounts of the curative. This led to greater interfacial adhesion between the phase and hence superior mechanical and dynamic properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Unwanted personal contact and risky situations in ten disney animated feature films
Authors: Hovdestad Wendy E. , Hubka David , Tonmyr Lil
Published: April 2009

The relationships between child maltreatment and the media have been examined in several recent papers. In the authors' previous work representations of neglect, and physical and emotional (but not sexual) child abuse were found in a content analysis of 45 Disney films released from 1937–2006. (Two additional Disney films, released in 2007, are included in the present analysis.) While conducting the content analysis the authors noted unexpected content in ten films. This paper presents an exploratory analysis of depictions of unwanted personal contact and situations that suggest risk due to unsupervised contact with malevolent or questionable strangers. These depictions are described and analyzed, their potential influences on child audiences are discussed, and implications for new research directions are suggested. Copyright © 2009 John Wiley & Sons, Ltd.
Multiple Mechanisms for Electron Transfer at Metal/Self‐Assembled Monolayer/Room‐Temperature Ionic Liquid Junctions: Dynamical Arrest versus Frictional Control and Non‐Adiabaticity
Authors: Khoshtariya Dimitri E. , Dolidze Tina D. , van Eldik Rudi
Published: April 2009

When all the mechanisms go marching in: Electrochemical devices consisting of Au electrodes coated by self‐assembled alkanethiol monolayers of variable thickness, a ferrocene/ferrocenium redox probe and [bmim][NTf2] (1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide) as the solvent (see picture), under variable overvoltage, temperature and pressure conditions, allowed the disclosure of three different electron‐transfer patterns.

magnified image

Electrochemical devices consisting of gold electrodes coated by electronically well‐behaved self‐assembled alkanethiol monolayers of variable thickness, a ferrocene/ferrocenium redox probe and a typical room‐temperature ionic liquid (RTIL) [bmim][NTf2] (1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide) as a unique reaction medium with an exceptionally broad spectrum of relaxational modes (probed under variable temperature and pressure conditions), have been used to vary the intrinsic electron‐transfer (ET) rate constant over eight orders of magnitude (from 0.1 to 3×107 s−1) by further tuning of the overvoltage. A remarkable interplay of ET mechanisms was observed, which was accompanied by the stepwise drop in the reorganisation free energy of the medium from 1.0 to 0.1 eV. The first mechanistic changeover to the dynamically arrested regime, with a locking ultra‐slow relaxation time of approximately 50 μs, occurred at donor–acceptor separations below 20 Å. Another mechanistic changeover to the full solvent friction regime, controlled by a medium relaxation process of approximately 100 ns, emerged for ET distances smaller than 8 Å.
Flame‐retardancy of a Cellulosic Fabric by the Application of Synergistic Effect between Ammonium Bromide and Antimony(III) Oxide
Authors: MOSTASHARI Seyed Morteza , MOAFI Hadi Fallah
Published: April 2009

The synergistic effect between ammonium bromide and antimony(III) oxide as a nondurable finish on the flammability of 100% woven plain cotton fabric (with a density of 144 g/m2, the number of yarns 21 per 10 mm), has been investigated in this study. The laundered totally‐dried, weighed specimens were impregnated with suitable concentration individual aqueous ammonium bromide and/or antimony(III) oxide suspension solutions and some sets were impregnated with appropriate admixed solutions of the both chemicals. A vertical flame spread test was then carried‐out to characterize the flammability of the samples. An acceptable synergistic effect was then experienced by using an admixed bath containing 0.1 molar ammonium bromide and 0.05 unit formal antimony trioxide solutions for impartation of flame‐retardancy to a cotton fabric. The optimum mass of the mixture required to impart flame‐retardancy was about 3.64 g of anhydrous additives per 100 g of fabric. The results obtained are in favor of Wall Effect Theory. Moreover synergistic effect indicating dehydration of the treated substrate by using this combination via thermogravimetry could be deduced.
Synthesis, Crystal Structure and Thermal Behavior of Co(en)3[B4O5(OH)4]Cl·3H2O and [Ni(en)3][B5O6(OH)4]2·2H2O
Authors: ZHENG Lijuan , ZHANG Jianjian , LIU Zhihong
Published: April 2009

Two novel transition‐metal complex templated borates containing crystalline water, Co(en)3[B4O5(OH)4]Cl·3H2O (1) and [Ni(en)3][B5O6(OH)4]2·2H2O (2), have been synthesized hydrothermally and characterized by elemental analysis, single crystal X‐ray diffraction, FT‐IR spectroscopy, and TGA. The crystal structure of compound 1 is characterized mainly by forming a 3D supramolecular network through four kinds of hydrogen bonds, O–H···O, O–H···Cl, N–H···Cl and N–H···O, among all components of Co(en)33+, [B4O5(OH)4]2−, Cl− and H2O. The crystal structure of compound 2 is characterized by forming a 3D supramolecular framework with large channels along axis a through O–H···O hydrogen‐bonding among the [B5O6(OH)4]− anions, in which the templating [Ni(en)3]2+ cations and crystalline water molecules are located.
A Novel Spectrophotometric Method for the Determination of Isoniazid Using Cu(II) as Spectroscopic Probe Ion
Authors: ZHANG Hua , ZHANG Yan , WEI Xianjun , DU Xinzhen , LI Quanmin
Published: April 2009

A novel method to determine isoniazid with high sensitivity and good selectivity has been established by using Cu(II) as a spectroscopic probe ion. The experiment indicated that Cu(II) was reduced to Cu(I) by isoniazid at pH 6.0, then the resulting Cu(I) was precipitated with SCN− to form CuSCN that could be stayed upon the surface of water phase in the presence of NaNO3. By determining the residual amount of Cu(II) in the water phase, the indirect determination of isoniazid could be achieved. Good linear relationship between the amount of the reacted Cu(II) and the concentration of isoniazid was observed, with the linear range being 0.050–4.50 µg·mL−1, and the detection limit being 0.048 µg·mL−1. This method has been successfully applied to determining isoniazid among pharmaceutical samples and patient urine samples.
Synthesis, Crystal Structures and Electrochemical Properties of O‐Chloropropyl and O‐Cyanopropyl Resorcinarenes
Authors: HAN Jun , ZHOU Rui , YAN Chaoguo
Published: April 2009

Tetraaryl and tetraferrocenyl resorcinarenes 1a–1d were fully alkylated with 1‐bromo‐3‐chloropropane or 4‐chlorobutyronitrile in refluxing acetone with potassium carbonate as base to give O‐3‐chloropropyl derivatives 2a–2d and O‐3‐cyanopropyl derivatives 3a–3d. The single crystal analysis shows that alkylresorcinarenes exist in an rccc (all cis) configuration and arylresorcinarenes in an rctt (cis‐trans‐trans) configuration. The electrochemical properties of tetraferrocenyl resorcinarenes were studied by cyclic voltammetry.
Bending‐induced switching of dynein activity in elastase‐treated axonemes of sea urchin sperm—Roles of Ca2+ and ADP
Authors: Hayashi Shuichi , Shingyoji Chikako
Published: April 2009

Flagellar beating is caused by microtubule sliding, driven by the activity of dynein, between adjacent two of the nine doublet microtubules. An essential process in the regulation of dynein is to alternate its activity (switching) between the two sides of the central pair microtubules. The switching of dynein activity can be detected, in an in vitro system using elastase‐treated axonemes of sea urchin sperm flagella, as a reversal of the relative direction of ATP‐induced sliding between the two bundles of doublets at high Ca2+ (10−4 M) at pH 7.8–8.0. The reversal is triggered by externally applied bending of the doublet bundle. However, the mechanism of this bending‐induced reversal (or backward sliding) remains unclear. To understand how the switching of dynein activity in flagella can be induced by bending, we studied the roles of ADP, which is an important factor for the dynein motile activity, and of Ca2+ in the bending‐induced reversal of microtubule sliding between two bundles of doublets at pH 7.5 and 7.2. We found that the reversal of sliding direction was induced regardless of the concentrations of Ca2+ at low pH, but occurred more frequently at low Ca2+ (<10−9 M) than at high Ca2+. At pH 7.5, an application of ADP increased the frequency of occurrence of backward sliding at high as well as low concentrations of Ca2+. The results indicate that ADP‐dependent activation of dynein, probably resulting from ADP‐binding to dynein, is involved in the regulation of the bending‐induced switching of dynein activity in flagella. Cell Motil. Cytoskeleton 2009. © 2009 Wiley‐Liss, Inc.
Design of Chiral Hydroxyalkyl‐ and Hydroxyarylazolinium Salts as New Chelating Diaminocarbene Ligand Precursors Devoted to Asymmetric Copper‐Catalyzed Conjugate Addition
Authors: Rix Diane , Labat Stéphane , Toupet Loïc , Crévisy Christophe , Mauduit Marc
Published: April 2009

The design and the synthesis of a set of new chiral hydroxyalkyl‐ and hydroxyaryl‐chelating diaminocarbene ligands is reported. Comparative catalytic studies show the importance of the scaffold design around the NHC unit to obtain a high enantiocontrol in Cu‐catalyzed asymmetric conjugate addition (ACA). Whereas low selectivities are observed when the stereogenic centre is placed within the N‐heterocyclic ring, an interesting match effect can be observed when central chirality is located within both of the two side chains, which enables up to 92 % ee in the catalysis reaction.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Gas‐Phase Model Studies Relevant to the Decomposition of Transition‐Metal Nitrates M(NO3)2 (M = Co, Ni) into Metal–Oxo Species
Authors: Schröder Detlef , de Jong Krijn P. , Roithová Jana
Published: April 2009

Electrospray ionization (ESI) of aqueous cobalt(II) and nickel(II) nitrate solutions inter alia affords the solvated, mono‐ and oligonuclear nitrato complexes [Mm(NO3)2m–1(H2O)n]+ (M = Co, Ni; m = 1–5; n = 1–4). The collision‐induced dissociation spectra of the mass‐selected ions imply that these ions correspond to genuine hydrated metal(II) nitrato complexes in that either cluster degradation through expulsion of neutral M(NO3)2 or sequential loss of water ligands take place. In the case of the lowest member of the series (m, n = 1), however, loss of water competes with homolytic cleavage of the N–O bond, which leads to the formation of [M,O2,H2]+ cations containing formal MIII. For m > 1, similar activation of the nitrato ligand was observed under harsher ionization conditions in ESI and provides access to cationic transition‐metal oxide clusters in the gas phase. In addition to the collision experiments, thermal reactions of the solvated nitrato complexes with nitrogen monoxide reveal bond‐activation pathways, which shed some light on the NO‐assisted pyrolysis of solid metal nitrates for the preparation of metal oxide catalysts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Arecoline‐induced phosphorylated p53 and p21WAF1 protein expression is dependent on ATM/ATR and phosphatidylinositol‐3‐kinase in clone‐9 cells
Authors: Chou Wen‐Wen , Guh Jinn‐Yuh , Tsai Jung‐Fa , Hwang Chi‐Ching , Chiou Shean‐Jaw , Chuang Lea‐Yea
Published: April 2009

Betel‐quid use is associated with liver cancer whereas its constituent arecoline is cytotoxic, genotoxic, and induces p53‐dependent p21WAF1 protein expression in Clone‐9 cells (rat hepatocytes). The ataxia telangiectasia mutated (ATM)/rad3‐related (ATR)‐p53‐p21WAF1 and the phosphatidylinositol‐3‐kinase (PI3K)‐mammalian target of rapamycin (mTOR) pathways are involved in the DNA damage response and the pathogenesis of cancers. Thus, we studied the role of ATM/ATR and PI3K in arecoline‐induced p53 and p21WAF1 protein expression in Clone‐9 cells. We found that arecoline (0.5 mM) activated the ATM/ATR kinase at 30 min. The arecoline‐activated ATM/ATR substrate contained p‐p53Ser15. Moreover, arecoline only increased the levels of the p‐p53Ser6, p‐p53Ser15, and p‐p53Ser392 phosphorylated p53 isoforms among the known isoforms. ATM shRNA attenuated arecoline‐induced p‐p53Ser15 and p21WAF1 at 24 h. Arecoline (0.5 mM) increased phosphorylation levels of p‐AktSer473 and p‐mTORSer2448 at 30–60 min. Dominant‐negative PI3K plasmids attenuated arecoline‐induced p21WAF1, but not p‐p53Ser15, at 24 h. Rapamycin attenuated arecoline‐induced phosphrylated p‐p53Ser15, but not p21WAF1, at 24 h. ATM shRNA, but not dominant‐negative PI3K plasmids, attenuated arecoline‐induced p21WAF1 gene transcription. We conclude that arecoline activates the ATM/ATR‐p53‐p21WAF1 and the PI3K/Akt‐mTOR‐p53 pathways in Clone‐9 cells. Arecoline‐induced phosphorylated p‐p53Ser15 expression is dependent on ATM whereas arecoline‐induced p21WAF1 protein expression is dependent on ATM and PI3K. Moreover, p21WAF1 gene is transcriptionally induced by arecoline‐activated ATM. J. Cell. Biochem. 107: 408–417, 2009. © 2009 Wiley‐Liss, Inc.
Synthesis of 8‐amino‐9‐β‐D‐ribofuranosylpurin‐6‐thione and related 6‐substituted‐8‐aminopurine nucleosides
Authors: Szekeres Gabor L. , Robins Roland K. , Boswell Kay H. , Long Robert A.
Published: April 2009

Acetylation of 8‐amino‐9‐β‐D‐ribofuranosylpurin‐6‐one (III), followed by chlorination of the tetraacetyl derivative 8‐acetamido‐9‐(2,3,5‐tri‐O‐aeetyl‐β‐D‐ribofuranosyl)purin‐6‐one (IV) with phosphorus oxychloride yielded 8‐aeetamido‐6‐ehloro‐9‐(2,3,5‐tri‐O‐acetyl‐β‐D‐ribofuranosyl)‐purine (V). The 6‐chloro substitutent of V was readily displaced with thiourea to give, after treatment with sodium methoxide 8‐acetamido‐9‐β‐D‐ribofuranosylpurine‐6‐thione (VIII). Chlorination of 8‐bromo‐9‐(2,3,5‐tri‐O‐acetyl‐β‐D‐ribofuranosyl)purin‐6‐one (IX) yielded 6,8‐dichloro‐9‐(2,3,5‐tri‐O‐acetyl‐β‐D‐ribofuranosyl)purine (X), which underwent nucleophilic displacement with ethanolic ammonia selectively in the 8 position. The resulting 8‐amino‐6‐chloro‐9‐β‐D‐ribofuranosylpurine (VII) was converted to 8‐amino‐9‐β‐D‐ribofuranosylpurine‐6‐thione (I), 8‐amino‐6‐methylthio‐9‐β‐D‐ribofuranosylpurine (II), and to 8‐amino‐6‐hydrazino‐9‐β‐D‐ribofuranosylpurine (XI).
Structure des bases de schiff dérivées de 4‐acylisoxazolin‐5‐ones
Authors: Maquestiau A. , Van Haverbeke Y. , Muller R. N.
Published: April 2009

L'analyse spectrale des bases de Schiff dérivées des 4‐acylisoxazolm‐5‐ones établit la prédominance d'une structure chélatée de type énaminone. L'influence de l'effet stérique des sub‐stituants sur la structure des composés est examinée.
1,3‐Dipolar cycloaddition reaction of benzodiazinium and naphthyridinium N‐imines with acetylenic esters
Authors: Tamura Yasumitsu , Miki Yasuyoshi , Ikeda Masazumi
Published: April 2009

1,3‐Dipolar cycloaddition of N‐imines derived from mono‐N‐amino salts of phthalazines, 2‐phenylquinoxaline, 1,5‐ and 1,8‐naphthyridines with dimethyl acetylenedicarboxylate: and methyl propiolate resulted in the formation of new tricyclic: heterocyclic ring systems with bridgehead nitrogen.
Reactions of the nitrosonium ion. VII. Syntheses of dihydroisoquinolines and oxazoles from azides in nitrile solvents
Authors: Doyle Michael P. , Spoelhof G. David , Zaleta Mary A.
Published: April 2009

N‐Alkylnitrilium salts are cleanly produced from alkyl azides by reaction with nitrosonium salts in nitrile solvents. Syntheses of 3,4‐dihydroisoquinolines from nitrilium ions formed in this method from 2‐phenylethyl azide are described. Oxazoles are readily formed from phenacyl azides by this general method; the advantages of oxazole syntheses through azide nitrosation are discussed.
The behaviour of 2‐nitrothiophene and of 3‐nitrothiophene with some nucleophiles
Authors: Dell'Erba Carlo , Novi Marino , Guanti Giuseppe , Spinelli Domenico
Published: April 2009

The reactivity of 2‐nitrothiophene (1) and of 3‐nitrothiophene (II) with some nucleophiles has been studied. According to calculated electronic densities I can receive nucleophilic attack at C3 and C5 depending on the nucleophile used, but II only at C2. With N‐lithium piperidine both I and II also give coupling products (VII and XI respectively) of the hithienyl type.
Heterocycles from substituted amides, V.. 1,2,3,5‐Oxathiadiazolin‐4‐one 2‐oxides from thionyl chloride and N‐hydroxyureas
Authors: Chupp John P. , Dahm Donald J. , Leschinsky Kindrick L.
Published: April 2009

The reaction of certain N‐hydroxy‐N‐methyl‐N′‐aryl ureas, 2, with thionyl chloride are shown to give a new heterocycle, 1,2,3,5‐oxathiadiazolin‐4‐one 2‐oxides, 3, in a synthesis that appears to have more severe structural requirements than the previously reported ring closures from α‐hydroxyacylanilides and thionyl chloride. Isolable amounts of 3 are obtained only if the aryl group contains deactivating substituents, and the hydroxy group is attached to the N‐alkyl nitrogen; otherwise, resin formation or ring chlorination are found to occur. The assigned structure as 3 was verified by a full three dimensional X‐ray analysis of a representative example, 3a, 3‐(4‐bromophenyl)‐5‐methyl‐1,2,3,5‐oxathiadiazolin‐4‐one.
The direct acylamination of pyridine 1‐oxides. Effect of substituents in N‐phenylarylimidoyl chloride. Trapping with thiols
Authors: Abramovitch R. A. , Tomasik P.
Published: April 2009

The effect of a para‐substituent in the benzoic acid portion of the arylimidoyl chloride on the nature and yield of products in the reaction with pyridine 1‐oxide has been studied. When an electron‐withdrawing substituent is present no acylamination product is formed and only 2‐ and 3‐chloropyridine are isolated. When benzenethiol is added a respectable yield of 3‐phenylthiopyridine is obtained, but alkanethiols gave low yields of 3‐alkylthiopyridines.
Determination de la structure d'halogenotriazoles‐1,2,4 par spectrometrie de masse
Authors: Bernardini Antoine , Viallefont Philippe , Daunis Jacques
Published: April 2009

Les spectres de masse de divers halogénotriazoles‐1,2,4 substitués sont décrits; les principales fragmentations sont données et leur utilité à la détermination des structures de composés isomères est montrée.
Naphthyridine chemistry: Ring enlargement to a pyrido[2,3‐b] azepine
Authors: Carboni S. , Da Settimo A. , Bertini D. , Ferrarini P. L. , Livi O. , Tonetti I.
Published: April 2009

The boron trifluoride‐catalyzed rearrangement of the epoxide derived from 3‐benzylidene‐ 7‐methyl‐2,3‐dihydro‐1,8‐naphthyridin‐4‐(1H)one (II) is described. The structure of the obtained 8‐methyl‐4‐phenyl‐1,2,3,4‐tetrahydro‐5H‐pyrido[2,3,‐b]‐azepin‐3, azepin‐3,5‐dione (X) has been elucidated with aid of chemical and spectral evidence.
1,3‐Dipolar cycloaddition reactions of 3‐acylimino‐1‐methylbenzimidazolium betaines
Authors: Tamura Yasumitsu , Hayashi Hironori , Ikeda Masazumi
Published: April 2009

3‐Acylimino‐1‐methylbenzimidazolium betaines undergo 1,3‐dipolar cycloaddition reactions with activated alkenes (methyl acrylate, acrylonitrile, and fumaronitrile) and methyl propiolate to produce 2‐substituted 1‐methylbenzimidazoles. The transformation involves the initial formation of a 1,3‐dipolar cycloadduct followed by the NN bond cleavage. The primary adducts can be isolated from the reaction with methyl acrylate and acrylonitrile.
Benzo[b] thiophene derivatives. XXII. Synthesis of the isomeric 5‐methyl‐6‐methoxy‐ and 5‐methoxy‐6‐methylbenzo[b] thiophene‐2‐carboxylic acids
Authors: Campaigne E. , Abe Yasuo
Published: April 2009

The two isomeric benzo[b] thiophene‐2‐carboxylie acids having methyl and methoxy groups at positions 5 and 6 have been prepared and characterized. Both acids have been decarboxylated to the corresponding isomeric 5,6‐disubstituted benzo[b]thophenes, and esterified to their methyl esters. The intermediate rhodanines, α‐mercaptocinnamic acids and corresponding disulfides are described. An unusual by‐product in the oxidative cyclization of β‐3‐methyl‐4‐methoxyphenyl‐α‐mercaptoacrylic acid with iodine is shown to be trans‐3‐methyl‐4‐methoxycinnamic acid, which can also be formed directly from the mercaptoacrylic acid by reduction with hydrogen iodide.
Synthesis in the diazasteroid group. V. Synthesis of the 9,14‐diazasteroid system
Authors: Yamazaki Takao , Matoba Katsuhide , Yajima Masao , Nagata Masanori , Castle Raymond N.
Published: April 2009

By the condensation reaction of 2‐chloroquinoline (X) and ethyl 2‐pyrrolidineacetate (II), 2‐[1′‐(2′‐carboethoxymethyl)pyrrolidyl]quinoline (XI) was prepared. Compound XI was converted to the quarternary base (XIII) having a 9,14‐diazasteroid skeleton by the reduction of the ester to the corresponding alcohol followed by the quaternarization via tosylation. Compound XIII was reduced with sodium borohydride to 9,14‐diazagona‐1,3,5(10)‐triene (III), which is suggested to have the trans‐anti‐trans conformation.
Rearrangement reactions of phenyl chloroformate derivatives of 2‐Hydroxyaminoacetanilides to hydantoins, ureas and hydantoie acid derivatives
Authors: Hell Stanley C. , Conklin George , Mccaully Ronald J.
Published: April 2009

Alkaline treatment of 2′‐benzoyl‐2‐(N‐carbophenoxy‐N‐hydroxyamino)‐4′‐chloroacetanilide (10) and its corresponding acetate 6 afforded respectively 5‐(2‐benzoyl‐4‐chlorophenyl)‐3‐hydroxy‐hydantoic acid (12) and 6‐chloro‐4‐phenylquinazolone (13). A study of the course of the reaction was carried out with the corresponding compounds that are devoid of the 2‐benzoyl group. An elucidation of the rearrangement is based on the isolation and independent synthesis of the heterocyclic intermediates.
Mechanistic aspects of the bromination of 10‐substituted phenothiazines
Authors: Chiou Huh‐Sun , Reeves P. C. , Biehl E. R.
Published: April 2009

The addition of 1 and 2 molar equivalents of bromine to a series of 10‐alkylphenothiazines, 1a‐d (methyl, ethyl, n‐propyl, and isopropyl, respectively), yields the corresponding 3‐bromo‐ and 3,7‐dibromo‐10‐alkylphenothiazines (11a‐d and 12a‐d, respectively). Evidence which supports the typical clectrophilic aromatic substitution mechanism is presented. Radical cations (12a‐d.+) arc produced when 12a‐d are treated with 1 or 2 molar equivalents of bromine. Upon boiling in acetic acid these radical cations are converted predominantly to 1,3,7,9‐lelrabromophenothiazine (5) and the parent 3,7‐dibromo‐10‐alkylphenothiazine (12a‐d) with the evolution of hydrogen bromide. The 10‐methyl radical (12a) gives, in addition, 1,3,7‐tribromo‐10‐methylphenothiazine (15). A mechanism if proposed for these reactions in which initial dealkylution of 12b‐d.+ to 3.7‐dibromophenothiazine radical cation (13) occurs followed by reduction of 13.+ by bromide ion to parent 3,7‐dibromophenothiazine (13). Subsequent bromination of 13 by molecular bromine produced in the previous redox reaction yields 1,3,7‐tribromo‐(14) and 1,3,7,9‐tetra‐bromo‐(5) phenothiazines. The small size of the methyl group allows 12a to be brominated at the 1‐position prior to dealkylation. In addition to undergoing bromination at the 3‐ and 7‐position, 10‐isopropylphenothiazine (1d) is oxidized to the radical cation 12e.+ when treated with bromine. 10‐Benzylphenothiazine (1e), however, undergoes oxidation to radical cation 1e.+ exclusively. This radical cation debenzylates readily at room temperature and is converted finally into phenothiazine.
A convenient nomenclature for fused β‐lactams
Authors: Bose Ajay K.
Published: April 2009

A new nomenclature is proposed which provides a convenient stereo‐description of diverse types of fused β‐lactams appearing in the literature in recent years.
Synthesis of some 3‐Methyl‐11H‐indolo[3,2‐c] [1,8]naphthyridines. A New heterocyclic ring system
Authors: Da Settimo A. , Primofiore C. , Biagi G. , Santerini V.
Published: April 2009

Some derivatives of 11H‐indolo[3,2‐c] [1,8]naphthyridine, a new heterocyclic system, have been prepared using the Fischer indole synthesis on the appropriately phenylhydrazones. The preparation of some substituted 5,6‐dihydro‐11H‐indolo[3,2‐c][1,8]naphthyridines is also described.
Acetic anhydride as a synthetic reagent
Authors: Kim Dong Han
Published: April 2009

Acetic anhydride has been used widely in synthetic organic chemistry, especially in syntheses and transformations of heterocyclic compounds. These utilities are reviewed under the following classification.
Acetylinic ketones. Part II.. Reaction of acetylenic ketones with nucleophilic nitrogen compounds
Authors: Baddar F. C. , Al‐Hajjar F. H. , El‐Rayyes N. R.
Published: April 2009

Aroylphenylacetylenes (I) reacted with ethyl and phenyl hydrazinecarboxylates (II) to give ω‐aroylacetophenone‐N‐ethoxycarbonyl‐(Vla‐f) and N‐phenoxycarbonyl‐(VIg‐l) hydrazones, respectively. When these were healed with acetic anhydride they were converted to 5‐aryl‐1‐ethoxycarbonyl‐and 1‐phenoxycarbonyl‐3‐phenylpyrazoles (VII), respectively, which on hydrolysis with rnethanolic potassium hydroxide gave the corresponding 5(3)aryl‐3(5)phenylpyrazoles (VIII).

Reaction of the above acetylenic ketones with guanidine hydrochloride in the presence of sodium carbonate gave the corresponding 2‐amino‐6‐aryl‐4‐phenylpyrimidines (XII). Similarly, reaction of benzoylphenylacetylene with thiourea and with urea in the presence of sodium ethoxide gave rise to 2,4‐diphenylpyrimidine‐2‐thione (XVIII) and 2,4‐diphenyl‐2(1H)pyrimidin‐one (XV), respectively.
Cyclic condensations of 2‐amino‐1,3,4‐thiadiazole with 1,3‐dicarbonyl compounds
Authors: Lauer R. F. , Zenchoff G.
Published: April 2009

The reactions of 2‐amino‐1,3,4‐thiadiazole with 1,3‐dicarbonyl compounds are described. 2,4‐Pentanedione gave 2‐thiocyanato‐4,6‐dimethylpyrimidine while diethylmalonate and ethyl acetoacetate yielded 5‐hydroxy‐7H‐1,3,4‐thiadiazolo[3,2‐a]pyrimidin‐7‐one and 7‐methyl‐5H‐1,3,4‐thiadiazolo[3,2‐a]pyrimidin‐5‐one, respectively. The structure of the latter compound was confirmed by a synthesis of the alternative isomeric structure (5‐methyl‐7H‐1,3,4‐thiadiazolo[3,2‐a]pyrirnidin‐7‐one) from 2‐amino‐1,3,4‐thiadiazole and α‐bromocrotonic acid.
Benzomorphan related compounds. III.. Structural determination of Δ3 ‐ and Δ4‐tetrahydropyridines by nuclear magnetic resonance
Authors: Bosch J. , Canals J. , Giralt E. , Granados R.
Published: April 2009

Observation of the nmr spectra of several Δ3 ‐ and Δ4‐tetrahydropyridines hydrochlorides provides a useful method for the structural determination of this type of compound. The Δ3 ‐ Isomers exist as one predominant epimer only whereas the Δ4‐isomers exist as a mixture of the two possible epimers. The respective assignments are discussed in view of the criteria previously applied in the study of this type of compound.
4‐Substituted‐4H‐pyrrolo[2,1‐c] [1,4]benzoxazines
Authors: Jirkovsky I. , Humber L. G. , Baudy R.
Published: April 2009

The condensations of 1‐(2‐hydroxyphenyl) pyrroles with a variety of carbonyl compounds are shown to give new 4‐substituted‐4H‐4‐methylpyrrolo[2,1‐c][1,4]benzoxazines. Some of the products were further functionalized. The ir, uv, and pmr spectra of the title heterocyclic system are discussed. Reaction of 1‐(2‐hydroxyphenyl) pyrrole with dimethyl acetylenedicarboxylate yielded dimethyl 3‐(2‐hydroxyanilino) phthalale; a mechanistic rationale which accounts for the result involves a rearrangement of the hypothetical Diels‐Alder adduct.
The interaction of cis and trans‐1‐cyclohexyl‐2‐phenyl‐3‐benzoylaziridine with lithium N‐Methylanilide
Authors: Tarburton Philip , Wall D. K. , Cromwell Norman H.
Published: April 2009

A reaction pathway for the rearrangement‐dehydrogenation of cis‐1‐cyclohexyl‐2‐phenyl‐3‐benzoylaziridine into 2‐cyclohexylamino‐3‐phenylindenone can now be suggested. Furthermore, a competing degradation pathway involving CC bond scission accounts for the major product in these reactions and leads to ω‐cyclohexylaminoacetophenone and benzaldehyde. Observed also is the fact that trans‐1‐cyclohexyl‐2‐phenyl‐3‐benzoylaziridine fails to undergo the rearrangement‐dehydrogenation reaction.
Nucleophilic character of alkyl radicals. XIV. Homolytic δ‐aminoalkylation of protonated quinoxaline
Authors: Caronna T. , Citterio A. , Crolla T. , Ghirardini M. , Minisci F.
Published: April 2009

A new general reaction of wide synthetic interest, involving homolytic δ‐aminoalkylation of quinoxaline in acidic medium, is described. Primary and secondary alkylamines, through the corresponding N‐chloroamines, and tertiary alkylamines, through the corresponding N‐oxides, are used. The mechanism of the reaction, involving intramolecular hydrogen abstraction by amino radical cations, and the unusual selectivity are discussed in terms of nucleophilic character of the alkyl radicals and of polar effects in the aromatic substitution.
Studies on the synthesis of heterocyclic compounds. Synthesis of 1,3,2‐benzoxathia‐ and 1,3,2‐benzodioxastibole derivatives
Authors: Anchisi Carlo , Corda Luciano , Maccioni Antonio , Podda Gianni , Cabiddu Salvatore
Published: April 2009

The preparation of 1,3,2‐benzoxathia‐ and 1,3,2‐benzodioxachlorostiboles (IIa‐b) by reaction of antimony trichloride with 2‐hydroxythiophenol (Ia) or 1,2‐benzodiol (Ib) is described. The halogen was easily removed. Thus a Wurtz‐like reaction gave the distibole compounds (IVa‐b), which were also produced by organolithium compounds or pyridine. The compounds Va‐b were obtained with sodium hydroxide, ethoxide and phenoxide, but spiran derivatives VIIa‐b, of antimony, were obtained by treating IIa‐b with 2‐hydroxythiophenol or 1,2‐benzodiol in the presence of triethylamine. The structure of the prepared compounds was determined by spectro‐scopic methods.
Isothiazoles VII: N‐hydroxyalkylation and mannich reaction of 4‐isothiazolin‐3‐one
Authors: Weiler Ernest D. , Miller George A.
Published: April 2009

Hydroxyalkylation and the synthesis of Mannich bases of 4‐isothiazolin‐3‐one are described. Conversion of hydroxyalkyl to haloalkyl derivatives and the preparation of 2‐arylcarbamoyloxy‐methyl‐4‐isothiazolin‐3‐ones are also reported.
On the grignard reaction of 2‐bromo‐3‐iodo‐ and 3‐bromo‐2‐chlorothiophene
Authors: Gronowitz Salo , Pettersson Kerstin
Published: April 2009

2‐Bromo‐3‐iodo‐ and 3‐bromo‐2‐chlorothiophene react with magnesium in the presence of 1,2‐dibrornoethane to give 2‐halo‐3‐thiophene magnesium halide which opens a useful route to 2,3‐disubstituted thiophenes having an electron‐withdrawing group in the 3‐position.
Nitrofuranyl heterocycles. XIIIN‐methyl‐3‐methylthio‐5‐(5‐nitro‐2‐furanyl)‐1H‐1,2,4‐triazoles
Authors: Benjamin Louis E. , Snyder Harry R.
Published: April 2009

A continuing search for new nitrofurans which might possess useful antimicrobial activity led to the synthesis of several 3‐mercapto‐5‐(5‐nitro‐2‐furanyl)‐1H‐1,2,4‐triazoles and their methylated derivatives. This paper describes the preparation of these compounds together with proof of structure of the N‐methylated products.
Synthetic studies of the antitumor antibiotic streptonigrin. II. Synthesis of the C‐D ring portion of streptonigrin
Authors: Liao T. K. , Wittek Philip J. , Cheng C. C.
Published: April 2009

Partial mclhylalion of gallopropiophenonc (4) followed by benzylation and base‐catalyzed condensation with ethyl acetate yielded 3‐(2‐benzyloxy‐3,4‐din]etlK>xy)benzoyl‐2‐butanonc (6). Animation of the latter and subsequent base‐catalyzed cyclization with ethyl cyanoacetate gave 4‐(2‐benzyloxy‐3,4‐dimethoxy)phenyl‐5,6‐dimethyl‐2‐oxo‐1,2‐dihydropyridine (8). Removal of the 2‐oxo group of 8 through chlorination and dechlorination and stepwise conversion of the 5‐cyano and 2‐methyl groups into the 5‐amino and 2‐carboxylic acid groups, respectively, with introduction and removal of protecting groups at proper stages, yielded the C‐D ring moiety of the antitumor antibiotic streptonigrin.
Synthesis of some N‐substituted 4,5‐dihydro‐7,8‐dirnethoxybenzothiazepin‐3‐one 1,1 ‐dioxides
Authors: Catsoulacos Panayotis , Camoutsis Ch.
Published: April 2009

Reaction of ethyl 3,4‐dimethoxyphenylpropionale with chlorosulfonic acid yielded 2‐carbo‐elhoxyethyl‐3,4‐dimelhoxybenzene sulfochloride, which was converted to 2‐earboethoxyethyl‐3,4‐dimethoxybenzcnesulfonamides by the action of ammonia or substituted aromatic amines. Alkaline hydrolysis of these sulfonumide esters furnished the corresponding acids. The reaction of acids with phosphorus pentachloride resulted in the key intermediates, the ehloroearboxycthyl‐3,4‐dimethoxybenzenesulfonamides. The latter was cyelized to N‐substituted 4,5‐dihydro‐7,8‐dirnelhoxybenzothizepine‐3 ‐one 1, 1‐dioxide. Reactions of benzolhiazepinonc ring and nrnr specttra are described.
On the synthesis of selenophene
Authors: Gronowitz S. , Frejd T. , Moberg‐Ogard A. , Trege L.
Published: April 2009

A convenient method for the preparation of selenophene on a semi‐large scale is described.
Synthesis of a new heterocyclic ring system 2,3,5,6,7,9,10,11‐octahydro‐lH‐cyclopenta[9,H)]benzo[i,j] quinolizine‐1,9‐dione
Authors: Dike Suneel Y. , Merchant J. R.
Published: April 2009

Reaction of 1,2,3,4‐tetrahydroquinoline (1) with different α,β‐unsaturated acids in the presence of PPA has been investigated. With acrylic acid, 1 affords two compounds identified as 1‐keto‐benzo[i,j]quinolizine (III) and 2,3,5,6,7,9,10,1 1‐octahy dro‐1H‐cy el open ta [9,10] benzo [i,j]‐quinolizine‐1,9‐dione (IV). A similar reaction of 1 with a‐methyl acrylic and crotonie acids gives compounds V and VI whose structures are analogous to that of IV. These were deduced from their spectral and analytical data.
Nouvelles synthèses de thiéno[3,2‐c] ‐ et thiéno[2,3‐c]pyridines
Authors: Maffrand J. P. , Eloy F.
Published: April 2009

Les auteurs décrivent une nouvelle méthode de synthèse des thiéno[2,3‐c]‐ et [3,2‐c]pyridines et de quelques dérivés tetrahydrogénés, basée sur des modifications de la reaction de Pomeranz‐Fritsch de formation des isoquinoléines.
The synthesis of 2‐amino‐7‐(β‐D‐ribofuranosyl)pyrrolo[2,3‐d]‐pyrimidin‐4‐one (7‐deazaguanosine), a nucleoside Q and Q* analog
Authors: Townsendxs Leroy B. , Tolman Richard L. , Robins Roland K. , Milne George H.
Published: April 2009

The synthesis of 2‐amino‐7‐(β‐D‐riholuranosyl)pyrrolo[2,3‐d ]pyrimidin‐4‐one (7‐deazaguanos‐ine, a nucleoside Q and Q* analog, has been accomplished hy two independcnl routes.
BCL‐2 and BAX proteins expression throughout the light–dark cycle and modifications induced by sleep deprivation and rebound in adult rat brain
Authors: Montes‐Rodríguez Corinne J. , Alavez Silvestre , Soria‐Gómez Edgar , Rueda‐Orozco Pavel E. , Guzman Khalil , Morán Julio , Prospéro‐García Oscar
Published: April 2009

It has been suggested that sleep has a restorative function; however, experimental support is limited. Hence, we investigated whether changes in the level of antiapoptotic BCL‐2 protein and proapoptotic BAX protein occur during sleep deprivation (SD) and sleep rebound, and evaluated the spontaneous changes in these proteins, along the light–dark cycle, in the adult male Wistar rat. Estimations were made in the prefrontal cortex, hippocampus, striatum, and pons. We observed that BCL‐2 exhibited diurnal variations in the prefrontal cortex and striatum, whereas BAX varied in the striatum and showed only small variations in the pons as measured by immunoblotting. The BCL‐2/BAX ratio exhibited diurnal variations in the prefrontal cortex and striatum. BCL‐2 and BAX levels were affected by 24 hr of total SD and 24 hr of sleep rebound. SD decreased the BCL‐2/BAX ratio in the prefrontal cortex and pons. Sleep rebound increased the BCL‐2/BAX ratio in the hippocampus. In conclusion, the BCL‐2/BAX ratio is high during the dark phase as compared with the light phase in the prefrontal cortex and during the light phase as compared with the dark phase in the striatum. SD decreased the BCL‐2/BAX ratio in the prefrontal cortex and pons, whereas sleep rebound increased it in the hippocampus. These changes point out structures in the brain that express these proteins as a response to the light–dark cycle. Similarly, SD and sleep rebound seem to change these proteins expression in some other brain structures, suggesting that cellular vulnerability might be altered by these changes. © 2009 Wiley‐Liss, Inc.
Neue Impulse aus der Goldkatalyse
Authors: Hashmi A. Stephen K.
Published: April 2009

A. Stephen K. Hashmi

Goldkatalysatoren liefern Beiträge zu wichtigen Themen der nachhaltigen Chemie: Oxidation mit molekularem Sauerstoff und kohlenhydratbasierte Bausteine aus nachwachsenden Rohstoffen.
Chemie als Schicksal
Authors: Bulmahn Maren
Published: April 2009

Hier sprechen sich Personen aus, deren Vorfahren Chemiker waren. Wir berichten von Menschen, die selber Chemiker sind, und von anderen, deren Nachkommen eines Tages Chemiker sein werden.
”Der Staat ist verantwortlich für die gesellschaftliche Vision“
Authors: Mertin Michael
Published: April 2009

Über Agendasetting und globale Kooperationsformen sprachen die Nachrichten aus der Chemie mit Michael Mertin, dem Vorstand Technologie der Jenoptik, beim Villa‐Hügel‐Gespräch in Essen. Der Physiker fordert in der Forschungsförderung für Unternehmen mehr Planung und Verlässlichkeit.
Nicht immer harmonisch
Authors: Keßler Eva
Published: April 2009

Das global harmonisierte System GHS wird nur nützlich sein, wenn möglichst viele Staaten möglichst wenig davon abweichen. Dafür sind noch Geltungsbereiche, Stofflisten etc. anzupassen.
A study of critical reasoning in online learning: application of the Occupational Performance Process Model
Authors: Mitchell Anita Witt , Batorski Rosemary E.
Published: April 2009

This study examined the effect of an online guided independent study on critical reasoning skills. Twenty‐one first‐semester Master of Occupational Therapy students completed an online assignment designed to facilitate application of the Occupational Performance Process Model (Fearing & Clark) and kept reflective journals. Data from the journals were analyzed in relation to the three sets of questions, question type and results of the Watson‐Glaser Critical Thinking Appraisal (WGCTA). This assignment appeared to be effective for enhancing awareness and use of critical reasoning skills. Differences in patterns of critical reasoning between students with high and low WGCTA scores and results of an inductive analysis of the journal entries are discussed. Future research investigating the types of feedback that effectively facilitate development of critical reasoning and whether students with high and low WGCTA scores might benefit from different types of instruction and/or feedback is recommended. Copyright © 2009 John Wiley & Sons, Ltd.
Prognosis in pediatric hematologic malignancies is associated with serum concentration of mannose‐binding lectin‐associated serine protease‐2 (MASP‐2)
Authors: Zehnder Aina , Fisch Urs , Hirt Andreas , Niggli Felix K. , Simon Arne , Ozsahin Hulya , Schlapbach Luregn J. , Ammann Roland A.
Published: April 2009

Background

Mannose‐binding lectin (MBL) and MBL‐associated serine protease‐2 (MASP‐2) are key components of the lectin pathway of complement activation. Their serum concentrations show a wide interindividual variability. This study investigated whether the concentration of MBL and MASP‐2 is associated with prognosis in pediatric patients with cancer.

Methods

In this retrospective multicenter study, MBL and MASP‐2 were measured by commercially available ELISA in frozen remnants of serum taken at diagnosis. Associations of overall survival (OS) and event‐free survival (EFS) with MBL and MASP‐2 were assessed by multivariate Cox regression accounting for prognostically relevant clinical variables.

Results

In the 372 patients studied, median serum concentration of MBL was 2,808 µg/L (range, 2–10,060) and 391 µg/L (46–2,771) for MASP‐2. The estimated 4‐year EFS was 0.60 (OS, 0.78). In the entire, heterogeneous sample, MBL and MASP‐2 were not significantly associated with OS or EFS. In patients with hematologic malignancies, however, higher MASP‐2 was associated with better EFS in a significant and clinically relevant way (hazard ratio per tenfold increase (HR), 0.22; 95% CI, 0.09–0.54; P = 0.001). This was due to patients with lymphoma (HR, 0.11; 95% CI, 0.03–0.47; P = 0.003), but less for those with acute leukemia (HR, 0.35; 95% CI, 0.11–1.15; P = 0.083).

Conclusion

In this study, higher MASP‐2 was associated with better EFS in pediatric patients with hematologic malignancies, especially lymphoma. Whether MASP‐2 is an independent prognostic factor affecting risk stratification and anticancer therapy needs to be assessed in prospective, disease‐specific studies. Pediatr Blood Cancer 2009;53:53–57. © 2009 Wiley‐Liss, Inc.
Two‐dimensional native electrophoretic analysis of respiratory supercomplexes from Yarrowia lipolytica
Authors: Nübel Esther , Wittig Ilka , Kerscher Stefan , Brandt Ulrich , Schägger Hermann
Published: April 2009

Mitochondria of the strictly aerobic yeast Yarrowia lipolytica contain respiratory complex I with close functional and structural similarity to the mammalian enzyme. Unlike mammalian mitochondria, however, Yarrowia mitochondria have been thought not to contain supercomplexes. Here, we identify respiratory supercomplexes composed of complexes I, III and IV also in Y. lipolytica. Evidence for dimeric complex I suggests further association of respiratory supercomplexes into respiratory strings or patches. Similar supercomplex organization in Yarrowia and mammalian mitochondria further makes this aerobic yeast a useful model for the human oxidative phosphorylation system. The analysis of supercomplexes and their constituent complexes was made possible by 2‐D native electrophoresis, i.e. by using native electrophoresis for both dimensions. Digitonin and blue‐native electrophoresis were generally applied for the initial separation of supercomplexes followed by less mild native electrophoresis variants in the second dimension to release the individual complexes from the supercomplexes. Such 2‐D native systems are useful means to identify the constituent proteins and their copy numbers in detergent‐labile physiological assemblies, since they can reduce the complexity of supramolecular systems to the level of individual complexes.