bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photolyse von ternären Fe(III)‐Komplexen mit Oxalat‐ und Phenolat‐Liganden
Authors: Roewer G. , Kempe G. 
Published: December 2004

Photolysis of Ternary Fe(III)‐Complexes with Oxalate and Phenolate LigandsThe overall iron(II) quantum yields of the photolysis of mixed ligand complexes [Fe(C2O4)3−nLn]3− (L = salicylate, sulfosalicylate or the dianion of catechol, sodium 3,5‐sulfocatechol, tetrachlorcatechol) in aqueous solution within the spectral region 436 nm ≤ λirr. ≤ 546 nm are much smaller than those of the complexes [Fe(C2O4)3−n(H2O)2n]3−2n (n = 0; 1; 2). This means that the intramolecular photoredoxreaction between iron(III) and the oxalate ligand is not sensitized by the L→Fe(III) charge transfer excitation. Moreover, filter effects through photoinactive complexes [FeL2(H2O)2]− or [FeL(H2O)4]+ probably give rise to the strong decrease of the quantum yields.
Kristallin‐flüssige Heterocycloalkane. I. Synthese und Eigenschaften substituierter 1,3‐Dioxane
Authors: Vorbrodt H.‐M. , Deresch S. , Kresse H. , Wiegeleben A. , Demus D. , Zaschke H. 
Published: December 2004

Liquid‐crystalline Heterocycloalkanes. I. Synthesis and Properties of Substituted 1,3‐DioxanesThe synthesis of 2,5‐disubstituted 1,3‐dioxanes is described, their melting and clearing points and their physical properties (dielectric anisotropy, viscosity, transition enthalpies, optical birefringence) are investigated. The cyano substituted 1,3‐dioxans 5 and 7 are valuable materials for application in displays.
Synthese und Reaktionsverhalten von 2‐Aryloxy‐s‐trithianen
Authors: Walther H. , Gross H. 
Published: December 2004

Synthesis and Reactions of 2‐Aryloxy‐s‐trithianes2‐Aryloxy‐s‐trithianes 4 had been prepared from 1‐tosyl‐imino‐1‐SIV‐1,3,5‐trithiane and phenolates. – By self‐condensation of 4 1,5‐bis‐(trithianyl)‐1,3,5‐trithiapentane 5 and triphenyl‐orthoformate 7 are formed, accompanied by further products, which had been isolated in pure state and identified unambiguously by H‐n.m.r. and mass‐spectra. In the presence of acids the 2‐aryloxy‐s‐trithianes 4 react with nucleophilic aromatic compounds such as phenoles, N,N‐dimethylaniline, pyrrole, indole, and thiophenes to give the C‐trithianylated products. With mercaptanes 2‐alkylthio‐s‐trithianes are formed.
Wittig‐Synthese und 13C‐NMR‐Analyse von pyridinanalogen Chalkonen
Authors: Bödeker J. , Radeglia R. 
Published: December 2004

Wittig Synthesis and 13C‐N.M.R. Investigation of Pyridineanalogous ChalconesWittig type reaction of the three isomeric pyridinealdehydes with benzoylmethyl‐enetriphenylphosphorane yields azachalcones 1a–c which have the E‐configuration. The complete 13C‐n.m.r. analysis of these compounds is reported. From the chemical shifts of the Cα‐signals and on the basis of a Hammett relationship σ‐values of the three isomeric pyridine groups are calculated and compared with other data.
Einfache Darstellung von N(2′‐Hydroxy)‐aryliden‐nitro‐anilinen als Cumarin‐Synthone
Authors: Czerney P. , Hartmann H. 
Published: December 2004

A Simple Route to N(2′‐Hydroxy)‐arylidene‐nitroanilienes‐Versatile Synthones for CoumarinesIn a three‐component reaction with ortho formic esters and nitroaniline activated phenols are easily transferred to N(2′‐hydroxy)‐arylidene‐nitroanilines. The reaction is commonly applicable and gives the N(2′‐hydroxy‐4′‐N,N‐dialkylamino)‐benzylidene‐nitroanilines 10 in good yields also with the air‐unstable m‐N,N‐dialkylaminophenols 8. The prepared 2‐hydroxy‐azomethines are convertable into boroncomplexes 14 and coumarine derivatives 17, respectively.
Zur Initiierung der Polymerisation des Vinylchlorids mit Mangan(III)‐acetylacetonat
Authors: Schellenberg J. , Opitz G. , Ulbricht J. 
Published: December 2004

On the Initiation of the Polymerization of Vinylchloride with Manganese(III) ‐acetyl‐acetonateThe initation reaction of the polymerization of vinyl chloride in dimethylformamide with manganese acetylacetonate is investigated. The reduction of the transition metal, the splitting of a ligand of the metal chelat and its incorporation into the polymer molecule is proved and the structure of the initiating radical is determined. The rate and efficiency of initiation is measured by the inhibition method.
Radikalreaktionen von N‐Heterocyclen. I. Synthese und Struktur eines N,N‐verknüpften Bipyrazols
Authors: Schulz Manfred , Mögel Liena , Riediger Werner , Nghiem‐Xuan‐Dung  , Radeglia Reiner 
Published: December 2004

Radical Reactions of N‐Heterocyclic Compounds. I. Synthesis and Structure of an N,N‐Linked Bipyrazole5(3)‐Amino‐3(5)‐(phenylamino)‐pyrazole‐4‐carboxylic acid ethyl ester (1), which is a very good antioxidant, reacts under mild reaction conditions with dibenzoyl peroxide or with tert.‐butoxy radicals under formation of a bipyrazole 4. Evidence of the structure of 4 is given by 1H‐n.m.r., 13C‐n.m.r., i.r. and u.v. spectroscopic measurements, respectively and especially by 15N‐n.m.r. measurements of 15N labelled compounds 1 and 4. The bispyrazole 4 reacts with Pb(IV)‐acetate, the product isolated was the 5‐amino‐e‐anilino‐1‐(1‐anilino‐2‐cyano‐2‐ethoxycarbonylethenyl‐azo)‐pyrazole‐4‐carboxylic acid ethyl ester (7). The formation of this substance is a chemical proof of the structure of 4.
Untersuchungen über die Autoxidation verzweigter Olefine. V. Allgemeine Gesetzmäßigkeiten
Authors: Bilas W. , Pritzkow W. 
Published: December 2004

Studies on the Autoxidation of Branched‐chain Olefins. V. General RegularitiesThe rates of oxidation and the yields of epoxides of unbranched and branched olefins are discussed. The rates of oxidation increase with the increasing number of alkyl groups bound at the CC‐double bond. Epoxide yields show no simple dependence on the olefin structure. The allyl radicals formed as intermediates of olefin oxidation are preferably attacked by oxygen either at the less hindered end (in the case of nonbranched olefins) or at the higher substituted end (in the case of branched olefins) of the allylic system. The reasons for these regularities are discussed. Where Z/E‐isomerism is possible, the (E)‐configuration in allylic radicals is more stable than the (Z)‐configuration, and therefore the (E)‐forms of the allylic hydroperoxides are preferably formed.
Die Nitril‐Carboxamid‐Umlagerung
Authors: Bischoff Christian , Schröder Edith , Gründemann Egon 
Published: December 2004

The Nitrile Carboxamide RearrangementBy reaction of cyclohexanone‐2‐carboxamide (4) with cyan amide 1‐cyano‐cyclohex‐1‐en‐2‐yl‐urea (6) is formed via nitrile carboxamide rearrangement. Whilst compound 6 with 1,2‐diaminobenzene hydrochloride forms 11‐amino‐1 H‐2,3,4,5‐tetrahydrodibenzo[b,e][1,4]diazepin hydrochloride (8 and 8a), compound 6 and 1,2‐diaminobenzene form hexahydro‐benzimidazo[1,2‐c]‐quinazolin‐6‐one (12). Compound 8 with sodium hydroxide yields 11‐amino‐1 H‐2,3,4,11a‐tetrahydrodibenzo[b,e]‐[1,4]diazepin (9). Compound 6 reacts with cyclohexylamine to form N‐(1‐cyanocyclohex‐1‐en‐2‐yl)‐N′‐cyclohexyl urea (10). Compound 10 with 1,4‐ or 1,2‐diaminobenzene hydrochloride yields compound 7 and 8. In alkaline solution 10 cyclises to 4‐amino‐3‐cyclohexyl‐2,3,5,6,7,8‐hexahydroquinazolin‐2‐one (11). Compound 4 and malonitrile form either 3‐amino‐4‐cyano‐1,2,5,6,7,8‐hexahydro‐isoquinol‐1‐one (13) or 1‐amino‐4‐cyano‐2,3,5,6,7,8‐hexahydro‐isoquinol‐3‐one (14). Compound 13 and alkaline formaldehyde react to cyanooctahydroisoquinoline‐[2,3‐c] [1,3,5]oxdiazin‐6‐one (17). 2‐Cyanoethyl‐cyclohexan‐one‐2‐carboxamide (22), prepared by Michael‐reaction from 4 and acrylonitrile, forms via nitrile carboxamide rearrangement 10‐cyano‐1,2,3,4,5,6,7,10‐octahydroquinolin‐2‐one (24) and 2‐(1′‐cyano‐cyclohexyl‐2′‐one)‐propionic acid (25). Nucleophilic attack of the NH2‐group at the cyanogroup of compound 22 forms 5‐(spirocyclohexan‐2′‐one)‐hexahydropyridin‐2,6‐dione (27).
α‐Substituierte Phosphonate. 39. Methandiphosphonsäureester durch UV‐induzierte Michaelis‐Becker‐Reaktion
Authors: Czekański T. , Gross H. , Costisella B. 
Published: December 2004

α‐Substituted Phosphonates. 39. Methane‐diphosphonic Esters by U.V.‐Induced Michaelis‐Becker‐ReactionDibromomethane resp. chlorbromomethane reacts with sodium dialkyl phosphite in heptane‐/liq.NH3 or in liq. NH3 by u.v. irradiation at low temperatures to give in good yields methane diphosphonic acid tetraalkylesters 1. In the same manner with sodium diethyl thionophosphite the corresponding methane‐bis‐thiophosphonic acid tetraethylester 4 is obtained.
Aza‐enamine. IV. Nachweis des Enamin‐Charakters von N,N‐alkylsubstituierten Aldehydhydrazonen anhand NMR‐ und UV‐spektroskopischer Untersuchungen
Authors: Gründemann E. , Brehme R. , Nikolajewski H. E. 
Published: December 2004

Aza‐enamines. IV. Proof of Enamine Character of N,N‐Alkylated Hydrazones Given by N.M.R.‐ and U.V.‐SpectroscopyHydrazones of the type R1CH  NR2 with R1 = p‐methoxyphenyl‐, 1, phenyl‐, 2, p‐nitrophenyl‐, 3, ethyl‐, 4 and R2 = morpholino‐, a, piperidino‐, b, dimethylamino‐, c, pyrrolidino‐, d and dicyclohexylamino‐, e have been investigated with regard to spectroscopic analogy to enamines. The conclusion has been drawn that aldehydehydrazones act similar enamines.
Azoperoxide. VIII. Synthese und Zerfall des Azo‐bis‐(isobutyl‐tert.‐butylperoxyoxalats)
Authors: Schulz Manfred , Gartz Jochen , Jüngling Thomas 
Published: December 2004

Azoperoxides. VIII. Synthesis and Thermolysis of the Azo‐bis‐(isobutyl‐tert.‐butyl‐peroxyoxalate)The decomposition of 2 was studied at 50°C in chlorobenzene, ethylbenzene, freone 113 as the solvents. The yield of the cage product 6 surprisingly was nearly 100%. The same result was obtained without a solvent at room temperature. In isopropanol the thermolysis of 2 gave the azo‐bis‐(isobutyl)‐monooxalate (7). Decomposition rates in the solvents mentioned were measured. The decomposition of a new bifunctional peroxide, the β‐tert.‐butylperoxyethyl‐tert.‐butylperoxy‐oxalate (8) also yielded nearly 100% of the cage product 11.
Über die katalysierte Flüssigphasenoxidation von cis‐ und trans‐Oct‐4‐en
Authors: Rothe D. , Schnurpfeil D. 
Published: December 2004

The Catalyzed Liquid‐Phase Oxidation of cis‐ and trans‐Oct‐4‐eneThe influences of MoO2(acac)2acac‐Acetylacetonat.

, MoO
3
and Co(acac)
3
on the liquid‐phase oxidation of cis‐ and trans‐oct‐4‐ene at 110°C were studied. In the presence of molybdenum catalysts the yield of epoxides and the stereoselectivity of epoxide formation are increased. The results are in good agreement with the hypothesis that molybdenum compounds effect only the stereospecific reaction of the hydroperoxides formed with the starting olefin yielding the corresponding epoxide.The cobaltic complex increases the rate of autoxidation, but has no remarkable influence on the yield of epoxides. In the presence of Co(acac)3 more trans‐epoxide is formed from cis‐oct‐4‐ene than in the uncatalyzed reaction. This can be explained by an increase of the lifetime of the intermediate peroxyalkyl radical, effected by complex formation of the radical with a cobalt species.
Zum Reaktionsverhalten von Carbonsäureamiden gegenüber Schwefelkohlenstoff und Isothiocyanaten
Authors: Richter M. , Strauss K. , Schädler H.‐D. , Augustin M. 
Published: December 2004

Reaction Behaviour of Amides with Carbondisulphide and IsothiocyanatesReactions of substituted arylamides, hetarylamides and furylacrylicamide 1 with carbon disulphide present a possibility to synthesize imino‐dithiocarbonic‐S,S′‐diester 5. The mechanism of the reaction and the reaction conditions are investigated. Quantum chemical investigations by simple HMO‐method in connection with the experimental results describe the reaction in dependence upon the influence of substituent in 2‐ and 4‐position to the phenylring. Further more is described the reaction of amide with isothiocyanates to thiourea 6 and isothiourea 7.The structures of the final products are determined by analytical dates.
Synthesen mit 1, 3‐Dithietanen. XIII. Synthesen von kondensierten Heterocyclen aus substituierten 5‐Thioxo‐Δ3‐pyrazolin‐4‐carbonsäureestern
Authors: Peseke K. , Vogel C. , Blaesche J. , Kollhof K.‐H. 
Published: December 2004

Syntheses with 1, 3‐Dithietanes. XIII. Syntheses of Condensed Heterocycles from 5‐Thioxo‐3‐pyrazoline‐4‐carboxylates3‐Amino‐2‐aroyl‐5‐thioxo‐3‐pyrazoline‐4‐carboxylates 1d–f react with bromoacetal‐dehydediethylacetale, phenacyl bromides, ethyl bromopyruvate, ethyl α‐chloro‐acetate or chloro‐acetylacetone to give ethyl dihydropyrazolo[5,1‐b]thiazolecarboxylates 2, 4, 5 or 7. The derivatives of ethyl tetrahydropyrazolo [5,1‐b]thiazolecarboxylates 8 or 9 are obtained by reaction of 1d–f with ethyl β‐anilino‐α‐chloro‐crotonate and oxalylchloride, respectively. The ethyl methylthiopyrazoline‐carboxylate 10d and an excess of hydrazine hydrate afford pyrazolo[3,4‐c]pyrazole 11. Compounds 10 react with phenyl isocyanate to give pyrazolo[3,4‐d][1,3]oxazin‐6‐ones 13. The dithietanes 12 and cinnamohydrazide yield pyrazolo[1,2‐a]pyrazolecarboxylates 15.
Chemische Synthese einiger im Zuckerteil abgewandelter kürzerer Oligodesoxyribonucleotide
Authors: Rosenthal A. , Cech D. , Veiko V. P. , Shabarova Z. A. , v. Janta‐Lipinski M. , Langen P. 
Published: December 2004

Chemical Synthesis of Some Shorter Oligodeoxyribonucleotides with Modified Sugar MoietyThe chemical synthesis of the dinucleotides 5′‐deoxy‐5′‐fluoro‐thymidyl‐(3′ → 5′)‐3′‐deoxy‐3′‐fluoro‐thymidine, 5′‐deoxy‐5′‐fluoro‐thymidyl‐(3′ → 5′)‐3′‐deoxy‐3′‐azido‐thymidine, 2′‐deoxy‐cytidyl‐(3′ → 5′)‐3′‐deoxy‐3′‐fluoro‐thymidine and the tetranucleotide 2′‐deoxy‐2′‐fluorouridyl‐(3′ → 5′)‐thymidyl‐(3′ → 5′)‐thymidyl‐(3′ → 5′)‐thymidyl‐(3′ → 5′)‐3′‐deoxy‐3′‐fluoro‐thymidine d(2′‐F‐UpTpTp‐3′‐F‐T) is described both in solution and in the solid phase.
Acylierung von Heterocyclen mit Kohlensäurederivaten. I. Kinetik und Mechanismus der Reaktion von 2‐Aminobenzimidazolen mit Arylcyanaten
Authors: Bacaloglu Ilse , The Ky Truong , Boeriu Carmen , Glatt Hans Horst , Bacaloglu Radu , Martin Dieter , Graubaum Heinz 
Published: December 2004

Acylation of Heterocycles with Carbonic Acid Derivatives. I. Kinetics and Mechanism of the Reaction of 2‐Aminobenzimidazoles with Aryl CyanatesThe second order rate constants for the reaction of 2‐amino‐benzimidazoles (2‐ABI) with aryl cyanates forming 2‐amino‐benzimidazole aryl ester imide 3 have been determined in dependence on substituent effects by u. v. measurements. The results are interpreted by a six‐membered cyclic transition state in which the electrophilic attack of the cyanate on the endocyclic N atom is catalyzed by an H bridge interaction of the exocyclic amino group of 2‐ABI with the OCN group.
Acylierung von Heterocyclen mit Kohlensäurederivaten. II. Endo‐ und exo‐Carbamoylierung von 2‐Amino‐benzimidazol‐Derivaten mit Isocyanaten. Mechanismus der Acylgruppenwanderung
Authors: Graubaum Heinz , Martin Dieter , Szeibert Dagmar , Breckner Michael , Glatt Hans Horst , Bacaloglu Radu , Czunderlick Carol 
Published: December 2004

Acylation of Heterocycles with Carbonic Acid Derivatives. II. Endo and Exo Carbamoylation of 2‐Amino‐benzimidazole Derivatives with Isocyanates. Mechanism of the Acyl Group Migration2‐Amino‐benzimidazoles react with isocyanates with good yields to give 2‐amino‐1‐carbamoyl‐aminobenzimidazoles 1 at −30°C and the corresponding 2‐carbamoyl isomeres 2 at room temperature, respectively. The isomerization mechanism was studied by crossover experiments and kinetic measurements and has been found to consist of inter‐ and monomolecular acyl transfer.
Synthese und Oxydation von 1‐(1,3‐Thiazol‐2‐yl)‐pyrazolid‐3‐onen
Authors: Richter A. M. , Mojjoukhine V. 
Published: December 2004

Synthesis and Oxydation of 1‐(1,3‐Thiazol‐2‐yl)‐pyrazolidin‐3‐onesThe 1‐(1,3‐thiazol‐2‐yl)‐pyrazolid‐3‐ones 4 are synthesized by reaction of 1‐thiocarbamoyl‐pyrazolidin‐3‐one 2 with α‐halogenaldehydes and α‐halogenketones, respectively. The structure of 4 is proved by their 1H‐n.m.r. and mass spectra. Oxydative dimerisation of 4 leads to the bisazomethinimines 10. The compounds 10 represent a new type of azomethinimines with a quinoid structure.
Hydroxybromierung von Norcaran
Authors: Haufe Günter 
Published: December 2004

Hydroxybromination of NorcaraneTreatment of norcarane (1) with N‐bromosuccinimide (NBS) and water results mainly in Markovnikov addition of the elements of hypobromous acid to the cyclopropane ring forming trans‐2‐(bromomethyl)cyclohexanol (2) (52%) and cis‐2‐(bromomethyl)cyclohexanol (3) (7%). In addition a deprotonation of the intermediately cationic species leads to the not isolated 3‐(bromomethyl)cyclohexene (12), which gives with a second mol of NBS and water t‐2‐bromo‐t‐3‐(bromomethyl)cyclohexan‐r‐1‐ol (4) (28%) and three isomeric minor compounds 5, 6, 7. The stereochemistry of the major products has been established by spectroscopic techniques and chemical methods.
Komplexe des Eisens mit aromatischen Liganden
Authors: Eľcov A. V. , Maslennikova T. A. , Kukuschkin V. Ju. , Shaburov V. V. 
Published: December 2004

Complexes of Iron with Aromatic LigandsThe reaction of FeCl3 · 6 H2O with several substituted o‐phenylene diamines forms complexes of the Fe(II)‐ion with o‐quinone diimines. Before the formation of these complexes there are a few of redox reactions between Fe(III)ions and the diamines. The Fe(III)/o‐quinone diimine‐complex is an intermediate which was characterized by means of spectroscopic methods. The two forms of 6‐oxy‐7‐nitrosobenzthiazoline produce only one 1:3 complex with Fe(II)ions. Also the N‐methyl‐6‐oxy‐7‐nitrosobenzthiazolium iodide forms a 1:3 complex. In the former complex the quinone‐oxim‐form is the ligand. The isolated complexes were characterized through elemental analysis and physical methods.
Steroide. 73. Gekoppelte Additionsreaktionen an 14,15‐ungesättigten Androstanen Einfluß des positiven Halogens auf die Regioselektivität
Authors: Ponsold K. , Wunderwald M. 
Published: December 2004

Steroids. 73. Joint Addition Reactions to 14,15‐Unsaturated Androstanes. Influence of the Positive Charged Halogen on the RegioselectivityThe joint addition of positive charged halogens and nitrogenous nucleophils to 14,15‐unsaturated olefins is investigated. It was established that the regioselectivity of the addition reaction is different for bromine and iodine. This surprising result is discussed. Ring closure reactions of the addition products to the corresponding aziridines are investigated.
Synthesen von C‐Nucleosiden und C‐Nucleosidanaloga. I. Darstellung von 1‐(D‐galacto‐2,3,4,5,6‐Pentakisacetoxyhexanoyl)‐3‐alkyl‐ oder arylamino‐6,6‐dimethyl‐4,5,6,7‐tetrahydro‐benzo[c]thiophen‐4‐onen
Authors: Görges S. , Kristen H. , Peseke K. , Farkas I. 
Published: December 2004

Syntheses of C‐Nucleosides and Analogs of C‐Nucleosides. I. Preparation of 1‐(D‐galacto‐2,3,4,5,6‐Pentakisacetoxy‐hexanoyl)‐3‐alkyl‐or arylamino‐6,6‐dimethyl‐4,5,6,7‐tetrahydro‐benzo[c] thiophene‐4‐ones2‐(Alkyl‐ or Arylamino‐mercapto‐methylen)‐5,5‐dimethyl‐cyclohexane‐1,3‐diones 1 react in alkaline medium with 3,4,5,6,7‐penta‐O‐acetyl‐1‐bromo‐1‐deoxy‐D‐galacto‐heptulose 2b to give the title compounds 6d‐g.
Michael Reactions of Pyridinium‐1‐alkylacetamides
Authors: Katritzky Alan R. , Grzeskowiak Nicholas E. , Alvarez‐Builla Julio , Tarraga‐Tomas Alberto 
Published: December 2004

Michael‐Reaktionen von Pyridinium‐1‐alkylacetamidenDie leicht aus Methylpyridinium‐1‐acetat und primären Aminen zugänglichen Pyridinium‐1‐alkylacetamide 5 reagieren mit Chalconen und Natriummethylat in Ethanol in hohen Ausbeuten zu 3‐alkylaminocarbonylsubstituierten Tetrahydroindolizinen 6. Diese unterliegen einer schnellen und kompletten Ringöffnung mit Essigsäure zu Pyridiniumsalzen 8.Analoge Salze 7 erhält man direkt aus den Pyridinium‐1‐alkylacetamiden 5 durch Michael‐Addition an die Chalcone in Gegenwart von Dimethylamin als Katalysator.Um diese Michael‐Addukte zu den N‐Alkyl‐4, 6‐diaryl‐2‐pyridonen 9 zu cyclisieren, sind hohe Temperaturen erforderlich. Dabei werden niedrige Ausbeuten an diesen Produkten erzielt. Weiterhin entstehen die NH‐Pyridone und Chalcone als Nebenprodukte.
1H‐NMR‐, 13C‐NMR‐ und IR‐Untersuchungen zur Tautomerie von 15N‐markiertem 3‐Methyl‐1‐phenyl‐Δ2‐pyrazolin‐5‐on
Authors: Freyer Wolfgang , Köppel Hubert , Radeglia Reiner , Malewski GüNter 
Published: December 2004

1H‐N. M. R., 13CN. M. R., and I. R.‐Investigations Concerning Tautomerism of 15N‐Labeled 3‐Methyl‐1‐phenyl‐Δ2‐pyrazolin‐5‐oneThe behaviour of the 15N‐mono and dilabeled compound in dependence on temperature and solvent polarity is described. Chemical shifts, nJ(15N1H), and nJ(15N13C) coupling constants (n = 1 – 3) have been determined. In the cases of 2, 2, 2‐trifluoroethanole and hexafluoroisopropanole the Δ4‐pyrazolin‐3‐one is stabilized and detected by 3J(15N2H4) = 3 Hz, 1J(13C315N2) = 11, 0 Hz and δ(13C5). In HMPT the 5‐hydroxypyrazole form predominates and is characterized by 3J(15N1H4) = 5, 1 Hz and δ (13C5).Coupling constants 3J(15N2H4) and J(13C315N2) could not be observed in this solvent.In accordance with 1H‐ and 13C‐n. m. r.‐parameters i. r. measurements in dependence on temperature lead to the conclusion that in DMSO and THF for instance all three tautomers are present and variation of temperature does not change the equilibrium between the tautomers.A good relationship between the content of the CH2, OH and NH forms and the Donor Numbers (DN) and Acceptor Numbers (AN) by Gutmann has been found.
Thermische Untersuchungen zum Formierungsverhalten des Katalysatorsystems Cobaltacetylacetonat‐Triethylaluminium
Authors: Hoffmann U. , Anderson H. , Haberland D. 
Published: December 2004

Thermal Investigation of the Formation of the Catalyst System Cobalt Acetylacetonate – Aluminium TriethylThe formation of the Ziegler catalyst system cobalt‐tris‐ and cobalt‐bis‐acetylacetonate with triethylaluminium was investigated by means of quantitative differential thermal analysis and calorimetry in solution. From DTA and heat flow curves qualitative and quantitative relations were determined between Al/Co‐ratio and thermal reaction power. For both systems in both systems in the first step second order reactions are postulated and kinetic and thermodynamic parameters are evaluated, whereas the course and order of the following steps differ distinctively. For the complete reduction of one mole Co(III) or Co(II), respectively, every alkyl group of AlEt3 is suitable.
Oxidation von einigen Alkyl‐ und Alkenylferrocenen mit Bis (triphenylsilyl)‐Chromat(VI)
Authors: Holěek J. , Handlíř K. , Nádvorník M. 
Published: December 2004

The Oxidation of Some Alkyl‐ and Alkenylferrocenes by Bis(triphenylsilyl) Chromate (VI)In vorangehenden Mitteilungen [1–3] haben wir über die Oxidation von primären und sekundären Alkoholen mit Ferrocenyl‐Substituenten mittels Bis(triphenylsilyl)‐chromat(VI) in aprotischen Lösungsmitteln berichtet. Dabei konnte keine Oxidation des Ferrocens zum Ferricenium‐Kation beobachtet werden. Die Reaktionen verlaufen selektiv und führen mit hohen Ausbeuten zur Bildung der entsprechenden Carbonylverbindungen. In dieser Mitteilung sind die Ergebnisse unserer bisherigen Untersuchungen zur Oxidation von Alkyl‐ und Alkenylferrocenen mit Bis(triphenylsilyl)‐chromat(VI) unter ähnlichen Reaktionsbedingungen zusammengefaßt.
Synthese von 1‐(β‐D‐Arabinofuranosyl)‐pyrimidinen
Authors: Cech D. , Schwarz B. , Pein C. D. 
Published: December 2004

Syntheses of 1‐(β‐D‐Arbinofuranosyl)‐pyrimidinesNew synthetic methods of 1‐(β‐D‐arabinofuranosyl)‐pyrimidines are described. 1‐(β‐D‐arabinofuranosyl)‐uracil, 1‐(β‐D‐arabinofuranosyl)‐5‐fluorouracil, 1‐(β‐D‐arabinofuranosyl)‐thymine, and 1‐(β‐D‐arabinofuranosyl)‐cytosine can be obtained in a high yield by the splitting of the anhydrobond in 2,2′‐anhydropyrimidines in dipolar aprotic solvents, such as HMPT, DMF, and DMSO, respectively, in the presence of activated elemental copper.Unlike the formation of cyclopyrimidiens ribonucleosides are directly transformed to the corresponding arabinofuranosyl derivatives by the reaction with diphenylcarbonate and NaHCO3 in the presence of copper. The reaction proceeds probably via an intermediate formation of the cycloproduct. Further aspects on the mechanism are described.