bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrierung von Crotonaldlehyd und Acetaldol mit modifizierten Pd‐Trägerkatalysatoren I. Zum Einfluß einer Titaniummodifizierung auf Pd/AI2O3‐Katalysatoren
Authors: Bohm D. , Kripylo P. , Raminoarison M. 
Published: January 2005

Hydrogenation of Crotonaldehyde and Acetaldole with Modified Pd Carrier Catalysts. I. On the Influence of a Titanium Modification to Pd/Al2O3 CatalystsThe modification of Pd/Al2O3 catalysts with titanium was studied in the hydrogenation of crotonaldehyde and acetaldole. In the result of the titanium modification the hydrogenation activity is increased and the formation of carbon monoxide is decreased. An electronic and geometric ensemble effect should be the reason for the palladium titanium interaction. The mechanism of the acetaldole conversion to butyraldehyde at 160°C is mainly determined by hydrogenolysis in one step and at 200°C by two steps consisting in dehydratization and hydrogenation.
MINDO/3‐ und MMP2‐Berechnungen zur Energetik isomerer Kohlenwasserstoffe der Formel C7H8
Authors: Gey E. , Ondruschka B. , Bögel H. 
Published: January 2005

MINDO/3 and MMP2 Calculations on the Energetics for Hydrocarbon Isomers of the Formula C7H8MINDO/3 and MMP2 calculations are reported for 10 closed shell and 3 open shell C7H8 hydrocarbons to study their stability relative to toluene. The thermodynamics of selected equilibrium gas phase reactions is discussed using the calculated heats of formation for these isomeric hydrocarbons. In agreement with experimental results toluene is the most stable isomer. The spirocompound homofulvene reacts under CC bond scission and formation of the resonance stabilized cyclopentadienyl radical.
Ethylidencyclohexan ‐ Vorstufe für Allyl‐ und 1,2‐Dimethyl‐allylradikale in der Gasphase
Authors: Ondruschka B. , Vorwerk D. , Remmler M. 
Published: January 2005

Ethylidenecyclohexane ‐ Precursor of Allyl and 1,2‐Dimethylallyl Radicals in the Gas PhaseA systematic study of the thermolysis of ethylidenecyclohexane (1) and 1‐vinylcyclohexene (3) was made under VLPP‐MS‐conditions. The major fate of 1 is isomerization to 5‐methyl‐hepta‐1,5‐diene (2) which may then decompose to allyl (7) and 1,2‐dimethylallyl radical (6). The latter is highly unstable and therefore 6 is degraded to isoprene. Minor processes in thermolysis of 1 include further hydrogen elimination to 3 and double bond isomerization to 1‐ethylcyclohexene (4). Both cyclohexene derivates undergo most notably RDA‐fragmentation.
Pyrolysis Kinetics of Octalins
Authors: Ondruschka Bernd , Zimmermann Gerhard 
Published: January 2005

AbstractThe gas phase pyrolysis of three octalins has been studied in a conventional flow system in the temperature range between 500 and 725°C and at pressures up to 70 Torr (educt) and 1 atm (reaction system), respectively. The reactions follow a first‐order rate law. The overall rate coefficients are given by the following Arrhenius parameters. 9(10)‐octalin (1): log k1 (s−1) = (14.71 ± 1.6) − (260.0 ± 6.2) kJ mol−1/2.303 RT; 1(9)‐octalin (2): log k2 (s−1) = (13.62 ± 0.9) − (239.1 ± 3.7) kJ mol−1/2.303 RT; trans‐1‐octalin (3): og k3 (S−1) = (14.76 ± 0.5) − (272.6 ± 1.8) kJ mol−1/ 2.303 RT. The mechanism of the thermal degradation of 1 to 3 is related to Retro‐Diels‐Alder fragmentation.
Reactions of 4‐oxoalkanoic acids. III. Synthesis of 5‐Methyl‐ and 5‐Methylenepyrrolidin‐2‐ones by reaction of α‐angelica lactone with methylamine
Authors: Wedler Christine , Costisella Burkhard , Schick Hans 
Published: January 2005

AbstractA re‐examination of the reaction of α‐angelica lactone with methylamine in water confirmed that 5‐hydroxy‐1,5‐dimethylpyrrolidin‐2‐one (5) was formed almost quantitatively in a very fast reaction. Dehydration of this compound by vacuum distillation, however, unexpectedly afforded 1‐methyl‐5‐methylenepyrrolidin‐2‐one (6), a compound with an exocyclic double bond, but not the isomeric 1,5‐dimethyl‐4‐pyrrolin‐2‐one (7) with an endocyclic double bond, as earlier claimed in the literature. With an excess of methylamine in methanol α‐angelica lactone was transformed into 5‐methylamino‐1,5‐dimethylpyrrolidin‐2‐one (8). This re‐examination was made to get levulinic acid derivatives with potential suitability for new syntheses of 1,4‐dicarbonyl compounds.
Photo‐CIDNP‐Untersuchungen zum reversiblen Elektronentransfer zwischen 1,4‐Dihydropyridinen und Oniumsalzen
Authors: Ulrich S. , Timpe H.‐J. , Pfeifer D. 
Published: January 2005

Photo‐CIDNP‐Measurements on Reversible Electron Transfer between 1,4‐Dihydropyridines and Onium SaltsThe photooxidations of various 1,4‐dihydropyridines (PyH2) by iodonium, sulfonium and phosphonium salts (RnX+) were investigated by means of 1H‐90 MHz‐Photo‐CIDNP. A reversible electron transfer from excited singlet 1,4‐dihydropyridine to iodonium and sulfonium ions via the radical pair have been found using the KAPTEIN‐rules and CKO‐theory of radical pairs. The results obtained are discussed with a view to a two‐electron‐mechanism and compared with Photo‐CIDNP‐measurements on anthracene/RnX+‐ and Michler ketone/RnX+‐systems.
Revisitation of the Formaldehyde Aniline Condensation. IX. Raman and infrared study of N′,N″,N′‐triphenylhexahydro‐sym‐triazine, N′,N″,N‴,N″″‐tetraphenyloctahydro‐sym‐tetrazocine and their thermal interconversion
Authors: Bertoluzza A. , Bonora S. , Fini G. , Giumanini A. G. 
Published: January 2005

AbstractRaman and infrared spectra of the title compounds and their methylene deuterated analogues were recorded at temperatures ranging from 20 through 250°C. The spectra of the two oligomers of N‐methyleneaniline show quite distinct features and reveal the presence of different conformational structures. By comparison with the spectra of the deuterated compounds, the attribution of some bands is made possible.By slow heating the trimer over its apparent melting point, its infrared spectrum undergoes deep changes, becoming similar to that of the tetramer. The modifications persist when the sample is rapidly cooled to room temperature. The existence of an equilibrium between the two compounds is suggested and calorimetric data (DSC) support this hypothesis. No direct evidence for free lower species is obtained under these conditions, but a mechanistic picture nevertheless emerges rather clear.
Zur Kinetik der Umsetzung von n‐Tridecan mit dem Monomeren von Distickstofftetroxid
Authors: Minkov Dimiter , Slavčeva Juliana , Lavčieva Dimitrina 
Published: January 2005

Kinetics of the Interaction of n‐Tridecane with the Monomer of Dinitrogen TetraoxideThe kinetics of the interaction of n‐tridecane with the monomer of dinitrogen tetraoxide were studied by i.r.‐spectroscopy. The spectral characteristics of the reaction mixture prove the formation of nitrocompounds (NC) and nitrates (N) already in the first reaction minutes, and oxidation products (OP) as secondary products of the nitrogen‐containing compounds. The rate of formation of these compounds was determined at different temperatures. The activation energy was found to be 63.8 kJ/mol for the formation of N, 63.9 kJ/mol for NC, and 23.8 kJ/mol for OP.
Theoretische Untersuchungen zur Molekülgeometrie, zum elektronischen Spektralverhalten und intramolekularen Donor‐Akzeptorvermögen ausgewählter Diphenylchalkone
Authors: Gustav K. , Colditz R. , Jabs A. 
Published: January 2005

Theoretical Investigations on the Molecular Geometry, the Electronic Spectral Behaviour and the Intramolecular Donor‐Acceptor Properties of Selected Diphenyl ChalconesTheoretical completely‐optimized S0 and S1 molecular geometries of diphenylpropenone are presented. On this basis the influence of donor substituents within the styryl and/or benzoyl moieties on the electronic spectral behaviour and the intramolecular donor‐acceptor properties has been studied. The theoretical results are interpreted in context with the experimental data.
Zur Vilsmeier‐Formylierung von N‐Aryl‐3,5‐dimethyl‐1,1‐dioxo‐1,2‐thiazinen
Authors: Hasan H. , Fanghänel E. , Radeglia R. 
Published: January 2005

On the Subject of Formylation of N‐Aryl‐3,5‐dimethyl‐1,1‐dioxo‐1,2‐thiazinesBy the reaction of the N‐aryl‐3,5‐dimethyl‐1,1‐dioxo‐1,2‐thiazines 1a‐d with an excess of the Vilsmeier reagent DMF/POCl3 a twofold electrophilic substitution of the methyl groups and additionally a mono substitution of the thiazine ring in 6‐position takes place. The formed products 2a‐d with a trimethine structure in the side chains react with hydroxylamine to 1′,2′‐oxazol‐4′‐yl‐substituted 1,1‐dioxo‐1,2‐thiazines 3a‐d.
Hydrierung von Crotonaldehyd, Butyraldehyd und Acetaldol mit modifizierten Ni‐Trägerkatalysatoren. I. Zum Einfluß einer Kupfermodifizierung auf Ni/Kaolin‐Katalysatoren
Authors: Bohm D. , Hamann J. , Kripylo P. 
Published: January 2005

Hydrogenation of Crotonaldehyde, Butyraldehyde and Acetaldole with Modified Ni Carrier Catalysts. I. On the Influence of a Copper Modification of Ni/Kaolin CatalystsThe hydrogenation of crotonaldehyde, butyraldehyde and acetaldol in the presence of Ni‐Cu catalysts is a single‐centre reaction, whereas the decarbonylation of crotonaldehyde is a multi‐centre reaction. The ratio between the specific activities of the hydrogenation of the CC double bond and the carbonyl group is two. In the conversion of acetaldol the hydrogenolysis to butyraldehyde can be neglected in comparison with the hydrogenation to butan‐1,3‐diol.
Darstellung von 1‐Cyan‐4‐dimethylamino‐3‐(pyrid‐4‐yl)‐buta‐1,3‐dien‐1‐carbonsäure‐Derivaten und ihre Cyclisierung zu 3‐substituierten 2‐Amino‐5‐(pyrid‐4‐yl)‐pyridinen sowie den entsprechenden 1‐Oxiden
Authors: Hagen V. , Jänsch H.‐J. 
Published: January 2005

Synthesis of 1‐Cyano‐4‐dimethylamino‐3‐(4‐pyridinyl)‐1,3‐butadiene‐1‐carboxylic Acid Derivatives and Their Cyclisation to 3‐Substituted 2‐Amino‐5‐(4‐pyridinyl)‐pyridines Including the Corresponding 1‐OxidesThe vinylogous amidinium salt 1 is transformed to 1‐cyano‐4‐dimethylamino‐3‐(4‐pyridinyl)‐1,3‐butadiene‐1‐carboxylic acid derivatives 3a‐f by reaction with the cyanoacetic acid compounds 2a‐f in the presence of bases.Treatment of the 3a‐f with ammonia and hydroxylamine yields the 2‐amino‐5‐(4‐pyridinyl)‐pyridine‐3‐carboxylic acid derivatives 5a‐f and the corresponding 1‐oxides 6a‐f, respectively. The products 5d, e are also prepared via the 6d, e by reduction with phosphorus trichloride.
Nitriles in Organic Synthesis: Synthesis of aromatic amines, aminopyridines, pyrido[2,3‐b] pyridine and pyrido[2,3‐d]pyrimidine derivatives
Authors: El‐Taweel F. M. 
Published: January 2005

AbstractThe reaction of the α‐arylethylidenemalononitrile derivatives 1a, c with piperonylidenemalononitrile (2a) and with ethyl piperonylidenecyanoacetate (2b) yield 1‐amino‐3,5‐diaryl‐2,6‐benzenedicarbonitrile (3a, c). Phenylaminopyridines 5a, b were obtained from the reaction of 1a, b with phenyl isocyanate and pyridopyridine 6 from the reaction of 5b with benzylidenemalononitrile. Pyridopyrimidines 7b, c was formed from the reaction of 1b, c with phenyl isothiocyanate.
Kinetics and Mechanism of Azocoupling between quaternary 1,2,4‐triazolium salts and p‐N,N‐dimethylamino benzenediazonium tetrafluoroborate
Authors: Becker H. G. O. , Al Kurdi H. , Mun Gwan Kim , Schütz R. 
Published: January 2005

AbstractThe kinetics of azocoupling between 1‐benzyl‐4‐phenyl‐, 1,3,4‐triphenyl‐, 4‐benzyl‐1‐methyl‐, 1,4‐dimethyl‐, 1,4‐diphenyl‐3‐methylmercapto‐ and 3‐benzyl‐mercapto‐1,4‐diphenyl‐1,2,4‐triazolium salts, and p‐N,N‐dimethylamino benzenediazonium tetrafluoroborate are studied spectroscopically in methanol/water 1:1 (v/v) at various pH values following up the growing‐in of the respective azodyes.The competing reactions of the diazonium salt with the solvent and the buffer (NH3/NH4Cl), and of some bleaching of the azodye formed were studied separately and accounted for in the kinetic treatment.From the pH dependence of the coupling rate constants and by application of kinetic models it turned out that not the widely accepted one‐step deprotonation mechanism of the quaternary triazolium salts applied but a two‐step mechanism comprising of pseudobase formation and their subsequent deprotonation is valid.Using the pertinent kinetic model the pK values of pseudo‐base formation (pKR+) and their deprotonation (pKA) were determined by non‐linear regression.
1H‐ und 13C ‐NMR‐spektroskopische Untersuchungen an substituierten 1, 1‐Dioxo‐1, 2‐thiazinen; Additivität der Substituenteneffekte
Authors: Hasan H. , Radeglia R. , Fanghä E. 
Published: January 2005

1H‐ and 13C‐N.M.R. Spectroscopic Investigations of Substituted 1, 1‐Dioxo‐1, 2‐thiazines; Additivity of the Substituent Effects.The influence of various XCH2 substituents (X: Cl, Br, I, SCN, SO2CH3, SC(NH2)2⊕, Py⊕) in the 3‐, 5‐ and 3, 5‐position of the 1, 1‐dioxo‐2‐phenyl‐1, 2‐thiazine on the 1H‐ and 13C‐n.m.r. chemical shifts of the ring atoms is described. The substituent effects are additive. The 1H‐ and 13C‐n.m.r. chemical shifts of the 3, 5‐substituted 1, 1‐dioxo‐1, 2‐thiazines can be calculated from increments derived from the 3‐ and 5‐substitued compounds.
CLAISEN‐Kondensation mit ausgewählten Dithioestern ‐ Synthese spezieller 3‐Methylthio‐acrylnitrile
Authors: Mayer R. , Hartenhauer H. , Gruner M. 
Published: January 2005

CLAISEN‐Condensations with Selected Dithioesters ‐ Synthesis of Special 3‐Methylthio‐acrylnitriles.A useful synthetic route to the mono‐ and diheteroaryl‐3‐methylthio‐acrylnitriles 1 and 2 is demonstrated by the thioanalogous CLAISEN‐condensation.In the presence of sodium hydride in tetrahydrofurane or under PTC‐conditions heteroaryl dithiocarboxylic esters 3 react with CH‐acidic compounds 4 or 9 to form 3‐mercapto‐acrylnitriles (e. g. 5). Methylation leads to mono‐ and diheteroaryl‐3‐methylthioacrylnitriles 1 and 10 (type 2). In the same manner tetrathioterephthalic ester 6 reacts with two equivalents of CH‐acidic compounds yielding 8 and 11. By means of spectroscopic methods, especially 1H‐ and 13C‐n.m.r., the structures of the compounds obtained are confirmed.
Interfacial Activity of Hydroxyoximes and mechanism and kinetics of palladium(II) extraction
Authors: Szymanowski J. , Prochaska K. , Alejski K. 
Published: January 2005

AbstractSurface excess isothermers were determined and interpreted for systems containing 2‐hydroxy‐5‐t‐nonylbenzaldehyde oxime (1), 2‐hydroxy‐5‐t‐octylacetophenone oxime (2) and 2‐hydroxy‐5‐t‐octylbenzophenone oxime (3). These surface excess isotherms were used to predict reaction orders with respect to hydroxyoximes for various versions of interfacial process. Agreement with the experimental data was observed both for the interfacial and bulk aqueous mechanism. The surface activity of extractants cannot be recognized as the sole evidence for the interfacial mechanism of extraction. More experimental kinetic data are needed in order to determine the effect of hydroxyoxime concentration upon the reaction order. According to the interfacial mechanism, with the formation of the stable 2:1 complex as the limiting step the reaction order in hydroxyoxime equal to 1 is observed over a large range of hydroxyoxime concentration, but increases to 1.5‐2.0 for very low concentrations.
Spektroskopische Untersuchungen an organischen Carbonylverbindungen. VI. NMR‐Studien an substituierten β‐Diketonen und ihren vinylogen Derivaten
Authors: Gustav K. , Bartsch U. , Schütz H. , Machinek R. , Lüttke W. 
Published: January 2005

Spectroscopic Investigations on Organic Carbonyl Compounds. VI. N.M.R.‐Studies on Substituted β;‐Diketones and their Vinyloge Derivatives.13C‐ and 1H‐n.m.r.‐data of substituted β‐diketones and their vinyloge derivatives are presented. Most of the compounds exist chiefly in the enol‐form. Only in the case of 4‐dimethyl‐aminodibenzoylmethane a keto‐enol‐equilibrium is registered. The influence of the substituent A and the chainlength on the position of the enol proton is discussed.
Polymethinfarbstoffe mit Lichtabsorption im Nahen Infrarot
Authors: Fabian J. 
Published: January 2005

Polymethine Dyes with Light Absorption in the Near Infrared.There is a currently significant interest in days that absorb in the near infrared (NIR) region, These compounds are mainly used as laser days and photoreceptors of photodiode lasers. Many NIR dyes are of polymethinic structure such as polymethine cyanines and polymethine violenes. Knowledge about structure‐color relationships enables dyes of appropriate absorption features to be predicted.
Zur Reaktion von 2‐Aminothiophen‐3‐carbonitrilen mit Heterocumulenen
Authors: Gewald K. , Jeschke T. , Gruner M. 
Published: January 2005

The Reaction of 2‐Aminothiophene‐3‐carbonitriles with Heterocumulenes.The reaction of 2‐aminothiophene‐3‐carbonitriles (1) with phenyl isothiocyanate does not yield the expected thieno[2,3‐d]pyrimidine derivatives but the substituted dithieno‐[2′,3′:4, 3][2′,3′:8, 9]pyrimido[3, 4‐a]pyrimid‐7‐thiones (4). The compounds 4 also may be synthesized from 1 and thiophosgene. Analogously, from 1 and phenyl isocyanate the substituted dithieno[2′,3′:4, 3][2′,3′:8, 9]pyrimido[3, 4‐a]pyrimid‐7‐ones (9) arise in small yields. They are better obtainable from 1 and phosgene. Carbon disulphide react with 1 in pyridine to form a mixture of the thieno[2, 3‐d]pyrimid‐2, 4‐dithione (10) and the condensed compound 4. The ratio of products depends on the substituents in the 4, 5‐position of 1. The structures are investigated by n.m.r.‐spectroscopy. magnified image
Sodium Dihydridobis(2‐methoxyethoxo)aluminate as a suitable reducing agent in the cooligomerization of propadiene with propyne from MAAF catalyzed by a nickel based three component catalytic system
Authors: Čermák Jan , Soukupová Ludmila , Chvalovský Václav , Kharkova Elena M. , Krentsel Boris A. 
Published: January 2005

AbstractSodium dihydridobis(2‐methoxyethoxo)aluminate (SDMA) is a suitable reducing agent for in situ generation of zerovalent nickel in a catalytic system nickel(II) 2, 4‐pentanedionate/phosphorus(III) ligand/reducing agent. Although generally less polymer is formed in the propadiene/propyne cooligomerization catalyzed by this system when the reducing agent is triethylaluminium, at molar ratios Al/Ni = 3 and P/Ni = 3 no polymer is formed with SDMA and the yield of oligomers is comparable to that obtained with triethylaluminium.
On the Oxidation of (β‐Stannylvinyl)phosphines: Chemical and spectroscopic effects
Authors: Mitchell Terence N. , Heesche‐Wagner Kerstin , Belt Heinz‐Joachim 
Published: January 2005

AbstractBoth E‐ and Z‐(β‐stannylvinyl)phosphines are readily converted to the corresponding phosphine oxides by KMnO4 in acetone. However, the less reactive oxidising agents MnO2 and O2 react selectively with only the E isomers. N.m.r. studies indicate that this may be due to interactions between the phosphorus lone pair and the triorganostannyl moiety in the Z‐isomer, which make the latter less susceptible to attack. N.m.r. parameters for the phosphines and their oxides are compared.
Detection of Radicals at the Photolysis of tert‐Butyl Hydroperoxide in DMSO and water
Authors: Földes‐Papp Zeno , Gerber Gerhard , Stösser Reinhard , Schneider Gerd 
Published: January 2005

AbstractThe decomposition of tert‐butyl hydroperoxide by photochemically induced reactions in DMSOAbbreviations used: DMSO, dimethyl sulfoxide; DMSO‐d6, completely deuterium labelled dimethyl sulfoxide; cw‐ESR, continuous‐wave Electron Spin Resonance; u. v., ultra violet; DMPO, 5, 5‐dimethyl‐I‐pyrroline N‐oxide; TMPO, 3, 3, 5, 5‐tetramethyl‐l‐pyrroline N‐oxide.
and water was investigated by cw‐e.s.r. spectroscopy. The products tert‐butylperoxyl, methyl and sulfur‐centered free radicals were identified. The tert‐butoxyl free radical is involved in the primary process as shown by time‐resolved e.s.r. technique. On the basis of directly identified radical species, a mechanism for the photochemically induced reactions of tert‐butyl hydroperoxide in DMSO is proposed. At concentrations below 0.8 mol · l−1 the radical formation from tert‐butyl hydroperoxide proceeds by cleavage of the OO bond rather than by hydrogen abstraction.
Selective cyclisation of 2, 3, 4, 5‐tetra‐O‐acetyl‐galactaric acid bis‐[Alkylthio(thiocarbonyl)]hydrazide to Saccharide 1, 3, 4‐Oxadiazole, Thiadiazole, and thiadiazoline derivatives
Authors: Mansour El‐Sayed M. E. , Kassem Ahmed A. , Abass Tarek M. , El‐Toukhy Ahmed A. , Nassr M. A. 
Published: January 2005

AbstractThe synthesis of galactaric acid acetate bis[alkylthio(thiocarbonyl)]hydrazide (1, 2) is described. Selective cyclisation of both hydrazides 1 and 2 was investigated. Phosphorous oxychloride as cyclising agent led to dehydrative cyclisation and produced 1, 2, 3, 4‐tetra‐O‐acetyl‐1, 4‐bis(5‐S‐methyl or — benzyl) 1, 3, 4‐thiadiazol‐2‐yl galactotetritol (3) or (4). While thionyl chloride led to dehydrosulfurization and gave 1, 2, 3, 4‐tetra‐O‐acetyl‐1, 4‐bis(5‐S‐methyl or ‐benzyl)‐1, 3, 4‐oxadiazol‐2‐yl galactotetritol (5) or (6). Finally with triethyl orthoformate as cyclising agent, compounds 1 or 2, gave 3, 3′‐(2, 3, 4, 5‐tetra‐O‐acetyl‐galactar‐1.6 dioyl)bis[2‐ethoxy‐2, 3‐dihydro‐5‐S‐methyl or benzyl 1, 3, 4‐thiadiazole] (7) or (8).
Flüssig‐Flüssig‐Extraktion von Metallionen mit Lariatethern
Authors: Gloe K. , Mühl P. , Beger J. , Pöschmann C. , Petrich M. , Beyer L. 
Published: January 2005

Liquid‐Liquid‐Extraction of Metal Ions with Lariat Ethers.Lariat ethers of various ring size and substitution are synthesized and characterized by physical data and chemical analysis. The extraction behaviour of the crown compounds towards Na+, K+, Cs+ and Ag+ in a picric acid solution has been investigated. The extraction contants for 1:1 and 1:2 complexes are determined using the equilibrium distribution data. The results show that the flexible side chain in the investigated compounds has in no case a positive effect on the metal picrate extraction.
Über neue Pyrazolverbindungen. IV Darstellung und Cyclisierungsverhalten einiger akzeptorsubstituierter N‐(Pyrazol‐3‐yl)‐thioharnstoffe
Authors: Eisenächer Th. , Pech R. , Böhm R. 
Published: January 2005

New Pyrazol Derivatives. IV. Preparation and Cyclization of Some Acceptor‐Substituted N‐(Pyrazol‐3‐yl)‐thioureas.3‐Aminopyrazol‐4‐carboxylic acid derivatives (1, 2) were transformed by reaction with different isothiocyanates R2NCS to N‐(pyrazol‐3‐yl)‐N. ‐substituted thioureas (5,6).Ethyl 3‐amino‐1‐benzylpyrazol‐4‐carboxylate reacts with CSCl2 to form ethyl 1‐benzyl‐3‐isothiocyanatopyrazol‐4‐carboxylate (3) which yields with amines the corresponding N‐(pyrazol‐3‐yl)‐N. ‐substituted thioureas (5). As a byproduct in the reaction with CSCl2 N,N. ‐di‐(pyrazol‐3‐yl)‐thiourea (4) is formed. With hydrazine or phenylhydrazine N‐(pyrazol‐3‐yl)‐thiosemicarbazides (7a,b) are obtained.The thioureas (5,6) can be cyclized in basic solution to 4,5,6,7‐tetrahydropyrazolo[3,4‐d]pyrimidin‐4‐on‐6‐thiones (8) which on alkylation form 6‐alkylthio‐4,5‐dihydropyrazolo[3,4‐d]pyrimidin‐4‐ones (9). Methyl‐N‐(pyrazol‐3‐yl)‐N.‐benzoylisothiourea (10) reacts with ethylamine to form N‐benzoyl‐N. ‐ethyl‐N‥‐(pyrazol‐3‐yl)‐guanidine derivative (11) which on treatment with NaH in dimethylformamide yields 6‐benzoylamino‐5‐ethyl‐4,5‐dihydropyrazolo[3,4‐d]pyrimidin‐4‐one (12).By treatment with sulfuric acid the N‐(pyrazol‐3‐yl)‐thiourea derivatives (5,6) form new 6‐amino substituted pyrazolo[3,4‐d][1,3]thiazin‐4‐ones (13).
Calix[n]arenes. IV. Interaction of tert‐Butylcalix[n]arenes with Cyclic Amines
Authors: Görmar Gerhard , Seiffarth Klaus , Schulz Manfred , Leopoldina Chachimbombo Chitula 
Published: January 2005

Abstractp‐tert Butylcalix[n]arenes 1 and 2 react with the cyclic amines 3–8, 10 by proton transfer forming so‐called „exo‐complexes”︁ between the ammonium and phenolate groups. As well endocyclic as exocyclic amino groups are reactive.The nitroxyl radical 9does not react with 1 or 2 by the proton transfer reaction.These results demonstrate that an interaction between the nitrogen atom of HALS‐compounds, esp. compound 10, with calix[n]arene hydroxylgroups is possible, but an interaction between the corresponding nitroxyl radicals with calix[n]arene hydroxylgroups does not occur.