bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterocyclen aus CH‐aciden Nitrilen. V. Gemeinsame Einwirkung von Schwefel und Schwefelkohlenstoff auf methylenaktive Nitrile
Authors: Gewald Karl 
Published: December 2004

AbstractNitrile, die in α‐Stellung eine aktive Methylengruppe besitzen, reagieren mit Schwefelkohlenstoff und Schwefel basenkatalysiert zu 5‐Amino‐1,2‐Dithiolthionen‐(3), die sich in Gegenwart von starken Basen in Isothiazolderivate umlagern.
Preparation, Absorption Spectra and Electronic Configuration of some amino complexes of nickel (II) acetate
Authors: Narain Gopal 
Published: December 2004

AbstractThree hexaco‐ordinated complexes of nickel (II) acetate with ammonia, ethylenediamine and propylenediamine have been prepared. Conductivity measurements indicate the complexes to be non‐electrolytes. Molecular weight measurements confirm this. The visible absorption spectrophotometric measurements show a number of bands corresponding to the various permitted transitions of the metal and a discussion of the structure in the light of these transitions is presented.
Synthese von Diarylschwefeldiimiden durch basische Kondensation von N‐Sulfinyl‐arylaminen
Authors: Hörhold Hans‐Heinrich , Beck Jürgen 
Published: December 2004

AbstractDurch Umsetzung von N‐Sulfinyl‐arylaminen mit stark basischen Anionen (Alkoholat, Amid, Hydrid) werden in hohen Ausbeuten Diarylschwefeldiimide erhalten. Die Reaktion ist auf eine Vielfalt von substituierten N‐Sulfinyl‐arylaminen anwendbar, wobei die Substituenten sowohl Gruppen mit Elektronendonatorwirkung als auch solche mit Elektronen‐akzeptorwirkung sein können.
Metallorganische Peroxide, VII. Zum Mechanismus der Zersetzung von Bis‐organoantimonyl‐peroxiden. Teil I
Authors: Dahlmann J. , Winsel K. 
Published: December 2004

AbstractDer Zerfall der Bis‐(halogen‐triphenyl‐antimonyl)‐peroxide1 aundbwurde hinsichtlich der Zersetzungsprodukte, der Kinetik und des Einflusses verschiedener Faktoren untersucht. Es wurde gefunden, daß bei der Zersetzung neben einer heterolytischen Spaltung der O‐O‐Bindung unter 1.2‐Umlagerung bei dem bromhaltigen Peroxid1 aleicht eine Abspaltung von Singulett‐Sauerstoff erfolgt. Der Mechanismus dieser Reaktion wurde aufgeklärt.
Polyhalogenation of nitrogen containing heterocyclic compounds. II. Polychloro‐1,10‐phenanthrolines
Authors: Dénes V. , Chira R. , Fărcăsan M. , Ciurdaru Gh. 
Published: December 2004

Abstract1,10‐Phenanthroline can be chlorinated directly with sulfuryl and thionyl chloride giving a chromatographically separable mixture of polychloro compounds.
Kristallin‐flüssige Ketoximester
Authors: Weissflog W. , Schubert H. , König S. , Demus D. , Vogel L. 
Published: December 2004

AbstractDisubstituierte Acetophenonoximbenzoate 1a–q, 2a–j, 3a–d, 4a–b und 5a–b sind nematische Flüssigkristalle mit bemerkenswerter thermischer Stabilität und – unabhängig von den Flügelgruppen — relativ niedrigen Schmelzpunkten. Binäre und ternäre Gemische, deren Schmelztemperaturen auch theoretisch bestimmt wurden, sind weit unterhalb Zimmertemperatur flüssig und im Wechselstromfeld beständig. Der Austausch von CH3 durch C2H5 oder n‐C3H7 führt in 6a–d und 7 zu starken Klärpunktsdepressionen.
Mehrfunktionelle N‐Tenside. I. Nucleophile Substitutionen an Bischlornitrosoverbindungen. 1. Reaktionen mit Aminen, Mercaptanen und Natriumazid
Authors: Berger J. , Luong T. T. , Thielemann C. , Thong P. D. 
Published: December 2004

Polyfunctionalized N‐Tensides. I. Nucleophilic Substitutions with Bischloronitrosocompounds. 1. Reactions with Amines, Mercaptans and Sodium AzideChloronitrosation of alkenes gives bischloronitrosocompounds 1, which react with amines to α‐aminooximes (2 and 4), with mercaptans to α‐alkylthiooximes 11, and with sodium azide to α‐azidooximes 8. Reduction with LiAlH4 gives vicinal substituted diamines (6, 7, 10) from α‐amino‐or α‐azidooximes (2, 4, 8) and β‐alkylthioamines 13 from α‐alkylthiooximes 11.The determination of E‐ or Z‐configuration in the α‐substituted oximes is discussed.
Eine Methode zur Quantitativen Verfolgung von Festphasenreaktionen in der Peptidsynthese
Authors: Kaufmann Klaus‐Dieter , Raddatz Frank 
Published: December 2004

A Method for the Quantitative Control of Solid Phase Reactions in the Peptide SynthesisA quantitative control‐method of partial steps of a solid phase peptide synthesis is described, based on a hydrazinolytic cleavage of protected peptides from the solid support. A separation of the peptide hydrazides by gelchromatography on sephadex G 15 in dimethylformamide and a quantitative evaluation of the hydrazide‐content in the elution fractions is reported, which permits the control of the Nα‐deprotection step in the same way as the evaluation of the coupling yields of the desired sequence. The new method is discussed for the example of two solid phase syntheses of the pentapeptide N‐tert.‐butyl‐oxycarbonyl‐L‐valyl‐S‐benzyl‐L‐cysteinyl‐L‐alanyl‐L‐ leucyl‐O‐benzyl‐L‐tyrosine hydrazide.
Nucleophile Substitutionen an Bischlornitrosoverbindungen. III. Reaktionen mit Salzen und Estern der Dithiocarbazinsäure sowie der N‐Phenyldithiocarbazinsäure
Authors: Beger J. , Thielemann C. , Thong P. D. 
Published: December 2004

Nucleophilic Substitutions with Bischloronitroso Compounds. III. Reactions with Salts and Esters of the Dithiocarbazinic Acid and the N‐Phenyldithiocarbazinic AcidBischloronitroso compounds 1 react with salts of the dithiocarbazinic acid to give S‐(β‐oximinoalkyl)‐esters of the dithiocarbazinic acid. The esters easily cyclise to the corresponding 1,3,4‐thiadiazine‐2‐thiones. Esters of the dithiocarbazinic acid lead to 2‐alkylthio‐1,3,4‐thiadiazines. The structure of possible tautomeres follows from i.r.‐, u.v./vis‐ and n.m.r.‐spectra.
Reaktionen mit N‐Acylimino‐dithiokohlensäurediestern
Authors: Augustin M. , Richter M. , Salas S. 
Published: December 2004

Reactions with N‐Acylimino‐dithiocarbonic‐acid‐diesters.Reactions of N‐acylimino‐dithiocarbonic‐acid‐S,S‐diesters 1 with nucleophilic com‐pounds present new possibilities to synthesize heterocycles. With amines 1a reacts by mono‐ and disubstitution, respectively, of methylthio‐groups to isothioureas 2 and guanidines 3, with 1,2‐bi‐nucleophilic arenes to benzoheterocycles 4, with aliphatic diamines to imidazolidines 5, pyrimidines 6, diazepines 7 and the hexamethylene‐diamine‐derivatives 8. 1a reacts also with hydrazines to 1,2,4‐triazoles 9 and with hydrazides to the thiosemicarbazones 10 or 1,3,4‐oxadiazoles 11. Heterocyclisations of 1 with guanidines, thiourea, salts of thiourea and amidines give the 1,3,5‐triazines 12, 14, 15 and 16. N‐benzoyl‐dithiocarbonic‐acid‐methylester ‐amid reacts with CH‐acidic compounds to thiazoles 17. The structures of the final products are determined by i.r.‐, 1H‐n.m.r.‐, u.v.‐ and mass‐spectras.
Darstellung von trans‐4‐Diphenylphosphinyl‐stilbenen
Authors: Gloyna D. , Alder L. , Henning H.‐G. , Köppel H. , Siegmund M. , Schleinitz K.‐D. 
Published: December 2004

Synthesis of trans‐4‐Diphenylphosphinyl StilbenesThe reaction of 4‐tolyl‐diphenylphosphine oxide with N‐bromosuccinimide results in 4‐diphenylphosphinyl benzylbromide 5 which can be easily converted to (4‐diphenylphosphinyl)‐benzyl triphenylphosphonium bromide 6 and (4‐diphenylphosphinyl)‐benzyl diphenylphosphine oxide 7, respectively. In the presence of strong bases 6 and 7 react with aromatic aldehydes 8 to the 4‐diphenylphosphinyl substituted stilbenes 1. The yields depend on the nature of base and solvent. The trans configuration of 1 is determined by i.r. and 1H‐n.m.r. measurements.
Zur Strukturaufklärung der Bromierungsprodukte von N‐Aryl‐2,4‐dimethyl‐buta‐1,3‐dien‐sultamen‐1,4
Authors: Fanghänel E. , Mohamed H. , Keita Y. , Radeglia R. 
Published: December 2004

Structure Elucidation of Bromination Products of N‐Aryl‐2, 4‐dimethyl‐buta‐1,3‐diene‐sultames‐1, 4The structure of bromination products of N‐aryl‐2, 4‐dimethyl‐buta‐1, 3‐diene‐sultames‐1, 41a–d,fis determined by 13‐C‐n.m.r. spectroscopy. As mono bromination product of N‐phenylsultam1athe 4‐bromomethyl derivative2awas isolated. Dibromination of sultames1yields 1‐brom‐4‐brommethyl‐sultames3and by tribromination 1,3‐dibrom‐4‐brommethyl‐sultames4are obtained.
Anwendungen des Kern‐Overhauser‐Effekts. I. Strukturuntersuchungen an Z/E‐isomeren 2,3‐Diarylazetidin‐3‐olen
Authors: Fuhrmann J. , Köppel H. , Schleinitz K.‐D. , Henning H.‐G. 
Published: December 2004

Applications of the Nuclear Overhauser Effect. I. Investigations of the Structure of Z/E Isomeric 2,3‐Diarylazetidin‐3‐olesThe relative configurations of Z/E‐isomeric 2,3‐diaryl‐azetidin‐3‐oles are determined by mass spectrometry and 1H‐n.m.r.‐NOE‐measurements. The increase of the C(2)‐H line intensity by saturation of the OH‐signals demonstrates the Z‐position of the 2,3‐diaryl groups in the isomers 2a.
Eine einfache Synthese von β‐Chlorzimtsäurenitrilen nach einer modifizierten Vilsmeier‐Haack‐Arnold‐Reaktion
Authors: Liebscher JÜRgen , Neumann Bernd , Hartmann Horst 
Published: December 2004

A Simple Synthesis of β‐Chlorocinnamonitriles by a Modified Vilsmeier‐Haack‐Arnold‐ReactionA simple one‐pot synthesis of β‐chloro‐cinnamonitriles 2 can be achieved by treating acetyl arenes 1 first with formamide chlorides and subsequently with hydroxyl amine hydrochloride. The formamide chlorides used are conveniently prepared from an excess of dimethyl formamide and phosphoryl chloride. However it is also possible to employ other N,N‐disubstituted formamides or acid chlorides, respectively. For comparison purposes β‐chloro‐cinnamonitriles 2 have also been synthesized in a two‐step process. Thus 3‐aryl‐3‐chloro‐(2)‐iminium salts 4 are reacted with hydroxyl amine hydrochloride giving rise to 3‐chloro‐cinnamic aldoximes 5. The latter compounds are dehydrated to the corresponding nitriles 2 by refluxing in acetic anhydride following a known procedure.
Thermitase – eine thermostabile Serinprotease. I. Synthese von Alaninpeptidestern als Substrate des Enzyms
Authors: Jahreis Günther , Fittkau Siegfried 
Published: December 2004

Thermitase – A Thermostable Serine Protease. I. Synthesis of Alanine Peptide Esters as Substrates of the EnzymeThe synthesis of N‐acetylated and N‐succinylated peptide esters of alanine is described. The peptides are built up from the Z‐Abkürzung: Z = Benzyloxycarbonyl, Ac = Acetyl, Suc = Succinyl, OMe = Methylester, MA = Mischanhydridmethode, E = Ether, PE = Petrolether, Etac = Ethylacetat, AcOH = Essigsäure, Dibu = n‐Dibutylether, DMSO = Dimethylsulfoxid, DMF = Dimethylformamid, TEA = Triethylamin, Ac2O = Essigsäureanhydrid

protected peptides by liquid phase fragment condensation and by acylation of the deprotected peptide esters. The kinetic parameters K
m
and K
cat
of some compounds are presented.
Tetrathiafulvalene. XXI. Synthese von Tetrathiafulvalenen aus 2‐Alkylthio‐, 2‐Arylthio‐ und 2‐Alkylseleno‐1,3‐dithioliumsalzen
Authors: Fanghänel E. , Richter A. M. , Schukat G. 
Published: December 2004

Tetrathiafulvalenes. XXI. Syntheses of Tetrathiafulvalenes from 2‐Alkylthio‐, 2‐Arylthio‐ and 2‐Alkylseleno‐1,3‐dithiolium SaltsIn the reaction of 2‐alkylthio‐, 2‐arylthio‐ or 2‐alkylseleno‐1, 3‐dithiolium salts with trivalent phosphorus compounds in acetonitril tetrathiafulvalenes2are formed. As an intermediate we suppose a phosphorane, which reacts with further 1,3‐dithiolium salt to provide the tetrathiafulvalene. By the application of a 2‐alkylthio‐1,3‐dithiolium salt a monomethin dye is formed in a side reaction. When the reaction is carried out in methanol, the phosphorane is trapped by the solvent and a 2H‐1,3‐dithiolium salt is obtained.
Direkte und sensibilisierte Photoisomerisierung der α,δ‐Phenylfulgide
Authors: Ilge H.‐D. , Paetzold R. 
Published: December 2004

Direct and Sensitized Photoisomerization of α,δ‐PhenylfulgidesThe photoreactions starting from the E‐ and E‐E‐isomers of mono‐, di‐, tri‐ and tetra‐(substituted‐)phenylfulgides are investigated. The phenylfulgides show strong steric interactions in the molecular framework. For that reason internal conversion is the main deactivation process which increases in the series of mono‐, tri‐ and tetraphenylfulgides. The α,δ‐di‐(substituted‐)‐phenylfulgides show the highest photoreactivity. At room temperature in no case luminescence is observed from any E(E‐E)‐, Z(E‐Z, Z‐E)‐ or Z‐Z‐phenylfulgid isomer of the substances under study. Intersystem crossing cannot compete neither with thermal deactivation nor can it be observed by applying both the internal and external heavy atom effect. The phenylfulgides show typical ππ*‐photoreactivity: in the singlet state E‐Z‐isomerization about one double bond competes with electrocyclic ring closure; in the triplet state only simultaneous E‐Z‐isomerization about the two double bonds is observed. The steric and electronic substituent influences on the photoreactivity are interpreted. A first qualitative model of the isomerization reactions of the fulgides in the excited states is established.
Untersuchungen zur Bromierung/Dehydrobromierung von 17α‐Cyanmethyl‐17β‐hydroxy‐östr‐5(10)‐en‐3‐on
Authors: Menzenbach B. , Hübner M. , Ponsold K. 
Published: December 2004

Investigations on the Bromination/Dehydrobromination of 17α‐Cyanomethyl‐17β‐hydroxy‐estr‐5(10)‐en‐3‐oneBromination/dehydrobromination of 17α‐Cyanomethyl‐17β‐hydroxy‐estr‐5(10)‐en‐3‐one 1a in the presence of pyridine leads to 17α‐cyanomethyl‐17β‐hydroxy‐estra‐4, 9‐dien‐3‐one 2a. The reaction was studied in various solvents with several bromination agents. Intermediates and byproducts of the reaction were isolated and their structures elucidated.
Photochemische Untersuchungen an 3‐(9‐anthryl)‐substituierten Isoxazolinderivaten
Authors: Timpe H.‐J. , Lammel U. , Fišera Ľ. 
Published: December 2004

Photochemical Investigations on 3‐(9‐Anthryl)‐substituted Isoxazoline DerivativesThe photochemical and photophysical properties of anthryl substituted isoxazolines5a–cand6are caused by the anthracene ring. Absorption and fluorescence spectral data correspond to those of parent anthracene. By irradiation with light of the wavelength λ = 365 nm the products dimerizise at 9,10‐position of the anthracene ring. Excited singlet states of these isoxazolines are donors for an electron transfer to onium compounds.
Pyryliumverbindungen. 38. Zur Ringtransformation von 2,4,6‐Triaryl‐thiopyryliumsalzen mit Essigsäureanhydrid zu Arylbenzenen und Thiobenzophenonen
Authors: Zimmermann Thomas , Fischer Gerhard W. 
Published: December 2004

Pyrylium Compounds. 38. About the Ring Transformation of 2,4,6‐Triarylthiopyrylium Salts by Acetic Acid Anhydride to Arylbenzenes and Thiobenzophenones2,4,6‐Triarylthiopyrylium salts 5 react in the presence of an appropriate condensing agent (sodium acetate, carbonate, methoxide, tert‐butoxide or potassium acetate) with acetic acid anhydride to yield arylbenzenes 3 and thiobenzophenones 6. This ring transformation represents the first example of the conversion of the moiety into the thiocarbonyl group Under the same conditions 3,5‐dimethyl‐2,4,6‐triphenylthiopyrylium perchlorate (13) forms via [1,5]‐sigmatropic rearrangement the thiobenzophenone 15. The structure of the new compounds 6 was proved by spectroscopic methods as well as by degradation reactions. Thus, hydrogen peroxide converts 6a to the known benzophenone 4. Alkaline saponification gives the 2‐hydroxy‐benzophenone 8, whereas heating with hydrochloric acid causes a selective cleavage of the acetoxy group to the 2‐hydroxy‐thiobenzophenone 7.
MO‐LCAO Calculations on Polymethines. XXV [1]. The molecular and electronic structure of 3,3′‐dimethyl‐3,3′‐pyridocyanines and related non‐kekulè polymethine dyes
Authors: Fabian J. 
Published: December 2004

AbstractNon‐Kelulé polymethines are polymethine dyes that cannot be written by single Kekulé‐type formulae. As demonstrated with 3,3′‐dimethyl‐3,3′‐pyridocyanines (1) the electron distribution and term level ordering of them differ greatly from those of the related simple open‐chain polymethines (streptopolymethines), considering the latter ones as constitutive elements of these dyes according to Dähne's polymethine concept. Non‐Kekulé dyes are, however, closely related to isoconjugated classical polymethine dyes. The peculiar features of the non‐Kekulé polymethines are well understood in terms of simple MO theory. Orbital tracing assisted by MOA (molecular orbital analysis) reveals crossing between the frontier orbitals of these dyes and those of the related open‐chain polymethine substructures. Additional insight into peculiarities of1is gained at the semiempirical level by analyzing the π‐electronic system in terms of the heterocyclic end groups and the interconnecting odd‐alternant hydrocarbon (carbopolymethine) chain. Numerical predictions are made based on MNDO optimum geometries. According to CNDO/S and PPP calculations the non‐Kekulé dyes considered absorb at longer wavelengths than the isoconjugate classical dyes. In the case of the first members of series1the lowest‐energy transition is less determined by the characteristic polymethinin charge redistribution inherent to polymethine dyes than by notable heterocycle‐to‐chain charge transfer (CT). The interfragmental CT upon excitation reduces the transition probability of this electronic transition. Some calculations performed beyond the monoexcitation approximation indicate a certain birdicaloid character of the non‐Kekuléan dye structures. The exceptional position of these dyes is also indicated by the higher heats of formation of1relative to the isomeric classical dyes.
Computer Generation of Caged Frameworks which can be used as synthons for creating high‐energetic materials
Authors: Pivina Tatyana S. , Molchanova Marina S. , Shcherbukhin Vladimir V. , Zefirov Nikolai S. 
Published: December 2004

AbstractA methodology for computer‐assisted generation of novel highenergetic compounds with the given gross formula is described. On the first step, structures are generated as graphs in the form of connectivity matrices, using the GEM program. Each of these graphs is input into the MOLGEO program, yielding a number of possible stereoisomers in the form of 3D structures. Subsequent optimization by MM2 allowed to evaluate the precise molecular geometry and the enthalpy of formation. On the basis of these data, it is possible to estimate the energy content and the crystal density of the corresponding molecular crystals for each of the structures and. therefore, to evaluate their suitability for practical purposes.
Shaped Charge Jet Initiation on Explosive Charges equipped with barriers made up of various materials
Authors: Held Manfred 
Published: December 2004

AbstractThis paper describes initiation tests on cast TNT/RDX (35/65) explosive charges applying shaped charge jets with test set‐ups on which the HE charge was arranged either in contact to a 50‐mm thick barrier or after a 100‐mm thick barrier in a 15‐mm air gap. A variety of materials was attached to the barrier's rear side which, on one band, resulted in a varying shock wave attenuation and also in different bulging effects that are responsible for the differences in the initiation mechanisms observed on the two test arrangements. Materials with a lower density also provide, due to a less precompression of the IIM charge used on the arrangement “test charge in contact”, shorter buildup distances than materials with a higher density. An exception to this is a high ductile material such as e.g. steel. The build‐up distances, however, remain constant when arranging the explosive charge with an air gap. This backs up the hypothesis that most of all, bulging of the target is responsible for the sensitivity reduction observed on the test HE charges in contact with the barrier.
Safety investigations of trinitrotoluene/water emulsions
Authors: Teipel Ulrich 
Published: December 2004

AbstractIn the disposal of explosives, preparation of the dismantled material is necessary before subjecting it to a breakdown process. Knowledge of the material properties and determination of safety‐related parameters are major prerequirements when designing a disposal facility and increasing handling safety. When TNT is treated using emulsion processing, a desensitization of the TNT melt via the aqueous phase is obtained, in addition to increasing the surface area of the TNT phase. During the entire process of TNT treatment, the system is exposed to a wide range of different stresses as a result of the mechanical energy applied. This study presents the results of an investigation on the sensitivity of pure TNT melts and TNT/water emulsions at different concentrations on exposure to the applied impact or shock energies. It is found that the impact sensitivity of a TNT/water emulsion is lower by a factor of 4 when the TNT concentration has been reduced from 50 wt % to 30 wt %. On exposure to stress from a detonation shock wave, a desensitization of the system due to the aqueous phase is also found, so that the safety of the TNT treatment process can be increased by using a TNT/water emulsion when applying mechanical breakdown methods.
A MO‐SCF study of hydroxyl binding and hydroxyl diffusion in pure and fluorine‐containing hydroxyapatite
Authors: Wahlgren Ulf , Roos Björn , Forslind Erik 
Published: December 2004

AbstractHydroxyl diffusion and interhydroxyl binding in hydroxyapatite has been studied. LCGO‐MO‐SCF calculations have been carried out on groups of hydroxyl ions in a perfect and a vacancy‐containing crystal.Electrostatic crystal effects were accounted for by including the crystal potential field in the SCF calculations. Nearest‐neighbour interactions were calculated to first order. Effects exerted by fluorine impurities were considered for the vacancy‐containing crystal.The calculations indicate that narrow bandwidths obtained in nmr experiments on biological hydroxyapatite may be caused by a hydroxyl displacement mechanism and that no interhydroxyl hydrogen bonds exist in hydroxyapatite. The suggestion that the caries‐inhibiting properties of fluorine impurities in human dental enamel is caused by a diffusion‐binding mechanism is supported by the results.
Enhanced probability for the photoelectric effect in a Faraday cage
Authors: Avery John S. 
Published: December 2004

AbstractThe cross section for the photoelectric effect is calculated for the case where the photoionization takes place within a Faraday cage held at a constant electrostatic potential. When the geometry has spherical symmetry, and when the potential is repulsive, the cross section is enhanced by a factor E/(E − V0). The predicted effect is a purely quantum mechanical one, since according to classical electrodynamics, no forces due to the potential of the cage will act on a charged particle in the fieldfree region inside it. In quantum theory, the effect arises because the continuum states extend to the region outside the cage.
Ultraviolet carcinogenesis
Authors: Rosen Philip 
Published: December 2004

AbstractA theory of UV carcinogenesis is described in which damage to DNA in the form of pyrimidine dimers occurs in a critical operator region of the genome that controls the synthesis of divisional proteins. There is a chance that a mutation will occur in the region of the operator either during replication or during postreplication repair, so that unchecked growth will be passed on to daughter cells. Comparison with the experiments of Hart and Setlow (1973) indicates that agreement is semiquantitative.