bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactivity of 4‐acetyl‐3‐chloro‐5,6‐diphenylpyridazine towards some nucleophilic reagents, Synthesis of Some Fused Pyridazine Derivatives
Authors: Ismail M. Fekry , Sayed Fekria S. , El‐Khamry Abdel Moemen A. , Ali M. A. , Mansour M. M. 
Published: December 2004

Abstract4‐Acetyl‐3‐chloro‐5,6‐diphenylpyridazine (1), prepared by the action of phosphorus oxychloride on 4‐acetyl‐5,6‐diphenylpyridazin‐3(2H)‐one (2), reacts with hydrazine hydrate and phenylhydrazine to give the pyrazolinopyridazine derivatives (3a, b) respectively. Reaction of 1 with hydroxylamine hydrochloride gave the isoxazolopyridazine derivative (5), while its reaction with sodium azide in dimethyl formamide gave the tetrazolopyridazine derivative (8). Primary amines react with 1 to give either 9 or 10 depending upon the reaction conditions. Treatment of 1 with piperidine or morpholine gave the products 11a, b, respectivly. 4‐Acetyl‐5,6‐diphenylpyridazin‐3(2H)‐thione (13) was readily obtained by the action of thiourea on ethanolic solution of 1. The reactions of 1 with phenols were also investigated.
Synthesis of Some Itaconates via Wittig reaction
Authors: Awad William I. , Kandile Nadia G. , Wassef Wasfy N. , Mohamed Mansoura I. 
Published: December 2004

AbstractThe Wittig reaction of aromatic aldehydes with 1,2‐bis‐(ethoxycarbonyl) ethylidene triphenyl phosphorane (1) furnished oily mixtures of the two diastereomeric products (E) and (Z) (2). Alkaline hydrolysis of the diesters followed by fractional crystallization affords the corresponding (E)‐isomers (3) and (Z)‐isomers (4). The structures of these products are supported by elemental analysis, i.r., u.v., n.m.r. and its chemical behaviour.
Synthese von N,N‐pentamethylen‐thiocarbamidsäure‐S‐(1‐benzoyl‐2,2‐bis‐methylthio)‐vinylestern und deren Reaktionen mit N‐Nucleophilen
Authors: Dölling W. , Khoudary K. , Augustin M. 
Published: December 2004

Synthesis of S‐(1‐Benzoyl‐2‐bis‐methylthio)‐vinyl N,N‐Pentamethylene‐thiocarbamates and Their Reactions with N‐NucleophilesThe S‐(1‐benzoyl‐2‐bis‐methylthio)‐vinyl‐N,N‐pentamethylene‐thiocarbamates 3a–d are synthesized by reaction of S‐phenacyl‐N,N‐pentamethylene‐thiocarbamates (1a–d) with carbon disulfide under phase‐transfer conditions. These compounds 3a–d and the dithiocarbamates 5a–d react with N‐nucleophiles forming the ketene‐S,N‐acetals 6–14, the S‐phenacyl α‐(imidazolidine‐2‐ylidene)‐N,N‐pentamethylene‐thio‐ or ‐dithiocarbamates 15–22, S‐(substituted pyrazol‐4‐yl)‐ 23–28 and S‐(substituted isoxazol‐4‐yl)‐N,N‐pentamethylene‐thio‐ or ‐dithiocarbamates 39–46, respectively.
Zur Reaktion von „Pyrazolonblau”︁ mit Diazomethan
Authors: Hennig L. , Haessner R. , Rissanen K. 
Published: December 2004

About the Reaction of „Pyrazolone Blue”︁ with DiazomethaneThe reaction of “pyrazolone blue” with diazomethane was investigated. A pyridazinone derivative 3, a heterocyclic spiro‐cyclopropyl product 4 and a compound 7, which contains three pyrazolone and two diazomethane entities, are formed. 3 reacts with an excess of diazomethane to the methoxy derivative 6. The spiro‐cyclopropyl compound 4 is not stable and isomerizes to the corresponding 4,4′‐methylidene‐bispyrazolone 5. The structures of the products were established by spectroscopic methods and X‐ray analysis.
Oxidation of Cyclic Acetals as a preparative method of diol monoester production
Authors: Kuramshin E. M. , Kulak L. G. , Nazarov M. N. , Zlotsky S. S. , Rakhmankulov D. L. 
Published: December 2004

AbstractGlycol monoesters were produced by oxidation of acetals with oxygen, hydroperoxides, hydrogen peroxide, hydrotrioxide and ozon. Addition of salts of metals of variable valency and crown‐ether substantially increase the rate of oxidation and hydroxylation. The most efficient oxidizer is ozon.
Organophosphorus chemistry. 13 [1]. The Behaviour of 3‐Aryliminoxindoles toward Alkyl Phosphites
Authors: Abdou Wafaa M. , Abd El‐Rahman Naglaa M. , Mahran Mohamed R. H. 
Published: December 2004

Abstract3‐Aryliminoxindoles (6a–c) react with trialkyl phosphites (TAP, 2a–c) only in presence of a protonating agent (H2O or CH3COOH) to give the respective dialkyl 3‐(arylamino‐2‐oxo‐1H‐indol‐3‐yl)‐phosphonates (9a–i). Compounds 9 are equally obtained by reacting 6a–c with the appropriate dialkyl phosphite (DAP, 4a–c) in absence of solvent. The role displayed by the arylimine‐moiety on the reaction courses is discussed.A mechanism that accounts for formation of 9 from the reaction of anils 6 with TAP, is presented.Structural assignment are based upon analytical, chemical and spectroscopic (i.r., 1H‐n.m.r., 31P‐n.m.r. and m.s.) results.
Chemotherapeutic agents. XVI [1]. Synthesis of Pyrimidines and fused pyrimidines as leishmanicides
Authors: Ram Vishnu J. 
Published: December 2004

AbstractVarious mono and bicyclic pyrimidine analogs (3–15) were prepared as leishmanicides from 6‐aryl‐4‐chloro‐2‐methylthiopyrimidine‐5‐carbonitrile (2), obtained from the halogenation of 6‐aryl‐3,4‐dihydro‐2‐methylthio‐4‐oxopyrimidine‐6‐carbonitrile (1).
Galacturonsäurederivate. I. Galacturonate aus Acetyl‐ und Isopropyliden‐D‐galactopyranosen
Authors: Vogel Chr. , Boye H. , Kristen H. 
Published: December 2004

Galacturonic Acid Derivatives. I. Galacturonates from Acetyl‐ and Isopropylidene‐D‐galactopyranosesGalacturonic acid derivatives to be employed as glycosyl donors in saccharide synthesis are prepared from galacturonic acid itself or from galactose. Various syntheses of 1,2,3,4‐tetra‐O‐acetyl‐D‐galactopyranuronic acids (6) with differently protected carboxyl group and attempts of their conversion into galacturonpyranosyl bromides are described. The starting materials were 1,2;3,4‐di‐O‐isopropylidene‐α‐D‐galactopyranose and acetylated galactopyranose derivatives, respectively.
Zur Existenzfähigkeit von 2‐Imino‐2H‐1,3‐thiazinen
Authors: Schroth Werner , Spitzner Ronald , Ezzat Mounifa M. , Richter Monika , Freitag Sabine 
Published: December 2004

On the Existence of 2‐Imino‐2H‐1,3‐thiazinesThe title compounds2are readily liberated from the 2‐amino‐1,3‐thiazinium salts1by treatment with bases. Their stability depends sensitively on the substituents at the imino‐N. The imino‐N substituted2a–iare isolable as well‐defined coloured substances. Reaction of the2as well1with nucleophilic agents affords pyrimidine‐2‐thiones (4,9–11,16–18). In these ring transformations a nucleophilic addition at ring position 6 as primary reaction step is preferred. The imino‐N unsubstituted representatives display a more complicated behaviour; the highly enhanced reactivity prevents or handicaps, respectively, any isolation. As exemplified in the base‐induced ring‐transformation of1 mto the pyrimidine derivative19, these2are able to react as nucleophiles too, and versatile intermolecular self‐reactions are increasingly favoured.
Activation parameters and excitation yields of 1,2‐dioxetanes of photogenotoxic interest
Authors: Adam Waldemar , Beinhauer Axel , Hauer Hermann , Saha‐Möller Chantu 
Published: December 2004

AbstractThe chemiluminescent decomposition of functionalized 1,2‐dioxetanes was examined in toluene solution. Activation energies were measured by isothermal and nonisothermal kinetic methods. Quantum efficiencies were determined by Stern‐Volmer kinetics, using the fluorescers 9,10‐dibromo‐ and 9,10‐diphenylanthracene for the triplet and singlet excitation yields. The derivatives of 3‐hydroxymethyl‐3,4,4‐trimethyl‐1,2‐dioxetane (1a) have free energies of activation (ΔG≠) of ca. 25 kcal/mol, but the ΔG≠ values of the annelated benzofuran‐type dioxetanes (5) are ca. 1 kcal/mol lower. There exists a reasonable correlation between the free energies of activation (ΔG≠) for the thermal decomposition of the dioxetanes and their triplet excitation flux (EpT).
Bleaching Activators as Acylating Agents kinetics of the acetylation of piperidine by some bleaching activators
Authors: Hofmann Jörg , Just Gerhard , Moya Dally , Ostermann Sylvio , Pritzkow Wilhelm , Visothea Mok Po 
Published: December 2004

AbstractThe bleaching activators 1,5‐diacetyl 2,4‐dioxo‐hexahydro‐1,3,5‐triazine (DADHT), tetraacetyl ethylenediamine (TAED), tetraacetyl glycolurile (TAGU), N,N′‐diacetyl N,N′‐dimethyl urea (DDU) and pentaacetyl glucose (PAG) are efficient acetylating agents which convert primary and secondary amines into their N‐acetyl derivatives. The rates of the reactions of the bleaching activators mentioned with piperidine were determined in the temperature range 20 to 90°C using dioxane as the solvent. The kinetic constants can be regarded as rough measures of the activity of the bleaching activators.
Cyclisierungen mit Cyanthioacetamid in Gegenwart von Schwefel
Authors: Gewald K. , Schindler R. 
Published: December 2004

Cyclizations of Cyanothioacetamide in the Presence of SulphurCyanothioacetoamide 1 reacts with sulphur in the presence of triethylamine to form the 2,5‐diamino‐thiophene derivative 3 and in the presence of sodium ethoxide the 1,4‐dihydropyridine derivative 2, respectively. 3 easily undergoes ring opening to yield the butadiene derivative 6. Catalyzed by amine from 1, cyclic ketones, and sulphur the 2‐spiro[thieno[2,3‐d]pyrimidine‐4‐thiones] 8 arise. Analogously to other cyanoacetic acid derivatives 1 react with sulphur and isothiocyanates to form the 4‐amino‐Δ4‐thiazoline‐2‐thiones 9 and with sulphur and carbon disulfide to yield the 5‐amino‐1,2‐dithiol‐3‐thione derivative 12. Among the o‐amino‐thiocarboxamides 3, 9, 12 the compounds 3 and 9 can be converted into the 5,6‐heterocondensed pyrimidine‐4‐thiones 4 and 10.
Chlorides of antimony and tin as reagents for syntheses of cyclic and linear Chloropermethylpolysilanes
Authors: Derczewski B. , Wojnowski W. 
Published: December 2004

AbstractThe reaction of c‐Si6Me12 with SbCl5 proceeds with cleavage of the methyl groups from silicon and gives c‐ClSi6Me11 and c‐Cl2Si6Me10 as main products. The molar ratio of those compounds depends on solvent. The same chlorodemethylation reaction takes place if c‐Si6Me12 reacts with GaCl3.The reaction with SnCl4 proceeds with cleavage of the SiSi bonds of polysilane and α,ω‐dichloropermethylpolysilanes, with the 1,6‐Cl2Si6Me12 as the main product, are formed.
IR Optical Properties of a Pyrotechnic Screening Smoke
Authors: Scheunemann W. 
Published: December 2004

AbstractOptical properties of small droplets of aqueous solutions of zinc chloride were studied in the 3 μm to 12 μm spectral range. The droplets are generated by combustion of a pyrotechnic screening smoke composition containing hexachloroethane and zinc. Mass extinction coefficients were determined and interpreted by the theory of Mie.The optical constants of aqueous solutions of zinc chloride are markedly different from those expected for a screening smoke of low IR transparency.
Die chemische Beständigkeit aluminiumhaltiger Slurries
Authors: Lingens P. 
Published: December 2004

AbstractDie Prüfapparatur zur Ermittlung der Stabilität von Slurries, die Metallpulver enthalten, wird beschrieben. Weiterhin wird auf die Ausführung und auf die Auswertung der Prüfung eingegangen. Die Möglichkeit zur Vereinheitlichung der Meßmethode wird diskutiert.
Suggestions on standards for measurement and data evaluation in the underwater explosion test
Authors: Bjarnholt G. 
Published: December 2004

AbstractStandardized procedures for measurement and evaluation of data obtained in the underwater explosion test are needed to make possible comparisons of data obtained at different laboratories. In this paper specifications for the pressure gage and instrumentation as well as calibration and the use of a standard reference explosive are discussed. Evaluation standards for peak pressure, impulse, shock wave energy and bubble energy are suggested. A practical method for determination of the water shock energy lost when the primary shock travels from the charge to the gage is given, making it possible to determine the total expansion work performed by an explosive in an underwater explosion test. Performance predictions in rock blasting for explosives based on data obtained in the underwater explosion test are also discussed.
The rheology of a high‐concentration triaminotrinitrobenzene/trinitrotoluene (TATB/TNT) suspension
Authors: Billon H. H. 
Published: December 2004

AbstractThe rheology of a slurry of 1,3,5‐triamino‐2,4,6‐trinitrobenzene(TATB) in molten 2,4,6‐trinitrotoluene (TNT) suspension has been investigated. It was found that at high concentrations these suspensions are thixotropic. It has also been shown that these suspensions possess a shear‐dependent maximum packing fraction. This fact is relevant to the processing of these suspensions. A thixotropic model has been developed that successfully predicts flow curves for a chosen high concentration suspension.
Prediction of Life Times of Propellants ‐ improved kinetic description of the stabilizer consumption
Authors: Bohn Manfred A. 
Published: December 2004

AbstractAn equation for the decrease of stabilizer content in propellants is given, which describes the measured consumption of stabilizers such as diphenylamine, 2‐nitrodiphenylamine, acardite II and ethylcentralite very well. The equation was obtained with a kinetic formulation for the stabilizer depletion, which combines the reactions of first and zero order. According to this model, the times up to a complete consumption of the stabilizer are finite(they are infinite if the decrease is purely exponential), and can be calculated with the reaction rate constants of the model. The prediction of the life times is considerably improved. This new equation allows a normalized representation of the stabilizer decrease, which can reveal mechanistic changes in the course of the reaction.
Research on the Crack Mechanism of High‐Burning‐Rate Propellant in the solid rocket motor
Authors: Wang D. A. , Wang N. F. , Qin G. M. 
Published: December 2004

AbstractThrough the analysis and calculation to the flow field in the solid rocket motor using high‐burning‐rate propellant, the authors believe that the existence of pressure difference between the inside and outside of the propellant tube causes the propellant crack. In this paper, the design method to eliminate the pressure difference is discussed. The theoretical results were certified by the experimental results.
Thermo‐Oxidative Degradation of Polybutadiene Binders
Authors: Radhakrishnan T. S. , Rama Rao M. 
Published: December 2004

AbstractThermo‐oxidative degradation of hydroxy‐terminated polybutadiene (HTPB) and poly(butadiene‐acrylonitrile‐acrylic acid) terpolymer (PBAN) binders was studied in the presence of varying amounts of ammonium perchlorate (AP). It was found that the effect of AP on the nature and composition of the pyrolyzates was similar to the effect of increase in pyrolysis temperature. Activation energy for thermal degradation was found to be about 52 kJ/mol for both the polymers. The results are discussed in terms of a linear pyrolysis model.
Theoretical Modelling of the Combustion Processes of programmed splitting stick propellants
Authors: De Dios Rivera Juan , Hsieh Wen‐Hsin , Kuo Kenneth K. 
Published: December 2004

AbstractThe concept of programmed splitting of stick propellants offers a new method in controlling pressure‐time traces by increasing the burning surface area at the onset of splitting. This increase in burning surface area, also referred to as progressivity, leads to a higher performance of existing guns. The experimental work on combustion of programmed splitting stick (PSS) propellants in parallel to the present theoretical study was conducted and published by the authors. In this investigation, a theoretical model and computer code have been developed to simulate the burning and splitting processes of PSS charges and to gain a better understanding of physico‐chemical phenomena involved. In this theoretical model, the continuous gas phase is treated by a Eulerian approach, while the condensed phase (stick propellant) is divided into several representative groups and tracked as they move in the continuous phase, using a Lagrangian approach. The intergranular gas‐phase region is treated in a way similar to the continuous phase in the separated flow models for spray combustion. Numerical results are in agreement with experimental data, and can predict several features of the combustion processes that have been observed in partially burned grains recovered from test firings.
A constant of the motion for the two‐centre Kepler problem
Authors: Coulson C. A. , Joseph A. 
Published: December 2004

AbstractThe one‐centre Coulombic potential gives rise, in non‐relativistic mechanics, to additional constants of the motion which form the components of the Runge–Lenz vector. By a study of this vector, an extra constant of the motion is derived for the corresponding two‐centre problem. The result holds quite generally in a space of arbitrary dimension and is applicable to both classical and quantum mechanics; but breaks down when relativistic corrections, which destroy the extra symmetry of the one‐centre Coulombic potential, are taken into account. The effect of further Coulombic centres and of varying the form of the potential is briefly discussed. In particular a constant of the motion is derived for a two‐centre potential which has both Coulombic and simple harmonic terms. The relationship between these constants of the motion and the separation of the Hamiltonian into spheroidal coordinates is noted (this had previously been known only for the two‐centre Coulomb problem in three‐dimensional space). Finally the application to the hydrogen molecule ion, treated in the adiabatic approximation, is pointed out. The extra constant of the motion is seen to account for an observed apparent breakdown in the noncrossing rule for the potential energy curves.
Zur Clar'schen Theorie Lokaler Benzoider Gebiete in Kondensierten Aromaten
Authors: Polansky Oskar E. , Derflinger Gerhard 
Published: December 2004

AbstractPartant de la méthode HMO on vérifie qu'un postulate de Clar est justifié. D'après ce postulat il existe dans les hydrocarbures aromatiques condensés certaines régions localisées de caractère benzènoide. On propose un indice pour le caractère benzèneoide, butènoide, etc., de certaines parties de ces molécules, et on présente une méthode simple pour calculer ces indices. On discute l'importance de ces indices pour la réactivité chimique.
On the determination of the exact number of bound states of a given potential. I. General method
Authors: Joseph A. 
Published: December 2004

AbstractA general method is developed for determining the exact number of bound states for a given potential in a space of N dimensions (N ≧ 2). This is applied to a central potential of the form

where λ, r0, α are arbitrary positive numbers, and for which analytical solutions are obtained. Some properties of the degeneracy in the energy levels, with respect to the orbital angular momentum l, are also discussed.
The density matrix in the two‐particle function method
Authors: Mestechkin M. M. 
Published: December 2004

AbstractThe first‐ and second‐order density matrices D(N) and D for the function g(n) = AN[g(1, 2) …︁ g(N − 1, N)] are expressed by the g function itself and its density matrix D. In a singlet state the generating functions for spatial parts of these matrices are simply connected with there solvent of the Fredholm equation in which the spatial part of D is a kernel. Some special cases of g(1, 2) are considered. It isestablished that the number of large eigenvalues of D does not exceed that of different eigenvalues of D. Thus the degeneracy in the spectrum of D causes the appearance of such large eigenvalues.
Helium states II. Perturbation treatment of the ground state using the coordinates r< and r>
Authors: Ramaker D. E. , Hagnauer G. L. , Carlson R. E. , Gaetano R. F. , Crain H. , Schrader David M. 
Published: December 2004

AbstractIn an attempt to improve upon the convergence properties of the Hylleraas‐Scherr‐Knight‐Midtdal perturbation expansion for the ground‐state energies and eigenfunctions of the helium isoelectronic sequence, the term r is included in the zeroth‐order Hamil‐tonian. This term dominates the usual perturbation r for the ground state of these systems, and by removing it from H(1) we substantially reduce, in some sense, its size. In order to find the exact eigenfunction of the resulting zeroth‐order Hamiltonian it was found necessary to include in H(0) two additional terms involving the delta function δ(r1 − r2) = δ(r< − r>) and one such term in H(1). Approximate first‐ and second‐order eigenfunctions are calculated variationally giving the energies to fifth order. The results are disappointing. The errors in the energies to fifth order for He, Li+, and Be2+, although quite small, are significantly larger than the corresponding errors in the more conventional perturbation treatment. Reasons for the failure to improve upon the earlier results are discussed. A “paradox” noted some time ago by Snyder and Parr is examined in an Appendix.
Expansion of r12 and r in terms of analytical functions
Authors: Cressy Norman , Ruedenberg Klaus 
Published: December 2004

AbstractExpansions in terms of the spherical coordinates of two particles are given for the interparticle distance and its inverse. The expansions are characterized in that each term is a product of analytical one‐variable functions. While it is possible to find acceptable expansions for r12, those obtained for r exhibit extremely slow convergence, unacceptable for practical use. The same objections must be raised against related expansions of multi‐centered molecular integrals.
Angular dependence of the retarded dispersion energy
Authors: Meath William J. , Power Edwin A. 
Published: December 2004

AbstractThe Casimir–Polder retarded dispersion energy is calculated for non‐symmetric molecules and the energy is expressed in terms of body fixed axes for the dipole transition moments on each molecule. In the special case of molecules with cylindrical symmetry the potential energy is given in terms of the transverse and longitudinal polarizabilities and in terms of the angles defining the orientation of the axes of the molecules with respect to the intermolecular direction. In the limit of no retardation (R ≪ λ) the result becomes that of London and in the opposite limit of full retardation at large R the potential energy tends to that of Craig and Power.
Molecular electronic structure of metal phthalocyanines
Authors: Mathur S. C. , Singh Jai 
Published: December 2004

AbstractThe molecular–electronic structure of the metal phthalocyanines (Fe, Co, Ni and Cu) has been determined by the molecular orbital treatment. Coulomb integrals of the metal atom occurring in the secular determinants have been approximated equivalent to the valence state ionization energy (VSIE) of a metal orbital for a particular charge configuration. The calculated π‐electron charge densities have been found to be higher on the nitrogen atoms as compared to the other atoms in the molecule. This is in agreement with the e.s.r. studies of the metal phthalocyanines. To test the correctness of the molecular orbital calculations, the π‐π* transitions (14,000 cm−1 − 30000 cm−1), d‐d* transitions (20000 cm−1 − 60000 cm−1) and charge transfer transitions (15000 cm −1 − 30000 cm−1) have been calculated in the metal phthalocyanine molecules. The calculated frequencies have been compared with the observed ones and found in fair agreement.
Bond exciton model of alkenes and diene polymers
Authors: Partridge R. H. 
Published: December 2004

AbstractThe bond exciton model, developed originally for alkane molecules, is applied here to a range of alkene molecules and diene polymers. The necessary empirical parameters are derived by comparison of the theory with the vacuum‐ultraviolet absorption spectra of ethylene and a number of alkyl‐substituted ethylenes, and these values are used to predict the energies, intensities and polarizations of the lower energy allowed valence transitions of fine diene polymers. Despite its simplicity the bond exciton model is found to give results in quite reasonable agreement with the available experimental data, and suggests that considerable excitation energy transfer may occur along the main chains of certain diene polymers.