bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterocyclic syntheses with malonyl chloride. 15. 7‐Chloro‐3,4‐dihydro‐4,5‐dioxo‐3‐aryl(or‐alkyl)‐2‐thio‐2H,5H‐pyrano[3,4‐2‐e]‐1,3‐oxazine from aryl or alkyl isothio‐cyanates and their degradation with morpholine and ethanol
Authors: Al‐Rawi Jasim M. A. , Mahmood Abdul‐Hakim Th.
Published: December 2004

Substituted aromatic isothiocyanates with malonyl chloride yield 7‐chloro‐3‐substituted‐3,4‐dihydro‐4,5‐dioxo‐2‐thio‐2H,5H‐pyrano [3,4‐e]‐1,3‐oxazine (1).

Alkyl isothiocyanates with malonyl chloride yield a mixture of 7‐chloro‐3‐alkyl‐2‐thio pyranooxazine (2) and the 2‐oxo‐analogue (3).

The pyrano oxazine 1 react stepwise with morpholine undergoing replacement of the 7‐chloro substituent yielding the 7‐morpholino analogue (4), then the pyrone ring was opened producing 5‐morpholino carbonyl‐4‐oxo‐3‐substituted phenyl‐2‐thio‐1,3‐oxazine‐6‐ylacetomorpholid (5). Finally the oxazine ring was opened yielding 2‐substituted phenyl carbomyl‐3‐morpholino‐N,N‐glutaconoyldimorpholine (6).

Ethanol react with compound 1 at any molar ration causing the opening of the pyrone ring and retain the oxazine ring.

Mass spectra. 1H‐n.m.r., u.v. and i.r. spectroscopic data provided information about the fine structures of the products.
Enzymes in organic synthesis. 2. Synthesis of enantiomerically pure prostaglandin intermediates by Enzymatic Hydrolysis of (1SR, 5RS, 6RS, 7RS)‐7‐acetoxy‐6‐acetoxymethyl‐2‐oxabicyclo[3.3.0]octan‐3‐one
Authors: Theil Fritz , Schick Hans , Nedkov Peter , Böhme Monika , Häfner Barbara , Schwarz Sigfrid
Published: December 2004

Subtilisin DY as well as alkaline protease from Bacillus licheniformis 41 p catalyze the hydrolysis of (1SR, 5RS, 6RS, 7RS)‐7‐acetoxy‐6‐acetoxymethyl‐2‐oxabicyclo[3.3.0]octan‐3‐one (rac‐1) with practically useful enantio‐ and regioselectivity. Under the hitherto found optimal conditions (1S, 5R, 6R, 7R)‐7‐hydroxy‐6‐hydroxymethyl‐2‐oxabicyclo[3.3.0]octan‐3‐one (4), an important intermediate in prostaglandin syntheses, could be prepared in a yield of 16% with an enantiomeric excess of 99%. The enantiomer (ent‐4) was obtained with the same enantiomeric excess in 20% yield. The chemical yields are related to the racemic starting material rac‐1.
Synthese und Strukturermittlung von Sulfamoyl‐guanidinen
Authors: Schröder H. , Fischer E. , Michalik M. , Oehme G.
Published: December 2004

Synthesis and Structure Elucidation of Sulfamoyl Guanidines

A series of sulfamoyl guanidines 2a‐‐hyphen;p and 4 was synthesized by addition of sulfurylchloride to dialkylcyanoamides and subsequent aminolysis of the N,N‐dialkyl‐N′‐chlorosulfonyl‐chloroformamidines with primary or secondary amines. Advantageously, the aminolysis can be performed with trimethylsilylamines as amine component by continuous withdrawing of the formed trimethylchlorosilane.

Phase transfer catalyzed methylation led to a specific alkylation of the sulfamoyl group to form the 2‐(aryl‐methyl‐sulfamoyl)‐guanidines (5a‐‐hyphen;5g, 5h). All compounds were characterized by m.s.‐, i.r.‐, 1H‐n.m.r.‐ and 13C‐n.m.r.‐spectra. I.r. and 1H‐n.m.r. data show the existence of an intramolecular hydrogen bonding between the guanidine NH group and the SO2 group.
Tetrazolverbindungen. 1. 1‐Aryl‐5‐(2‐dialkylamino‐vinyl)‐1H‐tetrazole aus 3‐Chlor‐propen‐iminiumsalzen
Authors: Fischer G. W. , Herrmann M.
Published: December 2004

Tetrazole Compounds. 1. 1‐Aryl‐5‐(2‐dialkylamino‐vinyl)‐1H‐tetrazoles from 3‐Chloropropeniminium Salts

3‐Chloropropeniminium salts 1 react with excess sodium azide in refluxing alcohols to give mainly 1‐aryl‐5‐(2‐dialkylamino‐vinyl)‐1H‐tetrazoles 3; in minor quantities isomeric 5‐aryl‐1‐(2‐dialkylamino‐vinyl)‐1H‐tetrazoles 4 are formed. The reaction involves splitting off N2 and C → N migration of the aryl and dialkylaminovinyl group, respectively. A cross‐over experiment indicated that the rearrangement step proceeds intramolecularly. — The i.r., u.v., and n.m.r. spectroscopic data of the novel 1H‐tetrazoles 3 as well as the u.v. spectra of some new starting products 1k—v are reported.
Phase transfer catalysed alkylation of enamines of β‐keto carbothionic acid anilides with dihalogenoalkanes: Synthesis of Cyclic S,N‐Acetals of α‐Oxo Ketene
Authors: Bogdanowicz‐Szwed Krystyna , Kozicka Michalina , Lipowska Malgorzata
Published: December 2004

Alkylation of 2‐morpholino‐cycloalken‐1‐carbothionic acid anilides 1 and 2 with 1,3‐dibromopropane in a two‐phase system leads to 1‐morpholino‐cycloalken‐3‐aryl‐tetrahydro‐1,3‐thiazine‐2‐ylidene 3 and 4. Reactions of 2‐morpholino‐cyclopenten‐1‐carbothionic acid anilides 5 and 3‐morpholinothiocinnamic acid anilides 8 with 1,2‐dibromoethane yield 1‐morpholino‐cyclopenten‐3‐aryl‐thiazolidine‐2‐ylidene 7 and 2‐(2′‐phenyl‐2′‐oxo‐ethylidene‐3‐aryl)thiazolidine 9, respectively. Alkylation of 1‐indanone‐ and 1‐tetralone‐2‐carbothionic acid anilides 11 and 12 with dihalogenoalkanes yield 1‐oxo‐indanylidene‐ and 1‐oxo‐tetralidenethiazolidines 14, 16 and tetrahydro‐1,3‐thiazines 15, 17, respectively.
Oxidative dimerization of 4‐Alkyl‐6‐phenyl‐2,3‐dihydrooxazines
Authors: Spassov S. L. , Stoeva‐Yordanova K. P.
Published: December 2004

Reaction mixtures containing 4‐methyl‐(or ethyl‐)‐6‐phenyl‐2,3‐dihydrooxazine kept for some weeks in contact with air at room temperature yielded products of oxidative dimerization (dimorpholinofurans). The structures of the new compounds were determined on the basis of spectral studies and chemical transformations.
Hydropyrene, alicyclische Modellverbindungen für GC–MS‐Untersuchungen
Authors: Mann G. , Sicker A. , Herzschuh R. , Engewald W. , Praefcke K.
Published: December 2004

Hydropyrenes, Alicyclic Model Compounds for GC–MS Investigations

Hydrogenation of asymmetric and symmetric hexahydropyrene gives the five possible aromatic decahydropyrenes via different octahydropyrenes. From these compounds some dodecahydro‐ and tetradecahydro‐pyrenes, the four isomers of perhydropyrene with chair conformations and five new stereoisomers with twist boat six‐membered rings are obtained. The configurations of the hydrogenated pyrenes are assigned using chromatographic retention indices and mass spectrometric fragmentation in combination with force field calculations.
Studies on the Thermal Conversion of Long‐chain Alkynes at high temperatures in the gas phase
Authors: Ondruschka B. , Zimmermann G. , Ziegler U. , Kopinke F.‐D. , Teuber M.
Published: December 2004

In the gas phase pyrolysis of long‐chain alkynes C5 to C9 at 773 to 873 K, a remarkable portion of molecular reaction (retro‐ene analogous decompositions as well as cycloisomerizations of the parent alkynes to cyclopentenes alkylated in 3‐position) takes place besides the thermal conversion of the starting compounds via radical chain processes. The different products were separated by GC and the main products identified by means of different methods. The mechanisms of formation of the major products are discussed.
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

4‐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

The 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‐Nucleophiles

The 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 Diazomethane

The 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

Glycol 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

3‐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

Various 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‐galactopyranoses

Galacturonic 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‐thiazines

The 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

The 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

The 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 Sulphur

Cyanothioacetoamide 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

The 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

Optical 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

Die 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

Standardized 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

The 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.
High‐Melting Aromatic Nitrate Esters: Ethanolamine derivatives of polynitroaromatic compounds
Authors: Sitzmann Michael E.
Published: December 2004

The preparation and properties of high‐melting aromatic nitrate esters are described. An objective of the study is to provide nitrate esters that exhibit good short‐term stability at temperatures of 150°C and above.
Prediction of Life Times of Propellants ‐ improved kinetic description of the stabilizer consumption
Authors: Bohn Manfred A.
Published: December 2004

An 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

Through 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

Thermo‐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

The 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

The 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

Partant 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

A 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

The 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

In 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

Expansions 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

The 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

The 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

The 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.
One‐Center coulomb, two‐center hybrid, and two‐center coulomb integrals over STP functions
Authors: England Walter
Published: December 2004

Diatomic integral formulas involving Slater‐transform‐Preuss functions are obtained for the Coulomb and hybrid types. One‐center Coulomb integrals are also considered. All results have finite sums containing a one‐dimensional numerical integration.
Coupled Hartree‐Fock calculation of the uniform field quadrupole polarizabilities and shielding factors of S‐state ions
Authors: Bhattacharya A. K. , Mukherjee P. K.
Published: December 2004

Uniform field quadrupole polarizabilities and shielding factors of the first three ions of 2‐, 3‐, and 4‐electron sequences in their ground states have been calculated in the coupled Hartree‐Fock (CHF) scheme. For comparison the uncoupled Hartree‐Fock (UHF) results are also presented. It is observed that the uniform field quadrupole polarizabilities differ slightly in the two schemes and agree well with the UHF results of Lyons, Langhoff and Hurst. However the shielding factors differ appreciably in the two schemes and are completely different from those of Lyons et al. The cause of the difference in the shielding factor values is investigated.
Long‐range dispersion interactions involving excited atoms; The H(1s)–H(2s) interaction
Authors: Deal Walter J. , Young Ralph H.
Published: December 2004

The dispersion interaction between two nonoverlapping atoms (or molecules) is expressed in terms of single‐atom “polarizabilities.” The formulation is valid even if one atom (or both) is in an excited state. To illustrate the procedure, the dispersion interaction between a 1s and a 2s hydrogen atom is computed accurately through order R−10 (R = internuclear separation).
Validity of the three‐center, four‐electron model for stability of rare gas halides on the basis of exchange perturbation theory
Authors: Lombardi E. , Pirola L. , Tarantini G. , Jansen L. , Ritter R.
Published: December 2004

In a previous publication [1] we analyzed the stability of rare gas halides on the basis of exchange perturbation theory of the Rayleigh‐Schrödinger type, using a three‐center, four‐electron model. In this paper, the analysis is extended to a (n + 1)‐center, (n + 2)‐electron model for rare gas halides of composition RXn, where R is the rare gas atom and X the halogen atom, in order to investigate the validity of the three‐center, four‐electron model. The compounds analyzed are XeFn, XeCln, KrFn and KrCln with n = 3 and 4, in different geometric configurations and for different states of total spin S. As before, we use exchange perturbation theory in first and second orders. The results are in good agreement with those obtained in the previous analysis and with experiments. Specifically, it is found that chlorides of rare gas atoms are not stable, that XeF4 has the square‐planar configuration and that trifluorides cannot exist. The possible existence of KrF4 is discussed.
Correlation effects in the low–lying excited states of the PPP models of alternant hydrocarbons. I. Qualitative rules for the effect of limited configuration interaction
Authors: Čížek J. , Paldus J. , Hubač I.
Published: December 2004

Simple rules for an estimate of the correlation effects in the low‐lying states of alternant hydrocarbons, as described by the Pariser–Parr–Pople Hamiltonian, are formulated. These rules are based on the alternancy and spin symmetry classification of states in both strongly and weakly correlated limits and on the valence bond characteristics of those states in the fully correlated limit. It is shown that the largest effect of the electron correlation will be found for the singlet “minus” states (using Pariser's classification of the alternancy symmetry species), a smaller effect for the triplet “plus” states, and a much smaller effect for the remaining states. These rules are exemplified by limited CI calculations including all monoexcited and all mono‐ and bi‐excited configurations, respectively, for a number of π‐electronic systems. In view of these rules the success of the PPP model in the monoexcited CI approximation may be understood.
Resolvent technique and Padé approximants in configuration interaction calculations
Authors: Røeggen I.
Published: December 2004

A perturbation approach based on resolvent technique and Padé approximants is proposed. The eigenvalue of interest is part of a solution of two nonlinear algebraic equations. The nonlinear equations are arrived at by considering two different expression of the expectation value of the resolvent of an outer projection of the Hamiltonian. The first expression is based on the spectral resolution of the resolvent, and the second one is obtained by a power series expansion analogous to that applied in the derivation of the energy expression in the Brillouin–Wigner perturbation theory. The truncated power series is extrapolated by Padé approximants of type II. The method is tested on a CI calculation of the energy of the lowest 1Σ state of the B2 molecule.
Ab initio calculation of the electronic structure of TCNQ and its ions
Authors: Johansen Helge
Published: December 2004

Ab initio SCF‐LCAO‐MO calculations have been performed for TCNQ and its positive and negative ions in various electronic states. A basis set consisting of 412 primitive Gaussian type orbitals contracted to 180 was used in the investigation. The electron density distribution in TCNQ and the negative ions, and the redistribution upon ionization has been illustrated by plotting difference density contour maps. The quinone structure of the neutral TCNQ system undergoes a transformation to a benzenoid structure when electrons are added. Electronic transitions, ionization potentials and electron affinities have also been calculated.
Rearrangement correction to higher polarizabilities of two‐electron systems
Authors: Roy H. P. , Bhattacharya A. K.
Published: December 2004

In this paper we include the rearrangement correction (discussed in the preceding paper) in a coupled Hartree–Fock (CHF) calculation of atomic hyperpolarizabilities and other related properties. We have studied the effect of these corrections on properties like electric dipole hyperpolarizabilities, uniform electric field quadrupole polarizabilities and shielding factors in two‐electron ions and have noticed significant changes in the computed values over the CHF results.
Spin‐projected EHF method. III. Applications to π‐electron systems
Authors: Mayer I. , Kertész M.
Published: December 2004

The surely convergent procedure to obtain extended Hartree–Fock (EHF) solutions of the spin‐projected scheme, for which the equations are given in Part II, is applied to eleven π‐electronic systems with 2–10 electrons at the PPP level of integral approximations. The method takes into account a considerable part of the correlation energy. The symmetry properties of the EHF wave functions obtained are discussed together with some computational details. A simplified algorithm is also described.
Integral Hellmann‐Feynman computations on H3ABHn—H2ABHn+1 rearrangements
Authors: Trindle Carl , George John K.
Published: December 2004

Extensively optimized Lewis orbital (Frost model) structures are reported for CH3N, CH3NH+, CH3CH, CH3CH, CH3BH2, CH2NH, and CH2NH (spiro and planar). Electronic energy differences between these isoelectronic species were estimated by the integral Hellmann‐Feynman (iHF) formula, with the hope that satisfaction of the Hellmann‐Feynman conditions would lead to accurate iHF values of energy changes. We observed a strongly nonlinear relation between the iHF error and the departure of the overlap of wave‐functions of the structures from unity. MO computations in common orbital (not determinantal) basis sets for CH3NH+CH2NH (planar), CH3NCH2NH, and CH3CHCH2CH2 produced greatly improved iHF estimates of energy changes, reducing errors by as much as 80 times. Certain features of the static optimum structures and the transition densities suggested that the syn path for rearrangement of methyl carbene to ethylene is a general feature of rearrangements in these systems.
Calculation of j and jm symbols for arbitrary compact groups. I. Methodology
Authors: Butler P. H. , Wybourne B. G.
Published: December 2004

A systematic method is established for computing the coupling coefficients associated with arbitrary compact groups using only the general properties of the coefficients and the specific character theory of the relevant groups. The basic character theory is first outlined. Then a primitive set of 6j symbols is defined and their computation sketched with careful attention being given to matters of phase fixing. A recursive method is developed for calculating arbitrary 6j symbols using the primitive set. Finally, a primitive set of 3jm factors is set up and then the general 3jm factors computed recursively.
Calculation of j and jm symbols for arbitrary compact groups. II. An alternate procedure for angular momentum
Authors: Butler P. H.
Published: December 2004

The various orthogonality and sum rules which the 6j and 3jm symbols satisfy are sufficient to obtain the algebraic formulas for these symbols for SO3 ⊃ SO2. Character theory enters in that the j's and m's occurring in the various sums are given by the triangle rule

together with information on the symmetrized product and the branching, SO3 ⊃ SO2,

The resulting calculation is somewhat simpler, algebraically speaking, than previous calculations and has the pedagogical advantage that only the concept of an irreducible representation of a group is required, instead of the more elaborate concept of ladder operators.
Molecular symmetry and closed‐shell SCF calculations. I
Authors: Dupuis Michel , King Harry F.
Published: December 2004

For efficient integral evaluation, orbital basis functions are grouped into shells and integrals into blocks in the recently developed SCF program Hondo. This shell structure is ideally suited to the scheme of Dacre and Elder for using point group symmetry. An entire block of two‐electron integrals is eliminated if it is symmetrically equivalent to another block with a higher index (four label). Using the “petite list” of blocks of integrals, a skeleton Fock matrix is formed from which the true Fock matrix is generated by “symmetrization.” We prove two theorems which provide a clear and rigorous justification for this version of the Dacre–Elder procedure. We compare SCF calculations on the phosphorus molecule using Td symmetry with those using various subgroups of Td. The number of integrals computed is found to be approximately inversely proportional to the order of the group. Integral evaluation time and SCF iteration time are each linear functions of the number of integrals. The computer spends a negligible amount of time in executing symmetry‐related code, and the human effort involved is little more than picking the appropriate Schönflies symbol for the molecule.
Nonrigid molecule effects on the energy levels of XeF6
Authors: Trindle C. , Datta S. N. , Bouman T. D.
Published: December 2004

The geometric and electronic structure of XeF6 is not yet fully understood, even though most of the means of structure determination available to the chemist have been employed in an effort to describe the molecule. We suggest that many of the experimental anomalies and theoretical difficulties arise from the possibility of rapid polytopal rearrangement in this system, and put forward in this report an analysis which accommodates the experimental data. We show that easy rearrangement produces substantial splittings in rigid‐molecule energy levels, and with the aid of Longuet‐Higgins group theory developed expressly for flexible molecules, compute energy‐level schemes for a set of plausible rearrangement modes. By appropriate choice of parameters specifying the extent of splitting, we match the reported infrared and Raman spectra, and their temperature dependence. The puzzling “time lag” in the Raman (but not the infrared) spectrum is tentatively ascribed to selective relaxation of Raman‐active vibrational modes.
Completeness and linear independence of basis sets used in quantum chemistry
Authors: Klahn Bruno , Bingel Werner A.
Published: December 2004

Infinite sets of functions in Hilbert space are characterized by their completeness properties and the extent of linear independence. Different measures of linear independence such as orthonormality, Gram's determinant, the special measure of linear independence, and the asymptotic dimension are related to each other and with the degrees of completeness such as overcompleteness, exact completeness, and incompleteness as far as possible.
AMOS and insulator‐to‐metal transitions
Authors: Dugay M. , Debarge G.
Published: December 2004

We describe an attempt to use the AMO method for the investigation of insulator metal transitions. One of the main features of the calculation is that it permits an extension of the AMO method to finite temperatures.

The ability of the model to account for such transitions is emphasized for the special case of linear antiferromagnetic systems. We discuss possible generalizations by pointing out that there exists a connection with Peierls' model.
Molecular orbital studies of Al2F6 and Al2Cl6 using a minimal basis set
Authors: Curtiss L. A.
Published: December 2004

Ab initio minimal basis LCAO‐SCF molecular orbital (MO) calculations have been carried out on various structures of the AIF3 and AlCl3 dimers. A bridged D2h structure is found to be the most stable of the structures investigated for Al2F6. A similar structure was obtained for Al2Cl6 in agreement with the experimental evidence.
Formal theory of effective π‐electron hamiltonians
Authors: Brandow B. H.
Published: December 2004

We argue that the goal of developing a satisfactory general formalism for the justification of effective π‐electron Hamiltonians, as well as for ab initio calculation of their parameters (α, β, and γ), has now been achieved. The need for a fully linked many‐body formalism is emphasized; this feature requires a Rayleigh–Schrödinger (RS) type of degenerate perturbation theory. A number of apparently different degenerate RS perturbation formalisms are reviewed. Most of these formalisms are actually identical term‐by‐term, when their RS expansions are worked out explicitly; the formal relations that prove their complete equivalence are presented and discussed. One of these formalisms, a version developed by the author for related open‐shell problems in nuclear physics, is shown to be most convenient for many‐body applications. This is owing to the relatively simple and transparent nature of its general algebraic structure, which facilitates partial summation to infinite order. A simple and concise derivation is presented for the algebraic features of this preferred formalism, and its many‐body (linked cluster) aspects are briefly discussed. The recent development of a nonperturbative (coupled‐cluster) analog of this formalism is also described. Some practical issues are examined, including the choice of orbital basis. Illustrative numerical results are presented, based on the calculations of Iwata and Freed. Several remaining problems are described; these are both qualitative and quantitative in nature, and their resolution will require some detailed calculations.
Quantum‐Chemical and semiclassical calculations of intermolecular interactions of phospholipids
Authors: Frischleder H. , Lochmann R.
Published: December 2004

By use of empirical 0–1–6–12 atom–atom potential functions and the PCILOCC method intra‐ and intermolecular interactions of glycero–phosphoryl–ethanolamine model head groups in a planar layer crystal were calculated. Starting from investigations of the two‐dimensional energy‐contour diagrams the minima of energy as a function of all head group torsion angles were calculated using a gradient procedure. Within an interval of 15 kcal/mol above the energy of the global minimum we obtained about 30 local minima. These results demonstrate a high flexibility of the investigated phosphorylethanolamine head group in agreement with experiment. The ethanolamine moiety exists in enantiomeric conformations. With the torsion angles of the 0–1–6–12 energy minimization procedure PCILOCC calculations were carried out. These calculations yield the x‐ray conformation as the most stable one (unit‐cell stabilization energy = −36.3 kcal/mol). The PCILOCC as well as the potential function calculations show that the conformation of phospholipid head groups in layer crystals is determined by intramolecular as well as by intermolecular interactions with neighboring phospholipid molecules.
Conformational properties of biomacromolecules (proteins and nucleic acids) at low temperatures and the problem of interaction of biopolymers with water molecules and ions of dissolved salts
Authors: Andronikashvili E. L. , Mrevlishvili G. M. , Japaridze G. Sh. , Sokhadze V. M.
Published: December 2004

Methods for determining the thermal measurements of biological objects have found ever increasing application in biology. This paper analyzes the temperature dependence of the heat capacity of biopolymer solutions between 4–400°K. Four distinct temperature regions were discovered, and experiments on these temperature intervals are given.