bluuebunny/crossref_metadata_2025 huggingface dataset:
EPR‐Untersuchungen zur Photolyse halogenierter organischer Verbindungen. II. CHBr3 und CBr4 in glasartigen und polykristallinen Matrices
Authors: Stösser R. , Pritze B. , Abraham W. , Dreher B. , Kreysig D.
Published: December 2004

EPR‐Investigations on the Photolysis of Halogenated Organic Compounds. II. CHBr3 and CBr4 in Glassy and Polycrystalline Matrices

Photolysis of CHBr3, CDBr3 and CBr4 in glassy and polycrystalline matrices (alcohols, diethylether, benzene derivatives and KBr) at T ≥ 77 K yields stationary e.p.r.‐spectra in the range of effective g‐factor from 2.2 to 1.9. By comparison of the spectra of CHBr3 and CDBr3, exposed to γ‐rays and u.v. light respectively, and the spectra of these compounds in matrices it was shown that the photolysis in matrices produces the species \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CBr}_4\,^{_{\bar.}} $\end{document}, ·CBr3 and α‐Br‐radicals from the halogenated compounds and HĊO, ·CH3, CH3ĊHOH, RĊHOH, and ·C2H5 from the matrix. Photolysis of halogenated compounds in CH3OH and CD3OD yields only HĊO and ·CH3 together with a very small amount of bromine‐containing radicals. In all other investigated matrices the concentration of bromine containing species is controlled by physical and chemical properties of the matrix. Time development of the \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CBr}_4\,^{_{\bar.}} $\end{document}‐radical and of those generated from the matrix is different and gives insight into the complex photoreaction in solid matrices.
β‐Thiocyanatovinylcarbonylverbindungen. XI. Ungewöhnliche Substituenteneffekte bei der massenspektrometrischen Fragmentierung von β‐Thiocyanatovinylaldehyden
Authors: Herzschuh R. , Schulze B. , Mühlstädt M.
Published: December 2004

β‐Thiocyanatovinylcarbonyl Compounds. XI. Unusual Substituent Effects in the Mass‐spectrometrical Fragmentation of β‐Thiocyanatovinylaldehydes

The mass spectra of homologous Z/E‐isomers and constitutional isomers of β‐thiocyanatovinylaldehydes are discussed. The main fragmentation consisting of HCN‐loss from the molecular ion is influenced by the substituents so that the constitutional and steric isomers can be clearly distinguished by the \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm M - HC}\left. {\overline {\, {\rm N} \,}}\! \right| + /{\rm M + }^ \cdot $\end{document} ratio. Alkyl homologues with a hydrogen atom in γ‐position to the aldehyde group show an unusual intensive CN‐radical loss due to a „hidden hydrogen rearrangement”︁, which was proved by deuteration experiments.
1H‐, 13C‐ und 15N‐NMR‐Untersuchungen zur Tautomerie von Bispyrazolonen vom Typ der 4,4′‐Methyliden‐bis‐(3‐stearoylamino‐1‐phenyl‐pyrazolin‐5‐one)
Authors: Mistol J. , Grossmann N. , Pietsch H. , Fanghänel E.
Published: December 2004

1H‐N.M.R., 13C‐N.M.R., and 15N‐N.M.R.‐Investigations Concerning Tautomerism of Bispyrazolons of 4,4′‐Methyliden‐bis‐(3‐stearoylamino‐1‐phenyl‐pyrazolin‐5‐on) Type

With the help of 1H, 13C and 15N chemical shifts of the n.m.r. signals of the structure elements OH, NHCO, 13C‐5, 15N‐1, 15N‐2 and 15N‐2‐H and using the coupling constants nJ(15NH) and nJ(13C15N) (n = 1, 2) of the doubly 15N labelled bispyrazolone 1, a chelated and an associated species were shown to exist in the slightly polar solvent CDCl3. The chelated bispyrazolone (BC)ch contains one pyrazolone ring in the tautomeric NH form B and the other in the tautomeric OH form C. In the associated bispyrazolone (BB)as, both pyrazolone rings exist in the NH form B. Observation of the time, concentration and temperature dependence of the n.m.r. spectra of 1 resulted in the detection of complex exchange processes in tautomeric equilibrium. Apart from the intermolecular exchange process (BC)ch ⇌ (BB)as, another exchange process (BC)ch ⇌ (CB)ch occurs, with intermolecular interactions being involved. It has been established that in the case of substitution in the methylidene bridge (2, 3) the lefthand side of the equilibrium (BC)ch ⇌ (BB)as participates in the process to a greater extent than in the case of 1 (unsubstituted methylidene bridge).
Durch bisquartäre Ammoniumsalze katalysierte Zweiphasenreaktion von 1‐Bromoctan mit Natriumacetat und Kaliumacetat
Authors: Schiefer H. , Beger J. , Lorenz U.
Published: December 2004

Two‐Phase Reaction of 1‐Bromooctane with Sodium Acetate and Potassium Acetate Catalyzed by Diquaternary Ammonium Salts

New unsaturated diquaternary ammonium salts (diquats) were prepared in two ways from ditertiary amines 3 and 1‐bromoalkanes or from 1, 4‐dibromobut‐2t‐ene and tertiary monoamines. A comparison of their catalytic ability with that of saturated diquats and with that of corresponding monoquats was made. The reaction of n‐C8H17Br with NaOAc or KOAc in the two‐phase system liquid‐liquid without an additional solvent is catalyzed more effectively by the unsaturated diquats than by the saturated diquats and the monoquats. Most of the used quats catalyze the ester formation from NaOAc more effectively in the system liquid‐liquid, however, the ester formation from KOAc more effectively in the system solid‐liquid; KOAc is generally superior to NaOAc in both systems. Consequently, in the phase‐transfer catalyzed ester formation from alkali acetate and alkyl halides not only the structure of the quat but also the inorganic cation of the acetate have influence on the rate of conversion.
Derivatisierung von Aminen mit 4‐substituierten 7‐Nitrobenz‐2,1,3‐oxadiazolen
Authors: Heberer H. , Kersting H. , Matschiner H.
Published: December 2004

Derivatization of Amines with 4‐Substitured 7‐Nitrobenzofurazans

Electrophilc derivatives of 4‐nitro‐benzofurazan with different reactivities were used to synthesize 28 new mono‐ and disubstituted 4‐amino‐7‐nitrobenzofurazans 2b, 2d, 2f–2i, 2l, 2m–2n, 3b–3f, 3h–3j, 4e–4d, 4f–4k, 4m, 4o–4p. A reaction mechanism is proposed on the basis of the differences of the reactivities and a preliminary kinetic examination. The acid character of the NH‐function in monosubstituted compounds is demonstrated by means of spectroscopical investigation of pKa‐values.

Data from i.r., u. v./vis, and fluorescence studies are offered.
Synthese von substituierten 5‐Amino‐1,2,4‐triazolen
Authors: Evers R. , Fischer E.
Published: December 2004

Synthesis of Substituted 5‐Amino‐1,2,4‐triazoles

N‐Nitro‐amidino‐dithiocarbimidic acid dimethylester 1 reacts with monosubstituted hydrazines under formation of the substituted 5‐amino‐1, 2, 4‐triazoles. Disubstituted hydrazines give under the same conditions N‐nitro‐amidino‐S‐methyl‐isothiosemicarbazides.

The reaction of some more hydrazine derivatives with 1 yields the adequate substituted 1, 2, 4‐triazoles.
Aufklärung der Molekülstruktur von Rohölinhaltsstoffen durch NMR‐Spektroskopie. IV. Strukturtypen‐ und Strukturgruppenanalyse von Erdölfraktionen durch 1H‐NMR‐Spektroskopie
Authors: Deutsch K.
Published: December 2004

Elucidation of the Molecular Structure of Petroleum Constituents by N.M.R. Spectroscopy. IV. Analysis of Petroleum Fractions with Respect to Types of Structure and Structural Groups by 1H N.M.R. Spectroscopy

An improved method is presented which permits a quantitative analysis of crude oil products with a final boiling point below 400°C by means of the data of the 1H n.m.r. spectrum and the average boiling point of the petroleum fractions. The types of aromatic structures are distinguished with respect to mono‐, bi‐, and tricyclic aromatics, and additionally, further structural group information is obtained.
Cyclisierungsreaktionen β,γ‐ungesättigter Kohlensäurederivate. XI [1] Untersuchungen zur Stereochemie der Cyclofunktionalisierung β,γ‐ungesättigter Carbamidsäureester
Authors: Mühlstädt M. , Meusinger R. , Olk B. , Weber L. , Widera R.
Published: December 2004

Cyclization Reactions of β,γ‐Unsaturated Derivatives of Carbonic Acid. XI. Investigation of Stereochemistry of the Cyclofunctionalization of β,γ‐Unsaturated Carbamic Acid Esters

N, N‐Disubstituted β,γ‐unsaturated urethanes 1 have been cyclized to 3,5‐disubstituted oxazolidine‐2‐ones 3 by aromatic sulfenyl chlorides 2. The stereochemistry of the products and the cyclofunctionalization reaction were investigated.
On the Structure of Carbamoylated 2‐Phenylaminopyridines
Authors: Mørkved Eva H.
Published: December 2004

Unambiguous preparations of 2‐(N‐alkoxycarbonyl‐N‐phenyl)aminopyridine 1‐oxides are used to prove that the product from 2‐phenylaminopyridine 3 and phenyl isocyanate is the expected urea 2a. Recently a 1,2‐dihydropyridine derivative 1 [4] has been claimed to be the product from 3 and phenyl isocyanate. The exocyclic nitrogen of 3 invariably reacts as the nucleophile towards electrophiles such as carbonyl chloride, esters of chloromethanoic acid and aryl isocyanates. 1H n.m.r. and 13C n.m.r. spectra support the assigned structures of the products from these ractions.
Prostaglandins and Prostaglandin Intermediates. XVII [1]. Synthesis of the Main Metabolite of the PGF2α Analogue Cloprostenol
Authors: Theil Fritz , Costisella Burkhard , Mahrwald Rainer , Gross Hans , Schick Hans , Schwarz Sigfrid
Published: December 2004

The δ‐lactone 5, the main metabolite of the PGF2α analogue cloprostenol, is prepared in four steps from the homologous γ‐lactone 1 in an overall yield of 42% by conversion into the γ‐lactol 3, which is olefinated with diethyl 1‐cyano‐1‐dimethylamino‐methylphosphonate to the cyano enamine 4 and finally hydrolyzed under various conditions. The described reaction sequence represents an example for the general possibility of the ring enlargement of γ‐lactones to δ‐lactones.
Untersuchungen zu den Sondeneigenschaften von 7‐Hydroxy‐cumarinen in micellarer Cetyl‐triethyl‐ammoniumbromid‐Lösung – Hilfsmittel zur Beschreibung von micellaren Systemen
Authors: Knoll H. , Seidel A. , Hennig H. , Soboleva I. , Zaitzev N. , Kuzmin M. G.
Published: December 2004

Investigation on Probe Properties of 7‐Hydroxy‐coumarines in Micellar Cetyl‐triethyl‐ammoniumbromide Solution – Means for Characterization of Micellar Systems

Anions of 3‐substituted 7‐hydroxy‐coumarines (1a–c) as fluorescence probes have been studied in this work. Acid‐base equilibria in water and micellar solution of cetyl‐triethylammoniumbromide (cmc = 0,72 mmol l−1), fluorescence properties and fluorescence quenching by octacyano‐molybdate‐IV have been investigated. It has been confirmed that probe and quencher are completely micellized. Fluorescence life times and quenching constants per one quencher molecule in the micell of about 108 s−1 have been determined. The kinetics of saponification of the probe 3‐acetyl‐7‐hydroxy‐coumarine at pH = 12 in micellar solution has been followed by probe fluorescence.
Zur Chemie der 5‐Amino‐2‐phenyl‐1,2,3‐thiadiazoliumsalze
Authors: Gewald K. , Calderon O. , Hain U.
Published: December 2004

On the Chemistry of 5‐Amino‐2‐phenyl‐1,2,3‐thiadiazolium Salts

Treatment of the title compounds 1 with pyridine yield the phenylhydrazones of the 1,2,4‐thiadiazol‐3,5‐diyl‐glyoxylic acid derivatives 4. The amides 4a, b can also be obtained by reaction of the phenylhydrazono cyanacetoamides 3a, b with sulphur in the presence of pyridine. Nitriles react with 1 to form the phenylhydrazones of the 1,2,4‐thiadiazol‐5‐yl‐glyoxylic acid derivatives 6. Reduction of 6a yields the 1,2,4‐thiadiazol‐5‐yl‐glycine derivative 7. Depending on its condition the reaction of 1c with benzoyl acetonitrile yield either the 1,2,4‐thiadiazole or the 4‐amino‐thiazole derivative (6i or 8). From 1a and ethyl acetoacetate the phenylhydrazone of the thiazol‐2‐yl‐glyoxylic acid derivative 9 arises which can be reduced to yield the thiazol‐2‐yl‐glycine derivative 10. The addition of 1 onto isothiocyanates in the presence of pyridine yields the substituted N‐(1,2,3‐thiadiazol‐5‐ylidene)‐thioureas 12a, b. Carboxylic acids react with 1 in the presence of pyridine to form the 5‐Acylimino‐1,2,3‐Δ3‐thiadiazolines 13.
Ein einfacher Weg zu neuartigen Borhaltigen Spiroverbindungen
Authors: Hartmann H.
Published: December 2004

A Simple Route to a New Type of Boron‐containing Spirocompounds

The reaction of enolizable 1,3‐dicarbonyl compounds 6 with diol compounds 5 and boric acid results in a new typ of boron‐containing spiro‐compounds 10. By using different substituted 5 and 6 more than 40 new spiroboronates 10 have been prepared and characterized by means of spectroscopic and analytical data.
Intermediates of Prostanoid Synthesis. Stereospecific conversion of (+)‐5β‐hydroxycyclopenten‐2‐yl‐1β‐acetic acid γ‐lactone into (+)‐1β‐methoxycarbonylmethyl‐2β,3β‐(p‐nitrobenzylidene)‐dioxycyclopentan‐5‐one
Authors: Freimanis J. , Gerca L. , Turovskis I. , Liepinš E. , Lola D. , Mishnev A. , Bundule M. , Bleidelis J.
Published: December 2004

Starting from (+)‐5β‐hydroxycyclopenten‐2‐yl‐1β‐acetic acid γ‐lactone (1), (+)‐1β‐methoxycarbonylmethyl‐2β, 3β‐(p‐nitrobenzylidene)‐dioxycyclopentan‐5‐one (7) was prepared within 4 steps. Subsequent cleavage of the latter gives (−)‐3β‐hydroxy‐1‐methoxy‐carbonylmethylcyclopent‐1‐en‐5‐one (8a). Hydroxylation of the lactone (1) was found to give (+)‐2β,3β,5β‐trihydroxycyclopentyl‐1β‐acetic acid γ‐lactone (2a) with cis‐oriented hydroxy groups in respect to the lactone ring. No formation of the trans‐isomer, as has been reported earlier [4], was observed.
Synthesis of Some Pyrazolo‐Anisylethylamine Alkaloids amino acids and related compounds
Authors: Hamama W. S. , Hammouda M. , Afsah E. M.
Published: December 2004

Schmidt reaction of the pyrazolo‐β‐(p‐anisyl)‐propionic acid 3 gave the pyrazolo‐anisylethylamine 4. The related alkaloids 5 and 6 were obtained via double Mannich reaction of 4 with the bis‐Mannich base of cyclopentanone and transamination with gramine respectively. The pyrazolo‐phenylalanine 9 was obtained from the EAA adduct 7, through its Schmidt reaction to give 8 followed by hydrolysis, whereas the pyrazolo‐amino acid 12 resulted from the hydrolysis of the corresponding lactam 11.
Investigations about the Reducing Properties of Dimeric Dihydropyridines
Authors: Pragst F. , Šantrůček M.
Published: December 2004

The reaction of a series of bis‐[1,4‐dihydropyridinyl‐(4)] derivatives P2 with some benzyl halides, trans‐1,2‐dibromoethane and several heteroaromatic cations Q⊕ was investigated in acetonitrile/toluene with electrochemical and kinetic methods. For substrates with a reduction potential between −0.9 and −1.5 V the reaction occurs via the ratedetermining dissociation of P2 into free radicals P. as the real reducing agents, which transform the benzyl halides into the corresponding 1,2‐diarylethanes and Q⊕ into the corresponding dimeric product Q2. For the reduction of trans‐1,2‐dibromocyclohexane to cyclohexene a simultaneous transfer of two electrons to the substrate combined with the dissociation of P2 into two pyridinium ions P⊕ is proposed. In the case of a reduction potential more positive than −0.9 V (e.g. nitro substituted benzyl halides) P2 itself can act as the reducing agent with an increased reaction rate. With pyrylium ions Q⊕ a product P‐Q was detected by voltammetry and mass spectroscopy. In this case an electrophilic attack onto P2 instead of the electron transfer from P2 to Q⊕ cannot be excluded.
β‐Fur‐2‐yl‐α‐halogenacrylonitrile. VII. Reaktionen von β‐(5‐Brom‐fur‐2‐yl)‐α‐bromacrylonitril mit Mercaptan, Thioharnstoff und Thioharnstoffderivaten
Authors: Jähnisch K. , Seeboth H. , Kuban R. J.
Published: December 2004

β‐Fur‐2‐yl‐α‐halogenacrylonitriles. VII. Reactions of β‐(5‐Bromo‐fur‐2‐yl)‐α‐bromoacrylonitriles with Mercaptans, Thiourea and Thiourea Derivatives

β‐(5‐Bromo‐fur‐2‐yl)‐α‐bromoacrylonitrile 1 reacts with ethylmercaptan to yield β‐(5‐bromo‐fur‐2‐yl) β‐ethylthioacrylonitrile 3. With thiourea β,β′‐thio‐bis[β‐(5‐bromo‐fur‐2‐yl)]‐acrylonitrile 2 is formed. The pyrimidines 4 and 5 have been prepared by the reaction of 1 with s‐methylthiourea and 2‐aminothiazole, respectively. The structure of the new compounds were determined by means of x‐ray analysis, 1H‐n.m.r., 13C‐n.m.r. and mass‐spectroscopy.
Aza‐Enamine. VI. Umsetzungen von N,N‐Dialkylhydrazonen aromatischer Aldehyde mit Sulfonylisocyanaten
Authors: Brehme Rainer , Stroede Bernd
Published: December 2004

Aza‐enamines. VI. Reactions of N,N‐Dialkylhydrazones of Aromatic Aldehydes with Sulfonyl Isocyanates

The electrophilic attack of the sulfonyl isocyanates 2 on the arylaldehyde‐N,N‐dialkylhydrazones 1 takes place in dependence upon the substitutents R1 and NR2 at the nitrogen or carbon of the azomethine‐group giving the 5‐amino‐hexahydro‐1,3,5‐triazine‐2,4‐diones 3, the phenylglyoxylic‐acid‐sulfonamide‐N,N‐dialkylhydrazones 4 and/or the imidazolidine‐2,4‐diones 5.

The preparation and the u.v.‐, i.r.‐ and n.m.r.‐spectroscopic dates of the compounds 3–5 are reported.
Photochemie von Aminoketonen. X. Darstellung und diastereoselektive Photocyclisierung von N‐(β‐Benzoylethyl)‐N‐tosyl‐glycinamiden
Authors: Walther K. , Kranz U. , Henning H.‐G.
Published: December 2004

Photochemistry of Aminoketones. X. Preparation and Diastereoselective Photocyclization of N‐(β‐Benzoylethyl)‐N‐tosyl‐glycinamides

The title compounds 4 were prepared by MICHAEL‐like addition of N‐tosylglycinamides to phenyl‐vinyl‐ketone, generated from ω‐bromo‐propiophenone. 300 nm Irradiation of 4a–c (CO–NH) in benzene and acetone, respectively, causes, n, π*‐excitation and photocyclization to (3‐ref‐2‐cis)‐3‐hydroxy‐3‐phenyl‐N‐tosylprolinamides 5. Under the same conditions 4d–h (CONAlk2) yield (3‐ref‐2‐trans)‐prolinamides 6. The difference in diastereoselectivity is explained by intramolecular dipolar interaction in 4* and intramolecular hydrogen bondings in the intermediate hydroxybiradicals.
Fotochemische Primärprozesse von Xanthenfarbstoffen. VIII. Zum Einfluß von gemischten Mizellen auf die fotochemischen Primärprozesse von Selenopyronin und Erythrosin sowie die sensibilisierte Diazoniumsalzfotolyse
Authors: Ortmann W. , Fanghänel E.
Published: December 2004

Photochemical Primary Processes of Xanthene Dyes. VIII. Influence of Mixed Micelles on the Photochemical Primary Processes of Selenopyronine and Erythrosine and the Sensitized Photolysis of Diazonium Salts

The influence of the nonionic detergent dodecyltriglycol (DTG) on the escape rate of dye ions from cationic and anionic micelles is investigated. The rate constant of the escape of selenopyronine ions (Sp⊕) from mixed micelles of sodium dodecylsulfate (NDS) and DTG (1:1) (kA ≈︁ 3,2 · 104 s−1) is, as a result of the lower charge density, higher by the factor 10 than that from clean NDS‐micelles (kA ≈︁; 2,8 · 103 s−1). Erythrosine ions (Et2⊖) are tightly fixed to cetyltrimethylammoniumbromide (CTAB)‐micelles (kA ≈︁; 0,25 · 103 s−1) and to mixed micelles of CTAB and DTG (1:1). This may be a result of the twofold negative charge of the erythrosine ions. Properties of the mixed micelles (polarity, average aggregation numbers) are determined by using the dyes and pyrene as probes. The sensitized photolysis of diazonium salts by electron transfer from photoexited selenopyronine under aerobic conditions is more effective by a factor of 3–5 in the presence of anionic micelles than when in a water solution.
Zur Darstellung und selektiven Reduktion von geschützten Endothiopeptiden
Authors: Ripperger H.
Published: December 2004

On the Synthesis and Selective Reduction of Protected Endothiopeptides

The conversion of some protected peptides structurally related to nicotianamine into the corresponding endothiopeptides has been studied, using 2,4‐bis(4‐phenoxyphenyl)‐1,3,2,4‐dithiadiphosphetan 2,4‐disulfide, a modified Lawesson reagent. Regioselectivity was observed. The possibility of selective reduction of the thioamide group in the presence of t‐butyl ester and urethane groups was demonstrated.
Nucleophile Substitutionen an Kohlensäurederivaten. XX. Aminolyse des Bis(trichlormethyl)carbonates
Authors: Cotarca Livius , Bacaloglu R. , Csunderlik C. , Marcu N. , Tarnaveanu A.
Published: December 2004

Nucleophilic Substitutions at Carbonic Acid Derivatives. XX. Aminolysis of Bis(trichlormethyl)carbonate

The rate constants for the two steps of the reaction of bis(trichlormethyl)carbonate with substituted anilines have been determinated by conductivity measurements.

The first relatively fast step of the reaction is the nucleophilic attack of the amine to the bis(trichloromethyl)‐carbonate leading to trichloromethylurethane through a six or four centers transition state in which the carbon‐nitrogen bond is formed parallel with the transfer of the proton. In this reaction a phosgene molecule is also produced, which reacts very fast with amine to form a N,N′‐diarylurea.

The second, much slower step, is the nucleophilic attack of the amine to the trichloromethylurethane. Through a similar transition state in which the proton transfer has even a higher importance, a N,N′‐disubstituted urea and an other molecule of phosgene are formed.
Synthese und UV‐spektroskopische Charakterisierung von Carbeniumionen an Aerosil
Authors: Ulbricht Antje , Spange Stefan , Heublein Günther
Published: December 2004

Synthesis and UV‐spectroscopic Characterization of Carbenium Ions on Aerosil

The interaction of aerosil with various triphenylmethyl derivatives in the cationic vinyl polymerization in 1,2‐dichloroethane was studied. The adsorption of the triphenylmethylium ions onto aerosil surfaces strongly depends on both the type of substituents (R  CH3, OCH3, Cl, H and NO2) and the nature of the counter anion (SbCl6⊖, FeCl4⊖, SnCl5⊖, HSO4⊖, SO42⊖, F⊖, Cl⊖, Br⊖, CF3COO⊖, N3⊖ and SCN⊖). The binding of the triphenylmethylium ions with aerosil occurs via nucleophilic anions such as halides. Counter anions derived from metal halides as MtXn+1⊖ are not able bind on aerosil. Covalent compounds as triphenylmethyl halides are ionized by the acidic aerosil surface. The influence of substituents at the triphenylmethylium ion, the type of counter anions and the influence of water traces on surface — ionization are discussed.
Synthesis of Thiazolo(4,5‐b)‐quinoxalines and related compounds
Authors: Ammar Y. A. , Ismail I. M. , Sh. El‐Sharief A. M. , Mohamed Y. A. , Amer R. M.
Published: December 2004

The reaction of 2,3,7‐trichloroquinoxaline (1) or 2,3‐dichloro‐7‐bromoquinoxaline (2) with thiourea in DMSO gave 6,6′‐dichloro‐ or 6,6′‐dibromodiquinoxalino[2,3‐b:2′:3′‐e]1,4‐dithiien (3 or 4). However, 1 or 2 reacts with thiourea in ethanol to give (3 or 4) beside 7‐chloro‐ or 7‐bromo‐2‐imino‐2,3‐dihydrothiazolo[4,5‐b] quinoxaline (5 or 6) respectively. Interaction of 1 or 2 with acetone thiosemicarbazone gave 7‐chloro‐ or 7‐bromo‐3‐amino‐2‐imino‐2,3‐dihydro‐thiazolo[4,5‐b] quinoxaline hydrochloride (13 or 14) respectively. Cyclization of 7‐chloro‐ or 7‐bromo‐3‐amino‐2‐imino‐2,3‐dihydrothiazolo[4,5‐b]quinoxaline (15 or 16) on treatment with aromatic acid chlorides or isothiocyanates succeeded to give 19—21 or 28 and 29.
New syntheses of pyrazolo[3,4‐d]pyrimidine, pyrazolo[3,4‐d]pyridazine, isoindolinedione and pyrazole derivatives
Authors: Abdelhamid Abdou O. , Negm Abdalla M. , Abbas Ikhlass M.
Published: December 2004

Phenacylmalononitriles 2 react with hydrazines, acetic‐hydrochloric acid and with diazotised primary aromatic amines to afford phenacylpyrazole (5a,b), aminofurans (6a,b) and aminopyrazole derivatives (3a,d) respectively. The synthesised derivatives (3d, 6a) were the key materials for the synthesis of isoindolinedione, (7a–c) pyrazolopyrimidine (9, 10), and pyrazolopyridazine derivatives (11). The structures of the newly synthesised heterocycles were established on the basis of elemental analyses and spectral data besides synthesis via other routes.
Chinoxaline. XXVII. Synthese bis‐azolo[a,c]kondensierter Chinoxaline. II. Darstellung aus 4‐Formyl‐azolo[a]chinoxalinen
Authors: Vogel M. , Lippmann E.
Published: December 2004

Quinoxalines. XXVII. Synthesis of Bis‐azolo[a,c]‐fused Quinoxalines. II. Synthesis from Azolo[a]quinoxaline‐4‐carbaldehydes

The azolo[a]quinoxaline‐4‐carbaldehydes 2a–d were obtained from 4‐methyl azolo‐[a]quinoxalines 1a–d by Kröhnke reaction. 2a exists in the hydrate form. 2a–d react with tosylhydrazide giving the thermally labile compounds 3a–d in good yields. Treatment of 3a–d with a boiling solution of sodium ethoxide (Bamford‐Stevens reaction) leads to the fused quinoxaline systems 4a–d. 4d was also obtained from bis‐tosylhydrazone 10.
Furylvinylhalogenide. X [1]. Reaktionen von β‐Fur‐2‐yl‐β‐chlor‐α‐cyanacrylsäurederivaten mit Hydrazinen
Authors: Jähnisch K. , Schwertner S.
Published: December 2004

Furylvinylhalides. X. Reactions of β‐Fur‐2‐yl‐β‐chloro‐α‐cyanoacrylic Acid Derivatives with Hydrazines

β‐Fur‐2‐yl‐β‐chloro‐α‐cyanoacrylic acid derivatives 3 react with hydrazines yielding 3‐fur‐2‐yl‐5‐aminopyrazoles 5 or 3‐fur‐2‐yl‐4‐cyanpyrazolin‐5‐ones 6. In some cases the β‐hydrazino‐α‐cyanoacrylic acid derivatives 4, could be isolated.
Phosphororganische Antioxidatien. X [1]. Über die hydroperoxidzersetzende Wirkung von Phosphiten, Phosphoniten und Thiophosphiten
Authors: Köunig T. , Habicher W. D. , Schwetlick K.
Published: December 2004

Organophosphorus Antioxidants. X. The Hydroperoxide Decomposing Action of Phosphites, Phosphonites and Thiophosphites

The kinetics and mechanism of reactions of phosphites, phosphonites, thiophosphites and hydrogenphosphites with cumyl (CHP), t‐butyl (TBHP) and α‐tetralyl (THP) hydrogenperoxides has been studied by means of 31P‐n.m.r. spectroscopy, high performance liquid chromatography and iodometric titration.

All three valent phosphorus compounds studied initially react with hydroperoxides stoichiometrically to give the corresponding PO products and alcohol. Some species are able to decompose cumyl hydroperoxide catalytically to form phenol and aceton.

Acyloin phosphites decompose CHP catalytically after a stoichiometric reaction as thiophosphites do. Tetramethylpiperidinyl phosphites (“HALS‐phosphites”) react with hydroperoxides only stoichiometrically but with high velocity.

Phosphonites react with hydroperoxides in the same way as the corresponding phosphites. Their reactivity, however, is much higher.

Hydrogenphosphites are less reactive than phosphites in the reaction with hydroperoxides. They are able to act catalytically.
Some Aspects of Underwater Testing Method
Authors: Satyavratan P. V. , Vedam R.
Published: December 2004

Some of the interesting results obtained in the course of a large number of experiments carried out at IDL Chemicals Hyderabad are discussed in this paper:

A linear correlation was found between underwater energies and Trauzl lead‐block values. The correlation of the total energy was found to be better than the correlation of shock and bubble energies individually.

Variation of underwater energies with depth was observed. The shock energy decreased with depth and the bubble energy increased with depth, for three different types of explosives.

The effect of firing explosives with and without boosters were studied. In the case of an aluminized slurry explosive there was a slight increase in shock energy and no change in the bubble energy, when initiated with boosters. In the case of a powder explosive, the shock energy was found to decrease by 15% and the bubble energy by 4.7%, when initiated with boosters.

An attempt was made to study the statistical behaviour of underwater testing. The shock energy distribution appeared to be non‐normal. It indicated the possibility of the presence of two modes. The bubble energy distribution was normal and its variability was found to be very low. The total energy distribution was also non‐normal on account of shock energy distribution.

The need for standardization of various testing parameters such as the depth of the charge, the distance between the charge and the transducer, the geometry of the cartridge and the type of initiation, to get repeatable and internationally comparable results, is discussed. There is a need to develop complementary theory and additional measurements (if possible) to make the system more complete and acceptable for measuring the strength of explosives.
Synthesis of N,N′‐Bis(2‐Nitro‐Benzodifuroxanyl)‐1,3,5‐Trinitro‐2,6‐Diaminobenzene
Authors: Naixing Wang , Boren Chen , Yuxiang Ou
Published: December 2004

N,N′‐Bis(2‐nitro‐benzodifuroxanyl)‐1,3,5‐trinitro‐2,6‐diaminobenzene has been synthesized from 1,3‐diaminobenzene and trinitrotrichlorobenzene. The molecular structure of this compound has been determined by elemental analysis, IR, 1HNMR, and MS spectroscopies.
High Energetic High Density Materials: A BASIC Program (FCALC) for the design and selection of efficient high energetic materials containing nitro and azido groups
Authors: Senthilkumar Udayampalayam P. , Vijayalakshmi Rajagopalan , Jeyaraman Ramasubbu
Published: December 2004

A program named “FCALC” has been developed in BASIC language to calculate the detonation volumes (through a factor F) for various explosives as well as for any new organic structure. The number and kind of substiments that need to be incorporated into an unsubstituted organic compound in order to achieve maximum F factor, and thus maximum detonation velocity, can also be predicted. The program calculates F factors for a user‐defined set of combinations of substituents.
A New Kinetics and the Simplicity of Detonation
Authors: Walker Franklin E.
Published: December 2004

A review is presented of three experiments, as well as a number of molecular dynamics and quantum mechanics calculations. which cast in serious doubt the validity of some concepts and theories of detonation. This doubt led to numerous studies in search of more satisfying concepts, and the results of several of those studies are given. Particularly, a new concept of the kinetics of shock‐induced chemical reaction is presented. This process, designated as physical kinetics, is described as a nonequilibrium, nonthermal process in which chemical reaction rates are determined and regulated by the averaged vibrational velocities of the bonded atoms in condensed systems under the influence of high velocity shock waves. These velocities control the advance of the kinetic energy which leads to the very high impact velocities of the molecules and atoms which cause massive bond fracture in the molecules in extremely short times. It is shown that a detonation model based on the new kinetics model, with the major reactions occurring in times of the order of tenths of picoseconds and in distances on the order of tens of angströms ‐ in the shock or detonation front ‐ can provide a precise and satisfying mathematical and physical description of detonation phenomena.
Wellenmechanische Absolutrechnungen an Molekülen und Atomsystemen mit der SCFMOLC(LCGO) Methode. V. Bindungsbeteiligung der Inneren Elektronen des C‐Atoms
Authors: Preuss H. , Diercksen G.
Published: December 2004

Durch Vergleichen der “1s‐Einteilchenenergien” an den C Atomen in den Verbindungen C6H6, C5H, C3H6 (Cyclopropan), C2H4 sowie am freien C Atom wird im Rahmen von ab initio—Rechnungen gezeigt, dass die inneren Elektronen von den Bindungsvorgängen wesentlich beeinflusst sind. Die Ursachen werden diskutiert und eine Erklärung dafür angegeben. Der Zusammenhang dieser Energieänderungen mit den Bindungsverhältnissen, sowie die Bedeutung dieser Tatsache für gewisse Modellvorstellungen werden besprochen.
L'Etude Théorique des Systèmes Périodiques. I. La Méthode LCAOHCO
Authors: André Jean‐Marie , Gouverneur Louis , Leroy Et Georges
Published: December 2004

On décrit la méthode des orbitales cristallines, combinaisons linéaires d'orbitales atomiques (LCAOHCO), inspirée des procédés classiques de la chimie quantique et permettant d'étudier théoriquement les systèmes périodiques. On déduit la forme explicite de quelques grandeurs caractéristiques dans l'approximation de Hückel. La méthode est comparée à l'approximation dite des électrons “quasi‐atomiques” et appliquée aux polyènes, aux polyacènes, et au graphite. La validité générale du procédé est discutée dans la conclusion.
L'Étude Théorique des Systèmes Périodiques. II. La Méthode LCAOSCFCO
Authors: André Jean‐Marie , Gouverneur Louis , Leroy Et Georges
Published: December 2004

On décrit le formalisme de la méthode LCAOSCFCO permettant d'étudier les propriétés des systèmes périodiques conjugés et un procédé semi‐empirique pour évaluer les intégrales intervenant dans les éléments de matrice de l'operateur du champ autocohérent de ces systèmes.
The perturbation theory of the extended Hartree–Fock approximation for two‐electron atoms
Authors: Brown W. Byers , Nazaroff G. V.
Published: December 2004

The first‐order 1/Z perturbation theory of the extended Hartree–Fock approximation for two‐electron atoms is described. A number of unexpected features emerge: (a) it is proved that the orbitals must be expanded in powers of Z−1/2, rather than in Z−1 as expected; (b) it is shown that the restricted Hartree–Fock and correlation parts of the orbitals can be uncoupled to first order, so that second‐order energies are additive; (c) the equation describing the first‐order correlation orbital has an infinite number of solutions of all angular symmetries in general, rather than only one of a single symmetry as expected; (d) the first‐order correlation equation is a homogeneous linear eigenvalue‐type equation with a non‐local potential. It involves a parameter μ and an eigenvalue ω(μ) which may be interpreted as the probability amplitude and energy of a virtual correlation state. The second‐order correlation energy is 2μ2ω.

Numerical solutions for the first‐order correlation orbitals, obtained variationally, are presented. The approximate second‐order correlation energy is nearly 90% of the exact value.

The first‐order 1/Z perturbation theory of the natural‐orbital expansion is described, and the coupled first‐order integro‐differential perturbation equations are obtained. The close relationship between the first‐order extended Hartree–Fock correlation orbitals and the first‐order natural correlation orbitals is discussed. A comparison of the numerical results with those of Kutzelnigg confirms the similarity.
Eine Rechenzeitsparende Programmierung des Wellenmechanischen Self‐Consistent‐Field Verfahrens für Moleküle (SCFMOLCGO–Verfahren)
Authors: Preuss H. , Diercksen G.
Published: December 2004

Es wird eine rechenzeitsparende Programmierung eines SCF–Verfahrens für Moleküle (SCFMOLCGO–Verfahren) angegeben, die auf einer rationellen Behandlung der Zweielektronen‐Mehrzentrenintegrale beruht.
Symmetry components analysis of nuclear spin–spin coupling constants
Authors: Barbier Claudette , Berthier Gaston
Published: December 2004

Molecular symmetry properties are used to define “normal” spin–spin coupling constants corresponding to some irreducible representations of the symmetry point group of the molecule. The relationship between these normal coupling constants and the measured ones is established in closed form for the most common cases. The Ramsey perturbation formula is analysed into symmetry components by means of the Winger–Eckart theorem. Both contributions predicted by the molecular‐orbital method, i. e. direct coupling via σ electrons and indirect coupling via σ–π interaction are studied. Numerical calculations for the coupling constants of ethane, ethylene and acetylene were carried out without the mean excitation energy approximation by using SCFMO wave functions; overlap between atomic orbitals is systematically taken into account by calculating coupling constants. Theoretical and experimental results are compared in terms of symmetry components.
A theoretical consideration of the spectral properties of flavin tautomers and imino flavins
Authors: Song Pill‐Soon
Published: December 2004

The Hückel MO and semiempirical SCF–ASMO–CI methods have been employed to calculate transition energies of seven possible flavin tautomers and two imino flavins (Schiff bases). The calculated spectral transition energies indicate that the tautomerism and Schiff base formation are accompanied by a bathochromic shift with reference to the absorption spectrum of riboflavin. This shift is especially pronounced in the case of the 4‐enol forms of the isoalloxazine molecule. The 4‐enolic tautomers also have lowest triplet levels well below the triplets of other tautomers. The significance of the results has been discussed.
Expansion of linear combinations of slater‐type orbitals in eigenfunctions of the three‐dimensional isotropic harmonic oscillator
Authors: Lesk Arthur M.
Published: December 2004

Several classes of functions related to the Gaussian have been used with success as basis sets for the representation of atomic and molecular orbitals.

We have compared the representation of a hydrogen 1s orbital by a sum of Gaussian lobe functions with its expansion in eigenfunctions of the three‐dimensional isotropic harmonic oscillator. The lobe functions are shown to achieve better expectation values of the energy, with fewer terms. The lobe functions have the further computational advantage of not containing high powers of the radius.

It is concluded that the lobe functions are a superior basis set for use in calculations of the electronic structure of atoms and molecules.
On the behaviour of the wave function for the 23S state of the two‐electron atom in the region where both electron–nuclear distances are small
Authors: Sochilin G. B.
Published: December 2004

The expansion of the wave function for the 23S state of the two‐electron atom in the neighbourhood of the singularity at r1 = r2 = 0 is considered. The restrictions imposed on the variational functions by this expansion are discussed. For the 23S state of He, Li+, N5+ the behaviour of the variational function based on the Fock expansion in the neighbourhood of this singularity is investigated. The agreement of the variational coefficients with the theoretical coefficients is satisfactory. The calculated values of E and 〈δ(r2)〉 for He, Li+, N5+ are given.
Molecular correlation integrals. Two center one electron integrals containing a function of interparticle distance in one center expansion approximation
Authors: Joshi Bhairav D. , Kapoor K. L.
Published: December 2004

Two‐center one‐electron integrals needed in certain molecular correlated wave function calculations, using one‐center expansion approximation, have been studied. The form of the basic correlated function used in this study is

The parent integral is expressed in terms of an angular integral, and an auxiliary radial integral depending upon the variables r1, r2, and r12. Several analytical formulas, and a recursive formula are derived for the auxiliary integral, and other related integrals. All these formulas are given in computationally useful forms. Logical flow charts and FORTRAN programs were constructed for computing the basic integrals discussed in the paper. Numerical values of some integrals, thus obtained, are tabulated for comparisons.
Semiempirical approach to the problem of the radiative lifetime of the excited F‐color center
Authors: Berezin A. A.
Published: December 2004

It is emphasized that for the theoretical consideration of many problems of defect centers in crystals (especially of problems which need the correct asymptotic behavior of the wave functions) the semiempirical approach can be effective. As an example the spontaneous radiative time decay of the excited F‐center in alkali halides is calculated by using the experimental energies of absorption and emission bands.
Etudes en méthode de Hartree‐Fock avec projection … II. La fonction d'onde exacte d'un système de deux electrons dans un etat 1S comme projection d'un déterminant de Slater
Authors: Prat R. F. , Lefebvre R.
Published: December 2004

The ground state wave‐function of a two electrons atom may be represented to any accuracy by a 1S projected Slater determinant built on hypercomplex spin‐orbitals.
The distribution of electronic charge in the ground state of cubic boron nitride
Authors: Doggett G.
Published: December 2004

The distribution of electronic charge in cubic boron nitride is investigated using the bond orbital wave functions recently calculated by Coulson and Doggett. Plots of the one‐electron density function, in the (110) plane, are found to be insensitive to the choice of atomic basis functions, in contradistinction to the previously calculated effective atomic charges. A number of structure amplitudes are also calculated for each of the bond orbital wave functions.
Symmetry effects in the radiation damping of degenerate states
Authors: Craft Lawrence N.
Published: December 2004

Radiation damping of three atoms in a radiation field is studied for both a linear and closed‐chain configuration. One atom of the system is initially excited. Use is made of the Heitler‐Ma perturbation procedure up to second order. The discussion is developed in terms of the symmetry of the interactions within the system. The interactions arising from dipole transitions perpendicular to the plane of the closed chain are shown to be similar to the interactions in a two‐atom system, and the results are extended to cover larger rings.
Wellenmechanische absolutberechnung schwingungsspektroskopischer daten am äthylen
Authors: Swanstrøm P. , Janoschek R. , Preuss H.
Published: December 2004

The ethylene molecule has been investigated by means of the General SCF–MO–LC(LCGO) Program System for 12 different nuclear positions, taking all electrons into account. The equilibrium distances and angles as well as all force constants of the totally symmetric vibrations with the corresponding frequencies have also been calculated.
Fermi surfaces and electron–impurity interactions in simple metals
Authors: Foster Howard J.
Published: December 2004

A review is given of the current status of our work on electron transport properties and Fermi surfaces in simple metals. A simple classical model is proposed to extend existing theory to account for the effects of electron‐impurity interactions on the behavior of magnetoacoustic absorption and the size and shape of the Fermi surface in the alkali metal potassium. The theoretical prediction is compared with measurements of the magnetoacoustic absorptionand Fermi surface diameters in potassium crystals of different impurity levels. An attempt is made to explain, on the basis of the theory of electron–impurity interactions, the decrease by 9% in the Fermi diameter and the departure by 53% in the phase factors of the impure potassium crystal. The results are compared with observations on a zone refined potassium crystal which satisfies the nearly‐free‐electron model.
Mirror reflection symmetry and the phase relations for partially and almost filled shells of equivalent atomic electrons
Authors: Jucys A. P. , Rudzikas Z. B. , Savukynas A. J.
Published: December 2004

The mirror reflection symmetry which consists in the correlation of the substitution j → −j −1 with the reflection of the coordinate system and of m → −m with the reflection of the space with respect to the xy‐plane has been applied to the quasi‐spin formalism. The phases of the wave functions of the shell of equivalent atomic electrons treated as partially filled, as they relate to those when the same shell is treated as almost filled, have been established. The mirror reflection symmetry has been generalized for the supplementary quantum numbers used for distinguishing the terms of the same kind. The phases of the coefficients of fractional parentage of almost filled shell enabling us to determine them from those of partially filled shell have been specified. Corresponding phase relations for the matrix elements of operators have also been considered.
Group‐theoretical methods for determining permitted terms of the electronic states of polyatomic molecules and complexes in MO and HL schemes of calculation. II
Authors: Cherepanov V. I. , Shchetkov A. A. , Farberov D. S. , Men A. N.
Published: December 2004

Group‐theoretical methods for determining permitted terms of electrons in polyatomic molecules and complexes in the MO and HL methods are proposed. Essentially, the permutational symmetry of the electron system is utilized. Some concrete examples of the operation of these methods are considered.
All electron calculations of open‐shell polyatomic molecules. III. Perturbation treatment of the spin polarization in vinyl and methyl radicals
Authors: Millié Philippe , Lévy Bernard , Berthier Gaston
Published: December 2004

A first order perturbation treatment starting with SCF‐MO'S in canonical or equivalent quasi‐localized form is presented for the hyperfine coupling constants of vinyl and methyl radicals. The spin‐polarisation contribution to hyperfine splittings is found to be large, negative for the proton of the radical center in both radicals and positive for the β protons of vinyl.
Gaussian representations of charge overlap effects in intermolecular forces
Authors: Riera A. , Meath W. J.
Published: December 2004

The ground state HH+ and HH interactions are used as model interactions for investigating the feasibility of using Gaussian basis sets for representing charge overlap effects in intermolecular forces. The non‐expanded charge‐induced dipole energy and the non‐expanded dipole‐dipole dispersion energy, respectively, for these interactions are calculated using two types of Gaussian basis functions to represent the first order wave function, Ψ(1). Very good results for these interaction energies, which include charge overlap effects, are obtained for all interatomic separations by using small Gaussian basis sets to represent the interaction, that is Ψ(1), and/or the isolated atoms (the zeroth order wave function).
Symmetry eigenfunctions suitable for many‐electron theories and calculations. I. Mainly atoms
Authors: Bunge Carlos F. , Bunge Annik
Published: December 2004

An interpretation of degenerate symmetry spaces associated with a given atomic or molecular configuration is presented, and the theory necessary for atomic applications is discussed in detail. Löwdin's symmetric projection operator for spin and orbital angular momentum is applied on a well‐defined sequence of Slater determinants. In this way a degenerate LS space is divided into orthogonal invariant subspaces which can be classified according to internal couplings of angular momentum. A procedure is found which permits expression of each of these LS eigenfunctions as the smallest possible number of successively orthogonalized projected Slater determinants. In particular, minimum size Hartree‐Fock interacting spaces (important in rapidly convergent correlation energy calculations) are obtained in their most compact form. An optimum partition of degenerate spaces of three and four excited (atomic or molecular) configurations is obtained in general. Interpretations, simplifications, and systematizations in atomic configuration interaction calculations are discussed in light of present results.
Structure de l'ion fluoronium FH et chemin de la protonation du fluorure d'hydrogene
Authors: Leibovici Claude
Published: December 2004

The structure of the ion FH is investigated on the basis of semiempirical (INDO) and nonempirical (extended gaussian basis set) calculations. In agreement with experiment, both methods predict that, when going from FH to FH, there is a lengthening of the FH bond; also in agreement with infrared analysis, the calculations indicate a bent structure for the fluoronium ion (valence angle at about 120°). The analysis of the FH protonation path reveals the existence of a potential barrier which is exclusively produced by solvation effects; the dependence of the proton affinity of FH on the dielectric constant of the reaction medium is also discussed.
On the need of precision in the calculation of the LCAO density matrix of polymers
Authors: Delhalle J.
Published: December 2004

In this paper, we point out how the precision of the LCAO density matrix elements of polymers may affect the computed properties. We propose to use a more adapted approach in order to evaluate these quantities.
Dynamic polarizability of helium: A random phase approximation calculation
Authors: Linderberg Jan , Prato Domingo
Published: December 2004

The random phase approximation (RPA) or time‐dependent Hartree–Fock approximation (TDHF) is reconsidered for the calculation of the dynamic polarizability for atoms. An integral equation which admits a simple numerical treatment is established. The asymptotic approximation for the electron propagator is tested for its applicability by means of comparisons with earlier results.