bluuebunny/crossref_metadata_2025 huggingface dataset:
Ermüdungsprodukte des photochromen 2‐(2′,4′‐Dinitrobenzyl)‐pyridins
Authors: Klemm Dieter , Klemm Elisabeth
Published: December 2004

Fatigue Products of Photochromic 2‐(2′,4′‐Dinitrobenzyl)‐pyridine

Under prolonged irradiation or frequent repetitions of its photochromic cycle, 2‐(2′,4′‐dinitrobenzyl)‐pyridine 1 shows fatigue phenomena both in solid state and in solution. These phenomens — yellow discoloration, depression of the melting point, decrease of band intensity of the coloured form, shorter lifetime of the coloured form — are caused by irreversible redox processes and subsequent reactions at the methylene and ortho‐nitro groups which are essential for photochromism. Azomethine 2, ketone 3 and amine 4 are isolated as the major fatigue products.
Vergleich der Leistungsfähigkeit verschiedener Peptidchemischer Deblockierungsmethoden an einer synthetischen Insulin‐B‐Kette
Authors: Losse Günter , Naumann Wolfgang
Published: December 2004

Comparison of the Efficiency of Different Peptidechemical Deprotection Methods in the Case of Synthetic Insulin‐B‐chain

Synthetic insulin‐B‐chain in the novel protected form 1 allows an objective comparison of the efficiency of different peptide‐chemical deprotection methods in the case of a macromolecular, more complex polypeptide. In contrast to the until now exclusively applied Na/NH3‐ or HF‐method the deprotection by HBr/TFA in presence of specific additivs or by hydrogenolysis using special conditions shows significant advantages.
Photoinduzierte H‐Abstraktionen an Benzylarylethern durch Benzophenon
Authors: Baumann H. , Lindenlaub W. , Timpe H.‐J.
Published: December 2004

Photoinduced H‐Abstraction on Benzyl Aryl Ethers by Benzophenone

The triplet state of benzophenone abstracts in benzene of benzyl aryl ether 6 hydrogen atom from the CH2‐group. The formed α‐ether radicals 1 and diphenylhydroxymethyl radicals 8 react to form the three possible reaction products in statistical distribution. Benzaldehydes 2 and phenols 11 are formed in a side reaction.

From quantum yield measurements of the benzophenone reduction in dependence upon the concentration of benzyl phenyl ether 6a follows a rate constant of the H‐abstraction of 9.5 ·105 M−1s−1 which is in good agreement with measurements in presence of naphthalene as a quencher. The quenching constant for benzophenone triplet by naphthalene is 2 · 109 M−1s−1. For benzyl phenyl ethers substituted in the benzyl ring the reaction constant for the H‐abstraction reaction was determined, ϱ = −0,68,
Folgeprodukte halogenierter Aldehyde. XV. Derivate der Aryl‐(3,3,3‐trichlor‐2‐hydroxy‐propyl)‐ketone
Authors: Voigt H. , Miko A. , Zinner H.
Published: December 2004

Derivatives of Halogenated Aldehydes. XV. Derivatives of Aryl 3,3,3‐trichloro‐2‐hydroxy‐propyl Ketones

From aryl 3,3,3‐trichloro‐2‐hydroxy‐propyl ketones 1a–e, the oximes 6a–e, phenylhydrazones 5a–e, aryl 2,3,3,3‐tetrachloro‐propyl ketones 3b–d and aryl 3,3,3‐trichloropropen(1)‐yl ketones 2a–e are prepared. The phenylhydrazones 5a, b form the substituted Δ3‐1,2,4‐triazolines 4a, b by treatment with thiocyanic acid.
Synthese und mesomorphe Eigenschaften von 4‐[trans‐4‐n‐ Alkylcyclohexanoyloxy]‐benzoesäurephenyl‐ und 4‐Benzoyloxybenzoesäure‐cyclohexylestern
Authors: Deutscher H.‐J. , Seidel C. , Körber M. , Schubert H.
Published: December 2004

Synthesis and Mesomorphic Properties of Phenyl 4‐[trans‐4‐n‐alkyl‐cyclohexanoyloxy]‐benzoates and Cyclohexyl‐4‐benzoyloxybenzoates

Synthesis and liquid‐crystalline properties of terminal and lateral substituted phenyl 4‐[trans‐4‐n‐alkylcyclohexanoyl‐oxy]‐benzoates 1–13, cyclohexyl 4‐benzoyloxybenzoates 14–17 and phenyl 4‐benzoyloxybenzoates 18–23 are described. The effects of alicyclic part and of lateral substituents are discussed.
Zur Rhodium‐katalysierten Carbonylierung aromatischer Nitroverbindungen zu Isocyanaten. I. Katalysatoren und Reaktionsbedingungen
Authors: Unverferth K. , Höntsch R. , Schwetlick K.
Published: December 2004

On the Rhodium‐catalyzed Carbonylation of Aromatic Nitrocompounds to Isocyanates

The carbonylation of aromatic nitro compounds with carbon monoxide giving isocyanates at normal pressure and 100°C in the presence of rhodium complexes and a co‐catalyst has been studied. Isocyanates can be obtained in o‐dichlorbenzene with a selectivity of 50%. The main by‐product is the corresponding amine which destroys the co‐catalyst. Di‐μ‐chlorotetracarbonyldirhodium(I) is the active rhodium catalyst as the co‐catalyst reacts with the ligands of other rhodium complexes producing this complex in all cases. The most active co‐catalysts are MoCl5 and VCl4. Voluminous substituents in position 2 of the nitro compound increase the reaction rate, whereas substituents in position 4 have no unfluence. The reaction rate is independent of the carbon monoxide pressure.
Photochemie substituierter Cycloheptatriene. III. Sigmatrope Wasserstoffverschiebung an Arylcycloheptatrienen
Authors: Abraham W. , Buck K. , Csongár Ch. , Henke E. , Kreysig D.
Published: December 2004

Photochemistry of Substituted Cycloheptatrienes. III. Sigmatropic Hydrogen Shift in Arene Cycloheptatrienes

The monochromatic photoexcitation of substituted phenylcycloheptatrienes 1–8 exclusively gives rise to 1, 7‐hydrogen shift. The sequences of photoreactions of the isomeric compounds are discussed. The qualities and quantities of the hydrogen shifts of dimethylamino‐phenyl‐ycloheptatrienes 4–7 depend on the wavelengths of photoexcitations.
Synthese von 3 verkürzten, mehrfach durch Ala substituierten Analogen der Insulin‐B‐Kette in geschützter Form
Authors: Losse Günter , Stange Hans
Published: December 2004

Synthesis of 3 Shortened, Repeatedly by Ala Substituted Analogues of the Insulin B Chain in Protected Form

Starting from the previously described fragments of the insulin B chain with native or partielly modified amino acid sequence, the 3 terminal shortened, additionally in several positions by Ala respectively in position 6 by Val substituted analogues B1‐27(Ala9, Ala10, Ala27), B4‐27‐(Ala4, Ala9, Ala10, Ala27) (1) and B4‐27(Ala4, Val6, Ala9, Ala10, Ala27) were prepared in protected form.
Zur Konstitution der Farbform der photochromen ortho‐Nitrobenzylverbindungen
Authors: Klemm E. , Klemm D.
Published: December 2004

Constitution of the Coloured Form of Photochromic o‐Nitrobenzylpyridines

The reversibly highly coloured photochromic forms of dinitrobenzyl pyridines and tetranitro diphenylmethanes have structure of polymethines as evidenced by u.v.‐vis, i.r. and 1H‐n.m.r. spectra. There exists an analogy to the polymethines formed from 1‐methyl‐2‐(2′,4′‐dinitrobenzyl)‐pyridinium iodid and tetranitrodiphenylmethane and potassium hydroxide. The structure of the coloured form of the dinitrobenzylpyridines and tetranitrodiphenylmethanes are in agreement with their photochromic properties, especially with the u.v.‐vis‐absorption, the photochromism in substance and the influence of substituents on the photochromism.
Kurzzeitspektroskopische Untersuchungen an photochromen N‐substituierten Dinitrobenzylpyridinen
Authors: Klemm D. , Klemm E. , Graness A. , Kleinschmidt J.
Published: December 2004

Short‐Time Spectroscopic Investigations of Photochromic N‐Substituted Dinitrobenzylpyridines

By means of nanosecond laser absorption spectroscopy of N‐substituted photochromic dinitrobenzylpyridines is shown that in polar solvents the long wave absorbing polymethin coloured form forms independently on the electronic properties of the substituents at the pyridine nitrogen. The polymethin is formed either directly or via the nitronic acid immediately after irradiation by the laser impulse (20 ns). In nonpolar solvents, on the other hand, the polymethin is only produced if the substituent (e.g. in N‐oxide 6) is able to bind the hydrogen splitted from the methylen group by photoreaction. If this is impossible (e.g. N‐Methyl‐compound 5) only absorption of nitronic acid occur.
Modellrechnungen zum Gegenioneneinfluß auf die kationische Polymerisation; Geometrieoptimierung und Verhalten gemischter Halogenoantimonate SbClnBr
Authors: Hallpap Peter , Spange Stefan , Heublein Günther , Zwanzinger Heinz , Reinhold Joachim
Published: December 2004

Model Calculations on the Counterion Effect in the Cationic Polymerization; Geometry Optimization and Behaviour of the Mixed Halogenoantimonates SbClnBr.

The CNDO/2 method including geometry optimization with respect to the energy has been applied to calculate the structure and the electronic properties of the complex anions SbClnBr. Independently on the composition of the anions the bond lengths Sb‐X (X = Cl, Br) remain those of the pure antimonates.

The HOMOs are delocalized over the ligand sphere. They mainly contain components of Br and are lifted by increasing Br amount. The LUMOs have central atom character and are lowered by Br. Charge distribution and Wiberg bond indices indicate extra easy cleavage of the Sb‐Br bond if Cl holds a trans position to Br. The computed data agree with spectral properties, the acceptor behaviour and the decay trend of the antimonates SbClnBr.
New possibilities of applying of 1,1,1‐trichloro‐2,2‐bis‐(4‐chlorophenyl)ethane for the synthesis of self‐extinguishing and thermo‐resistant polyurethane or polyurea resins
Authors: Lesiak T. , Nowakowski J.
Published: December 2004

Neue Möglichkeiten zur Verwendung von 1,1,1‐Trichlor‐2,2‐bis(4‐chlorophenyl)ethan für die Darstellung von selbstlöschenden und wärmebeständigen Polyurethan‐ und Polyharnstoffharzen

Es werden Reaktionen zur Darstellung von 1,1,1‐Trichlor‐2,2‐bis(4‐chlor‐3‐aminophenyl)ethan, 1,1‐Dichlor‐2,2‐bis(4‐chlor‐3‐isocyanatophenyl)ethylen und 1,1,1‐Trichlor‐2,2‐bis(4‐chlor‐3,5‐diaminophenyl)ethan aus 1,1,1‐Trichlor‐2,2‐bis(4‐chlorphenyl)ethan beschrieben. Die Polyadditionsprodukte der Diisocyanate mit Diolen und Diaminen werden durch Derivatographie charakterisiert.
Spectroscopy and photochemistry of indigoid compounds. VI. Direct Trans → cis Photoisomerization of Indigoid Dyes
Authors: Haucke G. , Paetzold R.
Published: December 2004

Spektroskopie und Photochemie indigoider Verbindungen. VI. Direkte trans → cis Photoisomerisierung indigoider Farbstoffe

Wir haben die Fluoreszenz und die photochemische trans → cis Isomerisierung einiger indigoider Farbstoffe in flüssigen Lösungen bei 300 K und festen Gläsern bei 77 K, die Temperaturabhängigkeit der Fluoreszenzquantenausbeute und die Löschung der trans → cis Isomerisierung durch Elektronendonatoren in Benzen und Iodbenzen und durch O2 in Benzen untersucht. Diese und andere Ergebnisse werden vorgestellt und diskutiert. Es wird angenommen, daß die direkte trans → cis Photoisomerisierung — zumindest im ersten Schritt — über einen Singulett‐Zustand verläuft.
Aluminiumalkyle mit Heteroatomen. X. Elektronenstoßinduzierte Fragmentierung von Trimethylsilylalkanonen
Authors: Sonnek G. , Baumgarten K.‐G. , Habisch D.
Published: December 2004

Aluminium Alkyls with Heteroatoms. X. Electron Impact Fragmentation of Trimethylsilylalkanones

It has been shown that the fragmentation of trimethylsilyl alkanones on electron impact proceeds with a uniform mechanism which differs from that of silicon‐free ketones by the fact, that no α cleavage is observed.

It consists of a McLafferty rearrangement at the silicon‐free alkyl group, followed by a McLafferty‐type cleavage involving migration of the silyl group to yield the radical ion of the respective trimethylsilyl enolether.
Computeranalyse chemischer Reaktionsgleichungen mit Stöchiometriekorrektur
Authors: Weise Alfons
Published: December 2004

Computerized Analysis of Chemical Reaction Equations with Correction of Stoichiometry

A computer programme (SYNKL, synthonclassifier) was developed, which recognizes and separates synthon equations from reaction equations. The algorithm of the programme is based on an extensive silimarity proof and overlay of the most similar partial structures to encircel the synthon substructures. The programme is able to discern synthon substructures from nonstoichiometric appendants and to correct the stoichiometric differences in many cases.
Zur Reaktion von Cyanodithioformiaten mit primären Aminen
Authors: Kibbel H. U. , Kücken M. , Peters E. , Weber H.
Published: December 2004

Reactions of Cyanodithioformates with Primary Amines

N‐Alkyldithiooxamides 3 and N,N ‐dialkyldithiooxamides 4 were synthesized in good yields by reaction of cyanodithioformates 1 with primary aliphatic amines. N‐Alkylcyanothioformamides 2, intermediates in these reactions were obtained in very low yields only. The reaction of 1 and diaminoethane or 1.3‐diaminopropane afforded imidazolidine‐2‐thione 5a respectively perhydropyrimidine‐2‐thione 5b. The reaction of 1 with 1‐chloro‐2‐aminoethane did gave 2‐thiocarbamoylthiazoline 7.
1,2,3‐Triazabutadiene. XII. Abhängigkeit der 13C‐15N‐Kopplungskonstanten von der Z/E‐Isomerie der 1‐Phenyl‐3‐[3‐ethylbenzthiazolinyliden‐(2)]‐triazene und 1‐Phenyl‐1‐ethyl‐3‐[3‐ethylbenzthiazolinyliden‐(2)]‐triazenium‐ tetrafluoroborate
Authors: Fanghänel E. , Simova S. , Radeglia R.
Published: December 2004

1,2,3‐Triazabutadienes. XII. Dependence of the 13C‐ 15N Coupling Constants on the Z/E‐Isomerism of the 1‐Phenyl‐3‐[3‐ethylbenzthiazolinyden‐(2)]‐triazenes and 1‐Phenyl‐1‐ethyl‐3‐[3‐ethylbenzthiazolinyliden‐(2)]‐triazenium‐tetrafluoroborates

13C‐ and 15N spectra have been measured for the 15N‐labelled triazene 1 and triazenium salt 2. The 13C‐15N coupling constants are discussed in the light of the Z/E‐isomerism of the compounds. A significant nitrogen lone pair effect of the Z/E isomers on the magnitude of the coupling constant 1J(15N113C1·) was observed and discussed.
Derivate des Phosphorsäure‐o‐phenylenesters. 23. Verhalten von Brenzkatechylphosphortrichlorid gegenüber O‐funktionellen P(III)‐Verbindungen
Authors: Gloede J.
Published: December 2004

Derivatives of o‐Phenylene Phosphates. 23. Behaviour of Catechyl Phosphorus Trichloride towards Phosphites and Phosphinites

Catechyl phosphorus trichloride (1) reacts with triethyl phosphite (4), triphenyl phosphite (9), and the o‐phenylene phosphites (16a–d) by ligand exchange and with isopropyl diphenyl‐phosphinite (21) by ligand exchange and oxidation.
Über die SiN‐Bindung. XXXIX [1]. Kinetische Untersuchungen zur spontanen Hydrolyse, Alkoholyse und Phenolyse von Aminosilanen
Authors: Kaufmann K.‐D. , Gisbier D. , Grosse‐Ruyken H. , Rühlmann K.
Published: December 2004

Silicon‐Nitrogen Bonds. XXXIX. Kinetic Studies on the Spontaneous Hydrolysis, Alcoholysis, and Phenolysis of Silylamines

It could be shown by polarimetric and DC‐metric methods that hydrolysis, alcoholysis, and phenolysis of silylamines are of second order and lead to equilibria.

The rate of equilibrium establishment is determined by the position of a preceding protonation equilibrium and by steric effects. The position of the equilibria depends on inductive and steric effects. The enthalpy of activation for the ethanolysis of Me3SiNHPh was determined to 27,2 kJ/mol and the entropy of activation to –231 J/K · mol. The mechanism of the reactions is given.
Gibberellins. LXXXIII. Molecular and crystal structure of “Hydrogeno I”, a hydrogenolysis product of gibberellin A3 methyl ester
Authors: Kutschabsky L. , Reck G. , Adam G. , Argay G. , Czugler M.
Published: December 2004

Gibberellins. LXXXIII. Molekül‐ und Kristallstruktur von „Hydrogeno I”︁, einem Hydrierprodukt von Gibberellin‐A3‐methylester

Im Zusammenhang mit stereochemischen Untersuchungen an Gibberellinverbindungen wurde die Molekül‐ und Kristallstruktur von „Hydrogeno I”︁ 2, einem Produkt der katalytischen Hydrierung von Gibberellin‐A3‐methylester, durch Röntgenstrukturanalyse bestimmt. Verbindung 2 kristallisiert in der orthorhombischen Raumgruppe P212121 mit den Gitterkonstanten a = 10,316, b = 17,214 und c = 10,341 Å. Die Verfeinerung erfolgte bis zu einem R‐Wert von 0,074.
α‐Substituierte Phosphonate. 37. α‐Pyrrolomethanphosphonsäurederivate und N‐Vinylpyrrole
Authors: Gross H. , Beisert S. , Costisella B.
Published: December 2004

α‐Substituted Phosphonates. 37. Derivatives of α‐Pyrrolomethanephosphonic Acid and N‐Vinylpyrroles

Diethyl α‐aminomethanephosphonate 5a and its α‐aryl derivatives 5b–d react with 2,5‐diethoxytetrahydrofuran 1 to give diethyl α‐pyrrolomethanephosphonate 9a and the α‐aryl derivatives 9b–d, respectively. The pyrrolo derivatives 9 can be converted into the lithium salts 15 and 16, respectively, which with carbonyl compounds undergo the HORNER reaction yielding E/Z‐mixtures of N‐vinylpyrroles 18. In certain cases the intermediate of the HORNER reaction, the β‐hydroxyphosphonate 17, can be isolated. The pyrrolo‐analogue of stilbene, 18a, is formed only as E‐isomer. On treating the lithium salts 15 and 16 with 9 or with alkyl halides α‐C‐alkylated pyrrolo‐phosphonates 22 and 23, respectively, are obtained.
N, N‐Dialkylamide der 2‐Hydroxy‐2‐phenyl‐cyclopropan‐1‐carbonsäure – photochemische Darstellung und Strukturuntersuchung
Authors: Henning H.‐G. , Berlinghoff R. , Mahlow A. , Köppel H. , Schleinitz K.‐D.
Published: December 2004

N,N‐Dialkylamides of 2‐Hydroxy‐2‐phenyl‐cyclopropan‐1‐carboxylic Acid – Photochemical Synthesis and Determination of the Structure

Irradiation of N,N‐dialkylamides of β‐benzoylpropionic acid 2a, b in ether by n,π*‐excitation leads to the corresponding amides of the hitherto unknown 2‐hydroxy‐2‐phenyl‐cyclo‐propancarboxylic acid 3a, b, 4a, b. The photocyclization yields diastereomeric mixtures E:Z = 2.5–3:1. The determination of the relative configurations is based on the different tendency of dimerization of the E and Z diastereomers.
Über die Autoxidation einiger asymmetrischer p‐Dialkylbenzene
Authors: Blau K. , Pritzkow W.
Published: December 2004

The Autoxidation of Some Asymmetric p‐Dialkylbenzenes

The autoxidation mixtures of p‐ethyltoluene, p‐isopropyltoluene, and p‐ethylcumene were reduced with lithium alanate and the alcohols formed analyzed gaschromatographically. From the results obtained the relative reaction rates of primary, secondary, and tertiary CH‐bonds with the chain‐propagating peroxy radicals were estimated to 1 : 7 : 15.
d‐NMR‐Untersuchungen der behinderten Rotation am NC(X)‐Bindungsfragment. XV. Beeinflussung der Rotationsbarriere im NR2C(X)R1‐Bindungsfragment durch elektronische und sterische Substituenteneffekte
Authors: Kleinpeter E. , Behrendt S. , Beyer L. , Dietzsch W. , Borsdorf R.
Published: December 2004

d‐N.M.R. Investigations of the Restricted Rotation at the NC(X)‐Bonding Fragment. XV. Influence of the Rotational Barrier in the NR2C(X)–R1‐Bonding Fragment by Electronic and Steric Substituent Effects.

The rotational barriers ΔG≠ of the restricted rotation about partial C,N‐double bonds are determined for 4 series of urea‐derivatives, and analogous compounds by complete lineshape analysis and approximation equations. Some general conclusions are drawn about the validity range of the approximations independence on the low temperature splitting Δν, the possible corrections within the margin of error and the internal temperature measurement. The dependence of the determined free enthalpies of activation about the effect of heteroatoms X, the NR2‐substituents and the electronic and steric influence of the substituents R1 are discussed.
Effektivität der photochemischen Co‐C‐Bindungsspaltung in σ‐Alkyl‐Co(III) (salen)‐ und ‐Co(III) (salphen)‐Komplexen
Authors: Roewer G. , Kempe G. , Kolle B. , Just R.
Published: December 2004

Efficiency of the Photochemical Co‐C‐Bond Cleavage in σ‐Alkyl‐Co(III)(salen)‐and‐Co(III)(salphen)‐Complexes.

The photodealkylation rate of RCoIII(chel) X complexes (R = methyl, ethyl; chel = salen, salphen; X = H2O, py, PPh3) depends on the nature of ligands and solvents as well as on the concentration of oxygen and scavengers for alkyl radicals. The rapid recombination of the fragments R. and Co(chel)X is responsible for the low quantum yields of the anaerobic dealkylation. The quantum yields may reflect the H‐donating ability of the solvents used. Lewis bases X in the trans position generally cause a decrease of quantum yields relative to the pentacoordinated species RCo (chel). The anaerobic photolysis can be accelerated by the addition of scavengers for alkyl radicals (e. g. Koelsch radical, nitrosodurene, styrene). The quantum yield also increases in the presence of oxygen, preventing the recombination of the fragments of the cobalt‐carbon bond scission by forming alkyl‐peroxocomplexes ROOCo(chel)X.

α‐Hydroxyalkylradicals arising from the decomposition of the ROOCo(chel)X complexes via secondary reactions probably react with the starting σ‐alkyl complexes and cause the dependence of quantum yields on the light intensity.
Chemie angeregter Zustände. XII. MO‐Berechnungen zum Elektronenspektrum des Pyridin‐N‐Oxid – Eine kritische Analyse
Authors: Scholz Manfred
Published: December 2004

Chemistry of Excited States. XII. MO Calculation of the Electronic Spectrum of Pyridin‐N‐Oxid – A Critical Analysis

MO calculations (ab initio, HAM/3, INDO‐, CNDO‐ and PPP‐Typ including CI) are reported with regard to the interpretation of the u.v. spectrum of the title compound.

The different semiempirical methods show similar results concerning the energies of the ππ* transitions.

For the absorption at 5.72 eV, differences are found between the ab initio and all semiempirical calculations concerning the interpretation of this transition (A1 or B2).

None of the methods yields results exactly enough to predict the dipole forbidden (A2) and allowed (B1) nπ* transition energies.
Substituenteneinfluß auf die T1‐ Energie und auf S1‐T1‐Energiegap bei ω‐Phosphor‐substituierten trans‐Styrenen
Authors: Gloyna D. , Berndt K.‐G. , Wegener W.
Published: December 2004

Influence of Substituents on the T1 Energy and the S1‐T1 Energy Gap in ω‐Phosphorus Substituted trans‐Styrenes

The fluorescence and the phosphorescence of 4‐substituted ω‐diphenylphosphinyl trans‐styrenes 1 and analogous diphenylthiophosphinyl trans‐styrenes 2 at 77 K indicate together with some oxygen‐induced singlet‐triplet absorption spectra a bathochromic shift of the lowest singlet (S1) and the lowest triplet level (T1) relatively to the S1 and T1 level of the unsubstituted compounds 1a and 2a, respectively. Donor substituents X in 4‐position give rise to a shift of S1, which is in the most cases much greater than that of T1, so that the S1–T1 energy gap decreases. P(Y)R1R2 groups (Y = O, S) in ω‐position of 1 and 2 effect a small bathochromic shift of the T1 energy level only (130–900 cm−1 relatively to unsubstituted styrene). S1 is shifted 860–2080 cm−1 to lower energies, however.
Reactions with 3,1‐Benzoxazin‐4‐ones. II. Behaviour of 6,8‐dibromo‐2‐methyl‐3,1‐benzoxazin‐4‐one towards Friedel‐Craft and Grignard reactions
Authors: Ismail M. Fekry , Shams Nabil A. , Salem M. R. , Emara S. A.
Published: December 2004

Reaktionen mit 3,1‐Benzoxazin‐4‐onen. II. Verhalten von 6,8‐Dibrom‐2‐methyl‐3,1‐benzoxazin‐4‐on in Friedel‐Craft's und Grignard‐Reaktionen

6,8‐Dibrom‐2‐methyl‐benzoxazin‐4‐on (1) reagiert mit verschiedenen aromatischen Kohlenwasserstoffen unter Friedel‐Crafts‐Bedingungen zu O‐Acetylaminobenzophenon‐Derivaten 2.

Die Reaktion von 1 mit Organomagnesiumhalogeniden führt durch Addition von einem Mol des Reagenzes zu den Ketonen 2 und 5 bzw. durch Addition von zwei Mol zu den Carbinolen 4. Diese unterliegen in einigen Fällen einer gleichzeitigen Dehydratisierung, die zu den Benzoxazin‐Derivaten 6 führt.
Konfigurative Zuordnung über sterisch definierte Epoxidringe. VIII. Glycidonitrile. I. Synthese von 4‐Aryl‐1‐oxaspiro(2,5)octan‐2‐nitrilen und 4‐Aryl‐1‐oxaspiro(2,5)octan‐2‐carbonsäureestern
Authors: Fischer F. , Palitzsch P.
Published: December 2004

Determination of Configurations by the Aid of Sterically Corresponding Epoxides. VIII. Glycidic Nitriles. I. Synthesis of 4‐Aryl‐1‐oxaspiro(2,5)octane‐2‐nitriles and 4‐Aryl‐1‐oxaspiro(2,5)octane‐2‐carboxylic Acid Methyl Esters

The condensation of 2‐aryl‐cyclohexan‐1‐ones (1–5) with ClCH2CN or ClCH2CO2CH3 at 80°C in the presence of NaH and in dimethoxyethane yields the corresponding glycidic nitriles and the glycidic esters, respectively. The configuration and the preferred conformation of the two isomeric 1‐oxaspiro‐[2,5]octane derivatives (12 A and 12 B) formed have been determined by 1H‐n.m.r. spectroscopy. Some earlier results from BOEKELHEIDE and SCHILLING and from SCHWARTZMAN and WOODS have been corrected.
Zum Konformationsverhalten substituierter Benzoesäurephenylester ‐ Molekül‐ und Kristallstruktur der nematogenen Verbindung 4‐n‐Pentoxybenzoesäure‐4′‐(ß‐cyanethyl)‐phenylester
Authors: Baumeister U. , Brandt W. , Hartung H. , Jaskólski M.
Published: December 2004

On the Conformational Behaviour of Substituted Phenylbenzoates ‐ Molecular and Crystal Structure of the Nematogenic Compound 4′‐(ß‐Cyanoethyl)‐phenyl‐4‐n‐pentoxybenzoate

The title compound crystallizes in the monoclinic space group P21/n with a = 1567.6(2) pm, b = 915.5(1) pm, c = 1459.1(1) pm, β = 115.30(1)°, and four molecules per unit cell. The structure has been solved by direct methods and refined to R = 0.104. The molecules adopt a markedly stretched form and show a parallel arrangement of their long axes in the crystal lattice. The molecular and crystal structure is discussed in relation to the mesomorphic behaviour of the compound.

A theoretical conformational analysis has been performed for the isolated phenylbenzoate molecule using the EPEN/2 method, its results are compared with the experimental torsion angles in a series of substituted phenylbenzoates.
Extraction of copper from acid sulphate solutions by 2‐hydroxy‐5‐(1,1,3,3‐tetramethylbutyl)‐benzaldehyde,‐acetophenone and ‐benzophenone oximes
Authors: Szymanowski J. , Sobczyńska A. , Stepniak‐Biniakiewicz D. , Borowiak‐Resterna A.
Published: December 2004

2‐Hydroxy‐5‐(1,1,3,3‐tetramethylbutyl)‐benzaldehyde E‐oxime (1), 2‐hydroxy‐5‐(1,1,3,3‐tetramethylbutyl)‐acetophenone E‐oxime (2) and 2‐hydroxy‐5‐(1,1,3,3‐tetramethylbutyl)‐benzophenone E‐oxime (3) were synthesized and used for copper extraction from acidic sulphate solutions. The dissociation constants of the phenolic group of the oximes and the stability constants for their complexes with copper were determined. An extraction model is discussed taking under consideration the association of the oxime and the solvation of the complex.

It was found that 1 can extract copper more efficiently from acidic aqueous solutions and at a higher rate than 2 and 3. 1 is a stronger acid than 2 and 3. However, it is a weaker acid than the Z isomer of 3.

The proposed model fits the experimental data well. When the oxime is used in excess, solvation of the copper complex seems probable.
Komplexkatalyse. XV. Kationische η3‐Allyl‐bis(triorganylphosphit)nickel(II)‐Komplexe als Katalysatoren für die stereoreguläre Butadienpolymerisation
Authors: Taube R. , Schmidt U. , Gehrke J.‐P , Anacker U.
Published: December 2004

Complex Catalysis. XV. Cationic η3‐Allyl‐bis(triorganylphosphite)nickel(II) Complexes as Catalysts for the Stereoregular Butadiene Polymerisation

Synthesis and catalytic properties of [C3H5NiL2]PF6 complexes 1a–f with L = tri‐ethyl‐, ‐isopropyl‐, ‐phenyl‐, ‐o‐tolyl‐, ‐thymyl‐ and o‐biphenylylphosphite are described. It is shown how electronic and steric effects of the phosphite ligands in these complexes control their catalytic activity and selectivity in 1,4‐polymerization of butadiene.
Ionisation und Dissoziation von Triphenylmethylhalogeniden in Methylenchlorid
Authors: Heublein Günther , Bauerfeind Dietmar
Published: December 2004

Ionization and Dissociation of Triphenylmethyl Halides in Methylendichloride

The Winstein scheme is valid for triphenylmethyl halides in methylendichloride. The equilibrium of ionization and dissociaton has been determined by investigation of the ratio between the sum of concentrations of ionic species and the covalent form. Tritylbromide in methylendichloride shows an exothermic ionization but endothermic dissociation. In the case of tritylchloride ionization and dissociation are nearly independent on the temperature.
4′‐tert‐Alkylbenzo[15]krone‐5‐ether. Synthesen und Kaliumthiocyanat‐Komplexe
Authors: Beger J. , Meerbote M.
Published: December 2004

4′‐tert‐Alkylbenzo[15]Crown‐5‐Ether. Syntheses and Complexes with Potassium Thiocyanate

The title compounds 4 are synthesized either by alkylation of pyrocatechole 1 in 4‐position and followed by ring closure with 1,11‐dichloro‐3,6,9‐trioxaundecane or by alkylation of benzo[15]‐crown‐5 3. In most cases the way first mentioned gives better results. Analytical samples of the alkylated benzo[15]crown‐5 ethers 4 are obtained through complexing with KSCN.

Physical data and 1H‐n.m.r.‐spectra of 5 new pyrocatecholes 2 and 6 new benzo[15]crown‐5 ethers 4 are given.
Substituenteneffekte in den 13C‐NMR‐Spektren von diastereomeren Chalkondihalogeniden. V. Synthese, Stereochemie und Spektroskopie von Chalkonfluorhydrinen
Authors: Weber Fritz Gerd , Giese Hartmut , Köppel Hubert , Reinhold Monika , Strobel Rita , Radeglia Reiner , Storek Werner
Published: December 2004

Substituent Effects in 13C‐ N. M. R. Spectra of Diastereomeric Chalcone Dihalogenides. V. Synthesis, Stereochemistry and Spectroscopy of Chalcone Fluorohydrines

Chalcone fluorohydrins 1 and diastereomeric pairs of chalcone chlorohydrins 2 as standards are investigated in the i.r., 1H, 19F, and 13C n m. r. spectroscopy field. The substituent dependence of the spectral parameters is discussed.

The assignment of conformation and configuration on the basis of vicinal 1H1H, 1H19F, and 1H13C coupling constants is determined.
Methylation of 5‐Aldehydo‐6‐arylpyridazin‐3(2H)‐ones via reaction with dimethyl and pentamethyl cuprates
Authors: Shams Nabil A.
Published: December 2004

Me5Cu3Li2 in ether or ether‐pentane mixtures, converts the title compounds efficiently into the corresponding 4‐methyl derivatives (5) via conjugate methylation of either α,β‐unsaturated aldehyde or NCCC system, together with ⋍20% of 1,2 adducts (6 and 7). With Me2CuLi, however, the product contains, as an average, ⋍55% of 1, 2 adducts and ⋍45% of 1,4‐isomer. On the other hand, with MeMgI no 1, 2‐methylation could be observed and the only product obtaind is the 1, 4‐isomer.
Pyryliumverbindungen. XXIX [1] Substituierte Benzophenone aus 2,4,6‐Triaryl‐pyryliumsalzen und Methyl(en)ketonen
Authors: Zimmermann Thomas , Fischer Gerhard W.
Published: December 2004

Pyrylium Compounds. XXIX. Substituted Benzophenones from 2,4,6‐Triarylpyrylium Salts and Methyl(ene) Ketones

In the presence of piperidine acetate (or similar salts of certain dialkylamines), 2,4,6‐triarylpyrylium perchlorates 5 react with methyl(ene) ketones 6 to give benzophenones 7, the structure of which was proved by spectroscopic methods as well as by independent synthesis. Besides acetone and other acyclic ketones (e. g. alkyl methyl ketones, phenylacetone, desoxybenzoin, dibenzyl ketone) cyclic ketones (e. g. cyclopentanone, cyclohexanone, cycloheptanone, acenaphthenone) can also be used as ketone component 6; acetophenones react differently leading to hydrocarbons of the 1,3,5‐triarylbenzene type 15. The varying efficiency of the diverse amine salts and the mode of incorporation of the unsymmetrically substituted ketones suggest the intermediate formation of enamines 10 as crucial step of the ring transformations observed. This assumption is supported by isolation of the iminium salt 18 on reacting 3,5‐dimethyl‐2,4,6‐triphenylpyrylium perchlorate (16) with acetone/piperidine acetate.
Synthese von N‐Maleoyl‐aminosäuren und ‐peptiden
Authors: Augustin Manfred , Müller Wolfgang
Published: December 2004

Synthesis of N‐Maleoyl‐aminoacids and ‐peptides

N‐Maleoyl‐aminoacid‐N′‐hydroxysuccinimidesters 3 or N‐maleoyl‐aminobenzoic acids 5 are synthesized from N‐maleyl‐aminoacids 1 on different ways. N‐maleoyl‐aminobenzoic‐4‐nitro‐phenyl‐,‐2‐nitro‐phenyl‐or 2,4‐dinitro‐phenylesters 6, 7 and 8 will be obtained from 1 or 5. o‐Mercapto‐aniline, thiourea or cysteine react with 5 to benzothiazines 9, thiazolidines 10 and 1,4‐thiazines 11. from 5 the peptides 12 are yielded. The pentapeptide 13 are formed from 12 by addition of glutathione.
Radikalreaktionen an N‐Heterocyclen. IV. EPR‐Untersuchung des H‐Transfers zwischen aminischen Antioxidantien und Peroxy‐Radikalen
Authors: Tkáč A. , Omelka L. , Schulz M. , Mögel L.
Published: December 2004

Radical Reactions of N‐Heterocyclic Compounds. IV. ESR Investigation of H‐Transfer between Aminic Antioxydants and Peroxy Radicals

The N‐radicals of pyrazole‐, imidazole‐ and indole‐derivatives were prepared in comparatively high concentrations at room temperature in benzene or toluene and their e.s.r. signals were interpreted. In H‐abstraction by free or to Co(III)‐coordinated tert.‐butylperoxy radicals from bifunctional heterocyclic substituted amines 2–9, 11 the following efficiency was ascertained: unhindered OH > aniline‐NH > heterocyclic‐NH, hindered OH‐groups. No radical attack on the exocyclic NH2‐group took place.

The splitting constant concerning the heterocyclic nitrogen of nitroxyl radicals 5a, 10a was in the range aNendo = 0.7 to 0.85 mT in contrast to exocyclic nitroxyls 6a, 8a, 9a, 11a possessing aNexo = 1.0 to 1.1 mT. The interruption of the π‐conjugation between the heterocyclic and the aniline groups by insertion of a CH2‐group led to the decrease of the stability of the generated N‐radicals. In the case of anilinebenzimidazole 9 the Co(III)‐complexed endocyclic aminyl radical 9b was observed simultaneously with the exocyclic nitroxyl radical 9a.
Spektralverhalten von Pyrazolin‐5‐on‐Azomethinfarbstoffen – Quantenchemische Beschreibung der Substituenteneinflüsse
Authors: Weise A. , Mustroph H. , Winnig B. , Grossmann N. , Fanghänel E.
Published: December 2004

Absorption Behaviour of Pyrazoline‐5‐one Azomethine Dyes – Quantumchemical Description of the Influence of Substituents

The VIS absorption of the pyrazoline‐5‐one azomethine dyes 1a–h is measured in dependence of the substituents of the amino group.

HMO calculations confirm that the „x‐ and y‐bands”︁ have a strong charge transfer character. The absorptions in the visible region correspond to a transition from the HOMO mainly localized at the amino‐substituted phenyl to the complex acceptor 4‐imino‐pyrazoline‐5‐one (“x‐band”) or to the pyrazoline‐5‐one fragment (“y‐band”). The calculated transition energies correlate with the values νmax of the x‐band (r = 0.993). There is also a linear correlation between the square of the LCAO‐MO coefficients in position 7 and 6 of the dye and εmax (r = 0.978).
Umsetzung von (Z/E)‐1‐Aryl‐4‐arylmethylen‐pyrrolidin‐2,3,5‐trionen mit Enaminocarbonylverbindungen
Authors: Augustin M. , Jeschke P.
Published: December 2004

Reaction of (Z/E)‐1‐Aryl‐4‐arylmethylene‐pyrrolidine‐2,3,5‐triones with Enaminocarbonyl Compounds

Treatment of the α, β‐unsaturated ketones (Z/E)‐1a–e with alicyclic or aliphatic enamines afforded cyclic Michael adducts 2 and 3a–e, respectively. By dehydration of the N,O‐hemiacetals 3b–d the corresponding 1,4‐dihydropyridines 4a–c were obtained.

The acid‐catalyzed reaction of aminosubstituted maleimides with (Z/E)‐1e, aldehydes or indan‐1,2,3‐trione led to 5a–c, 6a–c, 7a–c and 8. O‐Methylation of the aryl‐bis(maleinimidyl)methanes 5c, 6c by using diazomethane gave 5d, 6d, whereas 5a cyclized spontaneously to the 1,4‐dihydropyridine 9a. Further 1,4‐dihydropyridines were prepared by cyclocondensation of 6a, b in the presence of ammonium acetate and oxidized to the pyridine derivative 10.
Electrochemistry of Organic Cations. VI. Investigations about the Cathodic Cleavage of Some Pyridinium and Triazolium Ions
Authors: Pragst F. , Henrion A. , Abraham W. , Michael G.
Published: December 2004

The electrochemical reduction of some N‐acylamino‐, N‐amino‐, N‐benzyl‐ and N‐phenacyl‐substituted pyridinium and triazolium ions is investigated in acetonitrile by voltammetric methods and potentiostatic electrolyses. The acylaminopyridinium ions 1 and the arylaminopyridinium ions 3 are cathodically cleaved into the pyridine derivative and the carboxylic amide or the aromatic amine. In the case of the 1‐benzyl‐4‐acylaminotriazolium ions 5 the reductive formation of hydrogen from the acidic N‐acylamino group is preferred and the corresponding ylide is formed, which reacts at more negative potential by splitting off the benzyl group. The reduction of the N‐phenacylpyridinium ion 7d occurs with splitting off the phenacyl radical, which dimerizes to 1,2‐dibenzoylethane in a good yield. In the case of N‐benzyl‐ and N‐p‐cyanobenzylpyridinium ions the cathodic dimerization to the corresponding bisdihydropyridines was found, whereas the electrolysis of the N‐nitrobenzylpyridinium ions occurs with cleavage of the N‐substituent‐bond, which is initiated by the primary formation of the nitrophenyl anion radical. It follows from electrogenerated chemiluminescence experiments that the cleavage of the cations 1 and 5 occurs with the uptake of one electron.
Dithiocarbonsäuren, Dithiocarbonsäureester oder Thiocarbonsäureamide aus methylenaktiven Chlormethylverbindungen und Schwefel
Authors: Thiel W. , Mayer R.
Published: December 2004

Dithiocarboxylic Acids, Dithiocarboxylic Esters, or Thiocarboxylic Amides by Reaction of Methylene‐active Chloromethyl Compounds with Sulfur

With a mixture of sulfur and amine in DMF at room temperature halomethyl compounds (1, 5–10) can be oxidized to give thiocarboxylic acids (2, 11–16) and their derivatives (3, 4, 17–35). We studied this reaction in detail especially with chloroacetic derivatives (11–15) or chloromethyl heterocycles (16) formally derived from chloroacetic acid.

The resulting thiooxalic acid derivatives (11–27) represent activated acids and very useful C2‐synthons, especially for the synthesis of heterocycles.

Oxidation in the presence of triethyl amine leads to dithiocarboxylates (11–16) which can be alkylated to dithioesters (17–27) in high yields.

As a rule, with different primary and secondary amines instead of tertiary amines these dithiocarboxylates or dithiocarboxylic esters can be transformed already at low temperatures to thioamides (28–35).
Bromination of pyridines. II. Bromination of Aminopicolines
Authors: Dunn A. D. , Currie A. , Hayes L. E.
Published: December 2004

The bromination of all ten possible aminopicolines 1–10 was investigated. In general, the major brominated product was that corresponding to electrophilic attack at the sites para or ortho to the amino group.
Kristallin‐flüssige 1,3,4‐Thiadiazole. II [1]. 1,3,4‐Thiadiazole mit Cyclohexanstrukturfragmenten
Authors: Schäfer W. , Rosenfeld U. , Zaschke H. , Stettin H. , Kresse H.
Published: December 2004

Liquid Crystalline 1,3,4‐Thiadiazoles. II. 1,3,4‐Thiadiazoles with Cyclohexanefragments

Preparation and liquid crystalline properties of disubstituted 1,3,4‐thiadiazoles (1 and 2) are described. The mesomorphic behaviour of the title compounds is compared with their benzoate analogues. The dielectric anisotropy of these compounds is negative.
Thiohydrazide und 1,3,4‐Thiadiazole durch Hydrazinolyse von Dithioestern
Authors: Thiel W. , Mayer R.
Published: December 2004

Thiohydrazides and 1,3,4‐Thiadiazoles by Hydrazinolysis of Dithiocarboxylic Esters

The reaction of 1,1‐dithiooxalicesters1and heteroaryldithiocarboxylicesters2with excess hydrazine yields stable thiohydrazides3and4, respectively. If the hydrazinolysis is carried out with only 0,5 equivalent hydrazine 1,3,4‐thiadiazoles6and7, equally substituted in position 2 and 5, result. 1,3,4‐Thiadiazoes are also formed by heating the isolated thiohydrazides3and4. The thiohydrazides3and4are also excellent starting compounds for the synthesis of unsymmetrically substituted 1,3,4‐thiadiazoles (8,9), especially for derivatives with carbamoyl or heteroaryl residues.
Ignition of composite propellant at subatmospheric pressures by means of carbon dioxide laser
Authors: Sofue T. , Iwama A.
Published: December 2004

Ignition behavior of solid propellant composed of 25 wt% polybutadiene and 75% ammonium perchlorate under subatmospheric conditions has been studied using a carbon dioxide laser whose radiant flux is uniformalized. Data of ignition time in Ar, N2 and He atmospheres, and critical radiant flux and pressures over which ignition might be achieved, were obtained. Moreover, the data were compared with theoretical values, taking account of variable heat conductivity for the ambient gases with a surface ignition hypothesis.

It is concluded that these ambient gases participate in the pre‐ and post‐ignition reactions and the ignition preventive behavior of He atmosphere is not predictable merely based on its high transport properties. The detailed observation of the ignition transient near the critical pressure revealed that the ignition in Ar atmosphere occurs in gas phase under less than 100 torr whereas in He atmosphere it occurs always at the condensed phase surface.
Investigation of the Explosive Properties of HMX/Al 70/30
Authors: Langen P. , Barth P.
Published: December 2004

The production of HMX/Al 70/30 and the investigation of the characteristic properties are described and a comparison to RDX/Al 70/30 properties made. According to first test results, the possibility of an increased performance compared to RDX/Al 70/30 may not be ruled out.
Gap‐Test‐Untersuchungen an gewerblichen Sprengstoffen
Authors: Trimborn F.
Published: December 2004

Das Prüfverfahren “Gap‐Test” ist bisher bei gewerblichen Sprengstoffen nicht in größerem Umfang eingesetzt worden. Dabei scheint es sowohl von seiten der Sicherheit als auch der Funktionsfähigkeit interessant zu sein. Dieses Prüfverfahren wird anhand einer speziellen Ausführung „Gap‐Test des BICT”︁ vorgestellt. Es wird über Ergebnisse an 24 gewerblichen deutschen Sprengstoffen berichtet. Die gefundene Empfindlichkeitsskala ist in guter Übereinstimmung mit der Erfahrung. Bei gelatinösen Sprengstoffen und Wettersprengstoffen wurden Besonderheiten beobachtet. Möglichkeiten und Grenzen der speziellen Versuchsanordnung werden erörtert.
Technical Improvements for SEC Studies
Authors: Su F. H. , Bien D. M. , Perng H. C. , Hu David , Wu Sam
Published: December 2004

An on‐line system to measure hoop‐strain of strain evaluation cylinders (SECs) has been developed. The experimental results compared with the data measured by intermicrometer are acceptable. A modified mathematical equation to calculate thermal expansion coefficient of propellant is proposed and gives excellent agreement in comparing with the data measured by thermomechanical analysis (TMA).
Flame Temperature Calculations at High Temperature and Pressure
Authors: Vladimiroff T. , Carignan Y. P. , Chiu D. S. , Macpherson A. K.
Published: December 2004

In the past, real gas effects on the flame temperature were evaluated using the virial equation of state. Usually, the virial expansion was truncated after the third term. In this work the equation of state for dense gases proposed by Haar and Shenker is considered. The implementation developed for H2O, CO, CO2, H2, and N2 by Powell, Wilmot, Haar and Klein is used. The contribution of all minor species is assumed to be approximated by a Lennard‐Jones gas with ϵ/k = 100 K and σ = 3.0 Å. It is found that the more conventional approach is valid up to a loading density of 0.2 g/cm3. As density increases real gas effects cause the calculated flame temperature to decrease and the calculated pressure to increase. A computer program to perform the calculations has been devised for a personal computer.
Heat of Fusion for 1,3,5,5‐ Tetranitrohexahydropyrimidine (DNNC) and its DNNC‐d6 deuterium labelled analogue
Authors: Shackelford Scott A. , Goldman Jeffrey F.
Published: December 2004

The heat of fusion for DNNC (1,3,5,5‐tetranitrohexahydropyrimidine) and its DNNC‐d6 analogue compound have been determined using differential scanning calorimetry analysis. No significant difference in the DNNC and DNNC‐d6 heat of fusion values was detected at the 95 and 99 percent student t confidence levels. Melting points were also determined for the subject compounds using this analysis technique. These melting points are compared to literature values obtained by conventional methods.
Study on Thermal Decomposition of Composite Propellants containing PCP polymer or PCP‐HTPB copolymer as a binder
Authors: Hung Chen‐Chia , Hwu Wen‐Hwa , Cheng Chin‐Sheng , Shyy Iou‐Ning , Yang Kuo‐Kai
Published: December 2004

A modified manometric vacuum stability test (MVST) apparatus as well as a differential thermal analyzer (DTA) and a thermogravimetric analyzer (TGA) were used to study thermal decomposition of a series of propellants. The solid propellants contained polycaprolactone (PCP) prepolymer or PCP‐HTPB copolymer as binder, ammonium perchlorate (AP) and a nitramine (RDX or HMX) as oxidants, aluminum as fuel, and bis(2,2‐dinitropropyl)acetal/formal (BDNPA/F) as plasticizer. The mixtures were cured with an isocyanate (Desmodur N‐100). It is found from MVST examinations that propellants containing PCP polymer are more stable than ones containing PCP‐HTPB copolymer. The PCP propellants were still stable after 40 hours heating at 135°C. The thermal decomposition reactions of prepared propellants during dynamic heating were indicated by two major stages of weight loss in the TGA traces.
Wellenmechanische Absolutrechnungen an Molekülen und Atomsystemen mit der SCFMOLC(LCGO) Methode. VI. Das Methan (CH4)
Authors: Janoschek R. , Diercksen G. , Preuss H.
Published: December 2004

Das CH4 wurde unter Berücksichtigung aller 10 Elektronen mit dem Allgemeinen Programmsystem/SCFMOLC(LCGO) Methode für 4 verschiedene Abstände RCH und für die Verdrillung eines Dreieckes HCH gegenüber der Gleichgewichtslage (s. Abbildung 1) berechnet. Es ergab sich im Minimum eine Gesamtenergie von −40.06 a.E., eine Bildungsenergie von 17.0 eV und eine Ionisierungsenergie von 14.8 eV. Der Bindungsabstand wurde zu RCH = 2.053 a.E. bestimmt. Die sich ergebenden Kraftkonstanten lieferten die Frequenzen ω1 = 3139 cm−1 und ω2 = 1865 cm−1.
The projection operator for a space spanned by a linearly dependent set
Authors: Berrondo Manuel , Löwdin Per‐Olov
Published: December 2004

The explicit form of a projection operator constructed from a linearly dependent set is found. The relationships with canonical orthonormalization and with the cofactor matrix of the set's metric matrix are discussed. Similar expressions are obtained for the inner projection of a positive definite operator using a linearly dependent set.
Poisson equation for molecular exchange, hybrid and coulomb electron repulsion integrals
Authors: Silver David M.
Published: December 2004

The various multicenter exchange, hybrid and Coulomb electron repulsion integrals that occur in molecular quantum mechanics are shown to satisfy a Poisson equation in which an overlap integral plays the role of a source distribution function. Two‐, three‐and four‐center exchange integrals arise from four‐center source functions; two‐ and three‐center hybrid integrals arise from three‐center distributions; and one‐ and two‐center Coulomb integrals have two‐center sources.
Conjugated molecules in strong magnetic fields
Authors: Labzowsky L. N. , Lozovik Yu. E.
Published: December 2004

The spin rearrangement of π‐electrons in the ground state of a conjugated molecule in a strong magnetic field H is discussed. The spin S of the molecule increases as the field H increases (intramolecular paramagnetism). The dependence S(H) for linear and cyclic conjugated molecules in the free‐electron model and in the Hückel‐London approximation is derived. For the cyclic molecules the diamagnetic effects are taken into account.
Potential energy integrals in semiempirical MO methods
Authors: Coffey Patrick
Published: December 2004

The two‐center core‐electron attraction integral VAB in zero‐differential overlap semiempirical MO methods is examined. It is concluded that core‐valence orthogonality and valence symmetrical orthogonalization effects must be considered, and that these effects provide justification for the CNDO/2 approximation VAB = ZBγAB.