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  • Organic Chemistry  (7)
  • Inorganic Chemistry  (2)
  • Half-electron method  (1)
  • Nuclear reactions  (1)
  • 1
    ISSN: 0375-9474
    Keywords: Nuclear reactions
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 93 (1996), S. 87-99 
    ISSN: 1432-2234
    Keywords: MNDO ; Half-electron method ; Analytical derivatives ; Z-vector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Using the Z-vector formalism the analytical gradient of the energy in the half-electron open-shell treatment is derived and implemented for semiempirical MNDO-type methods. The computation time is shown to scale asO(N 3) with the size of the system, with the memory requirements growing asO(N 2). The evaluation of the analytical gradient is significantly faster than the half-electron SCF calculation, so that routine full geometry optimizations become possible for large open-shell systems. The approach can easily be extended to the treatment of the small CI expansions typically encountered in semiempirical computations.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 328 (1986), S. 497-514 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Spectral Characterization of Blue Azo Dyes of the Benzene Series53 Donor-acceptor substituted azo dyes of the benzene series were prepared by diazonium-coupling reactions (1 a-s) or halogen-cyanide exchange (→2 a-x, 3 a-j). Described are the preparation of the amines 4 a-m and the coupling compounds 5 a-t and the procedure of diazotizing and coupling.The colouristic and spectroscopic data show that compounds of the general formula 1 are excellent brilliant blue azo dyes useful for dyeing polyester material.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: MO-LCAO Calculations on Sulfur-containing π-Electron Systems. L. Synthesis and UV/VIS Spectral Properties of Derivatives of 1H-Perimidine-2-thioncarbonic AcidEsters of the 1H-perimidine-2-dithiocarbonic acid are easily accessible from 1.8-diamino-naphthalene and chloroacetyl chloride and subsequent thiolation of the reaction product under mild conditions and alkylation. The dithioesters react with aliphatic and aromatic amines to form thioamides. Both the resulting dithioesters and thioamides are clearly distinguished by their colour from the vast majority of known derivatives of thioncarbonic acids. While dithioesters and thioamides are generally red and yellow, respectively, in solution the corresponding derivatives of the 1H-perimidine are blue and red, respectively. The detailed examination of the experimental data has revealed that the colour determining longest wavelength absorption bands are due to the π→π* rather than to the n→π* transitions. Due to the efficient mixing of the lowest energy locally excited (LE) state of the heterocyclic moiety and the lowest energy perimidine-to-substituent charge transfer (CT) state the low-intensity longwavelength π→π* transition of perimidine undergoes a pronounced red shift by acceptor substituents of high electron affinity in 2-position. This interpretation of the deep colour of the 1H-perimidine-2-thiocarbonic acid is in harmony with substituent effects and fully born out by Pariser-Parr-Pople(PPP) type calculations completed by additional analyses of electronic state (Baba-Suzuki-Takemura analysis) and electronic transitions (Ohta-Kuroda-Kunii analysis).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 334 (1992), S. 92-94 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4H-3,1-Benzothiazin-4-ones from Dithicarboxylic Esters and o-Aminobenzoic Acid
    Additional Material: 2 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 649-658 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thiohydrazides and 1,3,4-Thiadiazoles by Hydrazinolysis of Dithiocarboxylic EstersThe reaction of 1,1-dithiooxalicesters 1 and heteroaryldithiocarboxylicesters 2 with excess hydrazine yields stable thiohydrazides 3 and 4, respectively. If the hydrazinolysis is carried out with only 0,5 equivalent hydrazine 1,3,4-thiadiazoles 6 and 7, equally substituted in position 2 and 5, result. 1,3,4-Thiadiazoes are also formed by heating the isolated thiohydrazides 3 and 4. The thiohydrazides 3 and 4 are also excellent starting compounds for the synthesis of unsymmetrically substituted 1,3,4-thiadiazoles (8, 9), especially for derivatives with carbamoyl or heteroaryl residues.
    Additional Material: 7 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 55-64 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3,4-Thiadiazoles by Reaction of Dithiocarboxylic Esters with Carbonic Hydrazides1,1-Dithiooxalic esters 1 and heteroaryl dithiocarboxylic esters 2 react with carbonic hydrazides yielding 1,3,4-thiadiazoles. The 1-thiooxamoyl semicarbazides 3 or 1-heteroylthiocarbonyl semicarbazides 4, primarily formed by thioacylation of semicarbazide, where isolated. By cyclocondensation they yield 1,3,4-thiadiazole-2(3 H) ones 5, 6, or in the presence of acetic anhydride 3-acetyl-1,3,4-thiadiazol-2-ones- 7, 8, respectively.2-Amino- or 2-methylthio-1,3,4-thiadiazoles 11, 12 or 13, 14 are formed by reaction of the dithioesters 1, 2 with thiosemicarbazide or methyl dithiocarbazinate. By this way 1,3,4-thiadiazoles with heteroaryl- or carbamoylresidues in position 5 where synthesized for the first time.
    Additional Material: 8 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 243-262 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dithiocarboxylic Acids, Dithiocarboxylic Esters, or Thiocarboxylic Amides by Reaction of Methylene-active Chloromethyl Compounds with SulfurWith 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).
    Additional Material: 14 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 845-852 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5-Aminothiazoles from Dithiocarboxylic Esters and α-AminoacetonitrileCarbamoyldithiocarboxylicesters 1 and heteroaryldithiocarboxylic esters 2 react with α-aminoacetonitriles under mild conditions to form 2-carbamoyl-5-aminothiazoles 5 or 2-heteroaryl-5-aminothiazoles 6. The intermediate N-cyanomethylthiooxamides 3 can be isolated. The 2-heteroaryl-5-aminothiazoles 6 and their acyl derivatives 7 are highly fluorescent, in contrast to the azomethines 8 derived from 6.
    Additional Material: 5 Tab.
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  • 10
    ISSN: 0044-2313
    Keywords: Phase diagrams ; AcMX6 compounds (Ac = Th, U ; M = Ca, Sr, Ba, Eu, Ge, Sn, Pb ; X = Br, I) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation of Compounds in the Quasi-binary Systems AcX4—MX2 (Ac = Th, U; M = Ca, Sr, Ba, Eu, Ge, Sn, Pb; X = Br, I)T,x-phase diagrams of the systems ThI4—SnI2, ThI4—PbI2, ThI4—CaI2, and ThI4—SrI2 were established using thermoanalysis and x-ray methods. The only ternary compounds have a 1:1 composition. Further AcMX6 compounds (Ac: Th, U; M: Ca, Sr, Ba, Eu, Ge, Sn, Pb; X: Br, I) were synthesized and their structures investigated. Four structure types are found depending on the temperature and the Ac/M combinations. The structures of γ-ThSnI6 and β-ThSnI6 were determined with single crystal methods as representatives of a whole series of isotypic compounds.
    Notes: T,x-Phasendiagramme der Systeme ThI4—SnI2, ThI4—PbI2, ThI4—CaI2 und ThI4—SrI2 wurden mit thermoanalytischen und röntgenographischen Methoden erstellt. Als ternäre Phasen existieren nur die 1:1 Verbindungen. AcMX6 Verbindungen (Ac: Th, U; M: Ca, Sr, Ba, Eu, Ge, Sn, Pb; X: Br, I) wurden synthetisiert und strukturell untersucht. Sie treten in Abhängigkeit von der Temperatur bzw. der Ac/M Kombination in 4 Strukturtypen auf. Die Strukturen von γ-ThSnI6 und β-ThSnI6 konnten stellvertretend für eine ganze Reihe isotyper Verbindungen mit Einkristallmethoden aufgeklärt werden.
    Additional Material: 5 Ill.
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