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  • Chemistry  (29)
  • Organic Chemistry  (17)
  • INORGANIC AND PHYSICAL CHEMISTRY  (2)
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  • 1
    Publication Date: 2019-08-28
    Description: The model is presented of an electrolyzer for peroxodisulfuric acid, and it is analyzed mathematically. Its application for engineering and economic optimization is investigated in detail. The mathematical analysis leads to conclusions concerning the change in position of the optimum with respect to the various target functions due to changes of the individual design-caused and economic parameters.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: NASA-TM-88467 , NAS 1.15:88467
    Format: application/pdf
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  • 2
    Publication Date: 2019-08-27
    Description: In an electrochemical reactor with gas-evolving electrodes, the transporting action of the gas bubbles can be used to move the electrolyte in a cycle flow, when the structure of the flow channels is suitable. For an electrolysis cell with such a circulation system a mathematic model was set up and evaluated. It is shown that in this manner, a rapid flow through the electrode gap can be achieved without additional energy consumption, in addition to a low gas fraction and a low cell voltage. The cell voltage and the attainable cycle spread are investigated as a function of the geometric parameters for their optimum values.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: NASA-TM-77045 , NAS 1.15:77045
    Format: application/pdf
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 323 (1981), S. 33-40 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reduction of 1,3-Thiazinium Salts; Synthesis of 6,6′-Bi-1,3-Thiazinyls and 6,6′-Bi-1,3-Thiazinylidenes1,3-Thiazinium perchlorates 1 are linked together in a reaction with zinc powder or at a cathode forming 6,6′-bi-1,3-thiazinyls 3. This reaction proceeds via radical intermediates 2. Evidence of the existence of the very short-lived radicals is given by means of ring-disk-voltammogrammes as well as by electrochemical luminescence excitation. The 6,6′-bi-1,3-thiazinyls 3 undergo the reverse fission at a platinum anode resulting in thiazinium salts 1, whereas the dehydrogenation by chloranile yields the violet 6,6′-bi-1,3-thiazinylidenes 6.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 323 (1981), S. 924-926 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Electrochemical Synthesis of Cyclic Hydroxamic Acids Followed by Bamberger-RearrangementThe electrochemical reduction of 2-(o-nitro-phenylthio)acetic acid 1a results in the expected cyclic hydroxamic acid 3a and a rearranged product 4a by consuming 4 electrons. The analogous reduction of 2-(o-nitro-phenoxy)acetic acid 1b leads only to a rearranged product 4b. This fact has been explained by the Bamberger-rearrangement of the hydroxylamine intermediate 2a, b. Now the rearrangement of the expected products was shown as a new aspect to explain the formation of the products.
    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 326 (1984), S. 385-400 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical Reduction of 4-Substituted 7-Nitro-benzo-furazansThe electrochemical properties of 4-methoxy-, hydroxy-, alkylamino, and arylaminosubstituted 7-nitrobenzofurazans (1a-1h) are studied between pH 1,7 and 11,6 by use of buffer solutions containing different portions of various organic solvents. Reduction waves which are present in polarograms, are well reproducible and practicable for qualitative and quantitative analysis of amines. A mechanism of reduction is suggested by reason of polarographic and coulometric results. The half wave potentials are correlated with various substituent constants. A value of ϱ = + 0,32 follows from the determination of the reaction constant from the slope of the E 1/2 - σp - relation for the polarographic reduction of each nitro-function.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 487-504 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatization of Amines with 4-Substitured 7-NitrobenzofurazansElectrophilc 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.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 45-50 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical Carboxylation of Cinnamoyl-1,1-bis(alkylthio)ethylenesCinnamoyl-1,1-bis(alkylthio)ethylenes (1a-1h) are reduced electrochemically in the presence of carbondioxide in aprotic media. The attack of CO2 takes place either in 1- or 5-position of cinnamoyl-1, 1-bis(alkylthio)ethylenes (1a-1h) depending on the nature of the aryl substituents. If CO2 reacts in position 1 carbonic acids 3 are obtained, reaction of carbondioxide in 5- position leads to the acids 2. The effects of different aryl substituents on the halfwave potentials and the preparative electrolyses have been investigated.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 328 (1986), S. 261-274 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: UV-VIS- and IR-Spectroscopic Studies with N-Substituted 4-Amino-7-nitro-benzofurazansStarting from spectra of parent substance benzofurazan the influence of different functional groups (NO2, OH, NH2, NHAlk, NAlk2, NHAr, NArAlk) in 4- and (or) 7-position on the shape of spectra and the intensity of individual bands was examinated. It was tried to assign spectral bands to defined absorptions in the u.v./vis and i.r. range. The long-wave band in the solution-VIS-spectra of N-substituted 4-amino-7-nitrobenzofurazans was identified as a charge-transfer band. By the use of constants α, β, and π* by Kamlet and Taft the influence of different properties of solvents was correlated with band shifts in the UV/VIS range. A qualitative correlation was found between \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \nu _{{\rm max}} $\end{document} of the long-wave band in the VIS-spectra, the polarographic half wave potential E 1/2 and the sum of polar substituent constants Σσ* of Taft. These proportions were plotted in a three-dimensional diagram.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 328 (1986), S. 539-545 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical Carboxylation of Substituted Vinyl Ketonesα-Chlor-β-acyl-vinylsulphides (1a-f) and keten-S, N-acetales (3a,b) are reduced in the presence of CO2 at the cathode to yield the corresponding acids (4a-f resp. 5). Whereas the carboxylation of 1 proceeds via elimination-addition mechanism, the reduction of 3 is similar to the keten-S, S-acetales described earlier an EC (addition) EC (elimination) sequence.
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 649-654 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrochemical Reduction of Trichloroacetaldehyde-Olefin-Addition-ProductsTrichloroacetaldehyde reacts with different olefins forming addition products. In most cases this reaction results in 1, 1, 1-trichloro-2-hydroxy compounds (2a-d). But also a different route of reaction is possible. Thus 2, 3-dimethylbut-1-ene (1e) forms 4-trichloro-1, 1, 2-tetrahydroxy-furane (2e) and cyclohexene (1f) forms 3-trichloromethyl-2-oxabicyclo-2, 2, 2-octane (2f).All addition products are suitable starting materials for electrochemical conversions. In acidic electrolytes, on lead cathodes the electrochemical reduction results in a simultaneous cleavage of a C—Cl and a C—O bond to form the CH=CCl2-group (3a-f). In neutral electrolytes, on mercury cathodes, however, a reductive conversion of a CCl3 - group to a CHCl2-group takes place (4c, 4f).
    Additional Material: 2 Tab.
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