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  • 1
    Electronic Resource
    Electronic Resource
    Chemistry of cephalic secretion of fire beeTrigona (Oxytrigona) tataira (1984)
    Springer
    Journal of chemical ecology 10 (1984), S. 451-461 
    Details
    ISSN: 1573-1561
    Keywords: Fire bee ; Trigona (Oxytrigona) tataira ; Hymenoptera ; Apidae ; mandibular gland secretion ; enediones ; monoketones ; carboxylic esters ; hydrocarbons ; E-3-hepten-2,5-dione ; E-3-nonen-2,5-dione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Analysis of the volatile compounds derived from cephalic glands of the fire beeTrigona (Oxytrigona) tataira by GC-MS was undertaken. The following compounds were readily identified: hydrocarbons:n-C11H24,n-C13H28,n-C14H30,n-C15H32,n-C17H36,n-C23H48,n-C15H30,n-C17H34,n-C21 H42, andn-C23H46; carboxylic acids: palmitic acid, linoleic acid, linolenic acid, stearic acid, and oleic acid; carboxylic esters: dodecyl acetate, tetradecyl acetate, hexadecyl acetate, octadecyl acetate, and dodecyl decanoate; monoketones: 5-hepten-2-one, 3-hepten-2-one, 2-heptanone, and 5-nonen-2-one. Two major components of the mixture were identified asE-hepten-2,5-dione andE-3-nonen-2,5-dione. Structures of these novel compounds were suggested by their GC-MS behavior and the GC-MS behavior of their dimethoximes and proved by comparison with authentic synthetic samples. Trace amounts of the corresponding Z isomers and the saturated analogs, heptan-2,5-dione and nonan-2,5-dione, were also found. The possible functions of these glandular constituents are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00988091
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  • 2
    Electronic Resource
    Electronic Resource
    Separation and identification of isoflavones with on-line liquid chromatography-electrochemistry-thermospray mass spectrometry (1991)
    Weinheim : Wiley-Blackwell
    Electroanalysis 3 (1991), S. 777-782 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The on-line high-performance liquid chromatography-electrochemistry-thermospray mass spectrometry (LCEC-LC/MS) for separation and identification of the phenolic isoflavones genistein, formononetin, and Biochanin A is described. The isoflavones are separated on a C-18 reversed phase column with methanol: 0.1 M ammonium acetate pH (70:30 v/v) as eluent, which is compatible for both LCEC and LC/MS detection. Low ng detection is achieved with a conventional glassy carbon thin-layer electrochemical cell at 1.3 V vs. Ag/AgCl. Selected ion monitoring (SIM) mode LCMS results in detection levels at the 20-50 ng range, and the compounds are positively identified. In the on-line detection, the electrochemical cell is connected to the thermospray and the column effluent flows from the working electrode into the heated thermospray capillary tube. The results show that on-line coupling between a thin-layer LCEC and a thermospray-LC/MS can be used to characterize analytical systems.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140030810
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  • 3
    Electronic Resource
    Electronic Resource
    Use of EXAFS to probe electrode-solution interfaces (1991)
    Weinheim : Wiley-Blackwell
    Electroanalysis 3 (1991), S. 145-155 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A review of the development and application of extended X-ray absorption fine structure (EXAFS) spectroscopy for in situ structural characterization of chemical processes at he electrode surface is presented. The designs of the in situ electrochemical cells developed to date are shown. Applications are presented from the areas of metal passivation, spectroelectrochemistry, modified electrodes, underpotential deposition, and adsorption.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140030303
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  • 4
    Electronic Resource
    Electronic Resource
    A reticulated vitreous carbon spectroelectrochemical detector for flow injection analysis and liquid chromatography (1992)
    Weinheim : Wiley-Blackwell
    Electroanalysis 4 (1992), S. 487-493 
    Details
    ISSN: 1040-0397
    Keywords: Spectroelectrochemistry ; reticulated vitreous carbon ; detector ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A spectroelectrochemical detector for flow injection and liquid chromatography is described. The detector design has dimensions of a standard 1 cm sample cuvette with a replaceable reticulated vitreous carbon working electrode. No special cell holder or modifications to the spectrophotometer are required to use the detector. Chronocoulometry is used to indicate a trend from thin-layer behavior toward semi-infinite diffusion behavior as the electrode pore size increases. Ferro-/ferricyanide solutions were used to evaluate the flow injection characteristics of the detector. A sampling rate of 180 injections per hour was used. Linear calibration curves in the micromolar range were achieved with a reproducibility of 2-7%. A mixture of phenol, chlorophenols, and nitrophenols was used to investigated the simultaneous electrochemical and optical response for liquid chromatography.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140040416
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  • 5
    Electronic Resource
    Electronic Resource
    (Z)-2-Methoxy-1,2-diphenylvinylalkohol, ein bemerkenswert stabiles EnolDiese Arbeit wurde vom Schweizerischen Nationalfonds zur Förderung der wissenschaftlichen Forschung unterstützt. Prof. H. Dahn danken wir für Diskussionsbeiträge. (1983)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 95 (1983), S. 426-427 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19830950523
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  • 6
    Electronic Resource
    Electronic Resource
    (Z)-2-Methoxy-1,2-diphenylvinylalcohol. A Remarkably Stable EnolResearch supported by the Swiss National Science Foundation. We wish to thank Prof. H. Dahn for very helpful discussions. (1983)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 22 (1983), S. 551-563 
    Details
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.198305510
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  • 7
    Electronic Resource
    Electronic Resource
    Raman spectra and ab initio calculations for methyl nitrite and methyl-d3 nitrite (1990)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 21 (1990), S. 615-628 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman (4000-10 cm-1) and infrared (4000-80 cm-1) spectra of methyl nitrite, CH3ONO, and methyl nitrite-d3 were recorded in the gas and solid phases. Additionally, the Raman spectra of the pure liquids were recorded and qualitative depolarization values were obtained. Support for the interpretation of these new data is provided by ab initio calculations using the 6-31G* basis set. Complete equilibrium geometries have been determined for both conformers, as well as structures for every 30° rotation about the N—O bond. These calculations give a cis/trans barrier of 4015 cm-1 (11.5 kcal mol-1), a trans/cis barrier of 3504 cm-1 (10.0 kcal mol-1) and an enthalpy difference between conformers of 511 cm-1 (1.5 kcal mol-1) with the cis form being more stable. From a variable temperature Raman study of liquid methyl nitrite-d3 it is concluded that the cis form is also more stable in this phase with an enthalpy difference between conformers of 262 ± 3 cm-1 (750 ± 9 cal mol-1). A complete assignment of the vibrational fundamentals is proposed based on band contours, depolarization values, group frequencies and shift factors for the two isotopomers. These assignments are supported by normal coordinate analyses using the ab initio force fields to obtain frequencies and potential energy distributions for both conformers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250210914
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  • 8
    Electronic Resource
    Electronic Resource
    Raman and infrared spectra, conformational stability, barriers to internal rotation, ab initio calculations and vibrational assignment for bromodifluoroacetyl chloride (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 24 (1993), S. 1-10 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman (1800-10 cm-1) and infrared (2000-30 cm-1) spectra of bromodifluoroacetyl chloride, CBrF2CClO, are reported for the gas and polycrystalline solid. Additionally, the Raman spectrum of the liquid along with qualitative depolarization ratios have also been obtained. These data have been interpreted on the basis of an equilibrium between the gauche and the trans conformers (bromine atom trans to the chlorine atom) in the gas and liquid phases. From a study of the Raman spectrum of the liquid at various temperatures, a value of 851 ± 56 cm-1 (2.43 ± 0.07 kcal mol-1) was obtained for ΔH with the gauche conformer the more stable form. A similar study of the gas gave a value of 725 ± 150 cm-1 (2.07 ± 0.43 kcal mol-1), again with the gauche rotamer the more stable conformer. Hence the gauche conformer is the predominate rotamer in the gas and liquid and the only conformer present in the annealed solid. Aided by ab initio and scaled computations of the vibrational spectrum with the STO-3G* basis set and, for the trans conformer at the 4-31G*/MIDI-4* level of the theory, complete assignments of observed bands to fundamental vibrations of the gauche conformer are made, whereas partial assignment is reported for the trans conformer. The fundamental torsional mode for the gauche conformer was observed at 46 cm-1 but excited-state transitions were not observed so the potential function governing the conformational interchange could not be determined. Optimized geometries, dipole moments, unscaled and scaled vibrational frequencies and harmonic force fields are reported for both conformers. With the STO-3G*, basis set, the gauche conformer is calculated to be more stable than the trans conformer by 17 cm-1 (48 cal mole-1). These results are compared with the corresponding quantities for some similar molecules.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250240102
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  • 9
    Electronic Resource
    Electronic Resource
    Raman and infrared spectra, conformational stability, barrier to internal rotation, and ab initio calculations for 1,1-dichloromethyl methyl ether (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 25 (1994), S. 747-760 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman (3200-30 cm-1) and infrared (3200-50 cm-1) spectra of 1,1-dichloromethyl methyl ether are reported for the gas, liquid, amorphous solid and annealed polycrystalline solid. These spectral data were interpreted on the basis that in the fluid phases there is a mixture of trans and gauche conformers but only the trans conformer remains in the annealed solid. From the temperature-dependent relative intensity of Raman bands at 379 and 427 cm-1 in the liquid, an enthalpy difference of 656 ± 84 cm-1 (1.88 ± 0.24 kcal mol-1 or 7.85 ± 1.0 kJ mol-1) was obtained with the trans conformer the more stable form. Complete vibrational assignments are made for the much more abundant trans form, and a number of fundamentals are assigned for the gauche conformer with the aid of ab initio computations made with the 3-21G and 6-31G* basis sets. The harmonic force fields obtained using the 3-21G basis set are reported for both conformers together with scaled and unscaled wavenumbers and the accompanying potential energy distributions. The results are compared with the corresponding quantities obtained for some similar molecules.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250250903
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  • 10
    Electronic Resource
    Electronic Resource
    (Z)-2-Methoxy-1,2-diphenylvinyl Alcohol, A Remarkably Stable EnolThis work was supported by the Swiss National Science Foundation. We wish to thank Prof. H. Dahn for very helpful discussions. (1983)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 22 (1983), S. 405-405 
    Details
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstract.The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 551. DOI:10.1002/anie.198305510
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.198304051
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