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  • 2020-2022
  • 1990-1994  (4)
  • 1980-1984
  • 1965-1969  (4)
  • 1955-1959
  • 1910-1914
  • 1890-1899
  • 1800-1809
  • 1991  (4)
  • 1965  (4)
  • 1891
  • Alkenes
  • 1
    Electronic Resource
    Electronic Resource
    Monitoring exposure to simple epoxides and alkenes through gas chromatographic determination of hemoglobin adducts (1991)
    Springer
    International archives of occupational and environmental health 63 (1991), S. 27-31 
    Details
    ISSN: 1432-1246
    Keywords: Hemoglobin adducts ; Exposure control ; Gas chromatography ; Epoxides ; Alkenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A method for monitoring exposure to ethylene oxide (EO) and propylene oxide (PO) and their corresponding alkenes through the analysis of adducts to N-terminal valine in hemoglobin (Hb) using gas chromatography (GC) and electron-capture detection has been developed. The method is a further development of the so-called N-alkyl Edman method, which has thus far been carried out using gas chromatography-mass spectrometry (GC/MS). The correlation between GC and GC/MS determinations of adduct levels in human samples was found to be good. The newly developed GC method enables the determination of adducts to Hb from EO and PO down to levels of about 100 pmol/g globin. This adduct level corresponds to the expected increment from ethene in inhaled tobacco smoke in a smoker of about 10 cigarettes/day or from an average exposure to about 50 Wpb EO or 1 Wpm PO during working hours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00406194
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  • 2
    Electronic Resource
    Electronic Resource
    Estimating product yields of carbon-containing products from the atmospheric photooxidation of ambient air alkenes (1991)
    Springer
    Journal of atmospheric chemistry 13 (1991), S. 131-154 
    Details
    ISSN: 1573-0662
    Keywords: Alkenes ; tropospheric chemistry ; product yields ; sources ; transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The yields of products have been calculated for the reactions of hydroxyl radicals and ozone with 19 of the two-through-six carbon anthropogenic alkenes. Based on their rate of reaction, mechanisms of reactions and the ambient air distribution for these alkenes their seasonal ambient air yields have been estimated. Aldehydes predominate as products irrespective of season, with smaller yields of several ketones. Other minor products include carboxylic acids, carbon monoxide, carbon dioxide, and alkenes. About a two-fold increase is estimated in the yields of ‘hot’ biradicals and their products from summer to winter. One sensitivity analysis was made by recomputing yields at a different OH radical to O3 concentration than assumed most likely in the calculations discussed above. In addition, the sensitivity of product yields to an estimated range of seasonally averaged sunset-to-sunrise NO3 radical concentrations was calculated. The effects of free radical reactions are discussed, but these are believed to make a relatively minor contribution within the NO x -rich atmospheres that contain anthropogenic alkenes. The uncertainties in product yields associated with the range of NO3 radical concentrations assumed present is relatively small for aldehydes, as is the decrease in yield of the one carbon ‘hot’ biradical. Larger uncertainties occur for ketones. Significant decreases in yields occur for larger ‘hot’ biradicals, especially the branched-chain ‘hot’ radicals in the presence of NO3 radicals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00115970
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  • 3
    Electronic Resource
    Electronic Resource
    Ozonolysen von α-Oxo-alkenen: Zur Existenz von α-Oxo-ozoniden (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 947-956 
    Details
    ISSN: 0009-2940
    Keywords: Ozonolysis ; Alkenes ; α-Oxo- ; 1,2,4-Trioxolanes ; acyl- ; 3,3′-Bi-1,2,4-trioxolanes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ozonolyses of α-Oxo-alkenes: On the Existence of α-Oxo-ozonidesOzonolyses of nine acyclic (1a-i) and of two cyclic (14, 29) α-Oxo-alkenes on polyethylene or in pentane afforded in eight cases (1d-i, 14, 29) isolable α-Oxo-ozonides. α-Diozonides (9) are obtained from five of the acyclic α-Oxo-alkenes (1a, b, d, g, h). All isolated ozonides are labile; the 2,4-dinitrophenylhydrazones of the α-Oxo-ozonides, however, are very stable. Decomposition of the α-Oxo-ozonides affords not only the hitherto known fragments, but non-peroxidic isomers (8) of the ozonides, too.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240440
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  • 4
    Electronic Resource
    Electronic Resource
    {Bis[bis(trimethylsilyl)methyl]stannio(II)}bis(η2-ethen)nickel(O) und verwandte Verbindungen, Teil I (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1321-1325 
    Details
    ISSN: 0009-2940
    Keywords: Alkenes ; Nickel complexes ; Stannenes ; Metal-metal bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: {Bis[bis(trimethylsilyl)methyl]stannio(II)}bis(η2-ethene)nickel(O) and Related Compounds, Part IThe reaction of Ni(C2H4)3 and bis{bis(trimethylsilyl)methyl}-stannene affords the crystalline, coordinatively unsaturated complex (C2H4)2Ni = Sn{CH(SiMe3)2}2 (1). The NMR spectra of 1 show for the tin moiety a temperature-dependent solvate complex formation (thf) and for the nickel moiety a hindered rotation of the ethene ligands at low temperature. X-ray structure analysis indicates Sn - Ni multiple-bond character. Upon addition of donor molecules to 1 the addition compounds (C2H4)2Ni - Sn{CH(SiMe3)2}2(donor) [donor = NH3: 2a; pyridine: 2b; (Me2N)3PO: 2c] are obtained. According to the low-temperature NMR spectra the complexes are asymmetric in their ground state. Similar to the formation of the adducts 2a - c, the title compound 1 reacts with LiHAliBu3 as a source of LiH in ether/tmeda to form the hydride adduct [Li(tmeda)2]+ [(C2H4)2Ni - Sn{CH(SiMe3)2}2}2(H)]ominus; (2d). Displacement of the ethene ligands in 1 by CO yields with conservation of the Ni - Sn bond the complex (CO)3Ni= Sn{CH(SiMe3)2}2 (3). From this complex the donor adducts (CO)3Ni - Sn{CH(SiMe3)2}2(donor) [donor = NH3: 4a; pyridine: 4b; (Me2N)3PO: 4c] are prepared. For the donor-ligand carbonyl complexes the ground state has been shown to be asymmetric by low-temperature NMR spectra.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240603
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  • 5
    Electronic Resource
    Electronic Resource
    Eliminations from Olefins (1965)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 4 (1965), S. 49-68 
    Details
    ISSN: 0570-0833
    Keywords: Elimination ; Alkenes ; Alkynes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eliminations from olefins are very often initiated by bases, and usually lead to formation of acetylene derivatives. In view of the numerous side-reactions and subsequent additions or rearrangments observed, the nature of the base used is of considerable significance. Organometallic bases are very versatile. In addition to dehydrohalogenation, dehalogenation by metals, and also thermolytic and photolytic eliminations. (e.g. the retrodiene reaction with exchange of substituents) are discussed. Elimination from low-membered cyclic olefins yields cycloalkynes having strained ring-systems, and the existence of these can be demonstrated by trapping them. The mechanisms known for β-elimination (E2, E1 and E1cB) occur also in the case of olefins; however - due to the sp2-hybridization of the carbon atoms taking part - they are realized with different rates of reaction relative to saturated compounds. α-Eliminations from olefines having aryl residues in the β-position lead to formation of arylacetylenes by rearrangement of the carbon skeleton. The mechanism of this reaction, which is known as the Fritsch-Buttenberg-Wiechell rearrangement, is discussed in considerable detail, and several variations of the reaction are considered. According to present-day knowledge carbenes are involved in α-eliminations only when both β-positions of the olefin are occupied by aliphatic substituents, or when they are occupied by aromatic residues where rearrangement to acetylenes is impossible for steric reasons (as for example with 9-chloromethylenefluorene). With organolithium compounds a number of dehydrohalogenations, which are formally β-eliminations, actually proceed via deprotonation on the halogenbearing carbon atom (α-metallation). α-Metallations are the rate-determining steps when ether is used as solvent, but proceed quickly in tetrahydrofuran even at low temperatures. Compounds of the type \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$\raise1pt\hbox{$〉$}{\rm C}\raise1pt\hbox{=\kern-3.45pt=}{\rm C(Li)Cl}$\end{document} may be prepared by this method and are recognized as intermediates in α-eliminations.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196500491
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  • 6
    Electronic Resource
    Electronic Resource
    New Reactions of Alkylidenephosphoranes and their Preparative Uses. Part I: The Acid-Base Character of Phosphonium Salts and AlkylidenephosphoranesParts II and III will appear shortly in this journal. (1965)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 4 (1965), S. 583-587 
    Details
    ISSN: 0570-0833
    Keywords: Alkylidenephosphoranes ; Phosphonium salts ; Synthetic methods ; Phosphoranes ; Ylides ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phosphonium salts may be regarded as Bronsted acids, and alkylidenephosphoranes as the conjugate bases. Compounds of the two classes exist in equilibrium with each other. Phosphonium salts and alkylidenephosphoranes can be obtained by this “transylidation”. Other methods are also given for the preparation of members of both classes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196505831
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  • 7
    Electronic Resource
    Electronic Resource
    New Reactions of Alkylidenephosphoranes and their Preparative Uses. Part II. Alkylidenephosphoranes and Halogen CompoundsFor Part I see Angew. Chem. 77,609 (1965), Angew. Chem. internat. Edit. 4, 583 (1965). Part III will appear shortly in this journal. (1965)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 4 (1965), S. 645-660 
    Details
    ISSN: 0570-0833
    Keywords: Alkylidenephosphoranes ; Phosphonium salts ; Synthetic methods ; Phosphoranes ; Ylides ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of alkylidenephosphoranes with compounds containing halogens can be used to prepare ylides, which can be converted in to useful products, e.g. by hydrolysis, by thermal decomposition, or by other reactions. Examples of such products are ketones including cyclic, unsaturated, and branched-chain ketones (including cyclic, unsaturated, and branched-chain ketones), carboxlic esters (including those of unsaturated, branched- chain, polyenecarboxylic, acetylenecarboxylic, and allenecarboxylic acids), and aldehydes.
    Additional Material: 10 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196506451
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  • 8
    Electronic Resource
    Electronic Resource
    New Reactions of Alkylidenephosphoranes and their Preparative Uses IIIFor Part I, see Angew. Chem. 77, 609 (1965) Angew. Chem. internat. Edit. 4, 583 (1965); for Part II, see Angew. Chem. 77, 651 (1965); Angew. Chem. internat. Edit. 4, 645 (1965).. Alkylidenephosphoranes and Reagents Containing Multiple Bonds (1965)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 4 (1965), S. 830-838 
    Details
    ISSN: 0570-0833
    Keywords: Alkylidenephosphoranes ; Phosphonium salts ; Synthetic methods ; Phosphoranes ; Ylides ; Alkenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A few examples of preparatively useful syntheses using alkylidenephosphoranes and substances containing a C—N or C—C double bond are the preparations of olefins, allenes, pyran derivatives, and cyclopropane derivatives. Olefins, ketones, and monocyclic compounds can be obtained by autoxidation of alkylidenephosphoranes; α, β-dioxo compounds (including cyclicones) can be prepared by oxidation with peroxy-acids. Alkylidenephosphoranes can also be used for the synthesis of azines and Schiff bases. Of the many possibilities offered by the Wittig reaction, only the preparation of tritiated aldehydes and olefins will be considered.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.196508301
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