Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1975-1979  (30)
  • 1970-1974  (20)
  • 1870-1879  (5)
  • Chemistry  (54)
  • Azokupplung mit Halogenbenzoldiazoniumsalz
  • 1
    ISSN: 1618-2650
    Keywords: Best. von Val5-Angiotensin II Asp1-β-amid, Hypertensin, Peptidhormone ; Spektralphotometrie ; Azokupplung mit Halogenbenzoldiazoniumsalz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Am Beispiel des Octapeptids Val5-Angiotensin II Asp1-β-amid (Hypertensin-CIBA) wird die Möglichkeit aufgezeigt, Polypeptidhormone mit Tyrosin und/oder Histidin im Molekül über eine Kupplung mit p-halogensubstituierten Benzol-diazoniumsalzen quantitativ zu erfassen. Durch photometrische Bestimmung des Kupplungsprodukts konnten noch 1–2 nMol Hypertensin nachgewiesen werden. Eine Steigerung der Empfindlichkeit läßt sich durch Kupplung des Polypeptids mit radioaktiv markierten Diazoniumsalzen erreichen. Die als besonders günstig ermittelten Bedingungen für die Diazotierungs- und Kupplungsreaktionen werden mitgeteilt. Das Kupplungsprodukt war papier-chromatographisch einheitlich. Es handelt sich vermutlich um eine Monoazoverbindung. Unter den gewählten Bedingungen stellt sehr wahrscheinlich Tyrosin den kupplungsfähigen Aminosäurerest im Hypertensinmolekül dar.
    Notes: Abstract Through the azocoupling of Val5-angiotensin II-Asp1-β-amide (Hypertensin-CIBA) with p-halogene substituted benzenediazonium salts the possibility is shown for quantitative determination of polypeptides containing tyrosine and/or histidine. 1 to 2 nanomoles of the coupling-product could be measured photometrically. The detection limit can be lowered, if the polypeptide is coupled with a radioactive labelled diazonium salt. The preferable reaction conditions for diazotising and coupling are reported. The reaction-product showed an uniform behaviour in the used paper-chromatographic system. Probably it is a monoazo compound. Under the chosen conditions the tyrosyl group is very likely the reacting part of the hypertensin molecule.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 103 (1970), S. 3427-3436 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Reaction of (Nitrobenzyl)pyridinium Salts with PhenylhydroxylamineOn reaction with pheylhydroxylamine, (4-nitrobenzyl)pyridinium salts are first attacked at the nitro group. Elimination of pyridine yields nitrones of azoxy- and azobenzene derivatives. The structures assigned to the new compounds are confirmed by alternate synthesis.
    Notes: 4-Nitro-benzylpyridiniumsalze werden von Phenylhydroxylamin zuerst an der Nitrogruppe angegriffen. Unter Pyridin-Abspaltung entstehen Nitrone von Derivaten des Azoxy- und des Azobenzols, deren Konstitution durch unabhängige Synthesen gesichert wird.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monomolecular fragmentations of butadiyne- and 1,3-pentadiyne radical cations in their electronically excited states have been investigated by use of the photoelectron-photoion coincidence technique. Breakdown curves for the molecular and various fragment ions have been recorded over the ionization energy range of 9 to 17 eV. These breakdown curves reveal the extent of the competition between the radiative relaxation (ion fluorescence) and the non-radiative internal conversion followed by fragmentation for the decay of the first excited electronic states. Extensive hydrogen scrambling and/or ionic-carbon-skeleton isomerization takes place prior to fragmentation, as revealed by the breakdown curves obtained for the site specifically deuteriated 1,3-pentadiynes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enthalpy of formation of tris(methylidene)-cyclopropane (“[3]radialene”, 1) has been determined as ΔHfO = 396 ± 12 kJ mol-1 from three fragmentation reactions of its molecular ion 1+ formed from 1 by photoionisation using synchrotron radiation. Comparative electron impact measurements using conventional mass spectrometry were also performed. A treatment of the latter data is described which leads to satisfactory agreement with the photoionization data. The experimental value of ΔHfO(1) is compared with various theoretical estimates. The strain energy of 1 is calculated to be 226.3 kJ mol-1. Linear extrapolation of this quantity from the increase of strain in passing from cyclopropane to methylidenecyclopropane yields 282.4 kJ mol-1. The discrepancy between these values, already predicted by Dewar and Baird ten years ago from theoretical calculations, is discussed on the basis of maximum overlap considerations. The enthalpy of formation of bis(methylidene)cyclopropane is predicted to be ΔHfO= 309 kJ mol-1.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 2-Ethoxy-2-oxo-1,3,2-dioxaphospholane (1) is polymerized rapidly and in high yields to poly[oxy(ethoxyphoxyphosphoryl)oxyethylene] (3) by several alcoholates. The products are colourless and of high viscosity. They are soluble in water, alcohols, tetrahydrofuran, dioxane, methylene, chloride, chloroform, and dimethylsulfoxid; they are insoluble in ether and in hydrocarbons. Polymerization degrees up to 83 (M̄ = 12600) were found. In aqueous solutions no hydrolytic degradation is observed at room temperature within several days.A tentative anionic mechanism of polymerization and possible side reactions are briefly discussed.
    Notes: 2-Äthoxy-2-oxo-1,3,2-dioxaphospholan (1) wird durch verschiedene Alkoholate sehr schnell und in hoher Ausbeute zu Poly[oxy(äthoxyphosphoryl)oxyäthylen] (3) polymerisiert. Die Produkte sind hochviskos und farbols. Sie lösen sich in Wasser, Alkoholen, Tetrahydrofuran, Dioxan, Methylenchlorid, Chloroform und Dimethylsulfoxid; unlöslich sind sie in Äther und in Kohlenwasserstoffen. Polymerisationsgrade bis 83 (M̄ = 12600) wurden gemessen. In wäßriger Lösung bei Raumtemperatur erfolgte auch nach Tagen kein merklicher hydrolytischer Abbau.Der mutmaßlich anionische Polymerisationsmechanismus und mögliche Nebenreaktionen werden kurz diskutiert.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 725-739 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(vinyl alcohol) was crosslinked with terephthalaldehyde and was reacted with 2,4,6-trichloro-s-triazine, resp. 4-nitrobenzyl chloride, resp. 2-(3-aminophenyl)-1,3-dioxolane. Subsequent reactions gave reactive carriers, which could be used to obtain active immobilized enzymes with papain, trypsin, and glucose oxidase.The binding ability of the last carrier for the enzymes was investigated as a function of the offered amount of the enzyme during the immobilization. In the case of papain also the dependence of the content of reactive groups on the binding ability was investigate.Some properties of the immobilized hydrolases as activity, pH-activity profile, KM(app.)-values, storage- and thermostability, and stability after repeated application were determined.
    Notes: Aus mit Terephthalaldehyd vernetztem Polyvinylalkohol wurden durch Umsetzung mit 2,4,6-Trichlor-s-triazin, 4-Nitrobenzylchlorid beziehungsweise 2-(3-Aminophenyl)-1,3-dioxolan und Folgereaktionen reaktive Träger hergestellt, die mit Papain, Trypsin und Glucose-Oxydase aktive Enzympräparate ergaben.Das Bindungsvermögen des letztgenannten Trägers für die Enzyme wurde in Abhängigkeit von der zur Immobilisierung eingesetzten Enzymmenge sowie für Papain vom Gehalt an reaktiven Gruppen des Trägers untersucht.Für die immobilisierten Hydrolasen wurden die Eigenschaften wie Aktivität, pH-Aktivitäts-Profil, KM(app.)-Werte, Lager- und Thermostabilität, sowie Stabilität bei wiederholtem Einsatz bestimmt.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolymers from styrene and 1-vinylimidazoles (4a-f), form low spin adducts with iron(II) porphyrins and iron(III) porphyrins, when the content of imidazolyl groups in the polymer is ten mole percent or more. With polymers having a content of imidazolyl groups of less then one mole percent, only high spin adducts are observed. With terpolymers, in which the porphyrin is covalently bound to the copolymer the same phenomenon is observed. Only the high spin Fe(II) porphyrin adducts in the solid state adsorb molecular oxygen like cobalt(II) porphyrins under the same conditions. Adsorptions and desorptions of oxygen are much slower in the cases of iron(II) porphyrins than with the cobalt(II) porphyrins. Electronic and ESR spectra as well as susceptibility measurements were used to characterize the reported spin states.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hypothesis of Harwood and Patel, suggesting for the polymerization of 2-phenyl-1,3,2-dioxaphospholane a type of insertion reaction to explain the formation of ethylenediphosphinic ester structures besides the normal 2-hydroxyethyl(phenyl)phosphonic ester structures is extended to similar monomers and its theoretical consequences are examined. It is shown that in such a system mutual transformations between ω-hydroxyalkyl-P-acid and alkylenedi(P-acid)structures should occur, establishing a dynamic equilibrium and leading to a sort of azeotropic polymer, in which only one unique composition is kinetically stable. Equations relating to different kinetic parameters are deduced.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 3 (1979), S. 107-127 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The immobilization of various enzymes, mainly of hydrolases, by carriers with e.g. maleimide, benzoquinone, N-substituted sulfamic acid, and diazonium groups will be described. As basic polymer mainly poly(vinyl alcohol) was used which was derivatized. The immobilization of enzymes was performed also with synthetic wood pulp. The influence of unfolding of the enzyme chains during the immobilization reaction on the characteristics of the immobilization products as well as the influence of the spacer length on the immobilization was investigated. An example of a soluble immobilized trypsin product is given. Some aspects of the characterization of immobilized enzymes will be discussed. Also some examples of whole cell immobilization as well as of application of immobilized enzymes and immobilized whole cells will be described.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The ringopening polymerization of 2-ethoxy-2-oxo-4,5-dihydro-1,3,2-dioxaphosphorine (1) with alkoholates as initiators is characterized by the following facts: (a) Polymerization needs temperatures above 100°C and a reaction time of many days. (b) A polymerization-depolymerization equilibrium is formed. The maximum of conversion for 125°C and for bulk polymerization is 70%. (c) The enthalpie of polymerization is found to be 0±12,6 kJ mol - 1 (0±3 kcal mol - 1). (d) Only oligomers are formed. The yield of product with Pn 〉 5 is about 3%. The oligomers with Pn = 1 to 5 can be separated by thin layer chromatography and characterized by mass spectrometry.
    Notes: Die ringöffnende Polymerisation des 2-Äthoxy-2-oxo-4,5-dihydro-1,3,2-dioxaphosphorins (1) mit Alkoholaten als Initiatoren, ist durch folgende Merkmale gekennzeichnet: (a) Zur Polymerisation sind Temperaturen von über 100°C und Reaktionszeiten von vielen Tagen erforderlich. (b) Es stellt sich ein Polymerisations-Depolymerisations-Gleichgewicht ein. Für 125°C liegt der maximale Umsatz bei der Polymerisation in Substanz bei 70%. (c) Die Polymerisationsenthalpie hat den Wert 0±12,6 kJ mol - 1 (0±3 kcal mol - 1). (d) Es werden nur Oligomere gebildet. Die Ausbeute an Substanz mit Pn 〉 5 liegt um 3%. Die Oligomeren mit Pn = 1 bis 5 werden durch Dünnschichtchromatographie getrennt und durch Massenspektrometrie charakterisiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...