GLORIA

GEOMAR Library Ocean Research Information Access

feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    ISSN: 1434-4475
    Keywords: 13C Incremental system ; Substituted benzenes and naphthalenes ; INEPT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The aryl13C chemical shifts of Cl-substituted 4-amino-, 4-diazonium-N,N-dimethylanilines, N,N-dimethylanilines and differently substituted naphthalenes were assigned by means of different NMR methods. The assignments were compared with chemical shifts obtained by using empirical additivity relationship for mono substituted aromatic substances. As a means of substitutent interactions, the chemical shift difference between calculated and experimental values (Δδ c i ) has been used. In the presence of remarkable steric and electronic substituent interactions, large deviations from additivity (Δδ c i values up to 15.4 ppm) were found. Which originate primarily from steric interactions between the substitutents. In order to account therefore, correction increments have been developed by employing the Δδ c i values obtained from 1,2-disubstituted benzenes or naphthalenes. The13C chemical shifts of more than seventy substituted benzenes and naphthalenes have been predicted. The results corroborate that reasonable calculation of chemical shifts in sterically hindered benzenes is possible by using the extended additivity rule. The Δδ c i values are much lower and allow reasonable structural assignments. For external users of this incremental system, a computer program for IBM compatible PC/AT was developed. By means of this program, the13C chemical shifts for different benzenes and naphthalenes with or without 1,2-disubstituted correction increments will be calculated and the corresponding spectrum displayed. The program can assist the successful assignment of experimental13C chemical shifts.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: New aliphatic-aromatic polyethersulphones were obtained by polycondensation of bis(4-hydroxyphenyl)sulphone with bis(4-chloromethylphenyl) compounds of the general formula (Cl—CH2—Ar)2X, where X denotes a single bond, —CH2—, —CO—, —O—, —S—, or —SO2—. The polycondensation reaction was carried out in nitrogen atmosphere in high temperature boiling polar solvents using potassium carbonate as HCl-acceptor.Because of the different reactivity of bis(4-chloromethylphenyl) compounds used, the optimum conditions of the polyreaction are different for each polycondensate. For the whole group studied the following optimum conditions were determined: solvent N,N′-dimethylacetamide, reaction temperature 120°C, reaction time 30 min, solution concentration 0.8 mol/l at equimolar concentration of substrates. The obtained polymers have a weight-average molecular weight of M̄w between 10000 and 50000. They are of linear structure with an alternating polymer chain structure A-B-A-B.
    Notes: Durch Polykondensationsreaktionen von Bis-(4-hydroxyphenyl)-sulfon mit Bis-(4-chlormethylphenyl)-verbindungen der allgemeinen Formel (Cl—CH2—Ar)2X, wobei X eine Einfachbindung oder eines der zweiwertigen Brückenglieder—CH2—,—CO—,—O—,—S— oder—SO2—bedeutet, wurden neue aliphatisch-aromatische Polyethersulfone erhalten.Die Reaktionen wurden in hochsiedenden polaren Lösungsmitteln bei Anwendung äquimolarer Mengen an Substraten und eines 15proz. molaren Überschuses von Kaliumcarbonat als HCl-Akzeptor unter einer Stickstoffatmosphäre durchgeführt.Die verwendeten Bis-(4-chlormethylphenyl)-verbindungen unterscheiden sich hinsichtlich ihrer Reaktivität. Für die gesamte untersuchte Monomerreihe wurden die folgenden günstigsten Reaktionsbedingungen ermittelt:Lösungsmittel N,N′-Dimethylacetamid, Reaktionstemperatur 120°C, Reaktionszeit 30 min, Konzentration der Lösung 0,8 mol/l.Die erhaltenen Polykondensate besitzen ein mittleres Molekulargewicht M̄w von 10000-50000. Sie sind linear nach dem Typ A-B-A-B aufgebaut.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 331 (1989), S. 347-353 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-N.M.R. Studies of Substituent Effects of Polysubstituted Benzenes. I. 1,3,4,5-Tetrasubstituted Benzenes
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 312 (1970), S. 701-711 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An 40 Dialkyl-, Benzylalkyl- und Phenylalkylsulfonen werden die Einflüsse der Molekülreste und verschiedener Lösungsmittel auf die SO2-Valenzschwingungen untersucht. Induktive und mesomere Effekte wirken vorwiegend auf die symmetrische Schwingung, sterische Effekte und Lösungsmittel auf die antisymmetrische. Die integrale Absorptionsintensität der symmetrischen Schwingung alterniert mit zunehmender Länge der Alkylreste, die Intensität der antisymmetrischen Schwingung nimmt erst stark ab und nähert sich dann langsam einem für jede homologe Reihe verschiedenen Grenzwert. Lösungsmittel beeinflussen die integrale Intensität beider Schwingungen nur wenig.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...