Search for dissertations about: "base substitution"

Showing result 1 - 5 of 51 swedish dissertations containing the words base substitution.

  2. 1. Direct Catalytic Nucleophilic Substitution of Non-Derivatized Alcohols

    Author : Anon Bunrit; Joseph Samec; Joseph Moran; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; nucleophilic substitution; catalysis; alcohols; stereospecific; Lewis acid; Brønsted acid base; bifunctional; heterocycles; organisk kemi; Organic Chemistry;

    Abstract : This thesis focuses on the development of methods for the activation of the hydroxyl group in non-derivatized alcohols in substitution reactions. The thesis is divided into two parts, describing three different catalytic systems. READ MORE

  4. 2. Palladium-Catalyzed Nucleophilic Substitution of Alcohols : Mechanistic Studies and Synthetic Applications

    Author : Supaporn Sawadjoon; Joseph Samec; Takao Ikariya; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; palladium; nucleophilic substitution; mechanism; Organic Chemistry; Organisk kemi;

    Abstract : This thesis deals with the palladium-catalyzed nucleophilic substitution of π-activated alcohols in which the C–O bond of a non-manipulated hydroxyl group is cleaved. The thesis is divided in two chapters describing two different catalytic systems. READ MORE

  5. 3. Concerted or Stepwise? : β-Elimination, Nucleophilic Substitution, Copper Catalysed Aziridination and Ruthenium Catalysed Transfer Hydrogenation Studied by Kinetic Isotope Effects and Linear Free-Energy Relationships

    Author : Per Ryberg; Heinz F. Koch; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Organic chemistry; Kinetic isotope effect; linear free energy relationship; elimination; substitution; aziridination; transfer hydrogenation; Organisk kemi; Organic chemistry; Organisk kemi; organisk kemi; Organic Chemistry;

    Abstract : This thesis describes the use of kinetic isotope effects, linear free energy relationships and stereochamical studies to distinguish between different mechanistic alternatives and to obtain information about transition state structure.In the first part fluorine and deuterium kinetic isotope effects were determined for the base promoted HF elimination from 4-fluoro-4-(4’-nitrophenyl)butane-2-on. READ MORE

  6. 4. Comparative Genomics in Birds

    Author : Erik Axelsson; Hans Ellegren; Martin Lercher; Uppsala universitet; []
    Keywords : Molecular genetics; Birds; molecular evolution; macrochromosomes; microchromosomes; mutation rate; substitution rate; base composition; positive selection; genetic drift; population size; Genetik;

    Abstract : To shed light on forces that shape the molecular evolution of bird genomes, and in turn avian adaptations, comparative analyses of avian DNA sequences are important. Moreover, contrasting findings in birds to those of other organisms will lend a clearer view on general aspects of molecular evolution. READ MORE

  7. 5. An Environmental Approach to PVC Stabilisation

    Author : Paul Clucas; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; organic stabiliser; base catalysed dehydrochlorination; colour improvement ; dehydrochlorination stability; polymer-bound stabiliser; intrasequence lactonisation; co-stabiliser; PVC stabilisation; colour stability; labile chlorine substitution; neighbouring group participation;

    Abstract : We were interested in investigating the stabilisation behaviour of 6-aminouracils, a new class of heavy metal free thermo-stabiliser for PVC. We have therefore investigated the performance and mechanism of stabilisation for 1,3-dibutyl-6-aminouracil, both alone, and in combination with a sodium perchlorate co-stabiliser. READ MORE