Sökning: "nucleophilic catalysis"

Visar resultat 1 - 5 av 31 avhandlingar innehållade orden nucleophilic catalysis.

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

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

    Sammanfattning : 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. LÄS MER

  3. 2. Peroxyoxalate Chemiluminescence for Miniaturized Analytical Flow Systems

    Författare :Tobias Jonsson; Umeå universitet; []
    Nyckelord :peroxyoxalate; chemiluminescence; nucleophilic catalysis; non-nucleophilic base; imidazole; triazole; aminopyridine; miniaturized; flow system; capillary electrophoresis; multivariate; analytisk kemi; Analytical Chemistry;

    Sammanfattning : This thesis deals with the peroxyoxalate chemiluminescence (POCL) reaction and its application as a detection technique in flow systems for chemical analysis. Particularly, miniaturized flow systems aimed for separation of molecules. LÄS MER

  4. 3. (Photo)electrochemical Water Oxidation: From Catalysis to Functional Device

    Författare :Hao Yang; Licheng Sun; Marc Koper; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; artificial photosynthesis; solar fuels; water oxidation; nucleophilic attack; conjugated microporous polymer; host-guest chemistry; photoanode; perovskites; artificiell fotosyntes; solbränslen; vattenoxidation; nukleofil attack; konjugerad mikroporös polymer; värd-gästkemi; fotoanoder; perovskiter; Kemi; Chemistry;

    Sammanfattning : The key challenge within artificial photosynthesis is achieving efficient electro- or photo-driven water oxidation catalysis, a necessary process to supply the protons for the reduction reactions, thereby enabling solar fuel production. To facilitate efficient water (photo)electrolysis for solar fuel production, this thesis focuses on two aspects: 1) elucidating the O-O bond formation mechanism and developing efficient, stable, and economical water oxidation catalysts (WOCs); 2) exploring stable, low-cost, light-absorbing photoanode materials that have suitable band structures and excellent charge diffusion properties. LÄS MER

  5. 4. Calculations of Reaction Mechanisms and Entropic Effects in Enzyme Catalysis

    Författare :Masoud Kazemi; Johan Åqvist; Per E. M. Siegbahn; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Enzyme catalysis; Entropy; Cytidine deamination; Ribosome; Peptidyl-tRNA hydrolysis; Peptide bond formation; Empirical valence bond method; Density functional theory; Biology with specialization in Structural Biology; Biologi med inriktning mot strukturbiologi; Biokemi; Biochemistry; Biology with specialization in Molecular Biotechnology; Biologi med inriktning mot molekylär bioteknik;

    Sammanfattning : Ground state destabilization is a hypothesis to explain enzyme catalysis. The most popular interpretation of it is the entropic effect, which states that enzymes accelerate biochemical reactions by bringing the reactants to a favorable position and orientation and the entropy cost of this is compensated by enthalpy of binding. LÄS MER

  7. 5. Green Colloid Chemistry: Characterization of Environmentally Friendly Nonionic Surfactant Systems

    Författare :Christy Whiddon; Fysikalisk kemi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; nucleophilic substitution; alkylglucosides; bicontinious micelles; self-diffusion NMR; nonionic surfactants; micellar catalysis; Physical chemistry; pKa; Fysikalisk kemi;

    Sammanfattning : Phase diagrams of mixed alkylglucoside surfactants, n-nonyl-b-D-glucopyranoside and n-decyl-b-D-glucopyranoside (C9G1 and C10G1) have been examined for the purpose of determining the microstructure surrounding a closed-loop miscibiliyt gap. There are large deuterium isotope effects on the phase diagram. LÄS MER