Sökning: "concerted mechanism"

Visar resultat 1 - 5 av 43 avhandlingar innehållade orden concerted mechanism.

1. 1. 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

   Författare :Per Ryberg; Heinz F. Koch; Uppsala universitet; []
   Nyckelord :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;

   Sammanfattning : 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. LÄS MER

3. 2. Studies of the anomeric center : mechanism and synthesis

   Författare :Karl-Jonas Johansson; Harri Lönnberg; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Organic Chemistry; organisk kemi;

   Sammanfattning : This thesis is based on three publications and one appendix and is divided into two parts. The first part is a mechanistic study of the anomerization reaction of both aldo and keto glycosides and the second part is a synthetic study of a unusual type of glycosidic linker found in the lipopolysaccharide core Proteus Mirabilis 0270. LÄS MER

4. 3. Asymmetric Transfer Hydrogenation of Aromatic Ketones : Catalyst Development and Mechanistic Studies

   Författare :Sofia Nordin; Torbjörn Frejd; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Organic chemistry; transfer hydrogenation; aza-norbornyl structure; amino acid derivatives; amino alcohols; ruthenium; concerted mechanism; asymmetric catalysis.; Organisk kemi; Organic chemistry; Organisk kemi; organisk kemi; Organic Chemistry;

   Sammanfattning : This thesis describes the development and evaluation of new chiral Ru(arene)(amino alcohol) catalysts for the transfer hydrogenation of aromatic ketones using isopropanol as the hydrogen source. Two mechanistic studies of the Ru(arene)(amino alcohol) catalyzed transfer hydrogenation of acetophenone were also conducted. The Ru(arene)[(1S,3R,4R)-3. LÄS MER

5. 4. Quantum Chemical Modeling of Binuclear Zinc Enzymes

   Författare :Shilu Chen; Fahmi Himo; Luca De Gioia; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Quantum Chemical Modeling; Binuclear; Zinc; Enzyme; DFT; Mechanism; Theoretical chemistry; Teoretisk kemi;

   Sammanfattning : In the present thesis, the reaction mechanisms of several di-zinc hydrolases have been explored using quantum chemical modeling of the enzyme active sites. The studied enzymes are phosphotriesterase (PTE), aminopeptidase from Aeromonas proteolytica (AAP), glyoxalase II (GlxII), and alkaline phosphatase (AP). LÄS MER

7. 5. Autoproteolysis accelerated by conformational strain - a novel biochemical mechanism

   Författare :Denny Johansson; Göteborgs universitet; []
   Nyckelord :SEA domain; autoproteolysis; MUC1; conformational strain; protein folding;

   Sammanfattning : Natural fragmentation of polypeptide chains by autoproteolysis occurs in a number of protein families. It is a vital step in the maturation of several enzymes and in the formation of membrane-associated mucins that constitute a part of the protective mucus barrier lining epithelial cells. LÄS MER