Sökning: "transition metal free"

Visar resultat 1 - 5 av 73 avhandlingar innehållade orden transition metal free.

1. 1. New Reactions with Allyl- and Allenylboron Reagents : Transition-Metal-Catalyzed and Transition-Metal-Free Carbon-Carbon Bond Formation Processes

   Författare :Dong Wang; Kálmán J. Szabó; Jianbo Wang; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; carbon-carbon bond formation; cross-coupling; organoboron compound; allylboron reagent; allylation; transition metal; metal carbene; allenylboron reagent; transition metal free; diazo compound; tosylhydrazone; quinone; organisk kemi; Organic Chemistry;

   Sammanfattning : Organoboron compounds have been widely used in carbon-carbon bond formation reactions in organic synthesis and catalysis. This thesis is focused on cross-coupling reactions of allyl-, allenylboronic acids and their ester derivatives via transition metal catalysis or transition-metal-free processes. LÄS MER

3. 2. MECHANISTIC INVESTIGATIONS OF TRANSITION METAL CATALYZED REACTIONS

   Författare :Jonatan Kleimark; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; alkene insertion; allylic alkylation; catalysis; cross coupling; density funtional theory; free energy surface; iron; kinetic investigation; Mizoroki-Heck reaction; nickel; palladium; reaction mechanism; sulfinylation; transition metal;

   Sammanfattning : Transition metal catalyzed reactions have had a large impact on the human progress for the last century. Several extremely important areas, such as the agricultural industry and the plastic industry, have benefited from this development. LÄS MER

4. 3. Transition metal ion-chelating ordered mesoporous carbons as noble metal-free fuel cell catalysts

   Författare :Johanna Dombrovskis; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; mesoporous materials; electrocatalysis; EXAFS spectroscopy; fuel cell; transition metals; carbon;

   Sammanfattning : Polymer electrolyte membrane fuel cells offer promising possibilities for clean and efficient chemical to electrical energy conversion, though their high price makes them financially unappealing. This is to a large part due to the high cost of the noble metal catalyst used in fuel cells, which makes development of new, cheap and active catalyst materials necessary. LÄS MER

5. 4. Platinum-free Electrocatalysts : Design, Synthesis, and Energy Applications

   Författare :Yi Yang; Inna Soroka; Carina Lagergren; Serhiy Cherevko; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Pt-free electrocatalysts; γ-radiation induced synthesis; size; morphology; structure; and composition of nanocatalysts; ORR; catalytic activity and durability; formation mechanism of catalyst materials in aqueous solutions.; Kemi; Chemistry;

   Sammanfattning : Pt is one of the most commonly used catalysts for green energy applications, such as fuel cells, electrolyzers, and dye-sensitized solar cells. Although enormous effort has been put into improving the catalytic activity and minimizing the usage of Pt in the catalysts, the low abundance and high price of Pt still limit the large-scale commercialization of green energy devices and facilities. LÄS MER

7. 5. Catalytic Methods to Convert Allylic Substrates through Hydride and Proton Shifts : Transition Metal-Catalyzed and Organocatalyzed Approaches

   Författare :Samuel Martinez-Erro; Belén Martín-Matute; Franziska Schoenebeck; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Allylic substrates; Iridium catalysis; Base catalysis; Method development; Isomerization; Hydride shift; Proton shift; Mechanistic studies; organisk kemi; Organic Chemistry;

   Sammanfattning : The present thesis describes the development of new catalytic protocols to transform allylic substrates into a wide variety of versatile carbonyl and vinyl organic compounds. All procedures that are described in this work have in common the existence of one or more hydrogen shifts as key steps in the mechanism of the reactions. LÄS MER