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Identifier 000412998
Title Χημειοεκλεκτική και τοποεκλεκτική δισιλυλίωση αλκυνίων και αλλενίων από διυδροσιλάνια καταλυόμενη από νανοσωματίδια χρυσού
Alternative Title Chemoselective and regioselective disilylation of alkynes and allenes by bihydrosilanes catalyzed by gold nanoparticles
Author Σαριδάκης, Ιάκωβος Ε.
Thesis advisor Στρατάκης, Μανόλης
Reviewer Κατερινόπουλος, Χαράλαμπος
Βασιλικογιαννάκης, Γεώργιος
Abstract In the present scientific dissertation are presented novel methodologies for dehydrogenative disilylations of alkynes and allenes by dihydrosilanes (R2SiH2) catalyzed by gold nanoparticles supported on titania (Au/TiO2). It was found that: A. Au/TiO2 catalyzes efficiently the dehydrogenative cis-1,2-disilylation of terminal alkynes with dihydrosilanes. It is stressed that such reactivity of dihydrosilanes is unprecedented and stands in contrast to monohydrosilanes (R2SiH) which in the presence of Au/TiO2 react with alkynes forming stereoselectively β-(E)-hydrosilylation products. A plausible mechanism is postulated and involves the reaction of the initially formed complex R2HSi-Aun-H with a second dihydrosilane molecule forming the reactive complex R2HSi-Aun-SiHR2 (with the simultaneous H2 elimination) which is added with syn stereochemistry onto the alkyne’s π-system. Further exploitation of the disilylation product involves the Au/TiO2-catalyzed reactions either with water or with a second alkyne molecule producing substituted 2,5-dihydro-1,2,5-oxadisiloles or 1,4-disila-2,5-cyclohexadienes, respectively, with concomitant H2 release. B. Au/TiO2 is an efficient catalyst for the regiospecific and stereoselective β,γ-disilylation of terminal allenes with dihydrosilanes. It is accentuated that such reactivity among dihydrosilanes and allenes is unprecedented and the products are unknown in the literature. It is proposed that the same gold complex (R2HSi-Aun-SiHR2) interacts with the allene and adds exclusively in the least substituted double bond forming the disilylation products with E stereochemistry. Au/TiO2 also catalyzes the dehydrogenative formation of 3-vinyl-1,2,5-oxadisilolanes via reaction among the disila adducts and a water molecule
Language Greek
Subject Αλκύνια
Ετερογενής κατάλυση
Ηeterogeneous catalysis
Issue date 2017-11-23
Collection   School/Department--School of Sciences and Engineering--Department of Chemistry--Post-graduate theses
  Type of Work--Post-graduate theses
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