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Identifier

000352862

Title

Νέες φωτοχημικές αντιδράσεις ελευθέρων ριζών για την παραγοντοποίηση του φουλερενίου C60: συνθετικές εφαρμογές και μηχανιστικές μελέτες : εφαρμογή νέων υλικών του φουλερενίου C60 στην ετερογενή φωτοκατάλυση

Alternative Title

New functionalizations of fullerene C60 through photomediated free radical reactions: synthetic applications and mechanistic studies

Author

Τζιράκης, Εμμανουήλ Δημητρίου

Thesis advisor

Ορφανόπουλος, Μιχαήλ

Abstract

This dissertation describes new methods for the chemical modification of C₆₀ with a variety of organic compounds, including toluenes, anisoles, aldehydes, ethers, sulfides and alcohols. A new approach for the synthesis of the simplest hydrogenated fullerene, 1,2-C₆₀H₂, as well as the application of new photocatalytic materials C₆₀/Al₂O₃ and C₆₀/SiO₂ in heterogeneous photooxidations is also presented. This dissertation is organized as follows: In the First Chapter, a new photochemical cycloaddition of biscyclopropyl substituted alkenes to C₆₀, is described. This reaction proceeds regioselectively, affording the corresponding adducts with a cis-1 addition pattern, through a one-step high-yield process. The structural assignment of these compounds has been accomplished by the combined use of UV/Vis and different NMR spectroscopic techniques, as well as by HRMS analysis. These studies revealed the unique 5,4,5-tricyclic fused ring structure onto the fullerene core. In the Second Chapter, a convenient, highly efficient decatungstate-mediated chemical methodology to functionalize fullerenes with para-substituted toluenes, anisoles, and thioanisole, is demonstrated. This reaction affords the corresponding 1,2-dihydro[60]fullerene monoadducts in moderate to good yields. In the Third Chapter, a versatile photochemical methodology for the direct acylation of C₆₀ is presented. This method utilizes a wide variety of acyl radicals derived from aldehydes through a hydrogen atom abstraction process mediated by decatungstate. A decrease of the above reaction temperature was found to be effective in overcoming the decarbonylation process encountered in certain acyl radical additions to C₆₀. Moreover, the development of a new, straightforward protocol for the selective synthesis of the simplest [60]fullerene hydride, C₆₀H₂, from acylated fullerenes is also described. In the Fourth Chapter, a novel free-radical approach for the activation of the otherwise unreactive α-C-H bond in a series of structurally diverse ethers, including thioethers and crown ethers, is presented. The selective mono-addition of these radical species to C₆₀ enables the hitherto unexplored functionalization of C₆₀ with organic sulfides and ethers. Similarly, the hydroxyalkylation of fullerenes has been achieved through radical addition of alcohols to C₆₀. In the Fifth Chapter, the preparation of a series of SiO₂- and Al₂O₃-supported fullerene catalysts with varying C₆₀ content, as well as, the assessment of their catalytic activity in the heterogeneous oxidation of organic compounds under oxygen atmosphere, is presented. These catalysts exhibited significant conversion, turnover number and turnover frequency values, substantially higher than those achieved over the unsupported C₆₀. The easy separation of the solid catalysts from the reaction mixture, the high dispersion of the supported C₆₀, the high activity and stability as well as the retained activity in subsequent catalytic cycles, make these supported catalysts suitable for a small-scale synthesis.

Language

Greek

Subject

Fullerene C60

catalysis

cycloadditions

decatungstate anion (W10O32 4-)

free-radicals

photochemistry

photoinduced electron transfer

Φουλερένιο C60

αντιδράσεις ελευθέρων ριζών