Green photochemistry: solar synthesis of fine chemicals, development of novel porphyrin nano structured solid supported sensitizers and implementation of a novel photochemical microflow reactor.
Joyce, Kieran (2013) Green photochemistry: solar synthesis of fine chemicals, development of novel porphyrin nano structured solid supported sensitizers and implementation of a novel photochemical microflow reactor. PhD thesis, Dublin City University.
Full text available as:
This work describes the homogeneous dye sensitized photooxygenations of 1,5-dihydroxynaphthalene (1,5-DHN), β-citronellol and α-terpinene in a series of low molecular weight alcohols under both artificial light (500 W halogen lamp) and natural light (sunlight) conditions. The reactions were assessed for greenness using the twelve principles of green chemistry and several key factors were identified as having a significant negative impact on this greenness. These were primarily, waste generation due to column chromatography, high water wastage due to essential cooling and high electrical energy demand.
Upon identification of these factors, sensitizers were covalently bound to a series of solid supports including; Merrifield resins, silica nano particles and magnetic iron oxide nano particles. Covalent immobilisation of sensitizers onto these solid supports allowed for their facile removal from the reaction mixture post irradiation via centrifugation or external magnetic field. This subsequently eliminated column chromatography. Recyclability studies were also performed.
Furthermore, a low energy demanding photochemical microflow bubble reactor was developed. This system, in addition to the elimination of water cooling also saw significant increases in percent conversions to products under homogeneous conditions. Furthermore, in conjunction with silica and iron oxide solid support sensitizers superior energy efficiencies and space time yields were also achieved.
Archive Staff Only: edit this record