Title

Synthesis and Characterization of Aminotroponiminate-Zinc Functionalized Mesoporous Silica and Exfoliated Fluorosilica Nanomaterials as Efficient Catalysts

Date of Award

2010

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Advisor(s)

Tewodros Asefa

Keywords

Aminotroponiminates, Mesoporous silica, Fluorosilica, Nanocatalysts

Subject Categories

Chemistry

Abstract

The use of the highly ordered mesoporous silica SBA-15 as a scaffold for zinc aminotroponiminates (ZnATOs) and aminotroponates (ZnATIs) for the intramolecular hydroamination catalysis of non-activated alkenes was explored. The cyclization reactions were found to result in 59-93 % conversions in 8-12 h. Furthermore, recyclability studies proved that multiple catalytic cycles could be performed without loss of catalytic efficiency. The synthesis and characterization of highly ordered mesoporous fluorosilicas (OMFs) which contain 2.4-7.0 wt% F, corresponding to a loading of 1.3-3.7 mmol/g was also accomplished. Synthesis of these materials is carried out from parent mesoporous silicas (MCM-41 and SBA-15) under ambient conditions using dilute non-aqueous solutions of triethyloxonium tetrafluoroborate (Et 3 OBF 4 ). Fluorination of the mesostructures is accomplished with only minor alteration of the materials' overall order. The described synthetic procedure is also applied to sulphonic acid (-SO 3 H) functionalized SBA-15. Enhancement of the acid-catalyzed epoxide ring opening of styrene oxide in the presence of aniline to produce the corresponding β-aminoalcohol by the fluorinated materials is presented. Reaction at room temperature after 4 h using - SO 3 H functionalized SBA-15 result in 77% conversion while the as-synthesized OMF and OMF-SO 3 H materials exhibit 79% and 87% conversions, respectively. All material syntheses were characterized by compositional and structural analyses such as N 2 (g) sorption, small angle powder X-ray diffraction (XRD), solid state 13 C and 29 Si NMR, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS), as well as elemental and thermogravimetric analyses.

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