Date of Award
Doctor of Philosophy (PhD)
Dr. Daniel C. Whitehead, Committee Chair
Dr. Leah Casabianca
Dr. Shiou-Jyh Hwu
Dr. Modi Wetzler
The need for environmentally safe reagents for the promotion of organic transformations is critical in order to reduce hazardous waste and byproducts associated with industrial-scale chemical processes. We have developed two practical methods that obviate the need for harsh oxidative and toxic brominating reagents in electrophilic halogenation reactions.
In our hands, a catalytic loading of the inexpensive, commercially available V2O5 (~$0.25/g) promotes the bromolactonization of a series of substituted alkenoic acids in isolated yields up to 97% by means of the in situ generation of bromenium (Br+) from bromide (Br−) at room temperature. This process obviates the need for molecular bromine (Br2), known for its potent toxicity and threat to the human nervous system, instead relying on the use of less toxic bromide salts, such as ammonium bromide (NH4Br). The oxidation of halides to halenium equivalents has previously relied on the use of harsh oxidants like lead acetate or Oxone®. The system used by our group is promoted by the mild organic oxidant, urea-hydrogen peroxide (UHP), thereby making this process more environmentally benign. The methodology can be extended to afford high yields of α-brominated β-diketones.
Our group’s interest in vanadium catalysis through next turned to an investigation of polyoxometalates. Specifically, highly functional, anionic polyoxovanadates (POVs) developed in the Hwu laboratory posed a particular interest as possible catalysts for organic oxidations. A room temperature oxidation of alcohols using reduced polyoxovanadates Cs5(V14As8O42Cl) (III-2) and Cs11Na3(V15O36Cl)Cl5 (III-3) was explored. The selective oxidation of various substituted secondary benzylic alcohols were promoted in good to quantitative yields using only 2 mol % of catalyst III-2 in the presence of the terminal co-oxidant tert-butyl hydrogen peroxide (t-BuOOH). Further investigation has focused on kinetic studies of the transformation.
In a separate focus area, our group, in collaboration with the Alexis laboratory developed the preparation of nanoparticles comprised of a Poly(D,L-lactic acid)-poly(ethylene glycol)-poly(ethyleneimine) (i.e. PDLLA-PEG-PEI) tri-block co-polymer. These nanoparticles are capable of selectively capturing environmental contaminants of broad concern bearing aldehyde and carboxylic acid functional groups in the gas phase. These materials effected greater than 80% and 76% reduction of aldehyde and carboxylic acid vapors, respectively, with reductions of up to 98% in some cases. Further, we demonstrated the functionalization of kaolinite and montmorillonite clays with PEI on a multi-gram scale using wet impregnation preparative methods. The synthesized amino-kaolinite clay revealed significant efficiency in capturing volatile aldehydes, carboxylic acids, and sulfides with most of these assays showing 100% reduction of these vapors. Future studies will focus on similar evaluation of the remediation capabilites, with the MMT and MMT-PEI clay minerals.
Campbell, McKenzie Louise, "Investigating Materials that Promote New Organic Methodology and Remediation of Volatile Organic Compounds" (2016). All Dissertations. 2404.