Title

Light induced photochemical transformations: A "green" alternative in organic synthesis and chemical waste treatment

Date of Completion

January 2002

Keywords

Chemistry, Organic

Degree

Ph.D.

Abstract

The term “green” chemistry refers to the use of alternative chemical pathways in environmental pollution prevention. The strategy behind “green” chemistry includes the reformulation of synthetic routes so that less toxic reagents are used and/or byproducts are produced. By reducing or eliminating the use or generation of hazardous substances associated with a particular synthesis or process, chemists can effectively reduce the risk to human health and the environment. ^ Organic photochemistry is playing an increasingly important role in organic synthesis and as such the use of photochemistry can lead to alternative “greener” synthetic pathways. An inherent advantage of light is that it causes chemical transformation to occur under mild conditions without the use of strong bases, acids, oxidants or reductants. ^ A protecting group is often introduced into a molecule during a multistep synthesis to prevent a certain functional group from reacting or to direct that a chemical reaction proceeds selectively at another site of the molecule. For example, a central problem in organic synthesis is to ensure that a specific hydroxyl function in a multifunctional molecule is protected from unwanted reactions altogether or until such time as its intrinsic reactivity is required. The “green” photochemical removal of a benzyl-protecting group for alcohols was investigated under different reaction variables. In order to increase the rate of cleavage an interesting family of quinoline ethers was synthesized. ^ Epoxides are an interesting class of compounds, which are widely used in organic synthesis. Regioselective epoxidation followed by regioselective epoxide cleavage provides a powerful entry into specifically functionalized molecules. In this study the focus was to develop an efficient, environmentally benign, mild method for the photocleavage of epoxides. Light induced regioselective cleavage of epoxides was also investigated. ^ Acetonitrile is frequently used in many industrial and research operations. Its occurrence in chemical wastes presents a major environmental and ecological hazard, as this compound is toxic. Waste treatment with visible light (or sunlight) can offer advantages to chemical treatment. Research requiring a dye catalyzed photochemical stimulated conversion of acetonitrile to less harmful products was investigated. ^