Science Fair Projects Using Water Soluable Reagents

ABSTRACT

Mechanistic Investigations of Oxidative Transformations Using Water-Soluable Hypervalent Iodine Reagents

STUDENT: Arun P. Thottumkara
GRADE LEVEL: 12th Grade
CITY/STATE: Macomb, IL USA
AWARDS:

Intel International Science and Engineering Fair (ISEF).
Best in Category - Award in Chemistry.
This is the largest pre-college science fair in the world and is a prestigous competition.

National Siemens Westinghouse Competition in Math, Science and Technology - 2nd Place Winner (2003)

National Junior Science and Humanities Symposium Champion (2003)

I. Purpose
Selective oxidative transformations of functional groups are of paramount importance in synthetic organic chemistry. Hypervalent iodine reagents, such as Dess-Martin periodinane (DMP) and o-iodoxybenzoic acid (IBX), have found extensive use as mild and selective oxidizing agents, despite their limited solubility and shock-sensitivity. Given the disadvantages of common hypervalent iodine reagents and the growing demand for environmentally-friendly chemical processes, the experimenter decided to synthesize water-soluble hypervalent iodine oxidizing agents to be used as selective oxidizing agents in water and aqueous solvent systems.

II. Procedures Employed
The experimenter used common laboratory procedures for reaction set up, work up, and product isolation. For a more comprehensive description of the procedures employed in this study, please refer to the “Procedures” section of the research paper.

III. Conclusions
Herein, we report the syntheses of two new water-soluble and user-friendly derivatives of the well known IBX. The new reagents are shown to be chemoselective oxidizing agents for the oxidation of allylic/benzylic alcohols and the oxidation of benzyl ethers to the corresponding esters in aqueous media. In order to explain the selectivity of the reagent and the involvement of water in the reaction, two plausible reaction mechanisms for these oxidative transformations have been proposed with the first step being an enthalpically favored H atom abstraction in both mechanisms. A Hammett correlation study conducted by the experimenter verifies the presence of a radical intermediate in the oxidation of alcohols to the corresponding carbonyl compounds. Additional mechanistic investigations have shown the reactions to be sensitive to the pH of the reaction medium.

IV. Possible Applications:
The reagents offer a simple protocol for the oxidation of allylic/benzylic alcohols to the corresponding carbonyl compounds and for the oxidation of benzyl ethers to the corresponding benzoate esters. The reduced form of the reagent may be reoxidized and thus the reagent is cost-effective. The oxidation of benzyl ethers to benzoate esters also offers an alternate protocol for the debenzylation of benzyl ethers. Finally, oxidation reactions using these reagents are environmentally friendly as they are done in water or aqueous solvent systems.

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Chemistry Science Fair Projects using Oxidative Transformations - Water-Soluble Hypervalent Iodine Reagents was presented at the Illinois Junior Academy of Science.

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