ORGN 33 |
| Paul S. Engel1, Hua Mo1, Shaoming Duan1, and William B Smith2. (1) Department of Chemistry, Rice University, 6100 Main Street, Houston, TX 77005, (2) Department of Chemistry, Texas Christian University, Texas Christian University, Fort Worth, TX 76129 |
| Quinone type inhibitors such as p-benzoquinones and p-methylenequinones are used to prevent radical polymerization of vinyl monomers during manufacture, shipping and storage. We are exploring two aspects of the inhibition process: the rates of radical trapping and the possibility that trapping is reversible. a-Phenethyl radicals are employed to simulate growing polystyrene chains and yet afford low molecular weight products. A stable nitroxide is used as a radical clock to determine the rate at which inhibitors trap a-phenethyl radicals. The second aspect of this study is homolysis of the initial trapping adducts back to a-phenethyl radicals, which would obviously diminish the inhibition efficiency. The trapping adducts, which are phenoxyl radicals, were generated by reacting the corresponding independently synthesized phenols with nitroxide radicals or by photolysis of phenol oxalate esters. The results showed that trapping is indeed reversible 110 oC. The products and rate constants will be discussed in the presentation.
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Physical Organic Chemistry: Calculations, Mechanisms, Photochemistry and High Energy Species
8:00 AM-12:00 PM, Sunday, September 7, 2003 Sheraton New York -- Royal Ballroom A, Oral
Division of Organic Chemistry |