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| Format: | Artículo científico |
| Language: | en |
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Academia Brasileira de Ciências
2006
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| Online Access: | https://www.redalyc.org/articulo.oa?id=32778105 |
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Table of Contents:
- Photo-Fries rearrangements of 1-naphthyl (R)-2-phenylpropanoate in poly(vinyl acetate) and ethyl acetate. Influence of medium polarity and polymer relaxation on motions of singlet radical pairs Jinqi Xu Mathew George Richard G. Weiss Multidisciplinaria (Ciencias Naturales y Exactas) photo Fries radical pair stereoselectivity polymer relaxation Both the regio- and stereo-chemistries of the photoreactions of 1-naphthyl (R)-2-phenylpropanoate havebeen investigated in poly(vinyl acetate) films in their glassy (at 5◦C) and melted (at 50◦C) states and in ethylacetate. These results are compared with those from irradiations in polyethylene films and in n-hexane. Theregioselectivity of the intermediate 1-naphthoxy/(R)-2-phenylpropanoyl radical pair combinations is muchhigher in both the melt and glassy states of poly(vinyl acetate) films than that in the melt state of completelyamorphous polyethylene films, but the stereoselectivity of intermediate prochiral 1-naphthoxy/1-phenylethylradical pair combinations is much lower in poly(vinyl acetate). The results emphasize the need to control theratio between the rates of radical tumbling and translation, as well as the ratio between the rates of in-cagemotions and cage-escape, if high stereo- and regio-selectivities of combination products are to be achieved. Amechanistic picture of how the radicals of the intermediate pairs are affected by and interact with the variousmedia is advanced. 2006 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32778105 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.1 Vol.78