Selective functionalization of saturated hydrocarbons by Gif-type systems /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1991.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | A series of 1,1-diarylethylenes was cleanly cleaved to the corresponding ketones with significantly different yields. The most electron-rich olefin is the most reactive towards the Fe^v oxenoid species. The Fe^v oxenoid species has electrophilic character. Epoxides and 1,2-glycols are not the intermediates for the cleavage of carbon carbon double bonds under Gif type conditions. Competitive oxidation of different types of hydrocarbons by Gif system indicates that cleavage of methylidene of olefins is easier than oxidation of saturated secondary carbons. If the secondary carbon is attached to a benzyl group, the reaction rate is faster than that of other saturated secondary carbons. Oxidation of natural products having both saturated carbons and methylidene shows that the active iron species involved in each type of reaction are very similar. The oxidation yields are similar for both cleavage of double bonds and ketonization of secondary carbon. Saturated secondary carbon reacts with iron catalyst and gives intermediate A which has an iron carbon σ-bond (Fe^V-CHR^1R^2). A can be captured by BrCCl3 to form brominated compounds. However, because the life time of intermediate A (which bonds with benzylic carbon or carbon carbon double bonds) is short, it goes to next step immediately. Thus, there are no brominated compounds trapped in this case and only oxidation products are obtained. The non-radical mechanism of Gif type reactions for the oxidation of secondary hydrocarbons and cleavage of carbon carbon double bonds has been proved by adding BrCCl3 or PhSeSePh. Substrates with tertiary carbon may share radical behaviour but secondary carbon always undergoes the Gif mechanism. When the radical trapping reagent BrCCl3 is added and a radical chain reaction is strongly kinetically favoured (e.g. β-pinene), radical products will be the major products. In other words, the radical mechanism will take precedence over the Gif mechanism... |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | xiii, 91 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |