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8324884 
Journal Article 
Solvation Factors Affecting the Course of Solvolysis of Bicyclo [2.2.2] octyl Derivatives 
Kwart, H; Irvine, JL 
1969 
Yes 
Journal of the American Chemical Society
ISSN: 0002-7863
EISSN: 1520-5126 
91 
20 
5541-5546 
English 
In all familiar reactions having a bicyclooctyl cation intermediate, the product compositions distributed between the [2.2.2], exo-[3.2.1], and endo-[3.2.1] isomers are nearly invariant. Here, the acetolysis of the bicyclo[2.2.2]sulfoxonium ion also results in the same isomer distribution among the products. However, the change to the cationic sulfoxonium leaving group has altered several other aspects of the reaction course. The ratio of chloride to acetate product now appears to be very sensitive to the presence of LiClO4, small amounts of this additive increasing steeply the proportion of bicyclic acetate products. Moreover, added LiCl shows a pronounced induced common ion effect depressing the influence of LiCLO4 on the ROAc/RCl ratio. Studies of the relocation of a deuterium label in brosylate and sulfoxonium substrates have established that part of the product is formed via a pathway involving 7,2-hydride migration. This path is operative to the extent of 6% in the brosylate solvolysis and increases by more than a factor of 4 (26%) in the sulfoxonium case. The presence of added LiClO4 can induce an additional ca. 40% increase in 7,2 hydride shifting in the sulfoxonium ions. These results can be reconciled with the occurrence of a multiplicity of ion pairs in the low ionizing power medium. The solvation characteristic of the various ion pair species can regulate the behavior of the cationic reaction intermediate only insofar as it can control its longevity, and therefore the available time for competing rate processes to occur. On this basis the data can be interpreted to support the following order of the absolute rates of the competing process: bicyclic C-C bond shifting > methide ≅ hydride > phenide. © 1969, American Chemical Society. All rights reserved.