Correlation of solvolytic reactivities of 1,1,1-trifluoro-2-phenyl-2-propyl, 1-tert-butyl-1-phenylmethyl, and some related tosylates
Resource
Journal of Organic Chemistry 57 (11): 3041-3046
Journal
Journal of Organic Chemistry
Journal Volume
57
Journal Issue
11
Pages
3041-3046
Date Issued
1992
Date
1992
Author(s)
Abstract
Solvolysis of 1,1,1-trifluoro-2-phenyl-2-propyl tosylate (3), 2,2,2-trifluoro-1-(4′-methylphenyl)ethyl tosylate (4), 1-tert-butyl-1-phenylmethyl tosylate (5), 1-tert-butyl-1-(3′-chlorophenyl)methyl tosylate (6), and 1-(3′,5′-dichlorophenyl)-2,2,2-trifluoro-1-phenylethyl tosylate (7) in a variety of solvents were found to give log k - YOTs, plots with significant deviations from linearity (R = 0.95-0.98). The data points for those measured in aqueous acetone always showed depression from the line, whereas those measured in nonnucleophilic solvents were on the line. On the other hand, 3, 4, 6, and 7 all showed excellent linear relationships (R > 0.99) for log k against log k(5). Additional evidence for the limiting SN1 mechanism in the solvolysis of 5 was given. Similar to the previous work (refs 11-13) a new YBnOTs scale based on the solvolysis rates of 5 for correlating the solvolytic reactivity of benzylic tosylates involving charge delocalizations to the aryl moiety in the cationic transition states was then proposed. The advantages of using this new Y scale of solvent ionizing powers were discussed. The importance of solvent nucleophilicities in the solvolysis of primary benzylic tosylate 8 and unhindered deactivating secondary benzylic tosylates 9 and 10 was confirmed. © 1992, American Chemical Society. All rights reserved.
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journal article
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