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Steric deuterium isotope effect in the solvolysis of ( Z )‐[ Methyl ‐ D 3 ]‐2‐ethylidene‐1‐adamantyl iodide accelerated by F‐strain
Author(s) -
Ohga Yasushi,
Takeuchi Ken'Ichi
Publication year - 1993
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610060507
Subject(s) - chemistry , solvolysis , steric effects , deuterium , kinetic isotope effect , methyl iodide , iodide , medicinal chemistry , strain (injury) , stereochemistry , organic chemistry , hydrolysis , medicine , physics , quantum mechanics
The deuterium isotope effect in the solvolysis of ( Z )‐ and ( E )‐[ methyl ‐ d 3 ]‐2‐ethylidene‐1‐adamantyl mesylates [( Z )‐ and ( E )‐1d‐OMs] and iodides [( Z )‐ and ( E )‐1d‐I] was studied in 2,2,2‐trifluoroethanol at 25·0°C for mesylates and at 50·0°C for iodides. For the mesylates, which show a relatively small F‐strain effect, the ( Z / E ) H rate ratio (117 ± 1) is essentially identical with the ( Z / E ) D rate ratio (116 ± 1) at 25·0°C. On the other hand, for the iodides, which show a larger F‐strain effect, the ( Z / E ) H rate ratio (5413 ± 57) is greater than the ( Z / E ) D rate ratio (5040 ± 58) at 50·0°C. This indicates that ( Z )‐1h‐I has greater F‐strain than ( Z )‐1d‐I in the ground state. These results again confirm that the F‐strain effect in the ( Z )‐2‐ethylidene‐1‐adamantyl derivatives exists between the ( Z )‐methyl group and the leaving group atom directly attached to the reaction centre.