Dehalogenation reactions of vicinal dihalides. Part III. Dehalogenations of 1-chloro-2-iodo-1,2-diphenylethane induced by a variety of nucleophiles. The nucleophilic reactivity towards iodine
- 1 January 1973
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 1,p. 38-41
- https://doi.org/10.1039/p29730000038
Abstract
Dehalogenations of erythro-1-chloro-2-iodo-1,2-diphenylethane promoted by a variety of nucleophiles have been studied in methanol and, in the case of halide ions, also in NN-dimethylformamide. The susceptibility of iodine in this compound to undergo nucleophilic attack is extremely high and surpasses that of bromine by a factor larger than 106. An order of nucleophilic reactivity towards iodine bonded to a saturated carbon has been established. Dehalogenation rates follow approximately the Edwards equation with α and β values (2·13 and –0·12, respectively) indicating that polarizability and desolvation factors play a larger role than basicity in determining nucleophilic reactivity. The importance of the polarizability is also shown by the reactivity order of the halide ions in dimethylformamide which is I– > Br– > Cl–. As an electrophilic centre, iodine appears to have a susceptibility to be attacked by polarizable nucleophilies which is larger than that of the saturated carbon atom.Keywords
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