- Electrolytic Reduction of 1,4-Dihalonorbornanes at Mercury Electrodes in Dimethylformamide. Evidence for Propellane as an Intermediate
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Low-temperature (-34 deg C) electrolytic reduction of 1,4-dibromonorbornane at mercury cathodes in dimethylformamide containing tetraalkylammonium perchlorates yields norbornane, bis(1-norbornyl)mercury, and 1,1'-binorbornyl; reduction of 1,4-diiodonorbornane results in the same three products along with 1-iodonorbornane and other minor species.At potentials for which the mass balance is 100percent, norbornane and bis(1-norbornyl)mercury account for 98percent of the electrolysis products and the coulometric n value is precisely three.When tetramethylammonium perchlorate is utilized as the supporting electrolyte at -34 deg C, there is a range of potentials over which a pronounced polarographic current minimun appears; this low-temperature minimum is attributed to adsorbtion upon the electrode of complex species consisting of tetramethylammonium cations and halide ions.Three key observations suggest that propellane is an intermediate in the electrochemical reduction of the 1,4-dihalonorbornanes: (1) norbornane is derived from 1,4-dihalonorbornane via a three-electron process which does not involve 1-halonorbornane as intermediate; (2) bis(1-norbornyl)mercury is produced by electrolytic reduction of 1,4-dihalonorbornane but not by reduction of 1-halonorbornane; and (3) a species apparently obtained by two-electron reduction of 1,4-dihalonorbornanes is capable of undergoing oligomerization.A polarographic wave seemingly attributable to reduction of propellane is observed.
- Carroll, William F.,Peters, Dennis G.
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p. 4127 - 4134
(2007/10/02)
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