Stable Carbocations. 255. α-Ethylenehaloarenium Ions

Article abstract of DOI:10.1021/jo00190a016

Ionization of a series of p-halogen-substituted phenylethyl chlorides 1a-c under stable ion conditions gave via phenyl participation the corresponding 4-halo-α-ethylenebenzenium ions 2a-c.The stability of ions 2a-c is affected by the halogen atoms through their "back donation".Similarly, ionization of 9-(2-fluoroethyl)-10-bromoanthracene (7) gave 9-(α-ethylene)-10-bromoanthracenium ion 6 by similar anthryl group participation.Ionization of 1-(2-haloethyl)-4-bromonaphthalenes 11a,b, however, even at -110 deg C gave only the rearranged benzylic ion 12 without any detectable 4-bromo-α-ethylenenaphthalenium ion 10.