A STABILIZED CYCLOPROPYL CATION . SYNTHESIS AND SOLVOLYSIS OF 1-CHLOROBICYCLOPROPYL

The silver ion assisted acetolysis of 1-chlorobicyclopropyl (2), prepared by vapor phase chlorination of the parent hydrocarbon, produced only unrearranged 1-acetoxybicyclopropyl (8) (42.6%) and a mixture of trans- and cis-enol acetates 9 and 10 (34.8 and 22.6%). Similarly, silver ion assisted hydrolysis of chloride 2 produced ethyl cyclopropyl ketone, presumably via the intermediate 1-bicyclopropanol (13). Both solvolyses represent unique examples of a cyclopropyl cation which does not undergo rearrangement in preference to a direct reaction with the nucleophilic solvent. Rate data for solvolyses in 50 vol % aqueous ethanol were measured: 1-chlorobicyclopropyl, 70°, 2.74 X 10-5 sec-1; 95°, 1.58 X 10-4sec-1; ΔH‡, 16.9 kcal/mole; ΔS‡, - 30.4 eu; 1-chloro-1-isopropylcyclopropane, 150°, 2.78 X 10-6 sec-1. © 1968, American Chemical Society. All rights reserved.