J. Org. Chem. 1990,55, 4304-4311
4304
Solvolysis-Decomposition of 1-Adamantyl Chloroformate: Evidence for Ion Pair Return in 1-Adamantyl Chloride SolvolysistJ*2 Dennis N. Kevill,* Jin Burm K y ~ n gand , ~ Frederick L. Weitl Department of Chemistry, Northern Illinois University, DeKalb, Illinois 60115 Receiued December 20, 1989
In hydroxylic solvents, 1-adamantyl chloroformate reacts with loss of carbon dioxide and formation of both solvolysis and decomposition products. The rates of both processes are appreciably sensitive to solvent ionizing power, with the solvolysis slightly more so. The influence of anionic additives is discussed. For mixtures of hydroxylic solvents, the selectivities for the formation of solvolysis products are very similar to those observed in conventional solvolyses of 1-adamantyl derivatives. I t is suggested that l-Ad+Cl- ion pair intermediates are formed, and the observation of collapse requires that an identical collapse, corresponding to internal return, also occurs in 1-adamantyl chloride solvolysis. A comparison with solvolyses of other 1-AdOCOX compounds suggests that the initial ionization is not to l-Ad+(OCOCl)- and that the l-Ad+Cl- ion pair is formed either in a concerted process or via a very unstable (l-AdOCO)+Cl- ion pair.
Introduction A study of the decomposition of 1-adamantyl chloroformate to yield 1-adamantyl chloride in relatively inert solvents has been reported previ~usly.~Small amounts of accompanying solvolysis (
