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Disappearance rates of several 3-X-substituted nortricyclanes [X = H, CH,OH, CH,CI, Ac, OH, (CHJOH, OAc, CN, NO,, and 0x01 were measured in aqueous perchloric acid by g.1.c. According t o activation parameters, solvent deuterium isotope effects, and log k, versus H, and log k, versus olq correlations, the hydration mechanism is in most cases A S , 2 (or AdE2), i.e., protonation of the cyclopropane ring is the rate-determining stage of the reaction. The mechanism is different in the case of 3-methyl-3-hydroxynortricyclane (A-1 ) and 3-acetoxy-and 3-0x0-nortricyclane (A-2). The slope of the linear log k, versus olq correlation (-1.30 in 1 mol dm-3 HCIO, at 348.2 K) is between those measured for separate protonations of t w o olefinic carbons of 5-X-su bstituted norbornenes. The contradiction between the normal inductive effects of the 3-X-substituents and the weak effects of the methyl groups at the cyclopropane carbons can be rationalized by formation of an edge-protonated nortricyclane in the rate-determining stage of the reaction.

The disappearance of 3-and 1-acetoxynortricyclanes (1 and 2) in aqueous perchloric acid was followed by capillary gas chromatography at different temperatures and acid concentrations. According to the activation parameters, solvent deuterium isotope effects and parameters of excess acidity equations, the A AC 2 ester hydrolysis with two water molecules in the transition state is dominant at the lower acid concentrations studied (1-5.5 M HClO 4 ) and the Ad E 2 hydration of the cyclopropane ring is dominant at higher acid concentrations (6-8 M HClO 4 ) at 298 K. 3-Nortricyclanol (3) is formed via hydrolysis from 1, whose hydration products were not analyzed. 2-Norbornanone (4) is formed via both hydrolysis and hydration from 2.

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