1070-4280/01/3703-0345 $25.00 2001 MAIK Nauka / Interperiodica Russian Journal of Organic Chemistry, Vol. 37, No. 3, 2001, pp. 345 350. Translated from Zhurnal Organicheskoi Khimii, Vol. 37, No. 3, 2001, pp. 373 378. Original Russian Text Copyright 2001 by Okovityi, Platitsyna, Kas’yan. Theoretical Study of Alkaline Methanolysis of Alicyclic Epoxy Derivatives S. I. Okovityi, E. L. Platitsyna, and L. I. Kas’yan Dnepropetrovsk State University, Nauchnyi per. 13, Dnepropetrovsk, 320625 Ukraine Received September 3, 1999 Abstract The structures of epoxycycloalkane molecules and strains therein were calculated using the MM2MX procedure. Opening of the oxirane ring in these compounds in alkaline methanolysis was simulated by the PM3 method. The calculations were performed both for the gas phase and with account taken of solvent effect in macroscopic and supermolecular approximations. A model was developed, which takes into consideration contributions of electronic and steric factors in the supermolecular approximation. The cal- culated values of H showed a good agreement with the experimental rate constants of the corresponding reactions. Epoxy compounds are readily formed in living bodies via enzymatic processes. They are obtained on a laboratory or industrial scale with the aid of accessible oxidants [1, 2]. Numerous compounds belonging to this group are characterized by high reactivity with respect to various nucleophiles, such as amines, water, alcohols, etc. Reactions of epoxy derivatives, as well as their formation, are convenient models for studying important biological processes, specifically those responsible for carcinogenesis. Therefore, these reactions persistently attract interest and are extensively studied by both experimental and theoretical methods. A specific group of epoxy derivatives consists of compounds in which the oxirane ring is fused to an alicyclic fragment. Steric strains inherent to the latter should considerably affect the reactivity of the oxirane ring toward nucleophiles. We previously reported on the methanolysis of epoxycycloalkanes [3], and kinetic parameters of these reactions in various media were presented in [4]. The greatest activity was found for epoxycyclohexane (III) in the presence of both sulfuric acid and sodium methoxide. Some compounds, e.g., epoxycyclooctane, epoxy- cyclododecane, and exo-epoxynorbornane ( VI ), undergo opening of the oxirane ring only in acid medium [3, 4]. We also revealed considerably dif- ferent reactivities of two stereoisomeric epoxy deriva- tives: exo-(VI) and endo-epoxynorbornane (V); the exo isomer is more reactive in acid medium, and the endo isomer, in neutral and basic media. More recent MINDO/3 quantum-chemical calcula- tions [5], analysis of spectral parameters [6] and basicity [7] of epoxycycloalkanes, and theoretical [8] and experimental assessment of strain in their mole- cules by thermochemical methods [9] demonstrated a clear relation between the strain and electron density distribution in their molecules [10]. However, some important problems concerning the reactivity of epoxy derivatives remained unresolved. The goal of the present study was to obtain quanti- tative data on reactions of epoxycycloalkanes I VII with methanol. Compounds VIII and IX were studied for comparison. The mechanism of gas-phase opening of the oxirane ring in the parent compound IX and its closest homolog (methyloxirane) was studied in sufficient