Ring closure reactions. Part 6. Intermolecular models for intramolecular reactions. Reactions between long-chain alkanoate ions and alkyl bromides as intermolecular analogues of the lactonization of ω-bromoalkanoate ions

Abstract

The search for a general intermolecular model for lactonization of the anions of straight-chain ω-bromoalkanoic acids led to the determination of the rate constants of the S_N2 reaction between some alkanoate ions and alkyl bromides, involving straight-chains of varying lengths up to C₁₈ in both reactants. The experimental results show the appearance of a slight rate-enhancing effect on increasing chain length which may be attributed, at least in part, to lyophobic interactions of alkyl chains. Since on going from the C₄ to the C₁₈ reactants the observed rate varies by a factor of two, it is concluded that any of the reactant pairs in the set of compounds examined provide a reasonably good model for the intermolecular analogue of the lactonization reaction.