Kinetic Treatment of Irreversible Cyclooligomerization of Bifunctional Chains and its Relevance to the Synthesis of Many-Membered Rings

The reaction of a bifunctional reactant A-B under batchwise conditions to give macrocycles has been simulated by numerical integration of the proper system of differential rate equations. This was set up considering all the possible processes of concurrent cyclization and polymerization up to a polymerization degree of 12. In order to obtain meaningful yield data for the cyclooligomers, realistic sets of effective molarities (EM) have been considered. The results show how the yields of the various cyclooligomers vary as a function of the initial monomer concentration and provide useful guidelines to achieve maximum selectivity in the synthesis of a given ring. It is clearly shown that the yield of any cyclooligomer is a function of the whole set of EM values. This observation is the basis of a procedure here developed to evaluate EM data from experimental yields of cyclooligomers. Merits and limitations of more simplified kinetic schemes, which had been previously suggested, are discussed in light of the present results.