Syntheses of many-membered rings. Part 28 kinetic models for the irreversible cyclisation of two symmetrical monomers

Abstract

The reaction of two symmetrical bifunctional reactants A–A and B–B to give monomeric rings (two-component ring closure) has been simulated by means of two complementary kinetic models. These provide underestimated and overestimated values, respectively, of the yields of ring product as a function of both the initial concentration of monomers in batch processes and their rate of feed into the reaction medium in influxion processes (Ziegler high dilution conditions). The merits and limitations of the two models are discussed. Comparison with analogous results previously reported for the reaction of unsymmetrical bifunctional reactants A–B (one component ring-closure) shows that more stringent dilution requirements are to be met by the two-component reaction system. The merging of the influxion conditions into the batch-wise ones has also been investigated. It is shown that this occurs on increasing the feed rate beyond a certain critical value. Above this value the system can seemingly display an intriguing insensitivity to dilution.