Mass spectral determination of azomethyne macrocycle distributions formed in polycondensation reactions

Abstract

FAB–MS spectra have been used in order to detect the distribution of cyclic oligomers formed in the polycondensation of isophthaldehyde and ethylenediamine. The relative percentage of the macrocycles formed decreases in proportion to X^–2.5 according to a thermodynamic equilibrium. The relevant aspect for structural organic chemists is that such FAB–MS techniques can be generally used to determine, in a rapid and convenient way, the distribution of cyclic compounds formed in a polycondensation reaction without resorting to a prior separation of the oligomers formed. This fact can be of use in optimizing the reaction conditions so as to obtain macrocycles of the desired ring size.