Abstract
Stability of considerably labile imidazolidinone derivatives substituted at 2-position, such as 1-methyl-2-isopropyl-3-phenyl-4-imidazolidinone (IMO-2) and 1-methyl-2, 3-diphenyl-4-imidazolidinone (IMO-3), was examined kinetically. It was found that IMO-2 had a decomposition pattern similar to that of IMO-1 previously reported. Contrary to IMO-1 and IMO-2, the decomposition of IMO-3 proceeded by the pseudo-first order reaction over the whole pH region. Since benzaldehyde and α-methylaminoacetanilide did not participate in the reversible reaction at pH 7, it was evident that in neutral and alkaline region IMO-3 also decomposed by the pseudo-first order reaction. The pH-profile of the decomposition rate constant of IMO-3 showed a bell-shape pattern having a maximum value in pH 5. The relative decomposition rates of IMO-1, IMO-2, and IMO-3 at pH 5 decreased in the order of IMO-2, IMO-1, and IMO-3.
