KINETIC VERSUS THERMODYNAMIC CONTROL IN CHLORINATION OF IMIDAZOLIDIN-4-ONE DERIVATIVES

The monochlorination of 2,2,5,5-tetramethylimidazolidin-4-one (compound P) in chloroform at ambient temperature has been studied by use of H-1 NMR and UV measurements. It has been established that 3-chloro-2,2,5,5-tetramethylimidazolidin-4-one (compound MC3) is the kinetically controlled product of this reaction. The second-order rate constant for formation of MC3 was ca. 4.2 x 10(-2) M-1 s-1. Following formation of MC3, rearrangement occurred to produce 1-chloro-2,2,5,5-tetramethylimidazolidin-4-one (compound MC1). This reaction occurred slowly through a second-order process (k = 1.4 x 10(-5) M-1 s-1) and probably involves the formation of Cl+ with subsequent reaction with P to produce MC1. This work is relevant to the formation of a new class of biocidal N-halamine compounds.