β-Elimination Reaction of Antimicrobial L-5-Alk (en) ylthiomethylhydantoin-S-oxides

Abstract

The antimicrobial L-5-alk(en)ylthiomethylhydantoin-(±)-S-oxides (RHSO) decompose spontaneously via β-elimination under physiological conditions to give 5-methylenehydantoin and alk(en)yl thiosulfinates as antimicrobial principles. Attempts have been made to elucidate the mechanism of β-elimination reaction of RHSO in a buffer solution. The β-elimination of propyl derivative (I) at specified conditions of temperature and pH followed first-order kinetics. A linear relationship between the first-order rate constant and the concentration of hydroxide ion was also observed. Therefore, it has been shown that the β-elimination of I obeys the second-order kinetics. The second-order rate constant from L-5-propylthiomethylhydantoin-(+)-S-oxide [(+)-I] in water at 37°C was 4.20±0.31×10³/sec. M.