Kinetics of oxidation of twelve α-amino acids (AA) by N-chlorosuccinimide (NClS) in aqueous alkaline media have been studied and compared with those of N-bromosuccinimide (NBS) oxidation. Analysis of the results shows that the observed rate of oxidation is first-order in [oxidant] and zero-order in [substrate]. The rate of oxidation increases with increase in [OH−]free in [NClS], the exception being the amino acids having β-alkyl substituent such as valine, leucine etc. Perusal of the results shows that NC1S/NBS reacts with α-amino acid anion to produce α-amino acyl hypohalite which then decomposes in the rate-determining step to give the products. The intermediate α-amino acyl hypohalite is identified by UV-visible absorption spectra. Glycine behaves differently from other amino acids in both oxidants. The proposed mechanism is consistent with the observed kinetics.
十二种
α-氨基酸(
AA)在
水性碱性介质中与N-
氯琥珀
酰亚胺(NClS)的氧化动力学进行了研究,并与N-
溴琥珀
酰亚胺(
NBS)的氧化进行了比较。结果分析表明,观察到的氧化速率对[氧化剂]是一阶,对[底物]是零阶。在[NClS]中,氧化速率随着[OH−]自由浓度的增加而增加,例外的是具有β-烷基取代基的
氨基酸,如缬
氨酸、亮
氨酸等。结果的仔细审阅显示,NClS/
NBS与
α-氨基酸阴离子反应生成α-
氨基酰亚
氯,这在速率决定步骤中分解生成产物。中间体α-
氨基酰亚
氯通过紫外可见吸收光谱被鉴定。甘
氨酸在两种氧化剂中的行为与其他
氨基酸有所不同。所提出的机理与观察到的动力学相一致。