Kinetics and mechanism of oxidation of the drug intermediate 1-(2-Hydroxyethyl)piperidine by Bis(hydrogenperiodato)argentate(III)

Journal of the Brazilian Chemical Society

Shi Hongmei²  Jiong Zhang¹  Shuying Huo¹  Shigang Shen¹  Weijun Kang²  Tiesheng Shi¹ 

[1] ,Hebei Medical University School of Public Health Shijiazhuang Hebei ,China

关键词: 1-(2-hydroxyethyl)piperidine;    Ag(III);    oxidation;    kinetics;    mechanism;   

DOI  :  10.5935/0103-5053.20130165

来源: SciELO

【 摘 要 】

1-(2-Hydroxyethyl)piperidine (HEP) is involved in many drugs and drug leads, but its oxidation mechanisms are poorly understood. The oxidation of HEP by bis(hydrogenperiodato)-argentate(III) ([Ag(HIO6)2]5-;) in aqueous alkaline medium was shown, by electrospray ionization mass spectrometry (ESI-MS), to generate piperidine and formaldehyde as the major products. The reaction was monitored spectrophotometrically in the 25.0 to 40.0 ºC range revealing that the oxidation followed a first-order kinetics in [Ag(III)] and a fractional-order in [HEP]. A rate law and a reaction mechanism were proposed based on the study of the dependency of the pseudo-first-order rate constants, k obsd, on [OHˉ] and on [IO4ˉ]tot (total concentration of periodate). The mechanism involves the formation of a periodato-Ag(III)-HEP ternary complex, whose decomposition generates Ag(I) by means of two pathways: one independent and another facilitated by OHˉ. The reaction rate constants and associated equilibrium constants as well as the activation parameters of the rate-determining steps were calculated.

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