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

• Autor(a) principal: Hongmei,Shi
• Data de Publicação: 2013
• Outros Autores: Zhang,Jiong, Huo,Shuying, Shen,Shigang, Kang,Weijun, Shi,Tiesheng
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532013000800011
• topic: 1-(2-hydroxyethyl)piperidine; Ag(III); oxidation; kinetics; mechanism

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.