1-(2-Hidroxietil)piperidina (HEP) está presente em muitos fármacos e em protótipos de fármacos, mas seus mecanismos de oxidação são mal compreendidos. Assim, a reação de oxidação da HEP pelo bis(hidrogenoperiodato)-argentato(III) ([Ag(HIO6)2]5-;) foi investigada em meio alcalino aquoso. Piperidina e formaldeído foram identificados como principais produtos da reação através da técnica de espectrometria de massa com ionização electrospray. A cinética de oxidação foi acompanhada espectrofotometricamente no intervalo de temperatura de 25,0 a 40,0 ºC, verificando-se que a reação é de primeira ordem em [Ag(III)] e de ordem fracionária em [HEP]. O estudo da dependência das constantes de velocidade k obsd em relação a [OHˉ] e [IO4ˉ]tot (concentração de periodato total) possibilitou estabelecer uma lei de velocidade e propor um mecanismo de reação. O mecanismo envolve a formação do complexo ternário periodato-Ag(III)-HEP, seguido de sua decomposição a Ag(I) através de dois caminhos: um independente e outro facilitado por OH-. As constantes de velocidade e de equilíbrio bem como os parâmetros de ativação correspondentes às etapas determinantes de velocidade foram calculados.

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.

The oxidation of leucine, isoleucine and valine by bis(dihydrogen tellurate)argentate(III) ion was studied by stopped-flow technique. It was both first order with respect to Ag(III) complex and amino acids. A plausible mechanism was proposed form the kinetics study. And the rate equations derived from mechanism can explain all experimental phenomena. The activation parameters along with the second order rate constants were calculated.

The oxidation of 6-Aminocaproic acid by Ag(III) complex, dihydroxydiperiodatoargentate(III) (DPA), was studied in alkaline medium. The reaction was first order with respect to Ag(III) complex, and the order with respect to 6-aminocaproic acid was from one to two. A plausible mechanism involving a pre-equilibrium of adduct formation between the complex and reductant was proposed form the kinetics study. The rate equations derived from mechanism can explain all experimental phenomena, and the activation parameters along with rate constants of the rate-determining step were calculated