科研之友
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摘要
Oxidation of tetrahydrofurfurylamine (THFA) by a silver(III) complex anion, [Ag(HIO6)(2)](5-), has been studied in aqueous alkaline medium by the conventional spectrophotometry. The oxidation product of THFA has been identified as C4H8OCH2NO. Kinetics of the oxidation reaction has been followed in the temperature range of 25-40 degrees C and the reaction displays an overall second-order behavior: first-order with respect to both Ag(III) and THFA. Influences of [OH-] and [periodate] on the reaction rates have been examined. A reaction mechanism is proposed to involve two pre-equilibria, leading to formation of an Ag(III)-periodato-THFA intermediate complex. The intermediate complex undergoes a two-electron transfer from the coordinated THFA to the metal center through two parallel pathways: one pathway is spontaneous and the other is assisted by a hydroxide ion. A rate expression was derived from the reaction mechanism: k' = (k(a) + k(b)[OH-])K-1/(f([OH-]) [IO4-](tot) + K-1), where [IO4-](tot) is the total concentration of periodate, and k(a) = 0.053 +/- 0.011 M(-1)s(-1), k(b) = 2.06 +/- 0.06 M(-2)s(-1), and K-1 = (5.7 +/- 0.8)x10(-4) M at 25 degrees C and ionic strength of 0.30 M.
