Mechanistic study of the oxidation of N-phenyldiethanolamine by <Emphasis Type="Italic">bis</Emphasis>(hydrogen periodato)argentate(III) complex anion |
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Authors: | Shigang Shen Hongmei Shi Hanwen Sun Shuying Huo |
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Institution: | (1) College of Chemistry and Environmental Science, Hebei University, Baoding, Hebei Province, 071002, P.R. China |
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Abstract: | The kinetics of oxidation of phenyldiethanolamine (PEA) by a silver(III) complex anion, Ag(HIO6)2]5−, has been studied in an aqueous alkaline medium by conventional spectrophotometry. The main oxidation product of PEA has
been identified as formaldehyde. In the temperature range 20.0–40.0 °C , through analyzing influences of OH−] and IO
4
−
]tot on the reaction, it is pseudo-first-order in Ag(III) disappearance with a rate expression: k
obsd = (k
1 + k
2OH−]) K
1
K
2PEA]/{f(OH−])IO
4
−
]tot + K
1 + K
1
K
2 PEA]}, where k
1 = (0.61 ± 0.02) × 10−2 s−1, k2 = (0.049 ± 0.002) M−1 s−1 at 25.0 °C and ionic strength of 0.30 M. Activation parameters associated with k
1 and k
2 have also been derived. A reaction mechanism is proposed involving two pre-equilibria, leading to formation of an Ag(III)-periodato-PEA
ternary complex. The ternary complex undergoes a two-electron transfer from the coordination PEA to the metal center via two
parallel pathways: one pathway is spontaneous and the other is assisted by a hydroxide ion. |
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Keywords: | |
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