Abstract
The mechanism of cyanide oxidation by ferrate in water is discussed using DFT computations in the framework of the polarizable continuum model. The reactivity of three oxidants, monoprotonated, monoprotonated, and diprotonated ferrates is evaluated. This reaction is initiated by a direct attack of an oxo group of ferrate to the carbon atom of cyanide, followed by an H-atom transfer from cyanide to another oxo group to lead to an intermediate having cyanate (NCO-) as a ligand. The produced cyanate is oxidized by an oxo ligand of ferrate and exogenous oxygen molecule to CO2 and NO 2-. The initial C-O bond formation is found to be the rate-determining step in this reaction. The activation energy for the C-O bond formation is 51.9kJ mol-1 for nonprotonated ferrate, 44.4 kJ mol -1 for monoprotonated ferrate, and 41.4 kJ mol-1 for diprotonated ferrate, which indicates that the oxidizing power of the three oxidants is in the order of nonprotonated ferrate < monoprotonated ferrate < diprotonated ferrate. The general energy profile for cyanide oxidation by ferrate is downhill toward the product direction after the C-O bond formation, so cyanide is readily converted to the final products in water. The reaction kinetics of this reaction are analyzed from the calculated energy profile and experimentally determined pKa values.
| Original language | English |
|---|---|
| Pages (from-to) | 1212-1218 |
| Number of pages | 7 |
| Journal | Bulletin of the Chemical Society of Japan |
| Volume | 81 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - Oct 15 2008 |
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All Science Journal Classification (ASJC) codes
- Chemistry(all)
Cite this
Mechanism and kinetics of cyanide decomposition by ferrate. / Kamachi, Takashi; Nakayama, Tomonori; Yoshizawa, Kazunari.
In: Bulletin of the Chemical Society of Japan, Vol. 81, No. 10, 15.10.2008, p. 1212-1218.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Mechanism and kinetics of cyanide decomposition by ferrate
AU - Kamachi, Takashi
AU - Nakayama, Tomonori
AU - Yoshizawa, Kazunari
PY - 2008/10/15
Y1 - 2008/10/15
N2 - The mechanism of cyanide oxidation by ferrate in water is discussed using DFT computations in the framework of the polarizable continuum model. The reactivity of three oxidants, monoprotonated, monoprotonated, and diprotonated ferrates is evaluated. This reaction is initiated by a direct attack of an oxo group of ferrate to the carbon atom of cyanide, followed by an H-atom transfer from cyanide to another oxo group to lead to an intermediate having cyanate (NCO-) as a ligand. The produced cyanate is oxidized by an oxo ligand of ferrate and exogenous oxygen molecule to CO2 and NO 2-. The initial C-O bond formation is found to be the rate-determining step in this reaction. The activation energy for the C-O bond formation is 51.9kJ mol-1 for nonprotonated ferrate, 44.4 kJ mol -1 for monoprotonated ferrate, and 41.4 kJ mol-1 for diprotonated ferrate, which indicates that the oxidizing power of the three oxidants is in the order of nonprotonated ferrate < monoprotonated ferrate < diprotonated ferrate. The general energy profile for cyanide oxidation by ferrate is downhill toward the product direction after the C-O bond formation, so cyanide is readily converted to the final products in water. The reaction kinetics of this reaction are analyzed from the calculated energy profile and experimentally determined pKa values.
AB - The mechanism of cyanide oxidation by ferrate in water is discussed using DFT computations in the framework of the polarizable continuum model. The reactivity of three oxidants, monoprotonated, monoprotonated, and diprotonated ferrates is evaluated. This reaction is initiated by a direct attack of an oxo group of ferrate to the carbon atom of cyanide, followed by an H-atom transfer from cyanide to another oxo group to lead to an intermediate having cyanate (NCO-) as a ligand. The produced cyanate is oxidized by an oxo ligand of ferrate and exogenous oxygen molecule to CO2 and NO 2-. The initial C-O bond formation is found to be the rate-determining step in this reaction. The activation energy for the C-O bond formation is 51.9kJ mol-1 for nonprotonated ferrate, 44.4 kJ mol -1 for monoprotonated ferrate, and 41.4 kJ mol-1 for diprotonated ferrate, which indicates that the oxidizing power of the three oxidants is in the order of nonprotonated ferrate < monoprotonated ferrate < diprotonated ferrate. The general energy profile for cyanide oxidation by ferrate is downhill toward the product direction after the C-O bond formation, so cyanide is readily converted to the final products in water. The reaction kinetics of this reaction are analyzed from the calculated energy profile and experimentally determined pKa values.
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U2 - 10.1246/bcsj.81.1212
DO - 10.1246/bcsj.81.1212
M3 - Article
VL - 81
SP - 1212
EP - 1218
JO - Bulletin of the Chemical Society of Japan
JF - Bulletin of the Chemical Society of Japan
SN - 0009-2673
IS - 10
ER -