Copper-Catalyzed Oxidation of Cyanide by Peroxide in Alkaline Aqueous Solution

1995 ◽  
Vol 48 (4) ◽  
pp. 861 ◽  
Author(s):  
JK Beattie ◽  
GA Polyblank
Keyword(s):  
Aqueous Solution ◽  
Copper Complexes ◽  
Final Concentration ◽  
First Order ◽  
Alkaline Aqueous Solution ◽  
Catalysed Oxidation ◽  
Complex Forms ◽  
Kinetics Of ◽  
Catalyzed Oxidation ◽  
Destructive Oxidation

The oxidation of cyanide by peroxide in alkaline aqueous solution is catalysed by copper complexes. In the presence of excess cyanide, copper(II) is reduced to form the tricyanocuprate (I) complex. The cyanogen oxidation product is hydrolysed with disproportionation to cyanate and cyanide:2CuII+2CN-→ 2CuI+(CN)2(CN)2+2OH- → OCN-+CN-+H2OCuI+3CN- ↔ Cu(CN)32-The stoichiometry and kinetics of the catalysed oxidation have been investigated. Hydrogen peroxide oxidizes coordinated cyanide with a rate that is first order in peroxide and first order in copper but independent of cyanide concentration in the presence of excess cyanide. Cu(CN)32-+H2O2→ Cu(CN)2-+OCN-+H2O Cu(CN)2-+CN-↔ Cu(CN)32- When the excess cyanide is consumed and Cu(CN)2- becomes the dominant species, the reaction becomes more complex and less efficient. Under certain conditions the stoichiometry revealed a peroxide-to-Cu(CN)2- ratio of about 6 : 1, instead of the minimum of 2.5:1 required for the oxidation of the coordinated cyanide to cyanate and the CuI to Cu(OH)2. This suggests that peroxide is consumed by a copper- catalysed disproportionation, in competition with oxidation of the coordinated cyanide. An intermediate yellow complex forms while peroxide is present, before Cu(OH)2 finally precipitates. The consequence of this mechanism is that the most efficient process for the destructive oxidation of cyanide has a high cyanide-to-copper ratio, to minimize the final concentration of Cu(CN)2- which consumes peroxide inefficiently. The rate of the reaction depends on the concentration of copper, however, which must be large enough for a satisfactory turnover.

Dissociation kinetics of metal complexes in acid. Copper complexes of triazamacrocycles

1981 ◽  
Vol 34 (2) ◽  
pp. 291 ◽  
Author(s):  
PG Graham ◽  
DC Weatherburn
Keyword(s):  
Aqueous Solution ◽  
Copper Complexes ◽  
Activation Parameters ◽  
Macrocyclic Complex ◽  
Acid Dissociation ◽  
General Mechanism ◽  
Dissociation Kinetics ◽  
First Order ◽  
High Concentrations ◽  
Kinetics Of

The acid dissociation kinetics of the mono-copper complexes of 1,4,7-triazacyclononane, znn; 1,4,7-triazacyclodecane, zdn; 1,4,8-triazacycloundecane, zud; 1,5,9-triazacyclododecane, zdd; 2,2,4-trimethyl-1,5,9-triazacyclododecane, tmzdd; 1,5,9-triazacyclotridecane, ztd; and cyclohexane- r-1,c-3,c-5 triamine, ccha, were studied in aqueous solution over a range of acid concentrations (0.025-0.5 mol dm-3), I 1.0 (NaN03). A variety of kinetic behaviour is observed. Cu(znn)2+, Cu(zdn)2+ and Cu(zud)2+ display a first-order dependence upon [H+] with kH (298 K) 51 dm3 mol-1 s-1 (znn), 17 dm3 mol-1 s-1 (zdn), and 5.6 dm3 mol-1 s-1 (zud). Cu(zdd)2+, Cu(ztd)2+ and Cu(ccha)2+ show a dependence on [H+] at low acid concentrations but become acid-independent at high concentrations. The acid-independent rate constants are k1 (298 K) 2.2 s-1 (zdd), 15.4 s-1 (ztd) and k1 (283 K) 75 s-1 (ccha). Cu(tmzdd)2+ shows a rate law of the form rate = k+kH[H+] with k (298 K) 1.8×10 s-1 and kH (298 K) 2.0×10-3 dm3 mol-1 s-1. Activation parameters have been determined in all cases except Cu(ccha)2+ which was studied at 10�C. The results are compared with other macrocyclic complex systems, and a general mechanism for these reactions is discussed.

The mechanism of the oxidation of thiocyanate ion by peroxomonosulphate in aqueous solution. II. Kinetics of the reaction

1966 ◽  
Vol 19 (8) ◽  
pp. 1365 ◽  
Author(s):  
RH Smith ◽  
IR Wilson
Keyword(s):  
Aqueous Solution ◽  
Initial Rate ◽  
Stopped Flow ◽  
Thiocyanate Ion ◽  
First Order ◽  
Conductance Method ◽  
Rate Of Reaction ◽  
Kinetics Of

Initial rates of reaction for the above oxidation have been measured by a stopped-flow conductance method. Between pH 2 and 3.6, the initial rate of reaction, R, is given by the expression R{[HSO5-]+[SCN-]} = {kb+kc[H+]}[HSO5-]0[SCN-]20+ka[H+]-1[HSO5]20[SCN-]0 As pH increases, there is a transition to a pH-independent rate, first order in each thiocyanate and peroxomonosulphate concentrations.

scholarly journals EFFECT OF DIATOMEAOUS EARTH TREATMENT USING HYDROGEN CHLORIDE AND SULFURIC ACID ON KINETICS OF CADMIUM(II) ADSORPTION

2010 ◽  
Vol 2 (2) ◽  
pp. 107-112
Author(s):  
Nuryono Nuryono ◽  
Narsito Narsito
Keyword(s):  
Aqueous Solution ◽  
Sulfuric Acid ◽  
Hydrogen Chloride ◽  
Rate Constant ◽  
Diatomaceous Earth ◽  
Adsorption Rate ◽  
Physical Interaction ◽  
First Order ◽  
Adsorption Rate Constant ◽  
Kinetics Of

In this research, treatment of diatomaceous earth, Sangiran, Central Java using hydrogen chloride (HCl) and sulfuric acid (H2SO4) on kinetics of Cd(II) adsorption in aqueous solution has been carried out. The work was conducted by mixing an amount of grounded diatomaceous earth (200 mesh in size) with HCl or H2SO4 solution in various concentrations for two hours at temperature range of 100 - 150oC. The mixture was then filtered and washed with water until the filtrate pH is approximately 7 and then the residue was dried for four hours at a temperature of 70oC. The product was used as an adsorbent to adsorb Cd(II) in aqueous solution with various concentrations. The Cd(II) adsorbed was determined by analyzing the rest of Cd(II) in the solution using atomic absorption spectrophotometry. The effect of treatment was evaluated from kinetic parameter of adsorption rate constant calculated based on the simple kinetic model. Results showed  that before equilibrium condition reached, adsorpstion of Cd(II) occurred through two steps, i.e. a step tends to follow a reaction of irreversible first order  (step I) followed by reaction of reversible first order (step II). Treatment with acids, either hydrogen chloride or sulfuric acid, decreased adsorption rate constant for the step I from 15.2/min to a range of 6.4 - 9.4/min.  However, increasing concentration of acid (in a range of concentration investigated) did not give significant and constant change of adsorption rate constant. For step II process,  adsorption involved physical interaction with the sufficient low adsorption energy (in a range of 311.3 - 1001 J/mol).     Keywords: adsorption, cdmium, diatomaceous earth, kinetics.

Ruthenium catalysed oxidation of cyclohexanol

1982 ◽  
Vol 35 (6) ◽  
pp. 1245 ◽  
Author(s):  
P Becker ◽  
JK Beattie
Keyword(s):  
Aqueous Solution ◽  
Isotope Effect ◽  
Phosphate Buffer ◽  
Hydride Transfer ◽  
Deuterium Isotope Effect ◽  
Rate Law ◽  
Alkaline Aqueous Solution ◽  
Catalysed Oxidation

The oxidation of cyclohexanol by ferricyanide in alkaline aqueous solution is catalysed by micromolar concentrations of K3RuCl6. The rate law at 25.0�C in pH 11.9 phosphate buffer containing 0.50 M NaCl is -d[FeIII]/dt = [Ru](2klk2[alcohol][FeIII])/(2kl[alcohol] + k2[FeIII]) with kl 12 � 2 mol-1 1. s-1 and k2 (2.5 � 0.2) × 102 mol-1 1. s-1. A deuterium isotope effect of about 4 is observed when (D12)cyclohexanol is used. A mechanism consistent with these observations involves reduction of the RuIII catalyst by hydride transfer from the alcohol followed by reoxidation by ferricyanide to the original RulIII state.

Kinetics of the Reaction Between S2O3-- and I3- in Aqueous Solution

1974 ◽  
Vol 29 (1) ◽  
pp. 141-144
Author(s):  
T. S. Rao ◽  
S. I. Mali
Keyword(s):  
Aqueous Solution ◽  
Reduction Potential ◽  
Frequency Factor ◽  
Effective Concentration ◽  
Specific Rate ◽  
Platinum Foil ◽  
First Order ◽  
Entropy Of Activation ◽  
Kinetics Of ◽  
Foil Electrode

The kinetics of the reaction between has been studied under conditions of production of iodine at a known rate by the persulfate-iodide reaction and its consumption by S2O3-- . The effective concentration of iodine during the steady state is measured from its reduction potential at a bright platinum foil electrode. The reaction is of first order with respect to I3- and S2O3-- individually and hence of over all second order. The specific rate is 1.51 X 105 M -1 sec-1 and the frequency factor is 1.69 × 1012 M -1 sec-1 at 25 °C. The energy of activation for the reaction is 9.58 × 103 cal/mole and the entropy of activation is -2.55 cal/mole deg.

Osmium(VIII) Catalyzed Oxidation of Acetone and Ethylmethyl Ketone by Chloramine-T

1972 ◽  
Vol 27 (10) ◽  
pp. 1161-1163 ◽  
Author(s):  
S. P. Mushran ◽  
R. Sanehi ◽  
M. C. Agraval
Keyword(s):  
Acidic Medium ◽  
Present Note ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Slow Step ◽  
First Order ◽  
Chloramine T ◽  
Kinetics Of ◽  
Catalyzed Oxidation ◽  
High Redox Potential

The Osmium (VIII) catalyzed oxidation of acetone and ethylmethyl ketone by chloramine-T, in highly alkaline solutions showed first order dependence to chloramine-T and osmium (VIII). The order of the reactions with respect to alkali and ketone were found to be fractional, being ~-0.82 and 0.3 respectively. No effects of ionic strength were evident. The mechanism has been proposed on the basis of the formation of a complex between N-chlorotoluene-p-sulfonamide and osmium (VIII) in the slow step, which in turn oxidizes the enol anion of the reducing substrate in the fast step.During the study of the mechanism of oxidations by chloramine-T, the kinetics of the oxidation of α-hydroxy acids 1 in presence of osmium (VIII) as catalyst, glycerol2 in neutral and alkaline media, p-cresol3 in an acidic medium, hexacyanoferrate (II)4 in a feebly acidic medium (pH 6-7) and aliphatic aldehydes 5 in alkaline media have been investigated.Despite the high redox potential6 of the chloramine-T/toluene sulfonamide system (1.138 V at pH 12), the oxidation of acetone does not take place in absence of catalyst and that of ethylmethyl ketone proceeds only in highly alkaline solutions7 (NaOH>0.01 M). In the present note the kinetics of the osmium (VIII) catalyzed oxidation of acetone and ethylmethyl ketone have been recorded.

Kinetics of Glyphosate Adsorption on Composite Resin from Aqueous Solution

2013 ◽  
Vol 803 ◽  
pp. 157-160
Author(s):  
Zhen Zhen Kong ◽  
Dong Mei Jia ◽  
Su Wen Cui
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Composite Resin ◽  
Order Equation ◽  
Second Order ◽  
First Order ◽  
Basic Resin ◽  
Pseudo Second Order ◽  
Kinetics Of ◽  
Best Fit

The composite weakly basic resin (D301Fe) was prepared and examined using scanning electron microscopy and Fourier transform infrared spectroscopy. The adsorption kinetics of glyphosate from aqueous solution onto composite weakly basic resin (D301Fe) were investigated under different conditions. The experimental data was analyzed using various adsorption kinetic models like pseudo-first order, the pseudo-second order, the Elovich and the parabolic diffusion models to determine the best-fit equation for the adsorption of glyphosate onto D301Fe. The results show that the pseudo-second order equation fitted the experimental data well and its adsorption was chemisorption-controlled.

Kinetics and mechanism of gold(III) incorporation into tetrakis(1-methylpyridium-4-yl)porphyrin in aqueous solution

2004 ◽  
Vol 08 (11) ◽  
pp. 1269-1275 ◽  
Author(s):  
Ahsan Habib ◽  
Masaaki Tabata ◽  
Ying Guang Wu
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Kinetic Data ◽  
Ph Dependence ◽  
Equilibrium Constants ◽  
Hydroxyl Group ◽  
Net Charge ◽  
First Order ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of the reaction of the tetrakis(1-methylpyridium-4-yl)porphyrin tetracation, [ H 2( TMPyP )]4+, with gold(III) ions were studied along with equilibria of gold(III) species in aqueous medium at 25°C, I = 0.10 M ( NaNO 3). The equilibrium constants for the formation of [ AuCl 4-n( OH ) n ]- ( n = 0,…,4), defined as β n = [ AuCl 4- n ( OH ) n ]- [ Cl -] n / [ AuCl 4-][ OH -] n were found to be that log β1 = 7.94 ± 0.03, log β2 = 15.14 ± 0.03, log β3 = 21.30 ± 0.05 and log β4 = 26.88 ± 0.05. The overall reaction was first order with respect to each of the total [ Au (III)] and [ H 2 TMPyP 4+]. On the basis of pH dependence on rate constants and the hydrolysis of gold(III), the rate expression can be written as d [ Au ( TMPyP )5+]/ dt = ( k 1[ AuCl 4-] + k2[ AuCl 3( OH )-] + k3[ AuCl 2( OH )2-] + k4[ AuCl ( OH )3-])[ H 2 TMPyP 4+], where k1, k2, k3 and k4 were found to be (2.16 ± 0.31) × 10-1, (6.56 ± 0.19) × 10-1, (1.07 ± 0.24) × 10-1, and (0.29 ± 0.21) × 10-1 M -1. s -1, respectively. The kinetic data revealed that the trichloromonohydroxogold(III) species, [ AuCl 3( OH )]-, is the most reactive. The higher reactivity of [ AuCl 3( OH )]- is explained by hydrogen bonding formation between the hydroxyl group of [ AuCl 3( OH )]- and the pyrrole hydrogen atom of [ H 2( TMPyP )]4+. Furthermore, applying the Fuoss equation to the observed rate constants at different ionic strengths, the apparent net charge of [ H 2( TMPyP )]4+ was calculated to be +3.5.

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