Simultaneous Reaction Paths Research Articles

Properties and characterization of red mud modified by hydrochloric, sulfuric, and nitric acid for the catalytic oxidation of toluene

In this paper, red mud (RM), a solid waste with high alkalinity generated by the alumina production industry, was modified using three different acids. The catalytic efficiency of HNO3-MRM was the best, and the T10, T50, and T90 were 280 ℃, 325 ℃, and 361 ℃, respectively. The CO2 selectivity of HNO3-MRM was better than those of HCl-MRM and H2SO4-MRM. Further, the HNO3-MRM catalyst maintained high stability at 420 ℃. This good catalytic performance of HNO3-MRM is related to its high specific surface area, Fe3+ content, surface adsorbed oxygen content, and surface acidic sites. The reaction rate linearly increases with the number of surface acidic sites on the catalyst, indicating that surface acidity is an important factor affecting the catalytic activity of toluene. H2SO4 solution forms calcium sulfate with Ca2+ in the RM, resulting in a lower catalytic activity for H2SO4-MRM. Fe2O3, Al2O3, and SiO2 were the main components of HNO3-MRM. Fe2O3 was the active component of the catalyst, which played the role of the catalytic oxidation of toluene. Al2O3 and SiO2 were used as catalyst carriers. Moreover, the catalytic mechanism of toluene oxidation over the HNO3-MRM catalyst was studied. The catalytic oxidation of toluene on HNO3-MRM catalysts may have two simultaneous reaction paths. The first reaction path would be toluene → species benzyl→ benzaldehyde→ benzoic acid→ heptaldehyde→ CO2 and H2O. The second reaction path would be toluene → benzene →phenol → maleic acid →CO2 and H2O.

Mechanism for basic hydrolysis of N-nitrosoguanidines in aqueous solution.

A kinetic study was carried out on the hydrolysis of two N-nitrosoguanidines, 1-nitroso-1-methyl-3-tolylsulfonylguanidine (TSGNO) and 1-nitroso-1-methyl-3-benzoylguanidine (BCGNO). We observed an absence of buffer catalysis using H(2)PO(4)(-)/HPO(4)(2)(-), H(3)BO(3)/H(2)BO(3)(-), and HCO(3)(-)/CO(3)(2)(-) regulators and a complex dependency of the rate constant on the pH. We discovered the existence of three simultaneous reaction paths: spontaneous decomposition of the neutral form of the N-nitrosoguanidine, decomposition of the monoanion, and decomposition through the form of the dianion. The analysis of the kinetic data has allowed us to obtain the acidity constant for the formation of the monoanion of the N-nitrosoguanidine, with values of p = 11.5. The reaction rate for the process through the monoanion, k(2), decreases as the acidity increases. The application of the principle of nonperfect synchronization shows that the basicity and reactivity do not correlate when there exists a possibility of stabilization of the negative charge by resonance. This behavior is consistent with the mechanism E1cB whereby the stabler the negative charge, the slower the elimination reaction. When dealing with the case of the elimination through the neutral form we observe that the reaction rate increases together with the capacity of stabilization of the positive charge on the nitrogen atom adjacent to the imino group. For the reaction through the dianion we used a maximum value of k(3) = 10(10) s(-)(1) to estimate the value of p for the formation of the dianion of the N-nitrosoguanidine, obtaining values of p < 24.

Spontaneous isothermal decomposition of the uranyl carbonate complex (NH 4) 4[UO 2(CO 3) 3] at room temperature : Part III. Mechanism of the decomposition. Stability of the uranyl molecular orbitals

A mechanism for the spontaneous decomposition of ammonium uranyl carbonate starting with the dissociation of ammonium groups and continuing by further reactions is proposed and discussed. Two simultaneous reaction paths, which differ in their proportion of participation in the overall result, are considered for the first two reaction stages, and neutralization of hydrogen and hydroxyl ions takes place during the third stage. The results agree with the mass-balance calculations. The IR active frequencies are not shifted observably until the third stage where changes of chemical composition are only minor. New experimental material for discussion of some basic problems of uranyl bonding is supplied.

Kinetics and mechanisms of dissociation of metal chelates. II. The acid-catalyzed dissociation of tris(pyridine-2-acetaldehyde-N-Methylimine)iron(II)

The kinetics of the acid-catalyzed dissociation of tris(pyridine-2-acetaldehyde-N-Methylimine)iron(II) were investigated photometrically in 2 M HClLiCl mixtures, ranging from 2 × 10 −5 to 2 M in HCl. The rate of dissociation was shown to be first order in complex. Experimental rate data are in agreement with a mechanism previously suggested for related iron-diimine complexes with unsymmetric ligands. The mechanism consists of two simultaneous reaction paths differing by the sequence in which the bonds between the metal atom and the two different moieties of the ligand are broken. Values for the rate constants and activation parameters of the rate-determininig step were estimated and compared with the values reported for related iron-diimine complexes. The influence of the methyl group, present in the chromophore, on the bonding ability of the ligand is discussed on the basis of these values.

Reactions of N-heteroaromatic bases with nitrous acid. Part 4. Kinetics of the diazotisation of 2- and 4-aminopyridine 1-oxide

The kinetics of the diazotisation of 2- and 4-aminopyridine 1 -oxide have been studied in 0.0025–5.0M-perchloric acid. The reaction is of the first order in both the amine and nitrous acid. The rate coefficient of the reaction increases with an increase in the concentration of perchloric acid and of sodium perchlorate. In perchloric acid solutions whose ionic strength is maintained constant by the addition of sodium perchlorate the rate constant for the reaction does not show a linear dependence on the h0 parameter for the medium, in contrast to the reported linear relationship between the rate coefficient for the diazotisation of 2- and of 4-aminopyridine and the h0 function. The results suggest that diazotisation of 2- and 4-aminopyridine 1 -oxide proceeds by two simultaneous reaction paths both of which contribute significantly to the overall reaction rate. The first involves attack of the nitrous acidium ion on the free amine whilst the second involves attack of the same nitrosating agent on the protonated amine. The amines react faster in the free than in the protonated form. The free and protonated forms of 4-aminopyridine 1 - oxide are diazotised at a greater rate than the corresponding forms of 2-aminopyridine 1-oxide.

Kinetics and mechanism of dissociation of tris(pyridine-2-carbaldehyde-N-propylimine)- and tris(pyridine-2-carbaldehyde-N-methylimine)-iron(II)

The rate of dissociation of tris(pyridine-2-carbaldehyde-N-propylimine)iron(II), [Fe(ppi)3]2+, has been reinvestigated and the studies extended to tris(pyridine-2-carbaldehyde-N-methylimine)iron(II), [Fe(pmi)3]2+. Experimental rate data are in agreement with a mechanism consisting of two simultaneous reaction paths in which the order of bond breaking between the central metal atom and each of the different moieties of the ligand is reversed. Approximate values of rate constants and activation parameters of some of the elementary reaction steps have been obtained for these paths. Comparison with values reported for the complexes of 2.2′-bipyridine. [Fe(bipy)3]2+, and glyoxalbismethylimine. [Fe(gmi)3]2+, suggests that the differences between metal–pyridine and –aliphatic imine bond strengths are significantly reduced on passing from bipy and gmi to the ‘mixed’ ligands pmi and ppi.

ChemInform Abstract: A KINETIC STUDY OF THE LIGAND SUBSTITUTION REACTION OF TETRAMETHYLENEDIAMINETETRAACETATOCOBALTATE(II) WITH TRIMETHYLENEDIAMINETETRAACETATE

Chemischer InformationsdienstVolume 4, Issue 44 Organoelement Compounds ChemInform Abstract: A KINETIC STUDY OF THE LIGAND SUBSTITUTION REACTION OF TETRAMETHYLENEDIAMINETETRAACETATOCOBALTATE(II) WITH TRIMETHYLENEDIAMINETETRAACETATE HIROSHI OGINO, HIROSHI OGINOSearch for more papers by this authorTOSHIYUKI WATANABE, TOSHIYUKI WATANABESearch for more papers by this authorJONG-JAE CHUNG, JONG-JAE CHUNGSearch for more papers by this authorNOBUYUKI TANAKA, NOBUYUKI TANAKASearch for more papers by this author HIROSHI OGINO, HIROSHI OGINOSearch for more papers by this authorTOSHIYUKI WATANABE, TOSHIYUKI WATANABESearch for more papers by this authorJONG-JAE CHUNG, JONG-JAE CHUNGSearch for more papers by this authorNOBUYUKI TANAKA, NOBUYUKI TANAKASearch for more papers by this author First published: October 30, 1973 https://doi.org/10.1002/chin.197344419AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume4, Issue44October 30, 1973 RelatedInformation

A Kinetic Study of the Ligand Substitution Reaction of Tetramethylenediaminetetraacetatocobaltate(II) with Trimethylenediaminetetraacetate

Abstract The kinetics of the ligand substitution reaction of tetramethylenediaminetetraacetatocobaltate(II)(cobalt(II)–TDTA) with trimethylenediaminetetraacetate (TRDTA) was investigated by two different polarographic methods. The kinetic data at pH 4.9 to 5.6 were obtained by means of a conventional method in which the reaction was initiated by the mixing of two reactant solutions and was followed polarographically. However, this method could not be applied to solutions with pH values lower than 4.9, for the rate of the reaction is immeasurably fast in such a low pH region. The kinetic data at pH values down to 3.7 were obtained by analyses of the polarographic current which was observed in solutions containing TRDTA and the substitution-inert cobalt(III)–TDTA complex. From these data, it was found that the reaction proceeds through four simultaneous reaction paths, two paths of which are the nucleophilic substitution reactions, while the others are the dissociation reactions of cobalt(II)–TDTA complex ions.

Kinetics of Multidentate Ligand Substitution Reactions. VIII. Substitution Reactions of Diethylenetriaminepentaacetic Acid with Nickel(II) Iminodiacetate and Aspartate Chelates and of Cyclohexane-1,2-diamine-N,N,N′,N′-tetraacetic Acid with the Nickel(II) Aspartate Chelate

Abstract The substitution reactions of diethylenetriaminepentaacetic acid (DTPA) with nickel(II) chelates of iminodiacetic acid (IDA) and aspartic acid (Asp) and of cyclohexane-1,2-diamine-N,N,N′,N′-tetraacetic acid (CyDTA) with the nickel(II) chelate of aspartic acid were studied by employing the polarographic method. All the reactions studied were found to proceed through the following two simultaneous reaction paths: (Remark: Graphics omitted.) where NiX0 and NiX22− denote nickel(II)-IDA or Asp chelates of 1-to-l and 1-to-2 compositions respectively, and where Zm− indicates a completely-deprotonated DTPA or CyDTA anion. From a comparison of the rate constants of substitution reactions involving the nickel(II)-aspartate chelate with the corresponding rate constants of substitution reactions involving the nickel(II)-iminodiacetate chelate, the six-membered ring of the nickel(II)-aspartate chelate, as compared with its five-membered ring, was concluded to be more labile in the substitution reaction.

The kinetics of the autoxidation of ferrous ions in aqueous tripolyphosphate solutions.

Abstract The kinetics of the autoxidation of ferrous ions in tripolyphosphate solutions (pH 2–8) at an ionic strength of 0.20 m NaClO4 was studied using a spectrophotometric technique. The rate expression for the oxidation reaction is given by: d[Fe(III)]⁄dt=4kI[FeII(Htpp4−)][O2]+4kII[FeII(Htpp4−)2][O2], and 4kII found is to be 1.0×102 m−1 sec−1 at 15°C. The simultaneous reaction paths of FeII(Htpp4−)+O2\xrightarrowkIFeIII(Htpp4−)+O2- and FeII(Htpp4−)2+O2\xrightarrowkIIFeIII(Htpp4−)2+O2- are consistent with the results obtained. When there is an excess of the triphosphate solution in the pH range from 6 to 8, the latter may be the rate-determining step. The acceleration of the oxidation of the ferrous ions in the triphosphate solution may be due to the fact that the stabilization of the oxidation products, FeIII(Htpp4−) and FeIII(Htpp4−)2, is greater than that of the corresponding ferrous triphosphate complexes. As the activation parameters for the latter reaction, the experiments gave the values of ΔH\eweq∼10 kcal mol−1 and ΔS\eweq∼−25 cal mol−1. deg−1. The negative and relatively small value of the entropy of activation suggests that the activated complex is more extensively hydrated than is the ferrous complex of FeII(Htpp4−)2.

The Kinetics of Substitution Reactions Involving Metal Complexes. XIII. Reactions of Zinc(II) with meso-Butylenediaminetetraacetatocobaltatet(II) and with Propylenediaminetetraacetatocobaltate(II)

Abstract Kinetics of the substitution reactions of zinc(II) with meso-butylenediaminetetraacetatocobaltate(II) (cobalt(II)-meso-BDTA) and propylenediaminetetraacetatocobaltate(II) (cobalt(II)-PDTA) have been studied. The reaction of zinc(II) with cobalt(II)-meso-BDTA complex proceeds through two simultaneous reaction paths involving the acid dissociation reactions of the cobalt(II) complex. On the other hand, the reaction of zinc(II) with cobalt(II)-PDTA proceeds through four simultaneous reaction paths, of which two involve electrophilic substitution reactions and the others, the acid dissociation reactions of the cobalt(II) complex. This kinetic behavior is discussed on the basis of the natures of the ligands.

Kinetics of Multidentate Ligand Substitution Reaction. III. Substitution Reactions of BT with Cobalt(II) and Nickel(II) Chelates of N-(2-Hydroxyethyl)-ethylenediamine-N,N′,N′-triacetic Acid and 2,2′-Ethylenedioxybis[ethyliminodi(acetic acid)

Abstract BT can displace EDTA-OH and GEDTA from their cobalt(II) and nickel(II) chelate as in the case of the substitution reaction of BT with cobalt(II)-EDTA chelate or nickel(II)-EDTA chelate. In this paper, kinetics of the substitution reactions of BT with cobalt(II)- and nickel(II)-chelates of EDTA-OH and of GEDTA was studied spectrophotometrically. All substitution reactions were found to be first-order in BT and first-order in metal(II)-chelate of EDTA-OH or GEDTA, and to proceed through two simultaneous reaction paths analogous to those proposed for the substitution reaction of BT with cobalt(II)-EDTA chelate. Although EDTA-OH differs from EDTA by the presence of a hydroxyethyl group in place of one acetate group, its metal(II) chelate behaves in a nearly identical manner with EDTA chelate in the substitution reaction and the cleavage of the metal-nitrogen bond of the glycinate group is considered to be the probable rate-determining step. The substitution reactions of BT with GEDTA chelates are considered to be more favored thermodynamically over the reactions of EDTA-OH chelates, but were found to be less favored kinetically. This fact may suggest that the geometrical structure of metal(II)-GEDTA plays an important role in determining the rate of the substitution reaction of GEDTA.

Spectrophotometric Studies of the Solution Equilibria and the Kinetics of the Substitution Reaction between Eriochrom Black T and Cobalt(II)-Ethylenediaminetetraacetate Chelate

Abstract The solution equilibria and the kinetics of the substitution reaction between Eriochrom Elack T (BT) and cobalt(II)-EDTA chelate were studied spectrophotometrically. At the pH range from 8.50 to 9.50, BT was found to form only 1 to 1 normal chelate CoD with cobalt(II), the stability constant of which is 1020.0(μ=0.30). Kinetically, the substitution reaction was found to proceed through the following two simultaneous reaction paths, i) HD2−+CoY2−\oversetk1+\ightleftharpoonsCoD−+HY3− ii) HD2−\oversetrapid\ightleftharpoonsD3−+H+ D3−CoY2−−\oversetk2+\ightleftharpoonsCoD−+Y4− and k1+ and k2+ were determined to be 0.23 l mol−1 sec−1 and 6.76×102 l mol−1 sec−1, respectively, at 20°C.

The Kinetics of Substitution Reactions Involving Metal Complexes. X. Reactions of Zinc(II) with Ethylenediaminetetraacetatocobaltate(II) and Trimethylenediaminetetraacetatocobaltate(II)

Abstract Kinetics of the substitution reactions of zinc(II) with ethylenediaminetetraacetatocobaltate(II) and with trimethylenediaminetetraacetatocobaltate(II) have been studied. These reactions proceed predominantly through three simultaneous reaction paths, of which two involve electrophilic substitution reactions and the rest does the dissociation reaction of the complex. The rates of the reactions involving trimethylenediaminetetraacetatocobaltate(II) are larger than those involving ethylenediaminetetraacetatocobaltate(II) for all of the three simultaneous reaction paths. These results are discussed on the basis of the nature of the ligands and the stability of reaction intermediates.

The Kinetics of Substitution Reactions Involving Metal Complexes. IX. Reactions between Copper(II) and Propylenediaminetetraacetatoplumbate(II) and between Lead(II) and Propylenediaminetetraacetatozincate(II)

Abstract Kinetic studies of the reactions between copper(II) and propylenediaminetetraacetatoplumbate(II) and between lead(II) and propylenediaminetetraacetatozincate(II) have been carried out. It was revealed from these studies that the reactions proceed through four simultaneous reaction paths, of which two involve electrophilic substitution reactions and the others, the complex-forming reactions between entering metal ions and ligands dissociated from complexes. The rate constants were compared with those of the corresponding reactions involving metalethylenediaminetetraacetate and the effects of ligands on the reaction rates were discussed.

The Kinetics of Substitution Reactions Involving Metal Complexes. VIII. Reaction between Copper(II) and Ethylenediaminetetraacetatocobaltate(II) Complexes in Aqueous Solutions

Abstract The kinetic study of the substitution reaction of copper(II) ions and cobalt(II)-EDTA complexes in acetate buffer solutions has been carried out with the same procedure as that reported previously. The reaction was found to proceed, under the experimental conditions, through three simultaneous reaction paths similar to those found in the substitution reaction of copper(II) ions and lead(II)-EDTA complexes. The rate constants for three elementary reactions of those reaction paths were determined at ionic strength 0.2 at 5 and 15°C. A reaction path in which the dissociation of cobalt(II)-EDTA complex is rate-determining was not observed in this substitution reaction.

The Kinetics of Substitution Reactions Involving Metal Complexes. VI. Reaction between Lead(II) and Ethylenediaminetetra-acetatocobaltate(II) Complexes in Aqueous Solutions

Abstract The kinetic study of the substitution reaction of lead(II) and ethylenediaminetetraacetatocobaltate(II) complexes in aqueous solutions has been carried out by a similar method as reported previously. The reaction was found to proceed through four simultaneous reaction paths and to be characterized by involving the dissociation of ethylenediaminetetraacetatocobaltate(II) complexes as a rate-determining process. The rate constants of the rate-determining steps of four reaction paths were determined at ionic strength 0.2 at 5 and 15°C. It was confirmed also that this substitution reaction proceeds through both hydrated and monoacetato lead(II) ions.