Perchlorate acid media

Kolics A, Thomas A E and Wieckowski A 1996 CI-labelled and electrochemical study of chloride adsorption on a gold electrode from perchloric acid media J. Chem. See. Faraday Trans. 92 3727-36... 

Further substrate and solvent isotope effects were measured by Batts and Gold472 for the dedeuteration and detritiation of labelled 1,3,5-trimethoxy-benzene in aqueous protium- and deuterium-containing perchloric acid. Contrary to the observations above, they found the rate coefficients for dedeuteration to detritiation to be independent of the concentration of the catalysing acid (Table 125). Detritiation in the deuterium-containing aqueous perchloric acid media occurred 1.68 times faster than in the protium-containing media. 

Other examples of linear correlations of log rate coefficients with — H0 have been reported though most of them are deficient in some respect. Satchell474 observed such a correlation in the dedeuteration of anisole and benzene in various aqueous or acetic acid solutions of sulphuric acid, and aqueous perchloric acid, media at 25 °C. First-order rate coefficients are given in Table 127 along with those for dedeuteration of [4,5-2H2]-l,3,5-trimethoxybenzene and -2-hy-droxy-l,3-dimethoxybenzene475. For the ortho- andpara-monodeuterated anisoles the slopes of the log rate versus — H0 plots were the same for aqueous sulphuric acid and for acetic acid-sulphuric acid so that it was concluded that the A-l mechanism therefore applied to non-aqueous media as well as to aqueous media. The fact that the slope of the log rate coefficient versus —H0 plot was less (1.12) for benzene in aqueous perchloric acid than that (1.36) previously found in aqueous... 

The rate coefficients tor detritiation of some 3-substituted-l-tritiated azulenes were also measured in a range of aqueous perchloric acid media at 25 °C (Table 136). The log rate coefficients correlated with — HQ with slopes of 1.05, 1.08,... 

Challis and Long497 have used the fast flow technique described above (p. 217) to measure the equilibrium protonation of azulene in a range of aqueous perchloric acid media at 7.5 °C and hence the rates of the forward protonation and reverse deprotonation, the overall exchange rate being the sum of these. Some representat i ve values are given in Table 141. Coupled with data obtained at other temperatures... 

Only the obvious studies of aqueous plutonium photochemistry have been completed, and the results are summarized below. The course of discussion will follow the particular photochemical reactions that have been observed, beginning with the higher oxidation states. This discussion will consider primarily those studies of aqueous plutonium In perchloric acid media but will include one reaction in nitric acid media. Aqueous systems other than perchlorate may affect particular plutonium states by redox reactions and complex formation and could obscure photochemical changes. Detailed experimental studies of plutonium photochemistry in other aqueous systems should also be conducted. 

FeUu JM, Gomez R, Llorca MS, Aldaz A (1993) Electrochemical behavior of irreversibly adsorbed selenium dosed from solution on Pt(h,k,l) single crystal electrodes in sulphuric and perchloric acid media. Surf Sci 289 152-162... 

Silverman and Dodson made the first detailed isotopic study of this exchange system using the separation afforded by the addition of 2,2 -dipyridyl at pH 5, followed by the precipitation of the ferric iron with either ammonia or 8-hydro-xyquinoline. Dodson , using this separation method, had previously obtained an overall rate coefficient of 16 l.mole" sec at 23 °C for 0.4 M perchloric acid media. The exchange in perchlorate and perchlorate-chloride media was found to conform to a rate law, first order with respect to both total ferrous and ferric ion concentrations, with an observed rate constant (k bs) dependent on the hydrogen-ion concentration, viz. 

Am(V), Am02, undergoes disproportionation and redox reactions in aqueous acidic media, which can be followed by spectrophotometry at wavelengths of 812 m/ii for Am(III), 715 m t for Am(V) and 992 mpt for Am(VI). The earlier work " on solutions of Am(V) in hydrochloric, nitric , sulphuric , and perchloric acid media, which were hindered by a-radiation reactions ( Am), led to the conclusion that the rate law... 

The Pu(IV)+Fe(II) reaction proceeds stoichiometrically in perchloric acid media , viz. 

In perchloric acid media the reaction is extremely slow and is complicated by the formation of polymeric species of tin, and by heterogeneity. Rabideau has examined the kinetics in mixed perchlorate-chloride solutions, in which media no turbidity is apparent. The rate expression is complex, viz. 

Macia MD, Hertero E, Fehu JM. 2003. Fomtic acid oxidation on Bi-Pt(lll) electrode in perchloric acid media. A kinetic study. J Electroanal Chem 554/555 25-34. 

Partial rate factors for the meta positions of phenol and anisole have not been determined in perchloric acid media. The unavailability of such data is a handicap in interpreting the rate data on guaiacol and veratrole. To obtain approximate values for/0OH and/P0H for guaiacol, it was assumed that the partial rate factor 0.25, determined for the meta position of anisole in sulfuric acid (IS), closely approximated the corresponding factor in perchloric acid. 

The kinetics of the oxidation of piperidinone thiosemicarbazones by chloramine-T have been studied in acetic/perchloric acid media.95... 

Tiwari, S., Khan, M. U., Tiwari, B. M. L., Tiwari, K. S., Valechha, N. D. Kinetics and mechanism of oxidation of some 2-alkanones by selenium dioxide in aqueous acetic acid and perchloric acid media. Oxidation Communications 1999, 22,416-423. 

Perchloric Acid Media. In perchloric acid, solutions of Np(III), (IV), and (V) are oxidized after the absorption of 254 or 300 nm radiation in a stepwise fashion according to the following general reactions (15) ... 

Since 1958, more than 20 nuclides of actinides ranging from neptunium to einsteinium were identified and prepared for tracer studies. From neutron-irradiated uranium samples 2 9Np was adjusted to the pentavalent state and separated by TBP extraction from perchloric acid media. Plutonium-239 was separated by TBP extraction from nitric acid solution followed by anion exchange in a system of Dowex-1 resin and nitric acid. Neptunium-237 was separated from a spent fuel solution of JRR-1 (Japan Research Reactor -1) using anion exchange and TBP extraction. The TBP extraction in the hydrochloric acid medium is a simple and effective technique to purify neptunium from plutonium contamination. On the other hand, both anion exchange and solvent extraction with HDEHP could be used to separate tracer scale plutonium from irradiated neptunium targets. 

Figure V-25 Extrapolation to / = 0 of experimental data for the formation of ZrSO "" using the specific ion interaction theory. The data refer to perchloric acid media and are taken from [62RYA/ERM] ( ), [49CON/MCV] (o), [70PRA/HAV] (A), [69NOR] ( ) and [63AFIR/KAR] ( ). All the data have been recalculated in this review. The dashed lines are back-propagated data using the 95% uncertainties in the stability constant and interaction coefficient to / = 5 mol-kg . ...

The kinetics of chromic acid oxidation of D-galactose, D-mannose, L-arabinose, and D-xylose in perchloric acid media have been measured. The reaction was found to be first-order with respect to Cr and to [aldose] but showed a complex dependence on The activation parameters were... 

The oxidation of hydrazine by iodine has been re-investigated in perchloric acid media. This system has been studied previously but with conflicting results, especially in the [I ]-dependence term. Over the pH range 1.5-9.0, the stoicheio-metry is consistent with the reaction... 

Propan-2-ol is oxidized to acetone by vanadium(v) in perchloric acid media requiring a 2 1 stoicheiometry ... 

Catalysis by Ag was also observed in the peroxodiphosphate oxidation of As in perchloric acid media. The reaction rate is independent of [As ] and conforms to the expression... 

The redox reactions of uranium(m) with benzaldehyde and salicylaldehyde (L) have been investigated in perchloric acid media. Two moles of reductant are required for complete reaction and jg found t retard the rate. The rate law is of the form... 

Metal ions as Quenchers With metal ions as quenchers, stability of the oxidized, reduced forms and possible complexation with anions can alter significantly the course of the reaction. Chloride ions are known to associate with Cu(II) to form complexes of the type CuCl+, CuCl2. Fe(III), similarly, exists in the hexa-aquo form only in perchloric acid media and in solvents such as HCl or H2SO4 the ion is present in various complexed forms FeCl2 ", FeCl4, Fe(S04)2 . Due to a change in the nature of the quencher. 

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