Cerium IV ion

Consider the estimation of iron(II) ions by cerium(IV) ions in aqueous solution ... 

Another process for the production of dodecanedioic acid is by oxidation of cyclododecene using a two-phase system in which mthenium tetroxide serves as the oxidizing agent in the organic phase, and is regenerated in the second phase, an aqueous phase containing cerium(IV) ions (75). 

Under acidic conditions, perfluoroalkyl iodides (but not bromides) react with sodium hydrogen sulfite and cerium(IV) ions to form the corresponding sulfinates [76] (equation 69). 

Ionic strength adjuster buffer 565, 570 Ionisation constants of indicators, 262, (T) 265 of acids and bases, (T) 832, 833, 834 see also Dissociation constants Ionisation suppressant 793 Iron(II), D. of by cerium(IV) ion, (cm) 546 by cerium(IV) sulphate, (ti) 382 by potassium dichromate, (ti) 376 by potassium permanganate, (ti) 368 see also under Iron... 

Worked Example 8.1 In solution, the cerium(IV) ion reacts with aqueous hydrogen peroxide with a 1 1 stoichiometry. The reaction has a rate constant of 1.09 x 106 dm3 mol s. How fast is the reaction that occurs between CeIV and H202, if [CeIV] = 1CT4 mol dm-3 and [H202] = 1CT3 mol dm-3 ... 

In this method lg of soil is refluxed with 2M sodium hydroxide after centrifuging to remove solids. The clean extract is digested with perchloric acid-nitric acid at 265 °C. The iodine content of the extract is determined by the catalytic action of iodine on the oxidation of arsenic III ions with cerium IV ions. Between 96 and 97% recovery of added iodine spikes to soil were obtained by this method. 

In grafting reactions initiated by redox processes, there is an interaction of the intermediate products with the substrate polymer chains. There may also be a chain transfer reaction involved. It is sometimes difficult to make a clear distinction between a direct redox reaction and a chain transfer process. Three redox systems have been studied extensively in grafting onto cellulose persulfate ions 1, hydroperoxide/ferrous ions 2> 3 and cerium (IV) ions. ... 

Write a balanced half-reaction for the reduction of cerium(IV) ions to cerium(III) ions. 

Ceric ammonium nitrate is used as a volumetric oxidizing reagent in many oxidation-reduction titrations. Cerium(IV) ion is a strong oxidant simdar to permanganate ion. It is the most widely-used primary standard among all Ce(IV) compounds. Other apphcations of this compound are in organic oxidation reactions and as a catalyst in polymerization of olefins. 

The mechanism of grafting polymer side chains to cellulose by Cerium (IV) ions is best understood by the oxidation of pinacol with ceric sulphate investigated 1959 by Mino, Kaizerman and Rasmussen... 

Self-Test K.4B Cerium(IV) ions oxidize iodide ions to iodine and are themselves reduced to cerium(HI) ions. Write the net ionic equation for the reaction. 

Nitration of naphthalene by use of cerium(IV) ammonium nitrate suspended on silica gel, or in homogeneous solution, in the presence of alcohols, sodium or tetrabutylammonium nitrite and acid gives mainly l-alkoxy-4-nitronaphthalenes together with some of the 2-nitro isomers.34 The results are consistent with initial attack by N02- alone or complexed with cerium(IV) ion at the 1- and 2-positions in a ratio of 5 1. 

The availability of a-dioximes, which makes them the most common source of furazans also accounts for their widespread use in furoxan preparations. Divers oxidizing agents have been employed, including alkaline hypohalites, potassium ferricyanide, lead tetraacetate, oxides of nitrogen, cerium(IV) ion, AModosuccinimide (80H(14)1279), and phenyl-iodine(III) bistrifluoroacetate. Electrochemical oxidation has also been reported. 

Molybdate, chromates, iodides, bromides, cerium(IV) ions and also large amounts of coloured metallic salts reduce the sensitivity of the reaction. 

Sodium thiosulphate solution no precipitate (distinction from thorium and from cerium(IV) ions). 

Reactions of cerium(IV) ions To study these reactions use a 01m solution of cerium(IV) sulphate, Ce(S04)2.4H20 or cerium(IV) ammonium sulphate Ce(S04)2.2(NH4)2S04.2H20. These solutions should contain a few per cent of free sulphuric acid. Both solutions are orange-yellow. On standing a fine... 

Reducing agents (e.g. hydrogen sulphide, sulphur dioxide, hydrogen peroxide, and hydr iodic acid) These convert cerium(IV) ions into cerium(III). 

For oxidation-reduction reactions that occur in aqueous solution, it is often useful to separate the reaction into two half-reactions one involving oxidation and the other involving reduction. For example, consider the unbalanced equation for the oxidation-reduction reaction between cerium(IV) ion and tin(II) ion ... 

Cerium(IV) ion is a strong oxidizing agent that accepts one electron to produce cerium(III) ion ... 

Dipyridyl and orthophenanthroline form particularly stable complexes with iron. The octahedral [Fe(phcn)3] + ion (Fig. 2C4) is blood-red but is oxidised to pale blue [Fe(phen)3] without any structural change. for the system = 1.14 V, making the compound, also known as ferroin, a most useful redox indicator for the oxidation of Fe + ion Fe +/Fe + = 0.77 V) by cerium(IV) ion (E Ce +/Ce + = 1.45 V). 

Cerium(IV) ions are strong oxidizing agents in acidic solution, oxidizing arsenious acid to arsenic acid according to the following equation ... 

In an oxidation/reduction reaction, electrons are transferred from one reactant to another. An example is the oxidation of iron(II) ions by cerium(IV) ions. The reaction is described by the equation... 

Solutions of permanganate ion and cerium(IV) ion are strong oxidizing reagents whose applications closely parallel one another. Half-reactions for the two are... 

Cerium(IV) ions give a yellow colour in H2SO4 and HNO3 solutions, with maximum absorption in the UV region and e = 5.6-10 at 320 nm. 

Then Br02 reacts with cerium(III) ion to yield bromous acid and cerium(IV) ion (= cerium oxidation)... 

In the case of cerium exchanged zeolites, the ionic exchanges were carried out under nitrogen, in order to avoid the oxidation of cerium (III) ions. Part of the cerium (III) exchanged zeolite was calcined under oxygen for 6 hours at 540°C in order to convert cerium (III) to cerium (IV) ions. Lanthanum-cerium exchanged zeolites were prepared with the following composition 75% La, 25% Ce 50% La, 50% Ce and 25% La, 75% Ce. 

Similarly, the specific oxidation of glycols and related compounds has been found to proceed through the formation of intermediate chelates. For example, in the oxidation of 2,3-butanediol in nitric acid solution by cerium (IV) ions, the metal ion probably forms an intermediate chelate with the glycol, extracts an electron from the ligand, and is reduced to its lower oxidation state. A carbon-carbon bond in the glycol is broken in this process with the resultant formation of acetaldehyde (71). 

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