Nitric acid cerium complexes

NOjQH, 4-Pyridinecarboxylic acid, cobalt complexes, 23 113 NOjSCjHj, L-Cysteine, gold complex, 21 31 N03CjH7, Serine, copper complex, 21 115 NO,H, Nitric acid, cerium complexes, 23 178 cobalt complexes, 23 171 N03SC7Hs, o-Benzosulfimide (saccharin), metal complexes, 23 47 N05P2WC4 Hj, Tungstate(l -), pentacarbon-ylhydrido-, p,-nitrido-bis(triphenylphos-phorus)(l + ), 22 182... 

Tri-n-butyl phosphate, ( -C4H9)3P04. This solvent is useful for the extraction of metal thiocyanate complexes, of nitrates from nitric acid solution (e.g. cerium, thallium, and uranium), of chloride complexes, and of acetic acid from aqueous solution. In the analysis of steel, iron(III) may be removed as the soluble iron(III) thiocyanate . The solvent is non-volatile, non-flammable, and rapid in its action. 

The cobalt complex is usually formed in a hot acetate-acetic acid medium. After the formation of the cobalt colour, hydrochloric acid or nitric acid is added to decompose the complexes of most of the other heavy metals present. Iron, copper, cerium(IV), chromium(III and VI), nickel, vanadyl vanadium, and copper interfere when present in appreciable quantities. Excess of the reagent minimises the interference of iron(II) iron(III) can be removed by diethyl ether extraction from a hydrochloric acid solution. Most of the interferences can be eliminated by treatment with potassium bromate, followed by the addition of an alkali fluoride. Cobalt may also be isolated by dithizone extraction from a basic medium after copper has been removed (if necessary) from acidic solution. An alumina column may also be used to adsorb the cobalt nitroso-R-chelate anion in the presence of perchloric acid, the other elements are eluted with warm 1M nitric acid, and finally the cobalt complex with 1M sulphuric acid, and the absorbance measured at 500 nm. 

The cerium(IV) oxidation of lactyllactic acid49 and of 4-oxopentanoic acid50 in aqueous nitric acid solutions shows first-order dependence of the reaction on both cerium(IV) and substrate. A 1 1 complex formation between manganese(III) and amine, which later decomposes in the rate-limiting step, best explains the kinetics of oxidation of aliphatic amines by cerium(IV) in nitric acid medium in the presence of manganese(II).51 The kinetics of oxidation of naphthalene, 2-methyhiaphthalene, and a-naphthol with cerium(IV) in perchloric acid solutions have been studied.52 Use of a 50-fold molar excess of cerium(IV) perchlorate results in complete oxidation of fluorophenols to CO2, HCO2H, and HF in 48 h at 50 °C.53... 

It was one of Berzelius assistants and the curator of the mineral collections of the Stockholm Academy of Sciences, Carl Gustaf Mosander (1797-1858), who demonstrated the complexity of both "yttria" and "ceria." When Mosander heated some "cerium" nitrate in 1839, the salt partly decomposed, and on a treatment with dilute nitric acid, he succeeded in extracting a new earth. He called the new element lanthanum (German Lanthan) and its oxide "lanthana." Mosander retained the old name ceria (Ce) for the insoluble portion of the "ceric" oxide in nitric acid. 

In nitric acid solutions the potential is somewhat lowered ( ° = 1.61 V in 1.0 M HNO3), suggesting a partial complexation of the Ce " " aquo ion by nitrate. The stability and stoichiometry of soluble ceric nitrate complexes is not well established, but certainly must include at least CeNOj and probably Ce(N03)2 or mixed Ce(IV) OH-NO3 species. Since nitrate complexes are intermediate in stability between those of perchlorate (barely perceptible) and sulfate (moderately strong), cerium(IV) speciation in nitric acid probably also includes hydrolytic species. Ceric ammonium nitrate, (NH ljCefNOj), is a preferred ceric reagent, because it appears to minimize irreversible polymerization of Ce(IV). 

Since about 40% of R in minerals of the lighter lanthanides (large ionic radii) is cerium, it early attracted interest to remove the large majority of cerium in a simple process. Bromate oxidizes Ce(III) to a precipitate in solutions buffered by the reactive, but only slightly soluble base calcium carbonate. Ethers can extract ah orange cerium(IV) complex from nitric acid. Concentrates with minor amounts of other R can be recrystallized as (NH4)2Ce(N03). ... 

Their cerium complex is reported as stable to air and acid (although decomposed by hot nitric acid), properties which are not consistent with those of the known bis([8]annulene)actinide(IV) complexes. The infrared spectrum of their complex is also inconsistent with the presence of a planar [8]annulene ligand. We have attempted to duplicate the synthesis of cerocene by the method of Kalsotra, Multani, and Jain and have not been able to reproduce their reported results. 

The rate law for oxidation of alkane diols by cerium(IV) in nitric acid media suggests formation of intermediate Ce(IV)-diol complexes. With substrates where the —OH groups are separated by five or more carbon... 

Oxalic and malonic acids, as well as a-hydroxy acids, easily react with cerium(IV) salts (Sheldon and Kochi, 1968). Simple alkanoic acids are much more resistant to attack by cerium(IV) salts. However, silver(I) salts catalyze the thermal decarboxylation of alkanoic acids by ammonium hexanitratocerate(IV) (Nagori et al., 1981). Cerium(IV) carboxylates can be decomposed by either a thermal or a photochemical reaction (Sheldon and Kochi, 1968). Alkyl radicals are released by the decarboxylation reaction, which yields alkanes, alkenes, esters and carbon dioxide. The oxidation of substituted benzilic acids by cerium(IV) salts affords the corresponding benzilic acids in quantitative yield (scheme 19) (Hanna and Sarac, 1977). Trahanovsky and coworkers reported that phenylacetic acid is decarboxylated by reaction with ammonium hexanitratocerate(IV) in aqueous acetonitrile containing nitric acid (Trahanovsky et al., 1974). The reaction products are benzyl alcohol, benzaldehyde, benzyl nitrate and carbon dioxide. The reaction is also applicable to substituted phenylacetic acids. The decarboxylation is a one-electron process and radicals are formed as intermediates. The rate-determining step is the decomposition of the phenylacetic acid/cerium(IV) complex into a benzyl radical and carbon dioxide. 

Pu, Zr(+Nb), and Ce and iTithenlum complexes. Neptunium, plutonium, and cerium are made less extractable by reduction to lower oxidation states. Favorable separation of tiranlum from the other elements may be achieved by control.of the nitric acid and saltlng-out agent concentrations. Free halogens are extracted. These elements may be eliminated from solution prior to uranliim extraction. The halogens also combine chemically with a number of solvents eg,. 

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