Cerium III

21 CERIUM, Ce (Ar 140-12) - CERIUM(III) Cerium is a white-grey, soft metal, which melts at 795°C. In its compounds cerium can be tervalent and quadrivalent, forming cerium(III), Ce3+, and cerium(IV), Ce4+, ions respectively. 

Reactions of cerium(III) ions To study these reactions use a 0- 1m solution of cerium(III) nitrate Ce(N03)3.6H20. 

Ammonia or ammonium sulphide solution white precipitate of cerium(III) hydroxide, Ce(OH)3 (or Ce203.xH20), insoluble in excess of the precipitant, but readily soluble in acids. The precipitate slowly oxidizes in the air, finally becoming converted into yellow cerium(IV) hydroxide, Ce(OH)4 (or Ce02.xH20). Sodium hydroxide solution gives a similar result. The precipitation is prevented by tartrates and citrates. 

Oxalic acid or ammonium oxalate solution white precipitate of cerium(III) oxalate, insoluble in excess reagent (compare thorium and zirconium), and in very dilute mineral acids. 

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

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Nitrate. Cerium(III) nitrate hexahydrate [10294-41 -4] Ce(N03) 6H20, is a commercially available soluble salt of cerium, and because of ready decomposition to the oxide, it is used, for example, when a porous sohd is to be impregnated with cerium oxide. The nitrate is very soluble in water, up to about 65 wt %. It is also soluble in a wide range of polar organic solvents such as ketones, alcohols, and ethers. 

Cerium(III) oxysulfide [12442-45-4], is a high melting stable compound that precipitates out when steel is treated with a cerium-based metal... 

Miscellaneous Compounds. Among simple ionic salts cerium(III) acetate [17829-82-2] as commercially prepared, has lV2 H2O, has a moderate (- 100 g/L) aqueous solubiUty that decreases with increased temperature, and is an attractive precursor to the oxide. Cerous sulfate [13454-94-9] can be made in a wide range of hydrated forms and has solubiUty behavior comparable to that of the acetate. Many double sulfates having alkaU metal and/or ammonium cations, and varying degrees of aqueous solubiUty are known. Cerium(III) phosphate [13454-71 -2] being equivalent to mona2ite, is very stable. 

Cero-. ceroua, cerium(III). -ion, n. ceroua ion, eerium(III) ion. -salz, n. eerous salt, cerium (III) salt, -sulfat, n. ceroua sulfate, cerium(III) sulfate. 

Discussion. Iron(III) (50-200 fig) can be extracted from aqueous solution with a 1 per cent solution of 8-hydroxyquinoline in chloroform by double extraction when the pH of the aqueous solution is between 2 and 10. At a pH of 2-2.5 nickel, cobalt, cerium(III), and aluminium do not interfere. Iron(III) oxinate is dark-coloured in chloroform and absorbs at 470 nm. 

Solutions of cerium(IV) sulphate in dilute sulphuric add are stable even at boiling temperatures. Hydrochloric add solutions of the salt are unstable because of reduction to cerium(III) by the add with the simultaneous liberation of chlorine ... 

Alternatively, the hydroxy group can be converted to the tosyl ester168 or replaced by chlorine108,169 followed by a base-catalyzed elimination. 1-Benzoxepin-5-(4//)-one is reduced with cerium(III) chloride/sodium borohydride to the hydroxy derivative. After conversion to the p-toluenesulfonate, the double bond is formed in 2 upon treatment with potassium tert-pen-toxide.168... 

The addition of a phenylcerium reagent 0 PhCeCl, ) in tctrahydrofuran to the pyrazoline 4 at — 78 C using an equimolar ratio of cerium(III) chloride, phenyllithium and pyrazoline (CcCI3/ Cf,H,I-i/4 1 1 1) exclusively provides the desired pyrazolidine 5 in good yields (75-94%). This product can be converted to the diamine 3a (R = H) and subsequently into numerous N-sub-stituted derivatives of 3a (e.g.. 3b R = CH3) by means of simple standard procedures23. 

E.22 (a) How many CaH2 formula units are present in 5.294 g of CaH2 (b) Determine the mass of 6.25 X 1024 formula units of NaBF4, sodium tetrafluoroborate. (c) Calculate the amount (in moles) of 9.54 X 1021 formula units of Cel3, cerium(III) iodide, a bright yellow, water-soluble solid. 

Sfi.f-Test K.4B In aqueous solution, cerium(lV) ions oxidize iodide ions to solid diatomic iodine and are themselves reduced to cerium(III) ions. Write the net ionic equation for the reaction. 

Jorgensen CK (1996) Luminescence of Cerium (III) Inter-Shell Transitions and Scintillator Action. 85 195-214... 

Cerium(III) also proved to be an effective inhibitor of the oxidation of formic acid. As the oxidation of cerium(rri) to cerium(IV) is a 1-equivalent process, the inhibition furnishes additional evidence for the chromium(IV) species as intermediate. 

Returning to the explanation of induced reactions, we can say the following. Friend s proposal , according to which the error in the H2O2 determination is caused by reaction (83) catalyzed by manganese(II) or cerium(III) formed in the primary reaction between hydrogen peroxide and permanganate or cerium(IV) cannot be accepted. The reaction between the ions mentioned and peroxydisulphate at room temperature is very slow, and, furthermore, the increase in acidity —in contrast to its effect on the induced reaction —promotes the oxidation. There is... 

Bachmartn, K., Boden, J., and Haumann, I., Indirect fluorimetric detection of alkali and alkaline earth metal ions in capillary zone electrophoresis with cerium (III) as carrier electrolyte, /. Chromatogr., 626, 259, 1992. 

Palladium (II) chloride and ferric (III) chloride were purchased from Sigma Chemicals Co. Cerium(III) nitrate from Pfaltz Bauer, Inc. y-Al203 (100 m2/g) from Alfa Chemicals ethanol (HPLC grade) and nitrobenzene (Certified ACS) from Fisher Scientific. Bis(triphenylphosphine)palladium(II) dichloride was generously donated by Dr. Ivan J.B. Lin (National Dong Hwa University, Taiwan). All compounds were used without further treatment. Carbon monoxide (99.0%) was obtained from Praxair. 

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