Cerium chloride preparation

Metallic cerium is prepared by metahothermic reduction techniques, such as reducing cerous fluoride with calcium, or using electrolysis of molten cerous chloride or others processes. The metahothermic technique produces high-purity cerium. 

Mischmetal. Mischmetal [62379-61-7] contains, in metallic form, the mixed light lanthanides in the same or slightly modified ratio as occurs in the resource minerals. It is produced by the electrolysis of fused mixed lanthanide chloride prepared from either bastnasite or mona2ite. Although the precise composition of the resulting metal depends on the composition of chloride used, the cerium content of most grades is always close to 50 wt %. 

Procedure (copper in copper(I) chloride). Prepare an ammonium iron(III) sulphate solution by dissolving 10.0 g of the salt in about 80 mL of 3 M sulphuric acid and dilute to 100 mL with acid of the same strength. Weigh out accurately about 0.3 g of the sample of copper(I) chloride into a dry 250 mL conical flask and add 25.0 mL of the iron(III) solution. Swirl the contents of the flask until the copper(I) chloride dissolves, add a drop or two of ferroin indicator, and titrate with standard 0.1 M cerium(IV) sulphate. 

Addition of 2,6-dimethoxypyrimidine-4-cerium chloride 371 to the chiral lactone 370 occurred without racemization of the chiral center, and the product 372 was subsequently used in a successful total synthesis of (—)-7-epicylindro-spermopsin <2002JA4950, 2005JOC1963>. The cerium reagent was prepared situ from 4-bromo-2,6-dimeth-oxypyrimidine by sequential addition of butyllithium and cerium trichloride. Addition of the same dimethoxypyrimidine-4-cerium derivative to a chiral lactam has also been reported <1999J(P1)1193>. 

Reaction of anhydrous cerium(iii) chloride with RLi reagents affords organocerium compounds The cerium chloride is prepared by heating CeCl3(H20)7 in vacuo up to 140 °C and is in fact a monohydrate [CeCl3(H20)], see W.J. Evans, J.D. Feldman, and J.W. Ziller, J. Am. Chem. Soc., 1996,118,4581. Reaction is carried out at -78 °C, as decomposition is rapid at 0 °C, especially if a /3-hydrogen is present in the R group. The exact nature of the cerium species is uncertain. 

Cerium is prepared by methods similar to those used for other lanthanoids. It is obtained by passing an electric current through cerium chloride ... 

General procedure for the preparation of anhydrous cerium chloride... 

Organocerium reagents are prepared in situ by the reaction of organolithium compounds with anhydrous cerium chloride or ceriiun iodide, as shown in equation (1). A variety of organolithium compounds can be employed, including alkyl-, allyl-, alkenyl- and alkynyl-lithiums, which are all converted to the corresponding cerium reagents. 

Representative examples of the reactions of various carbonyl compounds with Grignard reagents under these conditions are listed in Table 5. It is emphasized that enolization, aldol reaction, ester condensation, reduction and 1,4-addition are remarkably suppressed by the use of cerium chloride. Various tertiary alcohols, which are difficult to prepare by the conventional Grignard reaction, can be synthesized by this method. 

The following procedure is recommended for the small-scale preparation of anhydrous cerium chloride. Cerium chloride heptahydrate (ca. 20 g) is placed in a round-bottomed flask connected to a dry ice trap. The flask is evacuated and heated to lOO °C for 2 h. The resulting opaque solid is quickly pulverized in a mortar and is heated again, in vacuo at the same temperature, for 2 h with intermittent shaking. A stirrer is then placed in the flask, which is subsequently evacuated, and the bath temperature is raised to 135-140 C. Drying is complete after 2-3 h of stirring. 

The preparations of tricyclopentadienyl cerium chloride, bisindenyl cerium dichloride, and dicycloheptatrienyl cerium dichloride are described by the reaction of... 

About 150 years ago metallic cerium was the first rare earth metal to be reduced to its metallic state by reduction of CeCb with Na or K (Mosander, 1827). This was about 40 years after the discovery of the rare earths by Lt. Arrhenius in 1787 in the town of Ytterby, Sweden. The cerium metal prepared by Mosander was a highly contaminated powdered product. Subsequently many other scientists have tried similar procedures and ended up with the same results. It was not until 1937 that Klemm and Bommer (1937) successfully reduced the rare earth chlorides with K in a sealed quartz ampule to prepare reasonably pure powdered rare earth metals. The metals were not separated from the KCl but were suitable for X-ray and magnetic property studies in their as-reduced form. 

Cerium reagents were shown to be reagents of choice in a few reactions, for instance the preparation of ketones from carboxylates, due to a high nucleophilicity and a low basicity. They are usually prepared from lithium reagents by trans-metallation with cerium chloride. The preparation of the required dry" cerium chloride-THF complex was made easier when sonication was effected.228... 

It was Carl Gustaf Mosander (Figure 17.8), from 1836 Berzelius successor as professor of chemistry, who started the great work of separating the almost inseparable. As Berzehus student from 1820 he soon came into his service. He prepared cerium sulfide and let it react with chlorine. Anhydrous cerium chloride CeClj, was formed, from which he prepared metalHc cerium by reduction with potassium metal. This was in about 1825. With all his work with different cerium compounds he began to... 

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