Cerium salt

Cerium Oxide. The most stable oxide of cerium is cerium dioxide [1306-38-3] Ce02, also called ceria or ceric oxide. When cerium salts are calcined in air or if oxygen is present, this tetravalent Ce(IV) oxide is formed, cerium sesquioxide [1345-13-7] can be prepared in strongly reducing... 

As it was shown in73, 74), methods that can be used to synthesize these copolymers of PAN are those of radical AN block copolymerization in the presence of an oxidation-reduction system in which the hydroxyl end groups of polyethylene oxide) (PEO)73) and polypropylene oxide) (PPO)74- oligomers serve as the reducing agents and tetravalent cerium salts as the oxidizing agents. 

Magnesium salts have long been employed for this purpose because MgO has a melting point of over 5000 °F (approximately 5070 °F/2800 °C) and forms complex salts with elements, such as vanadium, that have MPs of between 1500 and 2500 °F. Cerium salts generally are used in superior products, however, because they are much more efficient than magnesium (perhaps 3-5 times more efficient), but they also are much more expensive. 

Cerium octoate, in fuel additives Cerium salts, as fuel additives Cerium sulfonate, in fuel additives CFR21 172.615... 

The oxidation of an anthracene suspension in sulfuric acid conducted in the presence of cerium salts can serve as an example of mediated oxidation. In the bulk solution the Ce" ions chemically oxidize anthracene to anthraquinone. The resulting Ce ions are then reoxided at the anode to Ce". Thus, the net result of the electrochemical reaction is the oxidation of anthracene, even though the electrochemical steps themselves involve only cerium ions, not anthracene. Since the cerium ions are regenerated continuously, a small amount will suffice to oxidize large amounts of anthracene. 

Cationic polymerization of alkenes and alkene derivatives has been carried out frequently in aqueous media.107 On the other hand, the reaction of simple olefins with aldehydes in the presence of an acid catalyst is referred to as the Prins reaction.108 The reaction can be carried out by using an aqueous solution of the aldehyde, often resulting in a mixture of carbon-carbon bond formation products.109 Recently, Li and co-workers reported a direct formation of tetrahydropyranol derivatives in water using a cerium-salt catalyzed cyclization in aqueous ionic liquids (Eq. 3.24).110... 

Aubele et al. studied the aqueous Prins cyclization using cyclic unsaturated acetals as oxocarbenium ion progenitors and allylsilanes are used as nucleophiles. Cyclizations proceed efficiently inside Lewis acidic micelles (of cerium salt) in water. A variety of vinyl- and aryl-substituted tetrahydropyrans with excellent stereocontrol was obtained (Eq. 3.26).113... 

Cerium salt trihydrate, C2,H,sCe06.3H20, cerous benzoate. White to reddish-white powder. Sol in hot water or hot ale. 

The work on the electrochemical generation of a solution of ceric sulphate from slurry of cerous sulphate in 1-2 M sulphuric acid was abandoned by BCR due to difficulties encountered in handling slurried reactants. A 6kW pilot reactor operated at 50 °C using a Ti plate anode and a tungsten wire cathode (electrolyte velocity about 2ms 1) produced 0.5 M Ce(S04)2 on the anode with a current efficiency of 60%. The usefulness of Ce(IV) has been limited by the counter anions [131,132], Problems include instability to oxidation, reactivity with organic substrates and low solubility. Grace found that use of cerium salts of methane sulfonate avoids the above problems. Walsh has summarized the process history, Scheme 6 [133],... 

A serious drawback is the large amount of CAN (up to 2.5 molar amounts) needed. Cerium salts are highly toxic pollutants and must be removed from industrial effluents and wastewaters. Cerium (III) solutions from penem pilot plant solutions containing up to 1.2 M Ce(III) were recycled in a two compartment Electro Syn Cell. Typical recycling conditions Nation diaphragm with coated Ti-anode, applied current densities = 50-150 A/em2 yield > 90% processed amount about 475 kg CAN [46,126,136,137], The simultaneous determination of Ce(III) and Ce(IV) in the pilot plant solution and in solid CAN can be performed polarographically. As little as 0.3% Ce(NH4)2(N03)5 can be determined in Ce(NH4)2(N03)6 [136]. 

Fig. 3 Electrooxidation of p-methoxytoluene with cerium salt by an ex-cell method.

Cerium is separated from other rare-earth elements by an ion-exchange process in which it reacts with fluoride. This compound is then reduced with calcium metal (3Ca +2CeF — 2Ce + 3CaFj). Cerium can also be produced by the electrolysis of molten cerium salts. The metal ion collects at the cathode, and the chlorine or fluorine gases of the salt compound at the anode. 

Cerium(lll) chloride is used to prepare cerium metal and other cerium salts. It also is used as a catalyst in olefin polymerization, and in incandescent gas mantles. 

Cerium(III) chloride is prepared by the reaction of hydrochloric acid with a cerium salt, such as cerium hydroxide or carbonate, followed by crystaUization ... 

The pure compound is used in glazes and enamels as an opacifying agent. It also is used to make colored glass, imparting yellow color to the glass. The crude form is used in flaming arc lamps. Another application of this compound is in the preparation of several other cerium salts. 

A typical NH3 synthesis catalyst (10) contains iron oxide plus 1% K2O, 1-2% AI2O3, and may contain v l% CaO on the surface. After fusion and reduction the surface is largely metallic iron plus reduced promoters concentrated on the surface ( ). Sze and Wang (11) have shown that a catalyst washed with Ce(N03)3 and subsequently reduced is much more active than the conventional catalyst, Table II, Mischmetal salts may be substituted for the cerium salt. 

K bicarbonate, K chloride, K iodide, K metaphosphate, K perchlorate, K phosphate, K silico-fluoride, K urea oxalate, sodium ammonium sulfate, sulfur, zinc sulfate and Zr oxide It was claimed that methylene urea reduced the flash to a far greater extent than any of the organic compounds used, ft was also stated that cerium salts were much more effective than any other metallic salts investigated (Ref 4)... 

Cerium (III) molybdate Molybdic acid, cerium salt (9) (53986-44-0) (S)-(-)-a-Methoxy-a-(trifluoromethyl)phenylacetic acid Hydratropic acid, p,p,p-trifluoro-a-methoxy-, (S)-(-)- (8) Benzeneacetic acid, a-methoxy-a-(trilluoromethyl)-, (S)- (9) (17257-71-5)... 

Quadrivalent cerium salts may be volumetrically determined by arsenious acid in aqueous sulphuric acid solution using a manganese salt as catalyst, with potassium iodate present as a promoter.2 Excess of arsenious acid is used and back-titrated with permanganate. If nitric acid is present in place of sulphuric acid, an alkali chloride and a trace of iodine are used to promote the action of the manganese salt. Direct potentiometric titration with arsenious acid may also be employed. 

A perspective method for the production of HCP was proposed by Labarre et al 92-94) [t invo]ves radical graft-copolymerization of methyl methacrylate onto heparin effected by cerium salts (Ce4+). As well as other hydroxyl-containing polymers, heparin may react with cerium ions producing free radicals which may initiate graft-copolymerization of unsaturated compounds ... 

The prescribed quantity of Grignard reagent (and cerium salt) is 25% more than stoichiometric. This excess is required to ensure complete consumption of the ester. 

In order to generate SOI in acidic media, the reaction between sodium bisulfite and cerium ammonium nitrate should be employed. In (NH4)2Ce(N03)6, cerium has the oxidation state 4+. In acids, valence 4 cerium salts are strong oxidants. With the sulfite ion, the... 

With this end in view, phenyldimcthylsilyl tri-n-butylstannane was added under the influence of zero-valent palladium compound with high regioselectivity and in excellent yield to the acetylene 386 to give the metallated olefin 387 (Scheme 56). The vinyl lithium carbanion 388 generated therefrom, was then converted by reaction with cerium(lll) chloride into an equilibrium mixture (1 1) of the cerium salts 389 and 390 respectively. However, the 1,2-addition of 389 to the caibonyl of 391, which in principle would have eventually led to ( )-pretazettine, did not occur due to steric reasons — instead, only deprotonation of 391 was observed. On the other hand, 390 did function as a suitable nucleophile to provide the olefinic product 392. Exposure of 392 to copper(II) triflate induced its transformation via the nine membered enol (Scheme 55) to the requisite C-silyl hydroindole 393. On treatment with tetrafluoroboric acid diethyl ether complex in dichloromethane, compound 393 suffered... 

Fig. 5.15 I nfluence of cerium salt and calcination temperature on the isomerization performance of the Zr02-W-Ce-Pt catalyst.

The solution is remarkably stable, even at high temperatures. However, it has to be strongly acidic to prevent the precipitation of basic cerium salts. 

Addition of cerium salts accelerates the electrolytic oxidation of anthracene, naphthalene, and phenanthrene, which yield the corresponding quinones. The hydrocarbons may be in solution or in the form of a finely divided suspension. Anthracene, for example, is oxidised to Anthraqtjinone in 20 per cent, sulphuric acid anode current density is about 5 amps, per dm.2, and by the addition of 2 per cent, of cerium sulphate the current efficiency 8 is stated to reach nearly 100 per cent. 

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