Compounds cerium nitrate

SAFETY PROFILE Poison by intravenous and intraperitoneal routes. Moderately toxic by ingestion. Experimental reproductive effects. See also CERIUM COMPOUNDS and NITRATES. When heated to decomposition it emits toxic fumes of NOx. 

Ceda-based oxides can be obtained by the decomposition of some compound precursor, such as hydroxide, nitrate, halides, sulfates, carbonates, formates, oxalates, acetates, and citrates.For example, nanosize or porous cerium oxide particles have been prepared at low temperatures by pyrolysis of amorphous citrate," which is prepared by the evaporation of the solvent from the aqueous solution containing cerium nitrate (or oxalate) and citric acid. In the case of mixed oxides, the precursor containing some cations in the same solid salts is prepared. In the same manner of ceria particles, the precursors complexing some cations with citrates are useful to synthsize ceria-zirconia mixed oxides and their derivatives. Also. Ce02-Ln203 solid solutions, where Ln = La. Pr, Sm. Gd. and Tb, have been synthesized from the precursors obtained by the evaporation of nitrate solutions at 353 K in air from an intimate mixture of their respective metal nitrates. The precursors are dried and then heated at 673 K to remove niU ates, followed by calcination at 1073 K for 12h. 

N03)j, a newcomer to the arena of oxidants, is useful for the acetoxylation of aromatic side chains in benzylic positions [415, 416] and for the oxidation of methylene or methyl groups that are adjacent to aromatic rings to carbonyl groups [238, 415, 417]. The reagent also oxidizes alcohols to aldehydes [418, 419, 420, 421] and phenols to quinones [422, 423], cleaves vicinal diols to ketones and a-hydroxy ketones to acids [424, 425], and converts diaryl sulfides into sulfoxides [426]. A specialty of ammonium cerium nitrate is the oxidative recovery of carbonyl compounds from their oximes and semicarbazones [422, 427] and of carboxylic acids from their hydrazides [428] under mild conditions. 

Sodium bromate, NaBrOs, a white crystalline compound, converts acyloins into a-diketones under forcing conditions [740]. More often, this reagent is used as a reoxidant of ammonium cerium nitrate [421], cerium sulfate [741], or ruthenium trichloride [741] in oxidations of alcohols to aldehydes [421] or carboxylic acids [741]. 

Oxidation with ammonium cerium nitrate has to be done in 100% acetic acid (equation 165). In 50% acetic acid, carbonyl compounds are... 

Like the double bond, the carbon-carbon triple bond is susceptible to many of the common addition reactions. In some cases, such as reduction, hydroboration and acid-catalyzed hydration, it is even more reactive. A very efficient method for the protection of the triple bond is found in the alkynedicobalt hexacarbonyl complexes (.e.g. 117 and 118), readily formed by the reaction of the respective alkyne with dicobalt octacarbonyl. In eneynes this complexation is specific for the triple bond. The remaining alkenes can be reduced with diimide or borane as is illustrated for the ethynylation product (116) of 5-dehydro androsterone in Scheme 107. Alkynic alkenes and alcohols complexed in this way show an increased structural stability. This has been used for the construction of a variety of substituted alkynic compounds uncontaminated by allenic isomers (Scheme 107) and in syntheses of insect pheromones. From the protecting cobalt clusters, the parent alkynes can easily be regenerated by treatment with iron(III) nitrate, ammonium cerium nitrate or trimethylamine A -oxide. ° ... 

Chemicae Eormulas Common compounds o Cerium oxide CeiOs o Gadolinium oxide Gd203 o Lanthanum oxide LaiOs o Yttrium oxide Y2O3 o Cerium nitrate Ce(N03)3 o Cerium chloride CeCls... 

Cerium carbide and nitride have been tried as filaments for incandescent lamps.2 Pure cerium nitrate is used in the manufacture of gas mantles. The reducing action of cerous compounds is used for producing a variegated effect in dyeing fabrics. The salts of cerium are used for making aniline black and as a base for the alizarin group of dyestuffs. 

A facile approach to polysubstituted chiral dihydrofiirans starts from pyranose triflates and monoanions of 1,3-dicarbonyl compounds <94CC173S>. Treatment of cyclopropylsulfides of type 9 with ammonium cerium nitrate (CAN) gives furans by a tandem oxidative ring cleavage-cylization reaction <94CC1S29>. 

Rare earth compounds have been proposed as alternatives to chromate chemicals on the basis of being relatively benign. For example. Table 7.1 shows the LDjo for some simple salts. Clearly the LDj for the chromium chlorides is much lower than the other compounds. Importantly, the for cerium nitrate is... 

In a recent paper, Moutarlier et al. [15] have claimed that the use of cerium salts in sol-gel-based corrosion protection is limited due to the high solubility of the cerium ions. In all of the papers cited here, the authors limited themselves to the use of cerium chloride or cerium nitrate. In order to examine the influence of alternative anions, in the present study, cerium sulphate, cerium acetate hydrate (cerium Ac) and cerium acetylacetonate (cerium Acac) have been compared to cerium nitrate and cerium chloride. Additionally, attempts were made to limit the solubility of cerium chloride and cerium nitrate with the addition of acetylacetone to form complexes of the cerium ions. Table 10.1 gives the solubilities of the cerium compounds examined in this study. 

The cerium compounds used for these experiments were cerium acetylacetonate (cerium Acac), cerium nitrate hexahydrate (cerium nitrate), cerium chloride heptahy-drate (cerium chloride), cerium acetate hydrate (cerium Ac) and cerium sulphate. Additionally, cerium nitrate and cerium chloride were dissolved in ethanol and mixed... 

The cerium compounds examined in this study were selected to compare cerium compounds of different solubilities with cerium nitrate, which was proposed for corrosion protection on aluminium by Mansfeld et al. [12]. Cerium chloride and cerium nitrate are soluble in water, while cerium Ac, cerium Acac and cerium sulphate have only a limited solubility in water. According to the data from Table 10.1, the cerium compounds can be arranged in order of increasing solubility as follows ... 

In the case of cerium compounds with good solubility in the matrix such as cerium chloride and cerium nitrate, the reason for the good corrosion protection can be found in the lack of leaching into the solute. Because of the inability to leach, the coating material is not weakened, and, therefore, the barrier properties remain intact. Due to dispersion on a molecular scale, it could be expected that the pore size in these coatings would be smaller than in the case of matrix with insoluble salts which results in a denser matrix and better barrier properties (see Figs. 10.3 and 10.4). 

Ce(IV) extracts more readily iato organic solvents than do the trivalent Ln(III) ions providing a route to 99% and higher purity cerium compounds. Any Ce(III) content of mixed lanthanide aqueous systems can be oxidi2ed to Ce(IV) and the resultiag solutioa, eg, of nitrates, contacted with an organic extractant such as tributyl phosphate dissolved in kerosene. The Ce(IV) preferentially transfers into the organic phase. In a separate step the cerium can be recovered by reduction to Ce(III) followed by extraction back into the aqueous phase. Cerium is then precipitated and calcined to produce the oxide. 

The greater lability of 1-benzothiepin 1-oxides, compared to the parent compounds, may lead to differences in chemical behavior. Thus, treatment of the tricarbonyliron complex of 1-benzo-thiepin 1-oxide (8, X = SO) with ammonium cerium(IV) nitrate in acetone at — 30 °C leads, with the loss of sulfur monoxide, to naphthalene. In contrast, the iron ligand can be removed selectively from the corresponding 1-benzothiepin by ammonium cerium(IV) nitrate.23 92 For the synthesis of 1-benzothiepin 1-oxide, see Section 2.1.4.1,... 

One of the most promising processes is the active DeNO based on NO -trap materials. It has been developed for lean-burn gasoline engines. Cerium compounds are thought to intervene in different steps of the whole process (1) NO oxidation, (2) NO storage, (3) Nitrate desorption and NO reduction. Most probably, the main role of OSC materials is to accelerate HC partial oxidation during rich-spikes (giving CO and H2 as NO reducers). However, this beneficial effect of OSC compounds competes with a detrimental reaction,... 

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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