Cerium carboxylates

Garboxylates. Cerium carboxylates, water-insoluble, can be made (11) by double decomposition and precipitation using water-soluble precursors, or by reaction of an insoluble precursor directly with the organic acid. Cerous oxalate [139-42-4] 2-ethyIhexanoate (octanoate),... 

Paint Driers and Polymer Additives. Paints based on alkyd resins (qv) dry by the oxidation and cross-linking of unsaturated side chains. Metal catalysts are included in paint formulations to promote this drying. Cerium carboxylates, eg, the naphthenate, are used as through driers, ie, to promote drying in the body of the paint film rather than at the film s surface (44). 

Metal catalysts, included in paint formulations promote drying. Cerium carboxylates are used as Through driers, i.e. to promote drying in the body of the paint film [20]. 

Cerium carboxylates[21], such as cerium ocianoate, are needed to improve properties of silicone polymers. Comparable beneficial effects can be seen by incorporating into polymeric silicones the cerium as oxide. 

PO can be made degradable by means of additives. The types of additives include aromatic ketones (benzo-phenone and substituted benzophenones [47], qui-none), aromatic amines (trisphenylamine), polycyclic aromatic hydrocarbons (anthracene, certain dyes such as xanthene dyes), or transition metal organic compounds. The transition metal compounds of Fe, Co, Ni, Cr, Mn are widely used. Organo-soluble acetyl acetonates of many transition metals are photooxidants and transition metal carboxylates are also thermal pro-oxidants. Co acetylacetonate appears to be an effective catalyst for chemical degradation of PP in the marine environment. The preferred photoactivator system is ferric dibutyldithiocarbamate with a concentration range of 0.01. 1%. Scott has patented the use of organometallic compounds hke iron (ferric) dibutyldithiocarbamate or Ni-dibutyl-dithiocarbamate [48]. Cerium carboxylate [49] and carbon black are also used in such materials [50]. 

Substituted allylsilanes are available from the corresponding carboxylic acid esters by treatment with an excess of trimethylsilylmethylmagncsium chloride and cerium(UI) chloride followed by acid catalyzed elimination31. Lactones give rise to 2-([Pg.344]

Selective oxidation of methyl pyrroles 65 possessing an a-carboxylic ester and sensitive p-substituents can be accomplished using cerium triflate in methanol <96TL315>. Moreover, the resultant a-methoxymethylpyrroles 66 may be converted to dipyrrylmethanes 67 in a "one-pot" sequence by treatment with 48% HBr. The dipyrrylmethanes, in turn, can be further oxidized to dipyrryl ketones by ceric ammonium nitrate <96JHC221>. 

Cerium reagents have also been found to give improved yields in the reaction of organolithium reagents with carboxylate salts to give ketones. 

Organoytterbium chemistry has been developed in the last 20 years, although the development rate is much slower than the other lanthanides like samarium or cerium. Dianionic complexes that are produced from the reaction of ytterbium with diaryl ketones react with various kinds of electrophiles including carbon-heteroatom unsaturated bonds.35 Phenylytterbium iodide, a Grignard-type reagent, is known to have reactivity toward carbon dioxide,36 aldehydes, ketones,37,37 and carboxylic acid derivatives38,3811 to form the corresponding adducts respectively. 

Formates. — The simplest Tnowo-carboxylic acid is formic acid (HCOOH). Formate complexes have not been extensively investigated although Sakkar [353] has mentioned rare earth formates. The cerium group rare earths form spherulic formates which are hexagonal. This property is used to identify small amounts of these elements. These formates are prepared by dissolving freshly prepared rare earth hydroxides in formic acid. 

Di-/-butyl dicarbonate, 94 of carboxyl groups Cerium(IV) ammonium nitrate, 104 2,3-Dichloro-5,6-dicyano-l,4-benzoqui-none, 104... 

Oxo-4//-pyrido[l,2-a]pyrimidine-7-carboxylates 500 were obtained when 7-iodo-4T/-pyrido[ 1,2-a]pyrimidines 499 reacted with carbon monoxide in the presence of bis(triphenylphosphine)palladium(II) chloride catalyst and triethylamine (Scheme 29) (94MI2). From 7-iodo derivatives 499, 7-vinyl derivatives 501 and 7-(l-ethoxyvinyl) derivatives 502 were prepared with vinyltributyltin in the presence of Pd(PPh3)4 and with (1-ethoxy-vinyl)tributyltin in the presence of bis(triphenylphosphine)palladium(II) chloride catalyst, respectively, in toluene at 80°C. 7-(l-Ethoxy vinyl)pyr-ido[l, 2-a]pyrimidin-4-ones 502 were hydrolyzed to yield 7-acetyl derivatives 503. The acetyl group of compounds 503 was reduced with sodium borohydride in the presence of cerium(III) chloride in ethanol to give 7-(1 -hydroxyethyl)pyridopyrimidin-4-ones 504. 

Several examples have been described on Lewis acid and base catalyzed Michael additions. Cyclopentanone-2-carboxylic acid ethylester was added at room temperature to methyl vinyl ketone using 2 mol% FeCl3 -6 H20 as catalyst yielding > 90% of the addition product (Scheme 11) [31]. Cerium(III) chloride in the presence of sodium iodide [32] and trifluoro-methanesulfonic acid have been used as catalysts as well [33]. 

Cerium. Photooxidation of alcohols288 and carboxylic acids289 by Ce(IV) at 77 K proceeds via the formation of Ce(III) and organic radicals, which have been carefully studied by ESR technique. In aqueous nitric acid solution, N03 radicals are formed290. Photooxidation of Hg+ by Ce(IV) in an aqueous perchloric acid solution seems to involve the formation of an OH radical291. ... 

Hiatt et a/.34a-d studied the decomposition of solutions of tert-butyl hydroperoxide in chlorobenzene at 25°C in the presence of catalytic amounts of cobalt, iron, cerium, vanadium, and lead complexes. The time required for complete decomposition of the hydroperoxide varied from a few minutes for cobalt carboxylates to several days for lead naphthenate. The products consisted of approximately 86% tert-butyl alcohol, 12% di-fe/T-butyl peroxide, and 93% oxygen, and were independent of the catalysts. A radical-induced chain decomposition of the usual type,135 initiated by a redox decomposition of the hydroperoxide, was postulated to explain these results. When reactions were carried out in alkane solvents (RH), shorter kinetic chain lengths and lower yields of oxygen and di-te/T-butyl peroxide were observed due to competing hydrogen transfer of rm-butoxy radicals with the solvent. 

The mechanism of the decarboxylation of carboxylic acids by lead(IV),333 manganese(III),237 cobalt(III),249 and cerium(IV)288 has been well studied. Although there are some mechanistic differences, the formation of alkyl radicals by the reaction,... 

An alternative route for the oxidation of carboxylic acids not involving decarboxylation has been demonstrated for the reaction of manganese-(III)219 221 232 234 and cerium(IV).238a-b Carboxymethyl radicals are formed in the reaction. 

CARBONYL ADDITIONS, CERIUM(III) CHLORIDE-PROMOTED, 76, 237 Carbonyl compounds, reactions with organolithiums or Grignard reagents, 76, 228 Carboxylic acid amides, 77, 27 Cells, storage of, 76, 80 Centrifugation, 76, 78... 

Catalytic systems are by far the most studied methods for oxidizing alkyl side chains. Cobalt(II) acetate and cerium(III) acetate in the presence of a bromide ion activator in acetic acid with hydrogen peroxide are used for the transformation of toluenes to benzaldehydes, carboxylic acids and benzyl bromides (Figure 3.65). 

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