Oxycarbonates

Naturally occurring cadmium compounds are limited to the rare minerals, greenockite [1317-58 ] CdS, and otavite (1), an oxycarbonate, but neither is an economically important source of cadmium metal or its compounds. Instead, cadmium compounds are more usually derived from metallic cadmium [7440-43-9] which is produced as a by-product of lead—2inc smelting or electrolysis (see Cadmiumand cadmium alloys). Typically, this cadmium metal is burnt as a vapor, to produce the brown-black cadmium oxide [1306-19-0], CdO, which then acts as a convenient starting material for most of the economically important compounds. 

Treatment of ethyl 2,7-di-/ert-butylthiepin-4-carboxylate (24) with 3-chloroperoxybenzoic acid at — 78 °C results in the benzene derivative 25 only, and no sulfur-oxidized products 80 however, the stable 2,7-di-ter/-butylthiepin (26) can be oxidized with 0-benzyl 00-hydrogen monoper-oxycarbonate at — 78 °C to give the corresponding S-oxide 27, which was monitored by HNMR spectroscopy at — 40°C. At —15 C, sulfoxide 27 was converted, via extrusion of sulfur monoxide, with a half-life of 5.5 hours to the benzene derivative 28.87 The oxidation reaction of 26 with excess of the monoperoxycarbonate did not proceed to the S,S-dioxide, even though the parent thiepin 1,1-dioxide is known to be stable at room temperature.15... 

While there have been many non-isothermal studies of the decompositions of lanthanide oxalates, fewer detailed kinetic investigations have been reported. The anhydrous salts are difficult to prepare. La, Pr and Nd oxalates decompose [1097] to the oxide with intervention of a stable oxycarbonate, but no intermediate was detected during decomposition of the other lanthanide oxalates. The product CO disproportionates exten-... 

In a reaction of CDI with 2 -0,3 -Af-bis(benzyloxycarbonyl)-jV-desmethyl-6-0-methylerythromycin A the corresponding imidazolecarboxylate (K2C03, THF, 36% yield) was formed, which yielded in a further reaction with C6H5CH2OH the 4 -benzyl-oxycarbonic ester of this erythromycin A analogue in 40% yield.12413... 

Information available regarding the chemistry of lead in air is limited. Before the ban on sales of leaded gasoline, lead particles were emitted to the atmosphere from automobiles as lead halides (mostly PbBrCl) and as double salts with ammonium halides (e.g., 2PbBrCl NH4Cl. Pb3[P04]2, and PbS04 [Biggins and Harrison 1979 Ter Haar and Bayard 1971]). After 18 hours, approximately 75% of the bromine and 30-40% of the chlorine disappeared, and lead carbonates, oxycarbonates and oxides were produced. 

Catalysts were prepared by wet impregnation method. Among them, Ni/La203 exhibited high activity and selectivity for H2 production in the SRE reaction. The enhanced activity has been attributed to scavenging of coke deposited on the Ni surface by lanthanum oxycarbonate species... 

Gautier, E., Tranqui, D., and Chaillout, C. (1997) First steps in the structure determination of an oxycarbonate superconductor from electron diffraction intensities. In Electron crystallography 375-378, edited by D.L. Dorset, S. HovmdUer and X. Zou NATO ASl series, 347. 

Bismuth oxycarbonate is used in cosmetics, enamel fluxes, ceramic glazes, plastic and artificial horn products. It also is used as an opacifier in x-ray diagnosis and in medicine for treatment of gastric ulcers, diarrhea and enteritis. 

Bismuth oxycarbonate is prepared by adding sodium carbonate to a suspension of bismuth subnitrate in water. 

Zinc oxycarbonate is formed by the reaction of suspensions of the oxide or hydroxide with COj to produce the normal carbonate, a very rapid stream of carbon dioxide and. usually, a somewhat higher pH is required. 

Both normal and mixed carbonates are known. The former is precipitated, as Y2(C03)3 3H2O from Y31 solutions by alkali metal carbonates, which in excess dissolve the precipitate to form a soluble hydrated double carbonate. The oxycarbonate is also a double molecule, 3Y2(C03)3 2Y(OH)3, formed by action of CC)2, upon the hydroxide. 

On this basis a silicon therapy was developed in France. Two silicon containing preparations, DNR (60) [complex of potassium methylsiliconate with salicylic acid (or with other oxycarbonic acids)] and RDN (61) (cyclic ether of dimethylsilanediol and glycerol), are used in the treatment of cardiovascular diseases, cancer and virus infections. Investigations in this field have been carried out by N. Duffaut,... 

Because of the variety of conditions employed, the reported equilibrium pressures and temperatures between the various oxycarbonates probably do not have much thermodynamic significance. Therefore, only thermodynamic parameters for decomposition to PbO have been listed (Tables 2.35... 

The process consists in heating fatty or aromatic acids with a phenol or oxycarbonic acid containing at least two hydroxyl groups in the ortho position to each other with a dehydrating agent. The reaction may be best explained by the following example. 

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