Silver pyrophosphate

Silver Phosphates. Silver phosphate [7784-09-0], or silver orthophosphate, Ag3P04, is a bright yellow material formed by treating silver nitrate with a soluble phosphate salt or phosphoric acid. Silver pyrophosphate [13465-97-9], is a white salt prepared by the addition of a soluble... 

Changing the substrate from gold to silver has been shown to strongly affect the structure of the first few layers of CdS grown by ECALE. STM measurements carried out on the first CdS layer on Ag(lll) revealed a much less compact structure than the one found on Au(lll). This disparity was tentatively attributed to the different structure of the first S layer on Ag(l 11), as obtained by oxidative UPD from sulfide ion solutions, due to a higher affinity of sulfur for silver than for gold. The Cd layers were attained on S by reductive UPD from cadmium ion solutions. Precursors for both elements were dissolved in pyrophosphate/NaOH at pH 12 [43 5],... 

Compound (1) phosphorylates phosphate monoesters and alcohols, although with the latter a considerable excess of alcohol is necessary to obtain satisfactory yields. In the absence of mercuric ions the milder phosphorylating species (3) can be isolated which converts monoalkyl phosphates to pyrophosphate diesters in good yield but does not react appreciably with alcohols unless catalytic amounts of boron trifluoride are added. Amine salts of (3) are converted to phosphoramidates on heating. In the presence of silver ions, O-esters of thiophosphoric acid behave as phosphorylating agents and a very mild and convenient procedure suitable for preparing labile unsymmetrical pyrophosphate diesters, such as the... 

Silver ions will oxidatively desulphurize nucleoside and other phos-phorothioates to generate a phosphorylating agent. This reaction has been utilized for the preparation of nucleotide coenzymes and has the advantage that it can be carried out on a large scale without the formation of contaminating symmetrical pyrophosphates. 

Among arthropods, pyrophosphate granules isolated from barnacles have the capability to bind and effectively detoxify silver and other metals under natural conditions (Pullen and Rainbow 1991). In a Colorado alpine lake, silver concentrations in caddisflies and chironomid larvae usually reflected silver concentrations in sediments seston, however, showed a high correlation with lake water silver concentrations from 20 days earlier (Freeman 1979). 

Elemental composition P 38.73%, H 1.26%, O 60.01%. The compound may be identified by physical properties alone. It may be distinguished from ortho and pyrophosphates by its reaction with a neutral silver nitrate solution. Metaphosphate forms a white crystalline precipitate with AgNOs, while P04 produces a yellow precipitate and P20 yields a white gelatinous precipitate. Alternatively, metaphosphate solution acidified with acetic acid forms a white precipitate when treated with a solution of albumen. The other two phosphate ions do not respond to this test. A cold dilute aqueous solution may be analyzed for HPO3 by ion chromatography using a styrene divinylbenzene-based low-capacity anion-exchange resin. 

Nucleoside 5 -phosphorothioates have also been employed as activated nucleotide derivatives for synthesis of pyrophosphates.321 The interaction of tributylammonium 2, 3 -di-0-benzoyluridine 5 -phosphorothioate (73) with silver a-D-glucopyranosyl and a-D-galac-topyranosyl phosphates in pyridine solution, with subsequent de-benzoylation, gave the corresponding glycosyl esters in 60-70% yield. This procedure can probably be classified as a variant of the mixed-anhydride method, the driving force of the reaction being the formation of insoluble silver sulfide. 

Phosphates. — The 1 20 aqueous solution of sodium pyrophosphate should give a pure white precipitate with silver nitrate solution. 

Oxidation of organic substrates with molecular oxygen as the oxygen source and catalyzed by metal surfaces is industrially very important reactions. E.g. is ethylene oxide is produced in about 1 x 10 ° kg/year on a silver surface with ethylene and molecular oxygen as reactants, phthalic anhydride and maleic anhydride are produced in about 2 x 109 and 4 x 108 kg/year on a vanadyl pyrophosphate surface with o-xylene and n-butane, respectively, as substrates and molecular oxygen as the oxygen donor (ref. 1). 

A number of metal ions of variable valence, for example FeK, Ti111 and V11, can reduce silver. Among the more significant coordination compounds are those of iron and titanium. Iron(II) ion, in the presence of fluoride or pyrophosphate to sequester the Fem formed, is a developer. The bis(oxalato)ferrate(II) ion, [Fe(C204)2p, is also a developer in the presence of excess oxalate. 

Silver nitrate Copper sulfate Pyrophosphates, P207 l White precipitate soluble in dilute nitric acid and in dilute acetic acid Pale blue precipitate... 

Pyrophosphoric Acid, H4P207.—The history and chief modes of preparation of this acid have already been given (p. 170). A purer product was made by the double decomposition of a soluble lead salt with sodium pyrophosphate, Na4P207, whereby lead pyrophosphate, Pb2P207, was precipitated this -was then decomposed by H S.1 The silver salt, Ag4P207, yielded anhydrous H4P207 when warmed in a current of dry hydrogen chloride.2... 

Silver nitrate solution yellow precipitate of normal silver orthophosphate, Ag3P04 (distinction from meta- and pyrophosphate), soluble in dilute ammonia solution and in dilute nitric acid. 

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