18-Tungstic acid-2-arsenates

Carl Wilhelm Scheele (1742-1786) was another phenomenal chemist of the phlogistic era. He was actually the first discoverer of oxygen (1772-1774), on which he first published in 1777. He made other important discoveries including (i) chlorine and manganese, (ii) silicon fluoride and hydrofluoric acid from fluorspar, (iii) phosphorus from bone ash, phosphoric acid from the action of nitric acid on phosphorus, (iv) arsenic acid, molybydic acid, tungstic acid, arsenic... 

Complex tungstic acids arc numerous mid interesting. I hosplnirir, arsenic, antimonic, vanadic, and boric, acids condense with varying aiunuuis of tungstic acid. The ratio of the, otlner oxide, to W(), varies from 1 7 in 1 24 or more-... 

All txmgstic acid arsenates resemble closely the tungstic acid phosphates in their manner of preparation and their behavior. They are only a little less stable. 

Arsenic acid (1775), molybdic acid (1778), tungstic acid (1781). Distinction be-... 

Heteropoly compounds are composed not only of the weak, oxygen-containing metallic acids (tungstic, molybdic and vanadic), but also of moderately strong to weak acids of nonmetals, e.g., boric, silicic, phosphoric, arsenic, telluric, etc., acids. Stable heteropoly compounds very frequently show nonmetallic to metallic acid ratios of 1 12, 1 6 or 1 9. Since the heteropoly compounds form under conditions similar to those in which isopoly compounds are obtained, that is, only in solutions containing H+ ions, it is assumed that the building blocks of the heteropolyanions are isopoly anions [1]. 

Thionyl chloride, as well as other inorganic acid chlorides, reacts with polyols to form mixed esters (see under Sulfate esters. Chapter III). In the presence of pyridine, partial chlorohydrin formation may occur (95), Selenium oxychloride forms a selenite ester upon reaction with mannitol (96), Phosphorus pentachloride yields unsaturated chlorohydrins of mannitol and galactitol which have the composition CeHeCU (97), Extremely interesting are the so-called complexes of alditols with various inorganic polybasic acids, their salts, or anhydrides in aqueous solutions. Complexes with boric, molybdic, tungstic, and other acids, as well as the oxides of antimony and arsenic, have been reported. It is believed that these complexes are true esters with one or more moles of alditol, a chelate type of structure being involved at some point. For the hexitols a compound with boric acid such as the following is postulated (98),... 

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