Tungstic acid types

Salts of Molybdic and Tungstic Acids. What types of salts of molybdic and tungstic acids exist Give examples of isopoly- and heteropoly molybdenum and tungsten compounds. What is the composition of para- and metamolybdates and of para- and metatungstates Which molybdates and tungstates dissolve poorly in water ... 

The main types of non-ionic tensides are adducts of higher alcohols, alkylphenols and aliphatic acids with ethylene oxide. They are determined mostly by photometry, e.g. by using tungstic-phosphate acid and hydro-quinone. Non-ionic tensides are precipitated in the presence of calcium chloride with 2% tungstic-phosphate acid. After centrifuging, the dried precipitate is dissolved in concentrated HjSO and the red-brown colour caused by addition of hydroquinone is measured at 500 nm [14, 15, 21]. 

In view of their structure and molecular weight, all compounds of this type should be considered as salts of 12-tungstic-l-silicic acid H4[Si04(W30g)4 aq.] [R. Signer and H. Gross, Helv. Chim. Acta 17, 1076 (1934)]. 

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),... 

Isopropanol adsorption (at 40 C) and TPSR analysis was performed on the fully hydrated acid and after in situ calcination at 70, 115, and 320°C in order to obtain more insights on the role of the degree of hydration on the catalytic activity of the phospho-tungstic Wells-Dawson type acid. 

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