Tungsten VI oxide

Synthesis From Other Ring Systems. These syntheses are further classified based on the number of atoms in the starting ring. Ring expansion of dichlorocyclopropane carbaldimine (53), where R = H and R = ryl, on pyrolysis gives 2-arylpyridines. Thermal rearrangement to substituted pyridines occurs in the presence of tungsten(VI) oxide. In most instances the nonchlorinated product is the primary product obtained (63). 

Thorium oxide sulfide, 4826 Tin(II) oxide, 4829 Tin(IV) oxide, 4840 Titanium(IV) oxide, 4842 Triuranium octaoxide, 4871 Tungsten(IV) oxide, 4844 Tungsten(VI) oxide, 4856... 

A stoichiometric mixture of 3.478 g. (15 mmoles) of tungsten-(VI) oxide and 11.897 g. (30 mmoles) of tungsten(VI) chloride is placed in the reaction tube, and an excess of 1 mg. of tungsten(VI) chloride per milliliter of tube volume is added. The tube is sealed under vacuum and heated in a temperature gradient of 200/175°C. with the reaction mixture placed in the hotter part of the furnace (Fig. 14). After about 10 hours the reaction is complete, and 15 g. of tungsten(VI) tetrachloride oxide are obtained (98% yield). The analyses of the sublimed product by the H-tube method are somewhat inaccurate, because of the extreme moisture sensitivity of this substance (loss of hydrogen chloride by hydrolysis). Anal. Calcd. for W0C14 W, 53.82 Cl, 41.50 O, 4.68. Found W, 54.20 Q, 41.40 O, 4.46. 

A stoichiometric mixture of 1.834 g. (10 mg. atoms) of tungsten powder, 4.637 g. (20 mmoles) of tungsten(VI) oxide, and 11.897 g. (30 mmoles) of tungsten(VI) chloride is put into a reaction tube. An excess of 8 mg. of WC16 per milliliter of tube volume is added. The tube is sealed under vacuum and placed in a temperature gradient of 450/230°C. 

As originally synthesized by Bayer,3 dichromium tungsten(VI) oxide is prepared easily by direct solid-state reaction of the component oxides, chromium(III) oxide and tungstcn(VI) oxide. 

Dichromium tungsten(VI) oxide is a deep-purple powder possessing the trirutile type of structure. The compound crystallizes in the space group/>42/mnm. with Z = 2,a0 =4.582 A., c0 = 8.870 A. 

Typically, 38 g. (0.1 mole) of dichromium tungsten(VI) oxide and 18.7 g. (0.3 mole) of oven-dried, reagent-grade, magnesium fluoride are mixed and placed in a platinum crucible fitted with a cover. 

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