Zirconium tetraiodide

High purity zirconium was first produced by van Arkel and de Boer in 1925. They vaporized zirconium tetraiodide [13986-26-0] into a bulb containing a hot tungsten filament which caused the tetraiodide to dissociate, depositing zirconium on the filament. 

Zirconium tetraiodide [13986-26-0], Zrl, is prepared directly from the elements, by the reaction of iodine on zirconium carbide, or by halogen exchange with aluminum triiodide. The reaction of iodine with zirconium oxide and carbon does not proceed. The physical properties are given in Table 7. 

Zirconium tetraiodide is the least thermally stable zirconium tetrahaUde. At 1400°C, it disproportionates to Zr metal and iodine vapor. This behavior is utilized in the van Arkel-de Boer process to refine zirconium. As with the tetrachloride and tetrabromide, the tetraiodide forms additional adducts with gaseous ammonia which, upon heating, decompose through several steps ending with zirconium nitride. 

Zinc iodide, 4632 Zirconium(II) chloride, 4121 Zirconium dibromide, 0285 Zirconium tetrachloride, 4178 Zirconium tetraiodide, 4639 Zirconium trichloride, 4160... 

Zinc iodide, 4627 Zirconium dibromide, 0284 Zirconium tetrachloride, 4172 Zirconium tetraiodide, 4634 Zirconium trichloride, 4154 Zirconium(II) chloride, 4115 See also METAL PNICTIDES... 

The zirconium tetrahalides react with esters to form ZrX4 2 ester adducts (302, 303, 330, 407-410, 412) in which, coordination number six is attained. On the basis of dipole moments (Table XIII), it is concluded that the adducts have the cis structure. This has been supported, at least in the case of ZrCl4 2011300 0 02115, by the infrared spectrum (330). Oryoscopic studies in benzene solution of the 2 1 adducts of zirconium tetrachloride and ethyl formate, ethyl acetate, and ethyl butryrate show that these complexes tend to decompose to the 1 1 species, the extent of dissociation increasing with the number of carbon atoms in the acid radical. The estimated dissociation constant is about 5 x 10", whereas for the ethyl acetate adduct of zirconium tetrabromide it is only 2 X 10". The approximate dissociation constant of the complex zirconium tetraiodide 2 ethyl acetate is 3.5 x 10". The 1 1 species were synthesized by direct reaction in benzene with strictly stoichiometric ratios of the reactants. Oryoscopic determination of molecular weights of the 1 1 complexes indicate that these complexes generally... 

The disproportionation of zirconium triiodide is considered to proceed via an intermediate phase 470). The rates of zirconium tetraiodide effusion were measured in an effusion cell at 276°-325°C to the point where there was no further loss in weight. The temperature was raised to 350°-400°C whereupon further effusion of the tetraiodide was followed to constant weight. The heat of disproportionation for the overall process is about 40 kcal/mole. These data and the analyses of the residues are consistent with the reactions... 

ZnS ZINC SULFIDE (WURTZITE) 1843 Zrl4 ZIRCONIUM TETRAIODIDE 1876... 

The enthalpy of sublimation of solid zirconium tetraiodide to gaseous ZrG was given in Section V.4.3.3.1, as was the enthalpy of formation for Zrl4(er). These values are therefore used to determine the selected enthalpy of formation of Zrl4(g) ... 

SAL/SHE] Sale, F. R., Shelton, R. A. J., Studies in the chemical metallurgy of the titanium group metals I. The vapour pressure over solid zirconium tetraiodide, J. Less-Common Met., 9, (1965), 54-59. Cited on page 175. 

Figure 7-90. Energy cost of direct decomposition of zirconium tetraiodide as function of specific energy input triangles, experiments with microwave discharge squares, experiments with radiofrequency discharge solid line, modeling.

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