Titanium iodide

The iodide or van Arkel-de Boer process is a volatilization process involving transfer of an involatile metal as its volatile compound. It is used for the purification of titanium. The reaction of iodine gas with impure titanium metal at 175°C yields gaseous titanium iodide and leaves the impurities in the sohd residue. 

If no aqueous workup, but anhydrous cleavage of the reaction product 11 is performed with iodotrimethylsilane, the titanium iodide 12 can be recovered or used again in the same flask36. 

Titanium disulfide, 25 57, 58 Titanium disulfide electrodes sloping discharge curve, 3 414 Titanium esters, 25 1 Titanium fluorides, 25 47-49 Titanium halides, 25 47-55 Titanium hydride, 13 626 Titanium hydrides, 25 5 Titanium-hydrogen system, 25 3-5 phase diagram for, 25 5 Titanium iodides, 25 54-55 Titanium/isopropoxy/nitrilotriethoxy ratio, 25 93... 

Natta (119) has made an excellent summary of the catalysts which produced various structures of polybutadiene. The more acidic vanadium and titanium trichloride catalysts produced large amounts of trans 1.4-polymer. Less acidic titanium iodide, cobalt, and nickel catalysts produced high amounts of cis 1.4 structure (Table 9). 

Ihloi iosphoryl chloride (SPCl ) ClsPiSiCg) 859 Titanium iodide (Til) IlTi (g) 1352... 

Hg2l2(cr) Mercury iodide (Hggig) 1329 IgTijCcr) Titanium iodide (Til2)... 

Additionally, if the initiation reaction is more rapid an the chain propagation, a very narrow molecular weight distribution, MJM = 1 (Poisson distribution), is obtained. Typically living character is shown by the anionic polymerization of butadiene and isoprene with the lithium alkyls [77, 78], but it has been found also in butadiene polymerization with allylneodymium compounds [49] and Ziegler-Natta catalysts containing titanium iodide [77]. On the other hand, the chain growth can be terminated by a chain transfer reaction with the monomer via /0-hydride elimination, as has already been mentioned above for the allylcobalt complex-catalyzed 1,2-polymerization of butadiene. 

The highest purity (0.03% C and 0.006% N) is attained via the elegant recovery process of van Arkel and de Boer (method V below). This is based on the thermal decomposition of titanium iodide at 1100-1500 °C. 

Various pressures have been used for operation of the process, usually between a few millimetres and a few tens of millimetres of mercury. The influence of iodine and titanium iodide pressures upon reaction rate -is seen in Figs. 8.10 and 8.11 from Runnals and Pidgeon. ... 

Nikitin MI, Kosinova NM, Tsirelnikov VI (1992) Mass-spectrometric study of the thermodynamic properties of gaseous lowest titanium iodides. High Temp Sd 30 564-572... 

Use of titanium iodide systems can produce polymers with a c/s-content of 95% whilst the TiCU/Al alkyl systems will give ds-contents up to 80%. 

The medium cis- (c. 92%)-1,4-polybutadienes using the aluminium alkyl/titanium iodide system. 

The highest purity titanium is prepared for research purposes by the iodide process. Crude titanium is first reacted with iodine in an inert atmosphere to form titanium iodide. This can then be decomposed at the surface of a heated titanium... 

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