Generate barium metatitanate with molten barium carbonate (add barium chloride or sodium carbonate as auxiliary solvent):
TiO2+BaCO3=BaTiO3+CO2↑
Insoluble in water or dilute sulfuric acid, but soluble in hot concentrated sulfuric acid or molten potassium hydrogen sulfate:
TiO2+H2SO4=TiOSO4+H2O
Although the solution obtained by dissolving titanium dioxide in hot concentrated sulfuric acid is acidic, it can also be hydrolyzed when heated and boiled to obtain hydrated titanium dioxide (β-type titanic acid) which is insoluble in acids and alkalis. If alkali is added to the newly prepared titanium hydrochloric acid solution, fresh hydrated titanium dioxide (α-type titanic acid) is obtained, which is more reactive than β-type titanic acid and can be dissolved in dilute acid and concentrated alkali. After being dissolved in concentrated sodium hydroxide solution, the hydrated titanate with chemical formula Na2TiO3·H2O can be precipitated from the solution.
Titanium dioxide and carbon powder are pressed into a mass and coked, heated to 1070-1170K, to produce gaseous titanium tetrachloride.
TiO2+2Cl2+2C=TiCl4↑+2CO↑
This reaction is very important for the extraction of titanium. Magnesium or sodium can easily reduce titanium tetrachloride.
The reaction of titanium dioxide with COCl2 (phosgene), SOCl2 (thionyl chloride), CHCl3 (trichloromethane), CCl4 (carbon tetrachloride) and other chlorinating reagents can also be used to prepare titanium tetrachloride:
TiO2+CCl4=TiCl4↑+2CO2↑(The reaction is completed at 770K)
