Laboratory Methods of Inorganic Chemistry, 2nd English Ed. 1928

TITANIUM TETRACHLORIDE. 81

That portion of the distillate passing over above 60°, which,
however, is small in amount by this method of preparation, con-

tains a little silicon hexachloride, Si 2 Cla, boiling-point 145° to

146°, and some silicon octachloride, Si 3 Cl 8 , boiling-point 210°

to 215°.

Silicon tetrachloride is a colorless, mobile liquid, and shows

a high refractive index for light. It fumes strongly in the air,

and on being mixed with water it hydrolyzes, forming ortho-
silicic and hydrochloric acids:

SiCl 4 + 4 H 2 O = Si(OH) 4 + 4 HC1.

Preserve the preparation in a sealed flask. Dependent prepara-

tion: Tetraethyl Silicate, No. 158.

Instead of starting with pure silicon, the directions of Gatter-

mann * may be followed: Prepare an impure silicon by igniting

40 g. magnesium powder with 160 g. dried and sifted quartz

sand, and chlorinate the resulting mixture of silicon and mag-

nesium oxide by heating it to 300° to 310° in a long combustion

tube, placed in a " bomb " furnace, while passing a current of dry

chlorine. This method yields a product containing more of the

hexachloride and octachloride than when, as by the first method,

the chlorination is carried out at a higher temperature.

Silicon Chloroform. The compound SiHCl 3 can be obtained in

a corresponding manner if, instead of chlorine, dry hydrogen

chloride, free from air, is passed over the silicon powder at a

temperature of 450° to 500°. For the preparation of this com-

pound in larger quantities, and for its properties (boiling point,

33° to 34°), see Ruff and Albert, Ber. 38, 2222 (1905).

52. Titanium Tetrachloride from Rutile.
    A number of oxides which are not reduced by charcoal can be transformed
    into the corresponding chlorides by the simultaneous action of carbon and
    chlorine. This method was originated by Oersted in 1824, and perfected by
    Wohler for a number of different oxides. It has been, for decades, the most
    important, if not the sole, method for the preparation of certain chlorides
    (A1C1 3 , SiCl 4 , TiCl 4 , UC1 4 (No. 169), etc.). From a theoretical standpoint it is
    a good example of the displacement of an equilibrium by the removal of one
    or more of the products from the sphere of action, whereby a given reaction is
    enabled to become quantitative: the reduction of aluminium oxide cannot be

(^1) L. Gattermann, Ber. 22, 186; (1889) 27, 1943 (1894).