Chemical Properties
Colorless crystals, deliquescing in moist air. M.p. about 43°C.
A saturated aqueous solution (about 86% TlCl3 ? 4 H2O at 17°C)
is strongly acidic due to hydrolysis, and precipitates brown Tl2O3 .
xH2O when highly diluted. Readily soluble in alcohol and ether;
90-95% of the TlCl3 is extracted from a 6N HCl solution of TlCl3
by shaking with an equal volume of ether.
Synthesis
According to Meyer, TlCl ? 4H2O is prepared by passing Cl2
through a nearly boiling suspension of TlCl in a limited amount of
water. After intermediate Tl(I)-T1(III) chloro compounds have
dissolved, the solution is evaporated to a thin syrup with continuous addition of Cl2
. The water bath temperature should be 60-70°C. The syrup immediately solidifies to a slurry of fine,
white needles of TlCl ? 4 H2O on cooling in an ice bath, larger
crystals form on slower cooling. The crystals are rapidly filtered
and dried 24 hours over H2SO4 andKOH(virtually no efflorescence).
Cushman claims that TlC13 . 4 H2O crystals can only be dried between filter papers if loss of water is to be avoided. Hecht states
that he found no definite tetrahydrates.
TlCl + Cl2 + 4H2O = TlCl3 ? 4H2O
