Chloroauric Acid

Chloroauric acid

CAS No.:16903-35-8 is the inorganic compound with the formula HAuCl4. It is an orange-yellow solid, a common precursor to other gold compounds and an intermediate in the purification of gold metal. Commercial samples have the composition HAuCl4.n H2O with n = 3 or 4.

Chloroauric acid Application:  

Chloroauric acid is the precursor used in the purification of gold by electrolysis.

Liquid–liquid extraction of chloroauric acid is used for the recovery, concentrating, purification, and analytical determinations of gold. Of great importance is the extraction of HAuCl4 from hydrochloric medium by oxygen-containing extractants, such as alcohols, ketones, ethers and esters. The concentration of gold(III) in the extracts may exceed 1 mol/L. The most frequently used extractants for this purpose are dibutyl glycol, methyl isobutyl ketone, tributyl phosphate, dichlorodiethyl ether (chlorex).

In histology, chlorauric acid is known as “brown gold chloride”, and its sodium salt NaAuCl4 as “gold chloride”, “sodium gold chloride” or “yellow gold chloride”. The sodium salt is used in a process called “toning” to improve the optical definition of tissue sections stained with silver.