Chloroplatinic Acid

Chloroplatinic acid or hexachloroplatinic acid is an inorganic compound with the formula [H3O]2[PtCl6](H2O)x. A red solid, it is an important commercial source of platinum, usually as an aqueous solution. Although often written in shorthand as H2PtCl6, it is the hydronium (H3O+) salt of the hexachloroplatinate anion.The compound is also available as the hexahydrate

Like many platinum compounds, chloroplatinic acid is used in catalysis. This compound was first reported by John Speier and colleagues from Dow Corning Corporation to catalyze the addition of silyl hydrides to olefins, hydrosilylation. Typical of his reactions, Speier used isopropanol solutions containing trichlorosilane (SiHCl3), and methyldichlorosilane (CH3HSiCl2), with pentenes. Prior work on the addition of silanes to alkenes required radical reactions that were inefficient.[9][10] It is generally agreed that chloroplatinic acid is a precursor to the actual catalyst. A possible role for colloidal platinum or zero-valent complexes has also been considered.
Potassium determination
Chloroplatinic acid was popularized for the determination of potassium. The potassium is selectively precipitated as potassium chloroplatinate. Determinations were done in 85% (v/v) alcohol solutions with excess platinate ions, and the precipitated product was weighed. Potassium could be detected for solutions as dilute as 0.02 to 0.2% (m/v).
This method for determination of potassium was advantageous vs. the sodium cobaltinitrite method used previously, since it required a single precipitation reaction.[citation needed] Today, the concentration of potassium is determined with an ion-selective electrode. These modern methods remain subject to interference.
Purification of platinum
See also: Ammonium hexachloroplatinate
Treatment with an ammonium salt, such as ammonium chloride, precipitates solid ammonium hexachloroplatinate,.Heating the ammonium salt in hydrogen reduces it to elemental platinum. Platinum is often isolated from ores or recycled from residues thus.