Chloroauric acid

For gold, by contrast, - -3 is the element s best-known oxidation state and Au is often compared with the isoelectronic Pt (p. 1161). The usual route to gold(III) chemistry is by dissolving the metal in aqua regia, or the compound AU2CI6 in cone HCl, after which evaporation yields yellow chloroauric acid, HAUCI4.4H2O, from which numerous salts of the square-planar ion [AuCLj]" can be obtained. 

Sun, Y. and Xia, Y. (2004) Mechanistic study on the replacement reaction between silver nanostructures and chloroauric acid in aqueous medium. Journal of the American Chemical Society, 126, 3892-3901. 

Add 375 pi of the chloroauric acid solution plus 500pi of 0.2M K2CO3 to 100ml deionized water, cooled on ice to 4°C. Mix well. 

Add five 1-ml aliquots of the sodium borohydride solution to the chloroauric acid/ carbonate suspension with rapid stirring. A color change from bluish-purple to reddish-orange will be noted as the additions take place. 

Add 4.16 ml of the diluted phosphorus solution to the chloroauric acid/carbonate solution with mixing. 

With rapid mixing of the chloroauric acid/carbonate solution, quickly add 1ml of a 7 percent sodium ascorbate solution prepared in water. Maintain the solution cooling in an ice bath. Higher temperatures will create larger particle sizes. The color of the solution at this point will turn to a purple-red. 

Add 0.5 ml of the chloroauric acid solution to 200 ml of deionized water and bring to a boil while mixing. 

Add to the boiling, rapidly mixing solution of chloroauric acid, 3 ml of a 1 percent sodium citrate solution. 

Chloroauric acid 1-g glass vial chloroauric acid and 10 mL deionized glass-distilled water (see Note 1). 

Add 0.3 mL of 1 M sodium thiocyanate, with stirring, to 50 mL of deionized glass-distilled water containing 0.5 mL 10% chloroauric acid and 0.75 mL of 0.2 M potassium carbonate. 

Formula HAuCh MW 339.81 exists as tetrahydrate, HAuCh 4H20 MW 411.85 Synonyms chloroauric acid aurochlorohydric acid hydrochloroauric acid gold trichloride acid hydrogen tetrachloroaurate(lll). 

S-Diazo-S-isopropyl-asymfl. dJ-triazole Chloroaurate, C5H7N5 + AuClj, yel flocculent ppc, stable at RT but exploding violently on heating. It was obtd by treating 3 amino-5 isopropyl-asym-triazole, CjH qN + HNOj, with a coned sola of chloroauric acid. 

Aminomesitytenebisdi ozonium Chloroaurate Hydrochloride. Diazotization of triaminomesitylene trihydrochloride, followed by treatment with a soln of chloroauric acid, gave two expls, CjHjjNjCIgAuj and C HiaN, ClaAua, both solid... 

From a coned soln of chloroauric acid and diazorized aminopropyltriazole, there was separated 3-dtazo-3-ri-propyl-l, 2,4-triazole ckloroaurate, [(Q HjNj AuCl,)2-HaO], which darkened on heating and melted at 135° (dec) and 5-diazo-3-isopropyl-1,2,4-triazole chloro-amate, [cs H7NS -AuClj], as a yel ppt, stable at RT but exploded violently on heating and decamp in wSTjjj c soln Refs l)Beil 26, [190] 2)J.Reilly P.J. 

White phosphorus reduction. White phosphorus, and indeed sodium or potassium thiocyanate, are fast reducers. Chloroauric acid is boiled under reflux with white phosphorus (6) dissolved in diethylether. Boiling is continued until the solution turns from a brownish shade to red—this usually takes about 5 mm. This method produces gold particles m the smaller size range (2-12 nm) Accurate production of the particle size range is not easy, and, since the procedure is potentially highly dangerous, it is not commonly used... 

Ascorbate reduction This method (7) entails the fairly rapid addition of sodium ascorbate to chloroauric acid while stirring. If the reaction is carried out on ice, the gold particle size range is between 6 and 8 nm. Higher temperatures tend to increase the particle size The method is also really of academic interest nowadays, since it is not easy to control the final sphere diameter. 

Citrate reduction. Chloroauric acid is boiled under reflux with sodium citrate (5) until the solution turns red. Particle sizes achieved are in the range of 15-150 nm, and a particular diameter is chosen for a batch by adjusting the amount of citrate added to the boiling flask. This method has been used, therefore, for producing probes in the larger particle size range. 

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