Tetrachloroaurate

Pal, B., Sen, P.K. and Sen Gupta, K.K. (2001) Reactivity of alkanols and aryl alcohols towards tetrachloroaurate(lll) in sodium acetate-acetic acid buffer medium. Journal of Physical Organic Chemistry, 14, 284. 

The results indicated that the reaction time of 1 h was insufficient for the total reduction of gold. Figure 3 shows the Fourier transformed EXAFS of both a bulk gold(O) sample and nanoparticles produced by the reduction of tetrachloroaurate by oat biomass. 

Figure 2. Representative XANES of gold nanoparticles from an oat sample reacted with tetrachloroaurate for 24 h and a bulk gold sample recorded from a 1 pm gold film.

These results corroborated that alfalfa absorbed the Au(0) from the medium and translocated it through the vascular system. The EXAFS results (Figure 5, Table 3) showed that the Au atoms in plant samples had longer distances that the Au atoms in the tetrachloroaurate, but had equivalent distance to the Au atoms in the gold foil, which confirmed that the Au in plant samples was Au(0). 

Figure 4. XANES spectra of the tetrachloroaurate compound, the Au foil [Au(0)], and the Au in the agar and plant samples. (Reprinted from Ref. [28], 2002, with permission from American Chemical Society.)...

In another study, it was shown that the activity of hydrochlorination catalysts made by impregnation of activated carbon with tetrachloroaureate is due to the adsorption of [AuCy anions on the activated carbon [423]. Similar studies, dealing with the adsorption of aurocyanide, [Au(CN)2] , onto activated carbon, have revealed that aurocyanide does not convert to metallic gold up to temperature of about 240°C [424, 425]... 

Holt KB, Sabin G, Compton RG et al (2002) Reduction of tetrachloroaureate(III) at boron-doped diamond electrodes gold deposition versus gold colloid formation. Electroanalysis 14 797-803... 

Harada M, Asakura K, Toshima N (1993) Catalytic activity and structural analysis of polymer-protected gold/palladium bimetallic clusters prepared by the successive reduction of hydrogen tetrachloroaurate(ffl) and palladium dichloride. J Phys Chem 97 5103-5114... 

Fig. 1.12 (A) Increase in surface plasmon ab- and from mixtures with lower chitosan concen-sorptionasAu nanoparticles are produced from a tration (ii) or lower HAuCI4 amount (iii) six reaction mixture containing 1 % chitosan, 1 % different self-sustained nanocomposite films acetic acid and 0.01 % tetrachloroauric (III) acid showing the control over the optical properties. (HAuCU) (B) shiftofsurface plasmon absorption Reprinted with permission from [164], 2004, for films prepared from the previous mixture (i), American Chemical Society.

Very interesting transformations were reported in terminal alkynes RC=CH (R = alkyl, aryl, alkoxy, carboxylate, etc.). They react readily with nitric acid, in aqueous nitromethane (1 1) and in the presence of catalytic amounts of tetra-butylammonium tetrachloroaurate to give 3,5-disubstituted isoxazoles 15 in 35% to 50% isolable yield (92). The reaction might proceed via a nitrile oxide intermediate by attack of an electrophile (AuCh or H+) and of a nucleophile (N02 ) on the triple bond to form a vinyl nitrite, which is converted to a nitrile oxide by the action of gold(III) or of nitric acid (Scheme 1.8). 

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