Sodium Tetrachloroaurate(III)

NaAuCl4.2H2O
(NaAuCl4.2H2O)

[13874-02-7]  · AuCl4H4NaO2  · Sodium Tetrachloroaurate(III)  · (MW 397.80) (NaAuCl4)

[15189-51-2]  · AuCl4Na  · Sodium Tetrachloroaurate(III)  · (MW 361.76) (KAuCl4)

[13682-61-6]  · AuCl4K  · Potassium Tetrachloroaurate(III)  · (MW 377.87) (HAuCl4)

[16903-35-8]  · AuCl4H  · Hydrogen Tetrachloroaurate(III)  · (MW 339.78)

(catalyst precursor for the hydrochlorination of acetylene,1 oxidation of sulfides,2 and the synthesis of isoxazoles3)

Physical Data: mp 100 °C (dec).

Solubility: sol water, alcohols; sparingly sol diethyl ether.

Form Supplied in: golden-yellow crystalline solid.

Preparative Method: prepared from HAuCl4 (which is formed when AuCl3 is dissolved in HCl or when Au is dissolved in aqua regia) and NaCl to give orange-yellow crystals.

Handling, Storage, and Precautions: air stable.

Hydrochlorination.

Addition of hydrogen chloride to acetylene to afford vinyl chloride (eq 1) is a well established industrial process, currently accounting for 6% of the total world production of this versatile monomer. Although the industrial process utilizes Mercury(II) Chloride as the catalyst source,4 recent work demonstrates that gold(III) catalysts can also be employed for this transformation.1 Catalysts comprised of HAuCl4 supported on activated carbon are particularly active.

Oxidation of Sulfides.

Sulfoxides are important intermediates in organic synthesis and recent work has focused on improving their method of preparation.5 While it is well known that gold(III) halides oxidize organic sulfides to sulfoxides and sulfones,6-8 early work was stoichiometric in gold. More recently, studies have shown that AuCl4- can be employed in catalytic amounts under phase-transfer conditions to affect this reaction (eq 2). Oxidation under these conditions takes place selectively at the sulfur atom even in the presence of other oxidizable moieties such as vinyl, tertiary amino, hydroxy, and diol groups.

Reactions with unsymmetric disulfides are completely regiospecific, affording monosulfoxides where the more reactive sulfur has been oxidized. Symmetric disulfides afford monosulfoxides upon oxidation in higher yields than those obtained using traditional oxidizing agents such as Bromine.6 The greater activity of the analogous tetrabromoaurate(III) catalyst is exemplified in the oxidation of hindered dialkyl sulfides and aryl alkyl sulfides, as well as diaryl sulfides, which are not readily oxidized under mild conditions using AuCl4-.7 In a related study, a number of gold complexes were found to catalyze the oxidation of carbon monoxide at low temperatures.8

Synthesis of Isoxazoles.

Terminal alkynes react with nitric acid under biphasic conditions and in the presence of a catalytic amount of TBA+AuCl4- to give 3,5-disubstituted isoxazoles (eq 3).3 There appears to be no limitations on the nature of the R group and yields of isolated products range from 35-50%. Poor results are obtained using different metal chloride catalysts, and a biphasic system of nitromethane/water seems to be unique in promoting this transformation.


1. (a) Nkosi, B.; Coville, N. J.; Hutchings, G. J.; Adams, M. D.; Friedl, J.; Wagner, F. E. J. Catal. 1991, 128, 366. (b) Nkosi, B.; Adams, M. D.; Coville, N. J.; Hutchings, G. J. J. Catal. 1991, 128, 378. (c) Nkosi, B.; Coville, N. J.; Hutchings, G. J. CC 1988, 71. (d) Nkosi, B.; Coville, N. J.; Hutchings, G. J. Appl. Catal. 1988, 43, 33.
2. (a) Gasparrini, F.; Giovannoli, M.; Misiti, D.; Natile, G.; Palmieri, G. T 1984, 40, 165. (b) Gasparrini, F.; Giovannoli, M.; Misiti, D.; Natile, G.; Palmieri, G. T 1983, 39, 3181.
3. Gasparrini, F.; Giovannoli, M.; Misiti, D.; Natile, G.; Palmieri, G.; Maresca, L. JACS 1993, 115, 4401.
4. Hutchings, G. J.; Grady, D. T. Appl. Catal. 1985, 17, 155, and references therein.
5. Ruff, F.; Kucsman, A. JCS(P2) 1988, 1123.
6. Drabowicz, J.; Midura, W.; Mikolajczyk, M. S 1979, 39.
7. Gasparrini, F.; Giovannoli, M.; Misiti, D.; Natile, G.; Palmieri, G. JOC 1990, 55, 1323.
8. Haruta, M.; Kobayashi, T.; Sano, H.; Yamada, N. CL 1987, 405.

Stephen A. Westcott

University of North Carolina, Chapel Hill, NC, USA



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