Bright gold

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Fulminating gold or chloride pop Gold ( latin Aurum Fulminans ) is a yellow to yellow-orange amorphous heterogeneous mixture of various polymeric compounds of mainly gold (III) oxide , gold (III) hydroxide or gold (III) chloride with aqueous ammonia solution or ammonium salts . The compound is highly explosive with the friction and impact sensitivity of an initial explosive . So far the compound could not be clearly described with a chemical formula.

history

Knallgold was first described by the German alchemist Basilius Valentinus and Sebalt Schwertzer in his 1585 work Chrysopoeia Schwaertzeriana . Schwertzer dissolved a gold sample in aqua regia , added saturated ammonium chloride solution , let the solution precipitate and finally dried it with tartar . Chemists of the 16th and 17th centuries were very interested in this explosive gold compound, and many were injured by detonations during their experiments. Jöns Jacob Berzelius , a leading chemist and contemporary of John Dalton , exploded in 1809 a beaker with a specimen of bright gold in his hand, seriously injuring his left hand and eyes. In the 18th century, Carl Wilhelm Scheele demonstrated that ammonia promoted the formation of the complex and that the gas produced during the detonation mainly contains nitrogen . Jean Baptiste Dumas found out that foul gold contained hydrogen and chlorine in addition to gold and nitrogen . After decomposing a ground sample with copper (II) oxide , he found out that it is a salt with an ammonium - cation was and a cold nitrogen complex as the cation. In 1886, Friedrich Raschig proved that Knallgold is not a homogeneous compound, but rather a mixture of several compounds. Ernst Weitz investigated the compound in the 1910s according to the state of the art and came to the conclusion that Knallgold is a mixture of "Diamidoiminidoaurichlorid" and 2Au (OH) 3 ⋅ 3NH 3 . His conclusions on the chemical formula turned out to be incorrect, but they offered starting points for the work of later scientists.

Extraction and presentation

Knallgold results from the reaction of gold (III) oxide, gold (III) hydroxide or gold (III) chloride with aqueous ammonia solution or ammonium salts. The compound has a direct gold-nitrogen bond. It has been described as a dirty olive-green powder when made from gold hydroxide and ammonia water, or as a yellow to black powder when made from gold oxide and concentrated ammonia. The composition has been described by the formula AuNNH 3 · 1.5 H 2 O or as gold hydrazide . The composition Au 2 O 3 · 4NH 3 has also been reported. When it is burned, it produces a crimson smoke. When gold catalysts are manufactured by impregnation with ammonia, the explosive decay of these catalysts has been reported. Due to the immense interest in the study of gold in the history of chemistry, many processes have been developed to synthesize fused gold, but not all synthetic routes lead to the same end product.

According to Ernst Weitz and Steinhauser et al. very homogeneous samples can be produced by hydrolysis of [Au (NH 3 ) 4 ] (NO 3 ) 3 with Cl - . Different synthetic routes and the use of different amounts of ammonia in the precipitation of the samples lead to different end results due to the changing ratios of Au, N, H and Cl. Due to its physical and chemical properties, fatal gold cannot crystallize under normal methods , which makes determining the crystal structure a problem. After extensive crystallization attempts by Steinhauser et al. and vibrational spectroscopic investigations concluded that Knallgold is an amorphous mixture of polymeric compounds that are linked by μ-NH 2 and μ 3 -NH bridges. They also demonstrated that fiery gold is only sparingly soluble in acetonitrile and dimethylformamide . The latest EXAFS analyzes by Joannis Psilitelis showed that Knallgold has a square-planar tetraammine-gold (III) cation with four or one gold atom in the second coordination sphere. This geometry is supported by the diamagnetic character of the fancy gold. Since it has ad 8 electron configuration and is diamagnetic, it must have a square planar geometry.

Physical Properties

Flash gold is only sparingly soluble in most solvents, whereas it is well soluble in aqueous gold (III), ammonia and chloride systems.

use

Due to its high explosiveness , the friction and impact sensitivity and the resulting problematic handling, Knallgold has not yet found any technical application worth mentioning. Practical applications are mainly limited to the laboratory scale. In the 17th century, Johann Rudolf Glauber used the purple-red vapors produced by the detonations to vaporize objects with gold . An anonymous author from 1847 provides another recipe for matt gold-plating of objects without prior copper-plating of the background using fused gold. Because of its light-sensitive properties it was occasionally used in photography. It is noteworthy, however, that fused gold was one of the earliest initial explosives , long before more usable substances were developed and used, but here, too, the extremely problematic nature of the compound prevented its practical use as an explosive . There are well-functioning processes for the extraction of precious metals from electronic scrap using biogas , but the formation of fatal gold and other precious metal amines is currently preventing these processes from spreading further. Furthermore, a patent has been applied for a process for the extraction of high-purity gold for electronics from gold with low purity, in which fused gold is created as an intermediate product.

safety instructions

Knallgold is extremely reactive and it should be avoided that this substance is created even inadvertently by mixing gold chloride or hydroxide salts with ammonia or ammonium salts, as it is explosive even with the slightest contact. Precipitates of molten gold should not come into contact with water or ammonia solution. Gold (III) complexes with ammonia formed unintentionally should not be dried completely and dry substances should be protected from friction and impact. Safe disposal can be achieved by diluting with hydrochloric acid .

literature

  • Georg Steinhauser, Jürgen Evers, Stefanie Jakob, Thomas M. Klapötke, Gilbert Oehlinger: A review on fulminating gold (Knallgold) . In: Gold Bulletin . No. 41 , 2008, ISSN  2364-821X , p. 305-317 , doi : 10.1007 / BF03214888 (English, PDF ).

Web links

Individual evidence

  1. ↑ J. Dumas: Investigations on the fiery gold . In: Annals of Physics and Chemistry . No. 95 , 1830, pp. 493 , doi : 10.1002 / andp.18300950805 .
  2. ↑ a b c d e f g h Georg Steinhauser, Jürgen Evers, Stefanie Jakob, Thomas M. Klapötke, Gilbert Oehlinger: A review on fulminating gold (Knallgold) . In: Gold Bulletin . No. 41 , 2008, ISSN  2364-821X , p. 305-317 , doi : 10.1007 / BF03214888 (English, PDF ).
  3. ↑ Sebald Schwärtzer : Philosophy to prepare the Aurum Fulminans / and how to bring the same to the highest purification . In: Chrysopoeia Schwaertzeriana. This is: Sebaldi Schwaertzers, former famous Churfürstl. Saxon artists and real adepts, Manuscripta, From the True Preparation of the Philosophical Stone: How it was designed with his own hand before this, and by the Chur Prince. Saxon house has been kept in safekeeping in original form, along with the right key belonging to such manuscripts; Also different outlines of the useful stove, from an unadulterated copia, obtained through much effort and expense, now more than ever before everyone's eyes, and augmented with some useful appendices by various curious processes . Heil, Hamburg 1718, p. 84-86 ( 960223 Alch. 253 960223 Alch. 254 [accessed October 31, 2017] 1817 edition).
  4. ^ Geoffrey C. Bond: Catalysis by Gold . In: Imperial College Press . 2006, ISBN 1-86094-658-5 , pp. 76-77 (English).
  5. ↑ Joannis Psilitelis: Synthesis and crystal structure of new gold compounds. In: Dissertation, University Library Tübingen. 1999, pp. 43–44 , accessed April 25, 2018 .
  6. ↑ The galvanic gold plating according to the method of the HHrn. Christofle et al. Comp. in Paris. In: Polytechnisches Journal . 106, 1847, pp. 389-391.
  7. ↑ Patent US730800 : Published on 1903 , inventor: PE Schoenfelder. ‌
  8. ↑ LE Macaskie, NJ Creamer, AMM Essa, NL Brown: A New Approach for the Recovery of Precious Metals from Solution and From Leachates Derived from Electronic Scrap . In: Biotechnology and Bioengineering . tape 96 , no. 4 , 2007, ISSN  0006-3592 , p. 631-639 (English).
  9. ↑ Patent KR2009031006 : Method for manufacturing high-purity gold with low-purity gold. Posted on 2009 , Inventors: T. Tom, MJ Kim, BH Jung, NP Kook, IY Park, JU Ahn. ‌